ORCID Profile
0000-0003-0462-0277
Current Organisations
University of Adelaide
,
University of Wollongong
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Organic Chemistry | Biological And Medical Chemistry | Organic Chemical Synthesis | Medicinal and Biomolecular Chemistry | Organic Chemical Synthesis | Nanochemistry and Supramolecular Chemistry | Physical Chemistry (Incl. Structural) | Organometallic Chemistry | Natural Products Chemistry | Structural Chemistry | Bioinorganic Chemistry | Analytical Spectrometry | Biochemistry and Cell Biology | Biomaterials | Biologically Active Molecules | Characterisation Of Macromolecules | Electrochemistry | Physical Chemistry Of Macromolecules | Biochemistry and Cell Biology not elsewhere classified | Medical Biochemistry and Metabolomics not elsewhere classified | Biophysics | Data Storage Representations | Biological Sciences Not Elsewhere Classified | Cell Neurochemistry
ANZSRC Socio-Economic Objective (SEO)
Chemical sciences | Treatments (e.g. chemicals, antibiotics) | Expanding Knowledge in the Chemical Sciences | Crop and animal protection chemicals | Biological sciences | Treatments (e.g. chemicals, antibiotics) | Energy storage | Solar-photoelectric | Infectious diseases | Medical instrumentation | Earth sciences | Other | Expanding Knowledge in the Medical and Health Sciences | Human Pharmaceutical Treatments (e.g. Antibiotics) | Expanding Knowledge in the Biological Sciences | Global climate change adaptation measures |
Related Links
Publications
Alkaloids from the Roots of Stemona aphylla
Publisher: American Chemical Society (ACS)
Date: 17-04-2009
DOI: 10.1021/NP900030Y
Abstract: Three known compounds, stemofoline (1), (2'S)-hydroxystemofoline (2), and (11Z)-1',2'-didehydrostemofoline (3), along with two new alkaloids, stemaphylline (4) and stemaphylline-N-oxide (5), have been isolated from a root extract of Stemona aphylla. The structures of these alkaloids were determined on the basis of their spectroscopic data. The analysis of the crude dichloromethane extract by GC-MS in the EIMS mode showed the presence of alkaloids 1-4, the alkaloid 11, and stilbostemin R (12). The crude dichloromethane extract and 4 were tested for their comparative biological activities. The results of their acetylcholinesterase (AChE) inhibitory activities showed that the crude extract had higher activity than that of 4. The insecticidal properties of the crude extract and 4, using a topical application, showed that 4 had an activity similar to the positive control, methomyl, whereas the crude extract had much lower activity. Their antimicrobial activity against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas auruginosa ATCC 27853, and Candida albicans ATCC 90028 was weak (MIC 62.5-125 microg/mL, MBC 125-250 microg/mL, MFC 125 microg/mL) but much higher than that of the crude extract.
A structure-based design approach to advance the allyltyrosine-based series of HIV integrase inhibitors
Publisher: Elsevier BV
Date: 03-2018
Cationic biaryl 1,2,3-triazolyl peptidomimetic amphiphiles targeting Clostridioides (Clostridium) difficile: Synthesis, antibacterial evaluation and an in vivo C. difficile infection model
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.EJMECH.2019.02.068
Abstract: Clostridioides (formerly Clostridium) difficile is a Gram-positive anaerobic bacterial pathogen that causes severe gastrointestinal infection in humans. The current chemotherapeutic options are vastly inadequate, expensive and limited this results in an exorbitant medical and financial burden. New, inexpensive chemotherapeutic treatments for C. difficile infection with improved efficacy are urgently needed. A streamlined synthetic pathway was developed to allow access to 38 novel mono- and di-cationic biaryl 1,2,3-triazolyl peptidomimetics with increased synthetic efficiency, aqueous solubility and enhanced antibacterial efficacy. The monocationic arginine derivative 28 was identified as a potent, Gram-positive selective antibacterial with MIC values of 4 μg/mL against methicillin-resistant Staphylococcus aureus and 8 μg/mL against C. difficile. Furthermore, the dicationic bis-triazole analogue 50 was found to exhibit broad-spectrum activity with substantial Gram-negative efficacy against Acinetobacter baumannii (8 μg/mL), Pseudomonas aeruginosa (8 μg/mL) and Klebsiella pneumoniae (16 μg/mL) additionally, compound 50 displayed reduced haemolytic activity (<13%) in an in vitro haemolysis assay. Membrane-disruption assays were conducted on selected derivatives to confirm the membrane-active mechanism of action inherent to the synthesized hiphilic compounds. A comparative solubility assay was developed and utilized to optimize the aqueous solubility of the compounds for in vivo studies. The biaryl peptidomimetics 28 and 67 were found to exhibit significant efficacy in an in vivo murine model of C. difficile infection by reducing the severity and slowing the onset of disease.
Semisynthesis and Biological Activity of Stemofoline Alkaloids
Publisher: American Chemical Society (ACS)
Date: 17-02-2009
DOI: 10.1021/NP800806B
Abstract: The semisynthesis of the Stemona alkaloids (3'R)-stemofolenol (1), (3'S)-stemofolenol (2), methylstemofoline (3), and (3'S)-hydroxystemofoline (5) and the unnatural analogues (11E)-methylstemofoline (15) and 3'R-hydroxystemofoline (11) has been achieved starting from (11Z)-1',2'-didehydrostemofoline (4). This synthesis allowed, for the first time, access to diastereomerically enriched s les of 1 and 2 and the assignment of their absolute configurations at C-3'. These compounds were obtained in sufficient quantities to allow for their biological testing. In a quantitative assay as AChE inhibitors, (11Z)-1',2'-didehydrostemofoline (4) and (3'S)-hydroxystemofoline (5) were found to be the most active.
The structure, biological activities and synthesis of 3-hydroxylpyrrolizidine alkaloids and related compounds
Publisher: Bentham Science Publishers Ltd.
Date: 09-2005
Correction to Corrected Structure of Natural Hyacinthacine C1 via Total Synthesis
Publisher: American Chemical Society (ACS)
Date: 21-04-2020
Total Synthesis of Natural Hyacinthacine C5 and Six Related Hyacinthacine C5 Epimers
Publisher: American Chemical Society (ACS)
Date: 27-04-2018
Abstract: The total synthesis of natural (+)-hyacinthacine C
Positional Isomers of Biphenyl Antimicrobial Peptidomimetic Amphiphiles
Publisher: American Chemical Society (ACS)
Date: 03-02-2021
Reactions of iminoglycines with C60 fullerene and their unambiguous characterisation using NMR spectroscopy
Publisher: Elsevier BV
Date: 07-2006
A Pharmacological Strategy Using Stemofoline for more Efficacious Chemotherapeutic Treatments Against Human Multidrug Resistant Leukemic Cells
Publisher: EpiSmart Science Vector Ltd
Date: 12-2018
Isolation, biological activities, and synthesis of the natural casuarines
Publisher: Elsevier
Date: 2012
Corrigendum to In vitro cytotoxicity evaluation of some substituted isatin derivatives [Bioorg. Med. Chem. 15 (2007) 931-938] (DOI:10.1016/j.bmc.2006.10.035)
Publisher: Elsevier BV
Date: 06-2007
Hybrid flavan–flavanones from Friesodielsia desmoides and their inhibitory activities against nitric oxide production
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7RA02528A
Abstract: The first phytochemical investigation of Friesodielsia desmoides leaves and twigs led to the isolation and identification of three new hybrid flavan–flavanones, friesodielsones A–C ( 1–3 ), together with 18 known compounds ( 4–21 ).
Fullerene Van der Waals Oligomers as Electron Traps
Publisher: American Chemical Society (ACS)
Date: 24-07-2014
DOI: 10.1021/JA505949M
Abstract: Density functional theory calculations indicate that van der Waals fullerene dimers and larger oligomers can form interstitial electron traps in which the electrons are even more strongly bound than in isolated fullerene radical anions. The fullerenes behave like "super atoms", and the interstitial electron traps represent one-electron intermolecular σ-bonds. Spectroelectrochemical measurements on a bis-fullerene-substituted peptide provide experimental support. The proposed deep electron traps are relevant for all organic electronics applications in which non-covalently linked fullerenes in van der Waals contact with one another serve as n-type semiconductors.
A new xanthone and a biphenyl from the flower and twig extracts of Garcinia mckeaniana
Publisher: Informa UK Limited
Date: 16-12-2021
DOI: 10.1080/14786419.2019.1700505
Abstract: The phytochemical investigation of the flower and twig extracts of
An Investigation into the Cytotoxicity and Mode of Action of Some Novel N-Alkyl-Substituted Isatins
Publisher: American Chemical Society (ACS)
Date: 21-09-2007
DOI: 10.1021/JM0704189
Abstract: A range of substituted N-alkylisatins were synthesized and their cytotoxicity evaluated against several cancer cell lines in vitro. SAR studies indicated that the introduction of an aromatic ring with a one or three carbon atom linker at N1 enhanced the activity from that of the allyl, 2'-methoxyethyl, and 3'-methylbutyl N-substituted isatins. Furthermore, electron-withdrawing groups substituted at the meta or para position of the ring were favored over the ortho orientation. Of the 24 compounds screened, nine displayed sub-micromolar IC50 values and in general demonstrated greater selectivity toward leukemia and lymphoma cell lines over any of the carcinoma cell lines tested. 5,7-Dibromo-N-(p-methylbenzyl)isatin (6) was the most active compound, inhibiting the metabolic activity of both U937 and Jurkat cancer cell lines at 0.49 muM. Various N-alkylisatins were also found to dramatically alter lymphocyte morphology, destabilize microtubules, inhibit tubulin polymerization, induce G2/M cell cycle arrest, and activate the effector caspase-3 and -7.
Binaphthyl-anchored antibacterial tripeptide derivatives with hydrophobic C-terminal amino acid variations
Publisher: Beilstein Institut
Date: 09-08-2012
DOI: 10.3762/BJOC.8.142
Abstract: The facile synthesis of seven new dicationic tripeptide benzyl ester derivatives, with hydrophobic group variations in the C-terminal amino acid component, is described. Moderate to good activity was seen against Gram-positive bacteria in vitro. One cyclohexyl-substituted compound 2c was tested more widely and showed good potency (MIC values ranging from 2–4 μg/mL) against antibiotic-resistant strains of Staphylococcus aureus and Enterococci (VRE, VSE), and against Staphylococcus epidermidis .
Meet our editorial board member
Publisher: Bentham Science Publishers Ltd.
Date: 21-10-2015
Synthetic and spectroscopic studies on the structures of uniflorines A and B: structural revision to 1,2,6,7-tetrahydroxy-3-hydroxymethylpyrrolizidine alkaloids
Publisher: Elsevier BV
Date: 05-2008
Acetylcholinesterase inhibitory activity of chemical constituents isolated from Miliusa thorelii
Publisher: Elsevier BV
Date: 02-2018
Synthesis of spirocyclic azacycles from the cyclization of furan tethered N-acyliminium ions
Publisher: Elsevier BV
Date: 2012
Synthesis and antibacterial activity of some binaphthyl-supported macrocycles containing a cationic amino acid
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.BMC.2011.04.013
Abstract: As part of a programme investigating antibacterial cyclic macrocycles containing a cationic amino acid with an internal aromatic hydrophobic scaffold, we previously reported a macrocycle anchored at the 3,3'-positions of a 1,1'-binaphthyl unit. This was prepared via key intermediates containing an internal allylglycine and an allyl-substituted binaphthyl unit for a subsequent ring-closing metathesis reaction. This paper presents some structure-activity relationship studies with additional macrocycles based on this lead compound against Staphylococcus aureus together with the antibacterial activity of two related acyclic compounds.
Evaluation of an ethnopharmacologically selected Bhutanese medicinal plants for their major classes of Phytochemicals and biological activities
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.JEP.2011.06.032
Abstract: As many as 229 medicinal plants have been currently used in the Bhutanese Traditional Medicine (BTM) as a chief ingredient of polyherbal formulations and these plants have been in idually indicated for treating various types of infections including malaria, tumor, and microbial. We have focused our study only on seven species of these plants. We aim to evaluate the antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities of the seven medicinal plants of Bhutan selected using an ethno-directed bio-rational approach. This study creates a scientific basis for their use in the BTM and gives foundation for further phytochemical and biological evaluations which can result in the discovery of new drug lead compounds. A three stage process was conducted which consisted of: (1) an assessment of a pharmacopoeia and a formulary book of the BTM for their mode of plant uses (2) selecting 25 anti-infective medicinal plants based on the five established criteria, collecting them, and screening for their major classes of phytochemicals using appropriate test protocols and (3) finally analyzing the crude extracts of the seven medicinal plants, using the standard test protocols, for their antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities as directed by the ethnopharmacological uses of each plant. Out of 25 medicinal plants screened for their major classes of phytochemicals, the majority contained tannins, alkaloids and flavonoids. Out of the seven plant species investigated for their biological activities, all seven of them exhibited mild antimicrobial properties, five plants gave significant in vitro antiplasmodial activities, two plants gave moderate anti-Trypanosoma brucei rhodesiense activity, and one plant showed mild cytotoxicity. Meconopsis simplicifolia showed the highest antiplasmodial activity with IC(50) values of 0.40 μg/ml against TM4/8.2 strain (a wild type chloroquine and antifolate sensitive strain) and 6.39 μg/ml against K1CB1 (multidrug resistant strain) strain. Significantly the extracts from this plant did not show any cytotoxicity. These findings provide the scientific basis for the use of seven medicinal plants in the BTM for the treatment of malaria, microbial infections, infectious fevers, and the Trypanosoma brucei rhodesiense infection. The results also form a good preliminary basis for the prioritization of candidate plant species for further in-depth phytochemical and pharmacological investigations toward our quest to unearth lead antiparasitic, anticancer and antimicrobial compounds.
Synthesis of some cyclic indolic peptoids as potential antibacterials
Publisher: Elsevier BV
Date: 10-2006
Regioselective and diastereoselective borono-mannich reactions with pinacol allenylboronate
Publisher: American Chemical Society (ACS)
Date: 05-02-2015
DOI: 10.1021/OL503424K
Abstract: The first documented study of the borono-Mannich (Petasis) reactions of pinacol allenylboronate is described. The reactions of salicylaldehyde and primary and secondary amines are highly regioselective and give homopropargylamine and α-allenylamine products, respectively. In contrast, glycoaldehyde and chiral α-hydroxyaldehydes give exclusively anti-β-amino-β-allenyl alcohol products, irrespective of the nature of the amine component. These reactions are highly regio- and diastereoselective and can be employed using an enantiomerically enriched α-hydroxyaldehyde without detectable racemization.
Total synthesis of uniflorine A, casuarine, australine, 3-epi-australine, and 3,7-di-epi-australine from a common precursor
Publisher: American Chemical Society (ACS)
Date: 22-12-2010
DOI: 10.1021/JO902355P
Abstract: A flexible method for the diastereoselective total synthesis of the pyrrolizidine alkaloids uniflorine A, casuarine, australine, and 3-epi-australine and the unnatural epimer 3,7-di-epi-australine from a common chiral 2,5-dihydropyrrole precursor is described.
Selective targeting of 2′-deoxy-5-fluorouridine to urokinase positive malignant cells in vitro
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.BMCL.2010.03.029
Abstract: A urokinase targeting conjugate of 2'-deoxy-5-fluorouridine (5-FUdr) was synthesized and tested for tumor-cell selective cytotoxicity in vitro. The 5-FUdr prodrug 2'-deoxy-5-fluoro-3'-O-(3-carboxypropanoyl)uridine (5-FUdrsuccOH) containing an ester-labile succinate linker was attached to the specific urokinase inhibitor plasminogen activator inhibitor type II (PAI-2) and was found to preferentially kill urokinase-over expressing cancer cells. Up to 7 molecules of 5-FUdr were incorporated per PAI-2 molecule without affecting protein activity. This is the first time a small organic cytotoxin has been conjugated to PAI-2.
Synthesis and Structural Revision of Glyphaeaside C
Publisher: American Chemical Society (ACS)
Date: 30-04-2021
Palladium-Catalyzed Formal (3 + 2) Cycloaddition Reactions of 2-Nitro-1,3-enynes with Vinylaziridines, -epoxides, and -cyclopropanes
Publisher: American Chemical Society (ACS)
Date: 03-06-2021
The Roots of Neorautanenia mitis (A. Rich) Verdcourt: Further Evidence of Its Antidiarrhoeal Activity
Publisher: MDPI AG
Date: 09-01-2023
DOI: 10.3390/MOLECULES28020673
Abstract: Despite the current management options and therapeutics used in the treatment of diarrhoea, in Africa and Asia, diarrhoea remains a major concern, especially in children under the age of 5 years. Traditional knowledge of medicinal plants used in the management of diarrhoea symptoms can be explored for their efficacy. In Nigeria, the TMPs (Traditional Medicine Practitioners) have, over the years, employed medicinal plants in the management of diarrhoea symptoms. In our current and previous studies, we aimed at validating the effectiveness of Neorautanenia mitis in the management of diarrhoea as claimed by the TMPs. Out of the 20 compounds isolated from N. mitis, the compounds neodulin, pachyrrhizine, neotenone and dolineone were the most abundant, and in this study, neodulin showed a pronounced relaxation of the rhythmic contraction of the isolated rabbit jejunum in an organ bath in a concentration-dependent manner, with a complete relaxation at 60 µg/mL. Neotenone and dolineone showed a dose-dependent inhibition of defecation of 65.07%, and 50.01%, respectively, at 20 mg/kg in a castor-oil-induced diarrhoea model. This is a strong indication that compounds from N. mitis possess antidiarrhoeal properties, thereby giving credence to its traditional usage in diarrhoea therapy, and therefore validating its antidiarrhoeal activity and its being worthy of further investigation.
Chemical diversity and anti-acne inducing bacterial potentials of essential oils from selected Elsholtzia species
Publisher: Informa UK Limited
Date: 26-10-2017
DOI: 10.1080/14786419.2017.1395436
Abstract: Essential oils from the aerial parts of four Elsholtzia species Elsholtzia stachyodes, Elsholtzia communis, Elsholtzia griffithii and Elsholtzia beddomei were obtained by steam distillation and their chemical components were analysed by gas chromatography-mass spectrometry (GC-MS). Principle Component Analysis was used to identify the chemical variations in the essential oils from these plants, which could be categorised into two groups according to their main chemical components which are acylfuran derivatives and oxygenated monoterpenes. Additionally, the anti-acne inducing bacterial activity against Staphylococcus aureus and Staphylococcus epidermidis were evaluated. The oil from E. stachyodes was the most efficacious against the growth of S. aureus and S. epidermidis having MIC values of 0.78 and 1.56 μL/mL, respectively, and exhibited five times more effective than erythromycin (standard antibiotic).
Phytochemical Studies on Stemona Plants: Isolation of Stemofoline Alkaloids
Publisher: American Chemical Society (ACS)
Date: 12-11-2005
DOI: 10.1021/NP050361Y
Abstract: Six new stemofoline alkaloids, (2'R)-hydroxystemofoline (5), (3'R)-stemofolenol (6), (3'S)-stemofolenol (7), 1',2'-didehydrostemofoline-N-oxide (8), the first C(19) stemofoline alkaloid, methylstemofoline (9), and the first glycosidated Stemona alkaloid, stemofolinoside (10), and three known alkaloids, (2'S)-hydroxystemofoline (2), (11Z)-1',2'-didehydrostemofoline (3), and (11E)-1',2'-didehydrostemofoline (4), have been isolated from a root extract of an unidentified Stemona species. The structure and relative configuration of these new alkaloids have been determined by spectral data interpretation and from semisynthetic studies.
Synthesis of 2-acetyl-5-(1,2,3,4,5,6-hexahydroxyhexyl)thiazoles
Publisher: Springer Science and Business Media LLC
Date: 17-02-2011
Phytochemical Investigations of Stemona curtisii and Synthetic Studies on Stemocurtisine Alkaloids
Publisher: American Chemical Society (ACS)
Date: 04-11-2010
DOI: 10.1021/NP100474Y
Abstract: The isolation of two new Stemona alkaloids, 1-hydroxyprotostemonine and stemocurtisine N-oxide, and a new benzofuran, stemofuran L, from the root extracts of Stemona curtisii is reported. The major known alkaloids from this plant extract, stemocurtisine, stemocurtisinol, and oxyprotostemonine, were also isolated along with oxystemokerrine N-oxide. The nonalkaloid components of this extract included a new benzofuran derivative, stemofuran L, the known stemofurans F, J, and K, dihydro-γ-tocopherol, and stigmasterol. Stemocurtisine and stemocurtisinol were converted to their respective N-oxides by oxidation. Stemocurtisine was converted to a tetracyclic derivative by oxidative cleavage of the γ-butyrolactone ring, while stemocurtisinol gave a novel lactam derivative by oxidative cleavage of the C-4 side chain under basic conditions. The acetylcholinesterase inhibitory activities of some known and new alkaloids and their derivatives are also reported. All were 10-20 times less active as acetylcholinesterase inhibitors than the pyrrolo[1,2-a]azepine Stemona alkaloids stemofoline and 1',2'-didehydrostemofoline. None of the stemofuran compounds showed significant antibacterial or antifungal activities.
Synthesis and antibacterial studies of binaphthyl-based tripeptoids. Part 1
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.BMC.2010.02.033
Abstract: An efficient synthesis of 29 new binaphthyl-based neutral, and mono- and di-cationic, peptoids is described. Some of these compounds had antibacterial activities with MIC values of 1.9-3.9microg/mL against Staphylococcus aureus. One peptoid had a MIC value of 6microg/mL against a methicillin-resistant strain of S. aureus (MRSA) and a MIC value of 2microg/mL against vancomycin-resistant strains of enterococci (VRE).
A Mild and General Method for the Synthesis of 5-Substituted and 5,5-Disubstituted Fulleroprolines
Publisher: American Chemical Society (ACS)
Date: 21-02-2008
DOI: 10.1021/OL8002157
Abstract: The reductive ring-opening of fullerenyldihydropyrrole yields ethyl N-benzhydryl fullerenyl[60]glycinate, which is deprotected to give ethyl fullerenylglycinate. The free amine is able to react with a variety of aldehydes and ketones in a Mannich-type process to produce 5-substituted and 5,5-disubstituted fulleroprolines and represents a versatile and general strategy to this class of compounds.
Binaphthyl scaffolded peptoids via ring-closing metathesis reactions and their anti-bacterial activities
Publisher: Elsevier BV
Date: 06-2009
DOI: 10.1016/J.BMCL.2009.04.046
Abstract: An efficient synthesis of four new acyclic and four new cyclic binaphthyl-based cationic peptoids is described. These compounds had anti-bacterial activities with MIC values of 4-62 microg/mL against Staphylococcus aureus.
Oxidation of acyclic alkenes and allyl and benzyl ethers with DIB/t-BuOOH/Mg(OAc)2
Publisher: Elsevier BV
Date: 2012
A benchmark study for glacial isostatic adjustment codes
Publisher: Oxford University Press (OUP)
Date: 21-02-2011
Production and antifungal activity of cordytropolone and (-)-leptosphaerone A from the fungus Polycephalomyces nipponicus
Publisher: SAGE Publications
Date: 05-2019
Abstract: Cordytropolone (1) and (−)-leptosphaerone A (2) were isolated from the culture broth of the fungus Polycephalomyces nipponicus. The structures of these two compounds were elucidated by spectroscopic methods and from a comparison of the spectroscopic data with those reported previously. The structure of 1 was confirmed by X-ray crystallography for the first time while the leptosphaerone class (compound 2) was first isolated as its (+)-antipode from the fungus Polycephalomyces ( Cordyceps). The fermentation process was monitored weekly by High performance liquid chromatography analysis for 10 weeks. The predominant compound (1) was produced at ~0.65 mg/mg of dry extract at week 9. Compound 1 exhibited modest antipathogenic fungal activity against Collectrichum musae, Colletotrichum capsici, Colletotrichum gloeosporioides, Fusarium spp. TFPK301, F. spp. FOC1708, and Pestalotia spp. with percentage of mycelial growth inhibition values of 3.74 ± 0.70%, 12.86 ± 1.43%, 0.91 ± 0.56%, 5.46 ± 0.56%, 7.93 ± 0.61%, and 18.75 ± 5.24%, respectively, at 25 μg/mL.
Synthesis of hyacinthacine B3 and purported hyacinthacine B 7
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B918233K
Abstract: The synthesis of hyacinthacines B(3) and B(7) has confirmed the structure of the former alkaloid and shown that the structure of the latter is incorrect.
A concise synthesis of furo[3,2-c]coumarins catalyzed by nanocrystalline ZnZr4 (PO4 )6 ceramics under microwave irradiation
Publisher: Springer Science and Business Media LLC
Date: 20-04-2016
Diastereoselective Petasis‐Borono‐Mannich Crotylation Reactions of Chiral α‐Heteroatom (F, OBz, OH) Aldehydes: Rapid Access to Valuable Mono and Bicyclic Heterocyclic Scaffolds
Publisher: Wiley
Date: 17-08-2023
Abstract: The crotylation reactions of chiral α‐F, α‐OBz and α‐OH aldehydes under Petasis‐borono‐Mannich conditions using ( E )‐ or ( Z )‐crotylboronates and primary amines resulted in γ‐addition products in high dr and high er. α‐F and α‐OBz aldehydes gave 1,2‐ anti ‐2,3‐ syn and 1,2‐ anti ‐2,3‐ anti , products, respectively while an α‐OH aldehyde gave 1,2‐ syn ‐2,3‐ syn products. The stereochemical outcomes of reactions of the former aldehydes can be explained using a six‐membered ring transition state (TS) model in which a Cornforth‐like conformation around the imine intermediate is favoured resulting in 1,2‐ anti products. The 2,3‐stereochemical outcome is dependent upon the geometry of the crotylboronate. These TS models were also supported by DFT calculations. The stereochemical outcomes of reactions employing an α‐OH aldehyde can be rationalised as occurring via an open‐TS involving H‐bonding in the imine intermediate between the α‐OH group and the imine N atom. Representative products were converted to highly functionalized 1,2,3,6‐tetrahydropyridines and 3 H ‐oxazolo[3,4‐ a ]pyridine‐3‐ones which will be valuable scaffolds in synthesis.
Novel olanzapine analogues presenting a reduced H1 receptor affinity and retained 5HT2A/D2 binding affinity ratio
Publisher: Springer Science and Business Media LLC
Date: 22-06-2012
Abstract: Olanzapine is an atypical antipsychotic drug with high clinical efficacy, but which can cause severe weight gain and metabolic disorders in treated patients. Blockade of the histamine 1 (H 1 ) receptors is believed to play a crucial role in olanzapine induced weight gain, whereas the therapeutic effects of this drug are mainly attributed to its favourable serotoninergic 2A and dopamine 2 (5HT 2A /D 2 ) receptor binding affinity ratios. We have synthesized novel olanzapine analogues 8a and 8b together with the already known derivative 8c and we have examined their respective in vitro affinities for the 5HT 2A , D 2 , and H 1 receptors. We suggest that thienobenzodiazepines 8b and 8c with lower binding affinity for the H 1 receptors, but similar 5HT 2A /D 2 receptor binding affinity ratios to those of olanzapine. These compounds may offer a better pharmacological profile than olanzapine for treating patients with schizophrenia.
Alkaloids from the roots of stichoneuron caudatum and their acetylcholinesterase inhibitory activities
Publisher: American Chemical Society (ACS)
Date: 07-03-2014
DOI: 10.1021/NP400978X
Abstract: Four new stichoneurine-type alkaloids, stichoneurines F and G (1-2) and sessilistemonamines E and F (3-4), have been isolated from the root extracts of Stichoneuron caudatum. The structures and relative configurations of these alkaloids have been determined by spectroscopic methods and molecular modeling experiments. Compounds 1-4 were tested for their acetylcholinesterase (AChE) inhibitory activities against human AChE. Compound 3 showed significant inhibitory activity with an IC50 value of 9.1±0.15 μM.
[60] Fullerenyl amino acids and peptides: A review of their synthesis and applications
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4RA07310J
Abstract: This review reports on the latest progress in the synthesis of fullerenyl amino acids and related derivatives, and categorises the molecules into functional types for different uses: these include directly attached fullerenyl amino acids, fullerenyl N- and C-capping amino acids, and those amino acids in which the [60]fullerene group is attached to the amino acid side chain.
The Chemical Constituents and the Cytotoxicity, Antioxidant and Antibacterial Activities of the Essential Oil ofGraptophyllum pictum(L.) Griff.
Publisher: Informa UK Limited
Date: 02-01-2015
Synthesis and antimicrobial activity of binaphthyl-based, functionalized oxazole and thiazole peptidomimetics
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5OB01638J
Abstract: Thirty two new binaphthyl-based, oxazole and thiazole peptidomimetics were prepared, which showed antibacterial activity (MICs 1–16 μg mL −1 ) against both Gram positive and negative isolates.
Synthesis of enantioenriched α-heteroatom functionalised aldehydes by chiral organocatalysis and their synthetic applications
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1QO00101A
Abstract: Asymmetric organocatalysis is a versatile method for the enantioselective α-functionalisation of aldehydes. The synthetic scope for chiral α-heteroatom substituted aldehydes is examined including their applications in synthesis.
Reductive ring opening reactions of diphenyldihydrofullerenylpyrroles
Publisher: Elsevier BV
Date: 10-2007
Antioxidant neolignans from the twigs and leaves of Mitrephora wangii HU
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.FITOTE.2018.09.004
Abstract: Two new compounds, odoratisol E (1) and decurrenal A (2), together with 12 known compounds were isolated from the twig and leaf extracts of Mitrephora wangii HU (Annonaceae). All structures were elucidated by spectroscopic methods. The structure of compound (+)-6 was also confirmed by X-ray diffraction analysis. The absolute configurations of odoratisol E and decurrenal A were determined by comparison of their electronic circular dichroism (ECD) spectra with those of related known compounds. Most of the isolated compounds were evaluated for their antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. Compounds 4 and (+)-6 displayed potent ABTS radical scavenging activity with IC
Holocene relative sea-level changes and vertical movements along the Italian and Istrian coastlines
Publisher: Elsevier BV
Date: 09-2009
Synthesis of 7α-Methoxy-7-(4-phenyl-1H-1,2,3-triazol-1-yl)acetamino-3′-arylthio-cephalosporic Acid Derivatives from 7-Aminocephalosporic Acid
Publisher: MDPI AG
Date: 30-10-2023
Diastereoselective concise syntheses of the polyhydroxylated alkaloids DMDP and DAB
Publisher: Elsevier BV
Date: 2014
Metal-Catalyzed Cycloisomerization Reactions of cis-4-Hydroxy-5-alkynylpyrrolidinones and sis-5-Hydroxy-6-alkynylpiperidinones: Synthesis of Furo[3,2-b]pyrroles and Furo[3,2-b<
Publisher: American Chemical Society (ACS)
Date: 15-12-2009
DOI: 10.1021/JO9025385
The synthesis of carbon-linked bisbenzylisoquinolines via ruthenium-mediated olefin-metathesis
Publisher: Elsevier BV
Date: 08-2009
Carbazole alkaloids and coumarins from the roots of Clausena guillauminii
Publisher: Elsevier BV
Date: 09-2014
Divergent Pd-catalyzed cross-coupling of allenyloxazolidinones to give chiral 1,3-dienes and vinyloxazolidinones
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC03215K
Abstract: The first reported catalytic reactivity of 5-allenyloxazolidinones is the tightly controlled, ergent synthesis of chiral 1,3-dienes or 5-vinyloxazolidinones under Pd(0) catalysis.
N-Phenethyl and N-naphthylmethyl isatins and analogues as in vitro cytotoxic agents
Publisher: Elsevier BV
Date: 15-03-2008
DOI: 10.1016/J.BMC.2007.12.026
Abstract: A range of N-phenethyl, N-phenacyl, and N-(1- and 2-naphthylmethyl) derivatives of 5,7-dibromoisatin 2 were prepared by N-alkylation reactions. Their activity against human monocyte-like histiocytic lymphoma (U937), leukemia (Jurkat), and breast carcinoma (MDA-MB-231) cell lines was assessed. The results allowed further development of structure-activity relationships. The compound 5,7-dibromo-N-(1-naphthylmethyl)-1H-indole-2,3-dione 5a was the most potent against U937 cells with an IC(50) value of 0.19 microM.
The Pd-catalysed asymmetric allylic alkylation reactions of sulfamidate imines
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1SC03268B
Abstract: The Pd-catalysed asymmetric allylic alkylation (Pd-AAA) of prochiral enamide anions derived from 5 H -oxathiazole 2,2-dioxides has been developed.
Synthesis of Mono and Bis[60]fullerene-Based Dicationic Peptoids
Publisher: Wiley
Date: 21-11-2014
Semisynthesis and Acetylcholinesterase Inhibitory Activity of Stemofoline Alkaloids and Analogues
Publisher: American Chemical Society (ACS)
Date: 23-04-2010
DOI: 10.1021/NP100137H
Abstract: Semisynthesis of the known Stemona alkaloids oxystemofoline (7) and methoxystemofoline (8) has been achieved starting from (11Z)-1',2'-didehydrostemofoline (6), which confirmed their structures and absolute configurations. The synthesis of (1'R)-hydroxystemofoline (9) helped establish this compound as a natural product from Stemona aphylla. (1'S)-Hydroxystemofoline (10) and a number of related analogues were also prepared. In a TLC bioautographic assay, 9 was found to be the most active acetylcholinesterase inhibitor, but it was not as active as galanthamine.
Structural Revision of Stemoburkilline from an E-Alkene to a Z-Alkene
Publisher: American Chemical Society (ACS)
Date: 30-01-2009
DOI: 10.1021/NP800755P
Abstract: Semisynthesis studies starting from (11Z)-1',2'-didehydrostemofoline (4) indicated that the known Stemona alkaloid stemoburkilline is the Z-isomer and not the E-isomer as initially reported. The semisynthesis involved conversion of (11Z)-1',2'-didehydrostemofoline (4) to 11(S),12(S)-dihydrostemofoline (3) followed by a stereoselective base-catalyzed ring-opening reaction to give (Z)-stemoburkilline (8). The same product was obtained using a similar synthetic protocol starting from isostemofoline (6) via a based-catalyzed ring-opening reaction of 11(S),12(R)-dihydrostemofoline (1). A re-examination of the crude root extracts of Stemona burkillii Prain and further NOE studies established stemoburkilline as the Z-isomer (8).
Five-membered cyclic sulfamidate imines: versatile scaffolds for organic synthesis
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0OB01568G
Abstract: Five-membered ring cyclic sulfamidate imines (5 H -1,2,3-oxathiazole 2,2-dioxides) have received increasing attention as useful precursors for the synthesis of many valuable heterocycles. This review highlights recent developments in this area.
My 37 years of working with nitrogen heterocycles and alkaloids
Publisher: CSIRO Publishing
Date: 10-11-2022
DOI: 10.1071/CH22144
Abstract: This account highlights work from my laboratory at the University of Wollongong (UOW), concerning nitrogen heterocycles and alkaloids, from my appointment as lecturer in Chemistry in February 1985 to the present time as an Emeritus Professor since 2022. I am thankful to the Royal Australian Chemical Institute for the recognition of my work through the recent award of a Distinguished Fellow at the national conference in Brisbane in July 2022.
Intermolecular addition reactions of A-acyliminium ions (Part I)
Publisher: Georg Thieme Verlag KG
Date: 26-01-2009
Synthesis of 3-halo-2,5-disubstituted furans via CuX mediated cyclization-halogenation reactions
Publisher: Elsevier BV
Date: 03-2011
Synthesis of the Purported Structure of Glyphaeaside C and Proposed Revisions to the Structures of the Glyphaeaside Alkaloids
Publisher: American Chemical Society (ACS)
Date: 26-04-2023
Amides and Flavonoids from the Fruit and Leaf Extracts of Melodorum siamensis
Publisher: American Chemical Society (ACS)
Date: 29-01-2019
DOI: 10.1021/ACS.JNATPROD.8B00696
Abstract: Four new chalcones (1, 10, 13, and 14), a new flavanone, (9), a new amide (8), and 19 known compounds were acquired from Melodorum siamensis. The structures were established by NMR and MS data analyses. Compounds 1 (er 1.4:1) and 2 (er 1.1:1) were scalemic and were resolved to yield (-)-1 and (+)-1 and (-)-2 and (+)-2, respectively. The absolute configurations of these compounds were determined from experimental and calculated ECD data. The structures and configurations of (-)-2 and (+)-8 were identified by single-crystal X-ray diffraction analysis. Compound 11 showed nuclear factor-κB inhibitory effects (IC
Synthesis of novel N-protected hydrophobic phenylalanines and their application in potential antibacterials
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.EJMECH.2008.07.001
Abstract: An efficient synthesis of two new N-acetyl-4'-arylphenylalanines is described together with their incorporation into a number of cationic peptoid antibacterial agents, one of which had an MIC of 7.8 microg/mL against Staphylococcus aureus.
Scalemic Caged Xanthones Isolated from the Stem Bark Extract of Garcinia propinqua
Publisher: American Chemical Society (ACS)
Date: 10-05-2017
DOI: 10.1021/ACS.JNATPROD.7B00240
Abstract: Seven new caged xanthones, doitunggarcinones E-K (1-7), all as scalemic mixtures and 10 known compounds (8-17), were isolated from the stem bark extract of Garcinia propinqua. The structures were elucidated on the basis of spectroscopic methods. The separation of the enantiomers of 1-6 was achieved by semipreparative chiral HPLC. The absolute configuration of compound (+)-1 was determined by single-crystal X-ray crystallographic analysis using Cu Kα radiation. The absolute configurations of the other related compounds were determined from comparisons of their ECD spectra with that of compound (+)-1. Compounds (-)-6 and 7 showed cytotoxicity against a colon cancer cell line with IC
Diastereoselective Synthesis of the A-B-C Tricyclic Ring Structure of Stemocurtisine
Publisher: Wiley
Date: 09-11-2015
Antimalarial polyoxygenated and prenylated xanthones from the leaves and branches of Garcinia mckeaniana
Publisher: Elsevier BV
Date: 10-2016
Utilization of electrocoagulation for the isolation of alkaloids from the aerial parts of Stemona aphylla and their mosquitocidal activities against Aedes aegypti
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.ECOENV.2019.109448
Abstract: The electrocoagulation (EC) technique is an alternative method of isolating natural products with the advantage of minimizing the amounts of organic solvents required for this process, which are often harmful to the environment. In this research, the EC and the conventional solvent extraction methods were used in the isolation of Stemona alkaloids from the aerial parts of Stemona aphylla. A comparison was made between the amounts of the isolated alkaloids and the solvents used. The isolated alkaloids were evaluated for their larvicidal, ovicidal and oviposition-deterrent activities against the dengue vector, Aedes aegypti. The morphology and histopatology of the alkaloid treated larvae were also investigated. Two Stemona alkaloids, (2'S)-hydroxystemofoline and stemofoline, were isolated from both the EC and the conventional method. The amounts of (2'S)-hydroxystemofoline from the EC method was about the same as that obtained from the conventional method. However, the amounts of stemofoline obtained from the EC method were about two times larger than those obtained from the conventional method. Importantly, the EC method required six times less total organic solvents. The larvicidal activity assays of (2'S)-hydroxystemofoline and stemofoline showed that these were highly effective against Aedes aegypti larvae with LC
A tocotrienol quinone dimer and xanthones from the leaf extract of Garcinia nigrolineata
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.FITOTE.2019.104175
Abstract: Four new compounds (1-4) together with six known compounds (5-10) were isolated from the leaf extract of Garcinia nigrolineata. Compound 4 is a rare tocotrienol quinone dimer. The structures were elucidated based on NMR and MS data. All isolated compounds were evaluated for their antibacterial activities.
Reversal of Human Multi-Drug Resistance Leukaemic Cells by Stemofoline Derivatives via Inhibition of P-Glycoprotein Function
Publisher: Wiley
Date: 24-10-2014
DOI: 10.1111/BCPT.12331
Abstract: Our previous study reported multi-drug resistance (MDR) reversing properties of synthetic stemofoline derivatives (STFD), OH-A1, NH-B6 and NH-D6 on P-glycoprotein (P-gp) overexpressing leukaemic cells (K562/Adr) however, the mechanism was unclear. In this study, we further investigated whether the STFD reverse MDR through either the inhibition of P-gp function or expression in K562/Adr cells, or both. The P-gp functional studies showed that the STFD increased the accumulation of calcein-AM, rhodamine 123 and [(14) C]-doxorubicin in K562/Adr cells, while the effects have not been seen in their parental sensitive cancer cell line (K562). Further, the STFD did not alter the P-gp expression as determined by Western blotting. This study concludes that the STFD reverse MDR via the inhibition of P-gp function. The efficacy of the STFD to inhibit P-gp function followed the order: NH-B6 > OH-A1 > NH-D6. These compounds could be introduced as candidate molecules for treating cancers exhibiting P-gp-mediated MDR.
Nickel Phosphite-Catalyzed Tetradehydro-Diels-Alder Reactions of (E)-3-ene-1,8-diynes
Publisher: American Chemical Society (ACS)
Date: 10-04-2023
A Rare Alder-ene Cycloisomerization of 1,6-Allenynes
Publisher: Wiley
Date: 02-2022
Abstract: Thermally induced cycloisomerization reactions of 1,6‐allenynes gives α‐methylene‐γ‐lactams via intramolecular Alder‐ene reactions. The mechanism is supported by computational and deuterium labelling studies. This thermal, non‐radical method enables the discovery of a hitherto unknown route that proceeds via a ergent mechanism distinct from the previous [2+2] cycloisomerization manifold.
Diastereoselective borono-Mannich reactions on cyclic N-acyliminium ions
Publisher: Elsevier BV
Date: 02-2008
Synthesis of syn- and enantioenriched anti-β-amino alcohols by highly diastereoselective borono-Mannich allylation reactions
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1CC06775C
Abstract: A highly diastereoselective method for the synthesis of syn -β-amino alcohols and enantioenriched anti -β-amino alcohols has been developed involving α-hydroxyl aldehydes and chiral α-phenylaminoxyaldehydes or α-benzoyloxyaldehydes, respectively in Petasis borono-Mannich allylation reactions.
In vitro cytotoxicity evaluation of some substituted isatin derivatives
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.BMC.2006.10.035
Abstract: A range of substituted 1H-indole-2,3-diones (isatins) were synthesized using standard procedures and their cytotoxicity evaluated against the human monocyte-like histiocytic lymphoma (U937) cell line in vitro. SAR studies identified C(5), C(6), and C(7) substitution greatly enhanced activity with some di- and tri-halogenated isatins giving IC(50) values <10 microM. Of the 23 compounds tested, four were selected for further screening against a panel of five human cancer cell lines. These compounds, in general, showed greater selectivity toward leukemia and lymphoma cells over breast, prostate, and colorectal carcinoma cell lines. The most active compound, 5,6,7-tribromoisatin (2p), was found to be antiproliferative at low micromolar concentrations and also activated the effector caspases 3 and 7 in a dose-dependent manner. These results indicate that di- and tri-substituted isatins may be useful leads for anticancer drug development in the future.
Bioactive compounds from the roots of Strophioblachia fimbricalyx
Publisher: American Chemical Society (ACS)
Date: 27-06-2013
DOI: 10.1021/NP400268D
Abstract: Eight new compounds, fimbricalyxs B-D (1-3), fimbricalyxanhydrides A and B (4, 5), and fimbricalyxlactones A-C (6-8), together with three known compounds, trigonostemone (9), 3,6,9-trimethoxyphenanthropolone (10), and fimbricalyx A (11), were isolated from the roots of Strophioblachia fimbricalyx. The structures of the new compounds were elucidated on the basis of their spectroscopic data and, in the case of compounds 2, 4, and 7, confirmed by single-crystal X-ray crystallographic analysis. Compounds 1-4 and 8 were evaluated for their cytotoxicity (KB, MCF7, and NCI-H187 cancer cells) and antiplasmodial activity (Plasmodium falciparum, K1 multidrug-resistant strain). Fimbricalyx B (1) exhibited potent antiplasmodial activity with an IC50 value of 0.019 μM, while 4 was cytotoxic toward NCI-H187 cancer cells and showed antiplasmodial activities with IC50 values of 5.7 and 3.9 μM, respectively. In addition, the X-ray structure of 10 and the antiplasmodial activity of 11 are reported herein for the first time.
Synthesis and antibacterial studies of binaphthyl-based tripeptoids. Part 2
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.BMC.2010.05.005
Abstract: A compact synthesis of 15 new binaphthyl-based dicationic tripeptoids and one biphenyl based dicationic tripeptoid is described. Fourteen of these tripeptoids resulted from variation of the C-2' ether substituent of the binaphthyl unit. An O-iso-butyl ether binaphthyl derivative was found to be the most active against Staphylococcus aureus (MIC 1.95 μg/mL). The biphenyl analogue also showed good activity against S. aureus (MIC 1.95 μg/mL). These compounds, however, were less active against four vancomycin-resistant strains of enterococci (VRE) than some of our previously developed compounds that had an O-iso-pentyl ether substituent on the binaphthyl unit and a C-2 L-Leu moiety.
Antibacterial and Inhibitory Activities against Nitric Oxide Production of Coumaronochromones and Prenylated Isoflavones from Millettia extensa
Publisher: American Chemical Society (ACS)
Date: 12-08-2019
DOI: 10.1021/ACS.JNATPROD.9B00216
Abstract: A chemical investigation of leaf and root extracts of
Synthesis and inhibitory activities at mGluRs of 3-alkylated and N-alkylated cyclopentyl-glutamate analogues
Publisher: Elsevier BV
Date: 03-2013
Synthesis of 2-azaspiro[4.4]nonan-1-ones via phosphine-catalysed [3+2]-cycloadditions
Publisher: Elsevier BV
Date: 08-2005
Benzalkonium chloride in an orthodontic adhesive: Its effect on rat enamel demineralization using color-based image analysis
Publisher: Elsevier BV
Date: 2019
Synthesis of novel 3′-spirocyclic-oxindole derivatives and assessment of their cytostatic activities
Publisher: Elsevier BV
Date: 06-2007
Asymmetric synthesis of anti-1,2-amino alcohols via the borono-Mannich reaction: A formal synthesis of (-)-swainsonine
Publisher: American Chemical Society (ACS)
Date: 29-07-2006
DOI: 10.1021/JO0610661
Abstract: Chiral alpha-hydroxy aldehydes generated in situ by the ADH reaction of vinyl sulfones undergo a borono-Mannich reaction with beta-styrenyl boronic acid and primary amines to give anti-1,2-amino alcohols in high enantiomeric purities (83-95% ee). This new method allows much more rapid access to these valuable chiral building blocks that has been used in a short formal synthesis (10 synthetic steps from 4-penten-1-ol) of (-)-swainsonine.
Intermolecular addition reactions of A-Acyliminium ions (Part II)
Publisher: Georg Thieme Verlag KG
Date: 02-2009
α-Glucosidase Inhibitory Flavonoids and Oxepinones from the Leaf and Twig Extracts of Desmos cochinchinensis
Publisher: American Chemical Society (ACS)
Date: 05-03-2019
DOI: 10.1021/ACS.JNATPROD.8B00581
Abstract: Four new flavonoids (1-4), a new benzyl benzoate derivative (5), five new oxepinones (6-10), and 14 known compounds (11-24) were isolated from the leaf and twig extracts of Desmos cochinchinensis. Their structures were established by spectroscopic methods. The structure of 1 was also confirmed by X-ray diffraction data. The absolute configurations of 3, 4, and 6-10 were determined from comparisons of their ECD spectra with those of relevant reported compounds. Compounds 1, 2, 6, 8, 10, 12-15, and 17 showed α-glucosidase inhibitory activities with IC
DFT Mechanistic Insights into the Ni(II)-Catalyzed Enantioselective Arylative Cyclization of Tethered Allene-Ketones
Publisher: Wiley
Date: 25-09-2023
Synthesis of (+)-uniflorine A: A structural reassignment and a configurational assignment
Publisher: American Chemical Society (ACS)
Date: 03-06-2008
DOI: 10.1021/OL8009144
Abstract: The total synthesis of (+)-uniflorine A has allowed for the structural reassignment and the configurational assignment of the alkaloid (-)-uniflorine A from a 1,2,6,7,8-pentahydroxyindolizidine structure to (-)-(1 R,2 R,3 R,6 R,7 S,7a R)-1,2,6,7-tetrahydroxy-3-hydroxymethylpyrrolizidine (6- epi-casuarine).
Synthesis of 2′-aminoalkyl-1-benzylisoquinoline derivatives and medium sized ring analogues with mu opiod receptor binding activities
Publisher: Elsevier BV
Date: 06-2010
Alkaloids from the roots of Stemona javanica (Kunth) Engl. (Stemonaceae) and their anti-malarial, acetylcholinesterase inhibitory and cytotoxic activities
Publisher: Elsevier BV
Date: 03-2015
Diterpenoid alkaloids of Aconitum laciniatum and mitigation of inflammation by 14-O-acetylneoline in a murine model of ulcerative colitis
Publisher: Springer Science and Business Media LLC
Date: 04-08-2015
DOI: 10.1038/SREP12845
Abstract: Aconitum laciniatum is used in Bhutanese traditional medicine for treating various chronic infections and inflammatory conditions. We carried out in-depth isolation and characterization of the phytochemicals from the root component and determined the anti-inflammatory effects of the isolated compounds against chemically-induced colitis in mice. Five diterpenoid alkaloids - pseudaconitine, 14-veratroylpseudaconine, 14- O -acetylneoline, neoline and senbusine A - were isolated from A. laciniatum for the first time. Two of the alkaloids were tested for anti-inflammatory properties in the TNBS-induced colitis model in mice. Various parameters were measured to assess pathology including weight loss, clinical and macroscopic scores, histological structure and IFN-γ production in the gut. Of the two alkaloids tested, 14- O -acetylneoline showed significant protection against different parameters of colitic inflammation. Compared to control mice that received TNBS alone, mice treated with 14- O -acetylneoline experienced significantly less weight loss and had significantly lower clinical scores, macroscopic pathology and grades of histological inflammation. Moreover, colonic IFN-γ mRNA levels were significantly reduced in mice that received 14- O -acetylneoline compared to control mice that received TNBS alone. This alkaloid is now considered a novel anti-colitis drug lead compound.
Meet our editorial board member
Publisher: Bentham Science Publishers Ltd.
Date: 06-04-2016
Concise synthesis of α-substituted 2-benzofuranmethamines and other 2-subsituted benzofurans via α-substituted 2-benzofuranmethyl carbocation intermediates
Publisher: American Chemical Society (ACS)
Date: 11-01-2013
DOI: 10.1021/JO302554V
Abstract: Propargyl amines 4, where R(3) is aryl, undergo 5-exo-dig cyclization reactions under relatively mild conditions (AgNO(3), DMF, 60 °C, 1 h) to give 3-amino-2,3-dihydro-2-arylmethylidenebenzofurans 5 (R(3) = aryl). In contrast, substrates where R(3) is alkyl undergo competing 6-endo-dig and 5-exo-dig cyclization processes. The hydroxymethyl substrate 4 (R(3) = CH(2)OH), however, was smoothly converted to its corresponding 5-exo-dig cyclization product 5, likely due to the assistance of the primary hydroxyl group in the 5-exo-dig cyclization process by silver cation coordination. Under more enforcing conditions (AgNO(3), DMF, 100 °C, 18 h), the initially formed products 5 undergo a 1,3-allylic rearrangement to their corresponding 2-substituted benzofuran derivatives 6. This rearrangement can also be effected by treating 5 with AgNO(3) in DMF at 100 °C for 18 h or BF(3)·Et(2)O at rt. 2-(3-Butenyl)benzofurans 7 (Nu = allyl) can be prepared by treatment of 5 with BF(3)·Et(2)O and allyltributylstannane. Furan and MeOH could also be employed as external nucleophiles in these BF(3)·Et(2)O-promoted reactions.
Regioselective Synthesis of Novele-Edge-[60]fullerenylmethanodihydropyrroles and 1,2-Dihydromethano[60]fullerenes
Publisher: Wiley
Date: 12-2005
Isolation of linobiflavonoid, a novel biflavonoid from Linostoma pauciflorum Griff.
Publisher: Elsevier BV
Date: 09-2011
Structure, biological activities and synthesis of hyacinthacine alkaloids and their stereoisomers
Publisher: Bentham Science Publishers Ltd.
Date: 09-2012
Inhibition of TNF-α production in LPS-activated THP-1 monocytic cells by the crude extracts of seven Bhutanese medicinal plants
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.JEP.2013.05.055
Abstract: Seven studied medicinal plants Aconitum laciniatum, Ajania nubigena, Codonopsis bhutanica, Corydalis crispa, Corydalis dubia, Meconopsis simplicifolia and Pleurospermum amabile, are currently used in the Bhutanese Traditional Medicine (BTM) for the management of different types of disorders including the diseases that bore relevance to various inflammatory conditions. This study aimed to evaluate the inhibition of TNF-α production in LPS-activated THP-1 monocytic cells by the crude extracts of seven selected Bhutanese medicinal plants. It is expected to (a) generate a scientific basis for their use in the BTM and (b) form a basis for prioritization of the seven plants for further phytochemical and anti-inflammatory studies. Seven plants were selected using an ethno-directed bio-rational approach and their crude extracts were prepared using four different solvents (methanol, hexane, dichloromethane and chloroform). The TNF-α inhibitory activity of these extracts was determined by cytokine-specific sandwich quantitative enzyme-linked immunosorbent assays (ELISAs). The results were quantified statistically and the statistical significance were evaluated by GraphPad Prism version 5.01 using Student's t-test with one-tailed distribution. A p-value ≤0.05 was considered statistically significant. Of the seven plants studied, the crude extracts of six of them inhibited the production of pro-inflammatory cytokine, TNF-α in LPS-activated THP-1 monocytic cells. Amongst the six plants, Corydalis crispa gave the best inhibitory activity followed by Pleurospermum amabile, Ajania nubigena, Corydalis dubia, Meconopsis simplicifolia and Codonopsis bhutanica. Of the 13 extracts that exhibited statistically significant TNF-α inhibitory activity (p<0.05 p<0.01), five of them showed very strong inhibition when compared to the DMSO control and RPMI media. Six medicinal plants studied here showed promising TNF-α inhibitory activity. These findings rationalize the traditional use of these selected medicinal plants in the BTM as an in idual plant or in combination with other ingredients for the treatment of disorders bearing relevance to the inflammatory conditions. The results forms a good preliminary basis for the prioritization of candidate plant species for an in-depth phytochemical study and anti-inflammatory activity screening of the pure compounds contained within those seven plants.
Chemical composition and biological activities of the essential oil from leaves of cleidion javanicum bl.
Publisher: Informa UK Limited
Date: 2012
Synthesis of polyhydroxylated pyrrolizidine and indolizidine compounds and their glycosidase inhibitory activities
Publisher: Elsevier BV
Date: 11-2010
Coumarins and flavones from the fruit and root extracts of Micromelum integerrimum
Publisher: Informa UK Limited
Date: 05-11-0012
DOI: 10.1080/14786419.2018.1510400
Abstract: A phytochemical investigation of the fruit and root extracts of
1,2-Addition versus homoconjugate addition reactions of indoles and electron-rich arenes to α-cyclopropyl N-acyliminium ions: synthetic and computational studies
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9OB01363F
Abstract: α-Cyclopropyl- N -acyliminium ions towards reaction with indoles to give 5-(3-indoyl)-5-cyclopropylpyrrolidin-2-ones and, in the case of highly electron deficient indoles and electron rich arenes, spiroheterocycles.
Polyoxygenated Cyclohexenes and Their Chlorinated Derivatives from the Leaves of Uvaria cherrevensis
Publisher: American Chemical Society (ACS)
Date: 04-01-2019
DOI: 10.1021/ACS.JNATPROD.8B00794
Abstract: The chemical study of leaf extracts from Uvaria cherrevensis resulted in the identification of 11 new polyoxygenated cyclohexenes, cherrevenols A-K (1-11), and a new seco-cyclohexene derivative, cherrevenol L (12). Nine known compounds (13-21) were also isolated. Three of the isolated compounds are chlorinated polyoxygenated cyclohexenes. The structures of these compounds were determined using spectroscopic methods and, in some cases (compounds 2, 6, 8, and 10), single-crystal X-ray crystallographic structural analysis or chemical correlation (compounds 6 and 7). Compounds 6 and 7 were both isolated as scalemic mixtures (ee 23-24%).
Allenylation and Propargylation Reactions of Ketones, Aldehydes, Imines, and Iminium Ions Using Organoboronates and Related Derivatives
Publisher: Georg Thieme Verlag KG
Date: 18-01-2017
Progress toward the total synthesis of 9β-hydroxyvertine: Construction of an advanced quinolizidine intermediate
Publisher: Elsevier BV
Date: 09-2019
Correction to “Total Synthesis of Natural Hyacinthacine C5 and Six Related Hyacinthacine C5 Epimers”
Publisher: American Chemical Society (ACS)
Date: 16-04-2020
Antibacterial Prenylated Isoflavonoids from the Stems of Millettia extensa
Publisher: American Chemical Society (ACS)
Date: 14-08-2018
DOI: 10.1021/ACS.JNATPROD.8B00321
Abstract: The first phytochemical investigation of the stem extract of Millettia extensa resulted in the isolation and identification of six new isoflavones, millexatins A-F (1-6), together with 16 known compounds. The structures of these new compounds were determined on the basis of their spectroscopic data. Millexatin A (1) is a rare isoflavone containing three isoprenyl units on a modified A ring. Compounds 1, 6, 10, 11, and 14 displayed promising antibacterial activity with MIC values of 2-8 μg/mL.
Model support studies toward the total synthesis of the stemona alkaloid stemocurtisine
Publisher: Elsevier BV
Date: 09-2013
Synthesis of sterically congested 1,5-disubstituted-1,2,3-Triazoles using chloromagnesium acetylides and hindered 1-naphthyl azides
Publisher: Elsevier BV
Date: 02-2021
Antibacterial tetraoxygenated xanthones from the immature fruits of Garcinia cowa
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.FITOTE.2014.08.003
Abstract: A phytochemical investigation of the acetone extract from the immature fruits of Garcinia cowa led to the isolation of two novel tetraoxygenated xanthones, garcicowanones A (1) and B (2), together with eight known tetraoxygeanted xanthones. Their structures were determined by spectroscopic analysis. All isolated compounds were evaluated for their antibacterial activity against Bacillus cereus TISTR 688, Bacillus subtilis TISTR 008, Micrococcus luteus TISTR 884, Staphylococcus aureus TISTR 1466, Escherichia coli TISTR 780, Pseudomonas aeruginosa TISTR 781, Salmonella typhimurium TISTR 292 and Staphylococcus epidermidis ATCC 12228. α-Mangostin showed potent activity (MIC 0.25-1 μg/mL) against three Gram-positive strains and garcicowanone A and β-mangostin exhibited strong antibacterial activity against B. cereus with the same MIC values of 0.25 μg/mL.
Total Synthesis of Hyacinthacines B3, B4, and B5 and Purported Hyacinthacine B7, 7-epi-Hyacinthacine B7, and 7a-epi-Hyacinthacine B
Publisher: American Chemical Society (ACS)
Date: 05-05-2014
DOI: 10.1021/JO5005923
Abstract: The total synthesis of hyacinthacines B3, B4, and B5 and purported hyacinthacine B7, 7-epi-hyacinthacine B7, and 7a-epi-hyacinthacine B3 from a common anti-1,2-amino alcohol precursor is described. These syntheses confirmed that the proposed structures and absolute configurations of hyacinthacines B3, B4, and B5 were correct and disclosed that the proposed structure of hyacinthacine B7 was incorrect. Our synthetic and spectroscopic studies suggest that the natural hyacinthacines B5 and B7 are the same compounds however, without access to authentic s les this cannot be unequivocally proven.
Stereoselective synthesis of α-methylenecyclopentenones via a Diels-Alder/retro-Diels-Alder protocol
Publisher: Elsevier BV
Date: 11-2013
Alkaloids and styryllactones from Goniothalamus cheliensis
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.PHYTOCHEM.2018.10.014
Abstract: Eight previously undescribed compounds, including four alkaloids and five styryllactones together with 36 known compounds were isolated from the twig and leaf extracts of Goniothalamus cheliensis. Their structures were elucidated by extensive analysis of their spectroscopic data. The absolute configuration of (-)-(4S,5S,6R,7S,8S)-goniochelienlactone and (-)-(4S,5S,6R,7S,8S)-7-acetylgoniochelienlactone were established from single crystal X-ray analysis using Cu Kα radiation. The absolute configurations of the other related compounds were identified by comparisons of their ECD spectra with those of related known compounds. Most of the isolated compounds were evaluated for their cytotoxicities against human colorectal cancer cells (HCT-116). Griffithazanone A was the most potent with an IC
Inhibition of P-Glycoprotein Mediated Multidrug Resistance by Stemofoline Derivatives
Publisher: Pharmaceutical Society of Japan
Date: 2013
Abstract: Resistance to chemotherapy in cancer patients has been correlated to the overexpression of the ATP-binding cassette (ABC) drug transporters including P-glycoprotein (P-gp) that actively efflux chemotherapeutic drugs from cancer cells. We examined the multidrug resistance reversing property of stemofoline derivatives in drug-resistance human cervical carcinoma (KB-V1) and human leukemic (K562/Adr) cell lines that overexpress P-gp. Didehydrostemofoline and eleven of its derivatives were synthesized and the cytotoxicity and their effect on doxorubicin, vinblastine and paclitaxel sensitivity in drug resistant (KB-V1 and K562/Adr) and drug sensitive (KB-3-1 and K562) cell lines by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were determined. We found that three out of the twelve stemofoline derivatives including OH-A1, NH-B6 and NH-D6 showed commitment efficiency to increase sensitivity to doxorubicin, vinblastine and paclitaxel in KB-V1 cells and increase sensitivity to doxorubicin, and paclitaxel in K562/Adr cells whereas the effects have not been seen in their parental sensitive cancer cell lines (KB-3-1 and K562). These results indicate that stemofoline derivatives reversed P-gp-mediated multidrug resistance in vitro, and thus could be developed as effective chemosensitizers to treat multidrug-resistant cancers. The molecular mechanism of modulation of P-gp would be further determined.
Synthesis of α-Propargylglycinates Using the Borono-Mannich Reaction with Pinacol Allenylboronate and Potassium Allenyltrifluoroborate
Publisher: Wiley
Date: 14-07-2016
Total Synthesis of Calystegine B 4
Publisher: Wiley
Date: 28-05-2010
Abstract: The total synthesis of calystegine B 4 was achieved in 10 steps from (–)‐ D ‐lyxose by using a new synthetic strategy to obtain the requisite protected hydroxylated 4‐aminocyclohept‐2‐en‐1‐one without the problem of regioisomer formation that was a problem in the earlier synthesis of this natural product. The key steps included a Petasis–borono‐Mannich reaction and a ring‐closing metathesis reaction.
Isolation of tuberospironine A, a novel croomine derivative from Stemona tuberosa Lour.
Publisher: Elsevier BV
Date: 06-2012
Diastereoselective Ritter Reactions of Chiral Cyclic N-Acyliminium Ions: Synthesis of Pyrido- and Pyrrolo[2,3-d]oxazoles and 4-Hydroxy-5-N-acylaminopyrrolidines and 5-Hydroxy-6-<
Publisher: American Chemical Society (ACS)
Date: 29-02-2008
DOI: 10.1021/JO800007G
Abstract: Pyrido- and pyrrolo[2,3-d]oxazoles can be conveniently prepared in high yield from the Ritter reaction of nitriles and in situ generated chiral cyclic N-acyliminium ions. cis-4-Hydroxy-5-acylaminopyrrolidines and cis-5-hydroxy-6-acylaminopiperidines can be readily obtained by acid hydrolysis of these bicyclic heterocyclic compounds, respectively.
Antimalarial alkaloids from a Bhutanese traditional medicinal plant Corydalis dubia
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.JEP.2012.06.037
Abstract: Corydalis dubia is used in Bhutanese traditional medicine as a febrifuge and for treating infections in the blood, liver and bile which correlate to the signs and symptoms of malarial and microbial infections. To validate the ethnopharmacological uses of the plant and to discover potential new therapeutic drug leads. C. dubia was collected from Bhutan and the alkaloids were obtained using acid-base fractionation and separation by repeated column and preparative plate chromatography. The alkaloids were identified from analysis of their physiochemical and spectroscopic data and were tested for antiplasmodial, antimicrobial and cytotoxicity activities. A systematic extraction and isolation protocol yielded one new natural product, dubiamine, and seven known isoquinoline alkaloids, scoulerine, cheilanthifoline, protopine, capnoidine, bicuculline, corydecumbine and hydrastine. Among the four alkaloids tested, scoulerine showed the best antiplasmodial activity with IC(50) values of 5.4μM and 3.1μM against the antifolate sensitive and the multidrug resistant P. falciparum strains: TM4/8.2 and K1CB1, respectively. None of the alkaloids tested showed significant antimicrobial or cytotoxicity activities. The antiplasmodial test results, of the isolated alkaloid components, are commensurated with the ethnopharmacological uses of this plant.
Isolation of bioactive compounds from medicinal plants used in traditional medicine: Rautandiol B, a potential lead compound against Plasmodium falciparum
Publisher: Springer Science and Business Media LLC
Date: 13-09-2021
DOI: 10.1186/S12906-021-03406-Y
Abstract: Neorautanenia mitis , Hydnora abyssinica , and Senna surattensis are medicinal plants with a variety of traditional uses. In this study, we sought to isolate the bioactive compounds responsible for some of these activities, and to uncover their other potential medicinal properties. The DCM and ethanol extracts of the roots of N . mitis and H. abyssinica , and the leaves of S. surattensis were prepared and their phytochemical components were isolated and purified using chromatographic methods. These extracts and their pure phytochemical components were evaluated in in-vitro models for their inhibitory activities against Plasmodium falciparum , Trypanosoma brucei rhodesiense , Mycobacterium tuberculosis, α-amylase (AA), and α-glucosidase (AG). Rautandiol B had significant inhibitory activities against two strains of Plasmodium falciparum showing a high safety ratio (SR) and IC 50 values of 0.40 ± 0.07 μM (SR - 108) and 0.74 ± 0.29 μM (SR - 133) against TM4/8.2 and K1CB1, respectively. While (−)-2-isopentenyl-3-hydroxy-8-9-methylenedioxypterocarpan showed the highest inhibitory activity against T. brucei rhodesiense with an IC 50 value of 4.87 ± 0.49 μM (SR 5.83). All crude extracts showed inhibitory activities against AA and AG, with three of the most active phytochemical components rautandiol A, catechin, and dolineon, having only modest activities against AG with IC 50 values of 0.28 mM, 0.36 mM and 0.66 mM, respectively. These studies have led to the identification of lead compounds with potential for future drug development, including Rautandiol B, as a potential lead compound against Plasmodium falciparum. The relatively higher inhibitory activities of the crude extracts against AG and AA over their isolated components could be due to the synergistic effects between their phytochemical components. These crude extracts could potentially serve as alternative inhibitors of AG and AA and as therapeutics for diabetes.
The Chemical Constituents and Biological Activities of the Essential Oil and the Extracts from Leaves ofGynura divaricata(L.) DC. Growing in Thailand
Publisher: Informa UK Limited
Date: 04-05-2015
Cytotoxic and Antiplasmodial Compounds from the Roots of Strophioblachia fimbricalyx
Publisher: American Chemical Society (ACS)
Date: 24-09-2009
DOI: 10.1021/NP900352N
Abstract: The known phenanthrenone trigonostemone (1), along with a new phenanthrenone, 9-O-demethyltrigonostemone (2), and two new phenanthropolones, 3,6,9-trimethoxyphenanthropolone (3) and 4,6,9-trimethoxyphenanthropolone (4), were isolated from the roots of Strophioblachia fimbricalyx. Compound 2 showed cytotoxicity against NCI-H187, KB, and MCF7 cancer cells with IC50 values of 0.8, 0.8, and 2.9 microg/mL, respectively, while 3 and 4 showed reduced cytotoxicity. Compounds 2 and 3 displayed antiplasmodial activity in vitro (IC50 values of 2.7 and 3.2 microg/mL, respectively) against Plasmodium falciparum (K1, resistant strain). In addition, the antioxidant activity of 1-4 toward DPPH radicals was determined, but only compound 2 showed any discernible activity.
Four new C-benzyl flavonoids from the fruit of Uvaria cherrevensis
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.FITOTE.2018.08.020
Abstract: The phytochemical investigation of the fruit extracts of Uvaria cherrevensis led to the isolation and characterization of four new C-benzyl flavonoids cherrevenones A-D (1-4) together with 11 known compounds. The isolated compounds were characterized using spectroscopic techniques. Compounds 1, 3, 5 and 11 showed moderate inhibitory activities against the P. falciparum strains TM4/8.2 and K1CB1 with IC
New cyclic peptides via ring-closing metathesis reactions and their anti-bacterial activities
Publisher: Elsevier BV
Date: 12-2008
The history of the glycosidase inhibiting hyacinthacine c-type alkaloids: From discovery to synthesis
Publisher: Bentham Science Publishers Ltd.
Date: 04-07-2019
DOI: 10.2174/1570179416666190126100312
Abstract: The inherent glycosidase inhibitory activity and potentially therapeutic value of the polyhydroxylated pyrrolizidine alkaloids containing a hydroxymethyl substituent at the C-3 position have been well documented. Belonging to this class, the naturally occurring hyacinthacine C-type alkaloids are of general interest among iminosugar researchers. Their selective micromolar α -glycosidase inhibitory ranges (10 – 100 μM) suggest that these azasugars are potential leads for treating type II diabetes. However, the structures of hyacinthacine C1, C3 and C4 are insecure with hyacinthacine C5 being recently corrected. This review presents the hyacinthacine C-type alkaloids: their first discovery to the most recent advancements on the structures, biological activities and total synthesis. The hyacinthacine C-type alkaloids are of exponentially increasing interest and will undoubtedly continue to be reported as synthetic targets. They represent a challenging but rewarding synthetic feat for the community of those interested in accessing biologically active iminosugars. Since 2009, ten total syntheses have been employed towards accessing similarly related products but only three have assessed the glycosidase inhibitory activity of the final products. This suggests the need for an accessible and universal glycosidase inhibitory assay so to accurately determine the structure-activity relationship of how the hyacinthacine C-type alkaloids inhibit specific glycosidases. Confirming the correct structures of the hyacinthacine C-type alkaloids as well as accessing various analogues continues to strengthen the foundation towards a marketable treatment for type II diabetes and other glycosidase related illnesses.
Structural Reassignment of the Mono- and Bis-Addition Products from the Addition Reactions of N-(Diphenylmethylene)glycinate Esters to [60]Fullerene under Bingel Conditions
Publisher: American Chemical Society (ACS)
Date: 16-09-2005
DOI: 10.1021/JO051282U
Abstract: The addition of N-(diphenylmethylene)glycinate esters (Ph2C=NCH2CO2R) to [60]fullerene under Bingel conditions gives [60]fullerenyldihydropyrroles and not methano[60]fullerenyl iminoesters [C60C(CO2R)(N=CPh2)] as previously reported. Unequivocal evidence for the structure of C60C(CO2Et)(N=CPh2) was provided by INADEQUATE NMR studies on 13C enriched material. New mechanistic details are proposed to account for the formation of [60]fullerenyldihydropyrroles and their reductive ring-opening reactions.
Dual Gold‐Catalyzed Cycloaromatization of Unconjugated (E)‐Enediynes
Publisher: Wiley
Date: 17-01-2019
Abstract: A synthesis of unconjugated (E)-enediynes from allenyl amino alcohols is reported and their gold-catalyzed cascade cycloaromatization to a broad range of enantioenriched substituted isoindolinones has been developed. Experimental and computational studies support the reaction proceeding via a dual-gold σ,π-activation mode, involving a key gold-vinylidene- and allenyl-gold-containing intermediate.
Back matter
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3OB90163G
Cationic biaryl 1,2,3-triazolyl peptidomimetic amphiphiles: synthesis, antibacterial evaluation and preliminary mechanism of action studies
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.EJMECH.2019.02.013
Abstract: Synthetic small molecular antimicrobial peptidomimetics represent a promising new class of potential antibiotics due to their membrane-disrupting ability and their decreased propensity for bacterial resistance. A library of 43 mono- and di-cationic biaryl 1,2,3-triazolyl peptidomimetics was designed and synthesized based upon previously established lead biarylpeptidomimetics and a known pharmacophore. A reliable, facile and modular synthetic pathway allowed for the efficient synthesis of multiple unique scaffolds which were subjected to ergent derivatization to furnish the hiphilic compounds. In vitro testing revealed enhanced antibacterial efficacy against a range of pathogenic bacteria, including bacterial isolates with methicillin, vancomycin, daptomycin, or multi-drug resistance. Preliminary time-kill kinetics and membrane-disruption assays revealed a likely membrane-active mechanism for the tested peptidomimetics. An optimal balance between hydrophobicity and cationic charge was found to be essential for reduced cytotoxicity/haemolysis (i.e. membrane selectivity) and enhanced Gram-negative activity. The cationic biaryl hiphile 81 was identified as a potent, broad-spectrum peptidomimetic with activity against Gram-positive (methicillin-resistant Staphylococcus aureus - MIC = 2 μg/mL) and Gram-negative (Escherichia coli - MIC = 4 μg/mL) pathogenic bacteria.
Oxidative biotransformation of stemofoline alkaloids
Publisher: Informa UK Limited
Date: 2021
Foreword: ORGANIC-08 Research Highlights
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/CH09332
Stemofoline ethyl acetate solvate
Publisher: International Union of Crystallography (IUCr)
Date: 18-07-2009
Concise synthesis of (−)-steviamine and analogues and their glycosidase inhibitory activities
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3OB40374B
Abstract: A concise synthesis of (-)-steviamine is reported along with the synthesis of its analogues 10-nor-steviamine, 10-nor-ent-steviamine and 5-epi-ent-steviamine. These compounds were tested against twelve glycosidases (at 143 μg mL(-1) concentrations) and were found to have in general poor inhibitory activity against most enzymes. The 10-nor analogues however, showed 50-54% inhibition of α-L-rhamnosidase from Penicillium decumbens while one of these, 10-nor-steviamine, showed 51% inhibition of N-acetyl-β-D-glucosaminidase (from Jack bean) at the same concentration (760 μM).
Highly diastereoselective N-acyliminium ion cyclization reactions of a tethered furan
Publisher: Elsevier BV
Date: 12-2012
Potent α-glucosidase inhibitory activity of compounds isolated from the leaf extracts of Uvaria hamiltonii
Publisher: Informa UK Limited
Date: 23-12-2018
DOI: 10.1080/14786419.2018.1538996
Abstract: The phytochemical investigation of the leaf extracts of
Synthesis of furo[3,2-c]coumarins under microwave irradiation using nano-CoFe2 O4 @SiO2 -PrNH2 as an efficient and magnetically reusable catalyst
Publisher: Springer Science and Business Media LLC
Date: 05-2016
Binaphthyl-Based Dicationic Peptoids with Therapeutic Potential
Publisher: Wiley
Date: 11-12-2009
Parviflorals A-F, trinorcadalenes and bis-trinorcadalenes from the roots of Decaschistia parviflora
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.PHYTOCHEM.2013.07.017
Abstract: Trinorcadalenes, parviflorals A and B (1 and 2), and four bis-trinorcadalenes, parviflorals C-F (3-6), together with the known trinorcadalenes, syriacusins A (7) and C (8), scopoletin (9) and stigmasterol were isolated from roots of Decaschistia parviflora. Their structures were established by spectroscopic techniques. The CD spectra of the bis-trinorcadalenes (3-6) established their absolute configurations at the binaphthyl axis. Further, structure 6 was confirmed by a single-crystal X-ray crystallographic analysis. Compounds 2 and 6 showed antimalarial activity against Plasmodium falciparum with IC50 values of 11.45 and 6.85 μM, respectively. Compounds 1, 5, 7 and 8 also exhibited weak antifungal activity against Candida albicans, with IC50 values in the range of 37.03-197.68 μM. Compounds 1-3 and 5-8 showed weak antimycobacterial activity against Mycobacterium tuberculosis with MIC values in the range of 54.30-192.13 μM. In addition, several of these compounds possessed cytotoxicity towards the cancer cell lines, KB, MCF7 and NCI-H187 with IC50 values in the range of 2.20-90.09 μM.
2-Phenylnaphthalenes and a polyoxygenated cyclohexene from the stem and root extracts of Uvaria cherrevensis (Annonaceae)
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.FITOTE.2017.06.002
Abstract: Three new 2-phenylnaphthalene derivatives, cherrevenaphthalenes A-C (1-3), and a new polyoxygenated cyclohexene derivative, (-)-uvaribonol F (4) together with six known compounds, 5-10, were isolated from the stem and root extracts of Uvaria cherrevensis (Annonaceae). The structures of all isolated compounds were elucidated by spectroscopic analysis. The structures of 3 and 4 were further confirmed by single crystal X-ray diffraction methods. Compound 2 exhibited modest antiplasmodial activity against the P. falciparum stains TM4/8.2 and K1CB1 with IC
Resolution and identification of scalemic caged xanthones from the leaf extract of Garcinia propinqua having potent cytotoxicities against colon cancer cells
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.FITOTE.2017.10.009
Abstract: A new scalemic 8,8a-dihydro caged xanthone (1) was isolated from the leaf extract of Garcinia propinqua. Five other known natural products, the three caged xanthones (2, 5 and 6) and the two neocaged xanthones, (3 and 4) were also isolated as scalemic mixtures. Their structures were characterized by spectroscopic methods. The enantiomeric ratios (er) of compounds 1-6 ranged from 1:0.7 to 1:0.9. These compounds were also resolved by semipreparative chiral HPLC. The absolute configurations of (+)-2 and (+)-3 were determined by single-crystal X-ray diffraction analysis using Cu Kα radiation while the absolute configurations of the other compounds were determined by comparisons of their ECD spectra. Compounds (-)-4, (+)-4, (-)-5, (+)-5, and (-)-6 showed potent cytotoxicities against a colon cancer cell line HCT116 with IC
Modulation of P-glycoprotein by Stemona alkaloids in human multidrug resistance leukemic cells and structural relationships
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.PHYMED.2017.08.004
Abstract: Multidrug resistance (MDR) is a major reason for the failure of chemotherapy in the treatment of cancer patients. P-gp over-expression in MDR cancer cells is a multifactorial phenomenon with biochemical resistance mechanisms. Stemofoline (STF), isolated from Stemona bukillii, has been reported to be an MDR reversing compound. This study investigated whether other Stemona alkaloids that had been purified from Stemonaceae plants exerted MDR modulation activity. MTT assay was performed to determine the MDR reversing property of the alkaloids. Modulation of P-gp function by these compounds was investigated using cell cycle analysis and P-gp fluorescent substrate accumulation assays. P-gp expression was determined by Western blot analysis. We preliminarily examined the safety of these compounds in normal human fibroblasts and human peripheral blood mononuclear cells (PBMCs) using the MTT assay, and in red blood cells (human and rat) through in vitro hemolysis assays. Three of the eight alkaloids tested, isostemofoline (ISTF), 11Z -didehydrostemofoline (11Z-DSTF) and 11E-didehydrostemofoline (11E-DSTF), enhanced the chemotherapeutic sensitivity of MDR leukemic K562/Adr cells, which overexpressed P-gp. The P-gp functional studies showed that these three alkaloids increased the accumulation of P-gp substrates, calcein-AM (C-AM) and rhodamine123 (Rho 123) in K562/Adr cells, while this effect was not seen in drug sensitive parental K562 cells. Whereas, the alkaloids did not alter P-gp expression as was determined by Western blotting analysis. The alkaloids reversed MDR via the inhibition of P-gp function. For pharmaceutical safety testing, the alkaloids were found to be not toxic to normal human fibroblasts and PBMCs. Moreover, the effective compounds did not induce hemolysis in either human or rat erythrocytes. These compounds may be introduced as potential candidate molecules for treating cancers exhibiting P-gp-mediated MDR.
The boronic acid Mannich reaction in alkaloid synthesis
Publisher: Walter de Gruyter GmbH
Date: 13-12-2012
Abstract: Our work on the application of the boronic acid Mannich reaction to the synthesis of pyrrolizidine alkaloids is described.
Binaphthyl-1,2,3-triazole peptidomimetics with activity against Clostridium difficile and other pathogenic bacteria
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5OB00576K
Abstract: Designed binaphthyl-based, cationic peptidomimetic antimicrobials targeting C. difficile , incorporating a click-derived 1,2,3-triazole ester isostere at the C-terminus MICs of 4 μg mL −1 against three human isolates of C. difficile .
Metal-Catalyzed Cycloisomerization Reactions of cis-4-Hydroxy-5-alkynylpyrrolidinones and cis-5-Hydroxy-6-alkynylpiperidinones: Synthesis of Furo[3,2-b]pyrroles and Furo[3,2-b<
Publisher: American Chemical Society (ACS)
Date: 04-06-2009
DOI: 10.1021/JO9007942
Abstract: Furo[3,2-b]pyrroles and furo[3,2-b]pyridines can be conveniently prepared in good yields from the cycloisomerization reactions of cis-4-hydroxy-5-alkynylpyrrolidinones and cis-5-hydroxy-6-alkynylpiperidinones, respectively, using Ag(I), Pd(II)/Cu(I), or Au(I) catalysis. In one case, the cycloisomerization product was unstable and produced a furan derivative by a ring-opening reaction.
Oxazolidinones and 2,5-Dihydrofurans via Zinc-Catalyzed Regioselective Allenylation Reactions of l -α-Amino Aldehydes
Publisher: American Chemical Society (ACS)
Date: 14-06-2017
Abstract: The simultaneous control of diastereoselectivity and regioselectivity in Zn-catalyzed allenylation reactions of N-protected l-α-amino aldehydes is reported. A reversal in diastereoselectivity could be realized by variation of the α-amino aldehyde protecting groups. A range of 1-allenyl-2-amino alcohols were obtained with excellent regioselectivity and converted to oxazolidinones and dihydrofurans. Many of which could be isolated as single diastereoisomers and without significant erosion of ee, making this a practical catalytic synthesis of highly functionalized heterocycles.
Corrected Structure of Natural Hyacinthacine C1 via Total Synthesis
Publisher: American Chemical Society (ACS)
Date: 04-02-2019
DOI: 10.1021/ACS.JNATPROD.8B00879
Abstract: Hyacinthacines C
Exploiting the borono-Mannich reaction in bioactive alkaloid synthesis
Publisher: Walter de Gruyter GmbH
Date: 2008
Abstract: We have demonstrated that the borono-Mannich reaction is a versatile and efficient reaction for the diastereoselective preparation of chiral 1,2-amino alcohols. These Mannich products are valuable starting materials as shown in this report by the synthesis of bioactive polyhydroxylated pyrrolizidine and indolizidine alkaloids. Initial studies, directed at the more complex Stemona alkaloids and using the borono-Mannich reaction on cyclic N -acyliminium ions, are encouraging, as demonstrated by the synthesis of the pyrido[1,2- a ]azepine core structure of stemocurtisinol.
Antibacterial and cytotoxic activities of phenolic constituents from the stem extracts of Spatholobus parviflorus
Publisher: Informa UK Limited
Date: 26-12-2018
DOI: 10.1080/14786419.2018.1512990
Abstract: A new 2-arylbenzofuran, spathobenzofuran (
The discovery of allyltyrosine based tripeptides as selective inhibitors of the HIV-1 integrase strand-transfer reaction
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6OB00950F
Abstract: From library screening of synthetic antimicrobial peptides, an O -allyltyrosine-based tripeptide HIV-1 integrase (IN) inhibitor was identified. Subsequent optimisation afforded an analogue exhibiting an IC 50 value of 2.5 μM.
Diastereoselective Pd‐catalyzed Decarboxylative (4+2) Cycloaddition Reactions of 4‐Vinylbenzoxazinanones and 2‐Nitro‐1,3‐enynes
Publisher: Wiley
Date: 25-10-2023
Antimalarial and cytotoxic activities of pregnene-type steroidal alkaloids from Holarrhena pubescens roots
Publisher: Informa UK Limited
Date: 24-11-2017
DOI: 10.1080/14786419.2017.1408108
Abstract: The phytochemical investigation of an alkaloidal extract of Holarrhena pubescens roots led to the isolation and identification of a new pregnene-type alkaloid, mokluangin D (1), together with nine known steroidal alkaloids (2-10). The structure of the new metabolite was determined on the basis of spectroscopic analyses including 1D- and 2D-NMR spectroscopy and mass spectrometry. Compounds 3 and 4 showed potent antimalarial activity against Plasmodium falciparum K1 stain with IC
Synthesis of spirocyclic heterocycles from α,β-unsaturated N-acyliminium ions
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0OB02075C
Abstract: The reactions of α,β-unsaturated N -acyliminium ions, generated in situ from 4( S )- O -substitutedhydroxy-5-hydroxy-5-vinyl- N -alkylpyrrolidin-2-ones, with allylsilanes and indoles leading to the formation of spirocyclic heterocycles, are reported.
Phloroglucinol Benzophenones and Xanthones from the Leaves of Garcinia cowa and Their Nitric Oxide Production and α-Glucosidase Inhibitory Activities
Publisher: American Chemical Society (ACS)
Date: 20-12-2019
DOI: 10.1021/ACS.JNATPROD.9B00849
Abstract: Five new compounds-two phloroglucinol benzophenones, garciniacowones F (
Synthesis of castanospermine
Publisher: Elsevier BV
Date: 03-2008
Synthesis of Bridged Heterocycles via Sequential 1,4- and 1,2-Addition Reactions to α,β-Unsaturated N -Acyliminium Ions: Mechanistic and Computational Studies
Publisher: American Chemical Society (ACS)
Date: 08-02-2016
Abstract: Novel tricyclic bridged heterocyclic systems can be readily prepared from sequential 1,4- and 1,2-addition reactions of allyl and 3-substituted allylsilanes to indolizidine and quinolizidine α,β-unsaturated N-acyliminium ions. These reactions involve a novel N-assisted, transannular 1,5-hydride shift. Such a mechanism was supported by examining the reaction of a dideuterated indolizidine, α,β-unsaturated N-acyliminium ion precursor, which provided specifically dideuterated tricyclic bridged heterocyclic products, and from computational studies. In contrast, the corresponding pyrrolo[1,2-a]azepine system did not provide the corresponding tricyclic bridged heterocyclic product and gave only a bis-allyl adduct, while more substituted versions gave novel furo[3,2-d]pyrrolo[1,2-a]azepine products. Such heterocyclic systems would be expected to be useful scaffolds for the preparation of libraries of novel compounds for new drug discovery programs.
6-Hydroxy-5,6-seco-stemocurtisine: A novel seco-stemocurtisine-type alkaloid
Publisher: Elsevier BV
Date: 11-2013
Two new bioactive iridoids from Rothmannia wittii
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.FITOTE.2016.07.007
Abstract: The first reported study of the isolation and identification of compounds from the bark and fruit of Rothmannia wittii yielded two new iridoids, 6β-hydroxy-10-O-acetylgenipin (1) and 10-O-acetylmacrophyllide (2) together with six known iridoids 6β-hydroxygenipin (3), genipin (4), garjasmine (5), cerbinal (6), and mixture of β-gardiol (7) and α-gardiol (8) benzoic acid (9) vanillic acid (10) and stigmasterol (11). Their structures were elucidated by spectroscopic methods. Iridoid 1 showed antimycobacterial activity against Mycobacterium tuberculosis with a MIC value of 12.50μg/mL. Iridoid 2 showed cytotoxicity against the NCI-H187 cancer cell line with an IC50 value of 6.82μg/mL. In addition, 2 and 5 exhibited weak cytotoxic activity against KB and MCF-7 cell lines, while 4 was active against the NCI-H187 cancer cell line.
Erratum to “A new protoberberine alkaloid from Meconopsis simplicifolia (D. Don) Walpers with potent antimalarial activity against a multidrug resistant Plasmodium falciparum strain” [J. Ethnopharmaco
Publisher: Elsevier BV
Date: 05-2014
Antimalarial Oxoprotoberberine Alkaloids from the Leaves of Miliusa cuneata
Publisher: American Chemical Society (ACS)
Date: 03-2016
DOI: 10.1021/ACS.JNATPROD.5B01054
Abstract: Five new oxoprotoberberine alkaloids, miliusacunines A-E (1-5), along with nine known compounds, 6-14, were isolated from an acetone extract of the leaves and twigs of Miliusa cuneata. Their structures were elucidated by spectroscopic analysis. All isolated compounds were evaluated for their cytotoxicities against the KB and Vero cell lines and for antimalarial activities against the Plasmodium falciparum strains TM4 and K1 (a sensitive and a multi-drug-resistant strain, respectively). Compound 1 showed in vitro antimalarial activity against the TM4 strain, with an IC50 value of 19.3 ± 3.4 μM, and compound 2 demonstrated significant activity against the K1 strain, with an IC50 value of 10.8 ± 4.1 μM. Both compounds showed no discernible cytotoxicity to the Vero cell line at the concentration levels evaluated.
Sequential 1,4- and 1,2-addition reactions to α,β-unsaturated N-acyliminium ions: A new strategy for the synthesis of spiro and bridged heterocycles
Publisher: American Chemical Society (ACS)
Date: 07-11-2013
DOI: 10.1021/OL4029513
Abstract: Novel bicyclic and tetracyclic spirocycles and tricyclic bridged heterocyclic systems can be readily prepared from sequential 1,4- and 1,2-addition reactions of latent bis-nucleophiles to α,β-unsaturated N-acyliminium ions.
Synthesis and antibacterial activity of C2-symmetric binaphthyl scaffolded amino acid derivatives
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.EJMECH.2011.06.024
Abstract: The synthesis of eleven novel antibacterial agents is reported. The structures are based on a C(2)-symmetric binaphthyl scaffold which holds two identical chains consisting of a short linker, a basic amino acid and a small hydrophobic side chain. Antibacterial activity is revealed for a number of derivatives down to an MIC of 2 μg/mL (2 μM) against Staphylococcus aureus--comparable to vancomycin, and an MIC of 31 μg/mL (31 μM) against some vancomycin-resistant enterococcal strains.
The isolation of bioactive flavonoids from Jacaranda obtusifolia H. B. K. ssp. rhombifolia (G. F. W. Meijer) Gentry
Publisher: Walter de Gruyter GmbH
Date: 06-2012
DOI: 10.2478/V10007-012-0014-1
Abstract: The paper describes the bioassay-guided isolation, structure elucidation and anticancer evaluation of five flavonoids (-)-liquiritigenin ( 1 ), (-)-neoliquiritin ( 2 ), isoliquiritigenin ( 3 ), isoliquiritin ( 4 ) and formononetin ( 5 ) from the twigs of Jacaranda obtusifolia H. B. K. ssp. rhombifolia (G. F. W. Meijer) Gentry. The structures were elucidated based on 1 H, 13 C NMR, comprehensive 2D NMR, MS analyses and comparison with previously reported spectral data. Compounds 1 and 3 were demonstrated to be inhibitory in vitro against NCI-H187 (small cell lung cancer) with IC 50 values of 30.1 and 16.6 μg mL -1 , respectively. The isolates were non-cytotoxic to Vero cells (African green monkey kidney).
Composition and antituberculosis activity of the volatile oil of Heliotropium indicum Linn. growing in Phitsanulok, Thailand
Publisher: Wiley
Date: 2006
DOI: 10.1002/FFJ.1577
Synthesis of stemofoline analogues as acetylcholinesterase inhibitors
Publisher: Elsevier BV
Date: 09-2012
Syntheses of spiro[cyclopropane-1,3′-oxindole]-2-carboxylic acid and cyclopropa[c]quinoline-7b-carboxylic acid and their derivatives
Publisher: Elsevier BV
Date: 2007
A new protoberberine alkaloid from Meconopsis simplicifolia (D. Don) Walpers with potent antimalarial activity against a multidrug resistant Plasmodium falciparum strain
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.JEP.2013.09.052
Abstract: The aerial components of Meconopsis simplicifolia (D. Don) Walpers are indicated in Bhutanese traditional medicine for treating malaria, coughs and colds, and the infections of the liver, lung and blood. This study is to validate the ethnopharmacological uses of this plant and also identify potent antimalarial drug leads through bioassays of its crude extracts and phytochemical constituents. Meconopsis simplicifolia (D. Don) Walpers was collected from Bhutan and its crude MeOH extract was subjected to acid-base fractionation. Through repeated extractions, separations and spectroscopic analysis, the alkaloids obtained were identified and tested for their antimalarial and cytotoxicity activities. Phytochemical studies resulted in the isolation of one new protoberberine type alkaloid which we named as simplicifolianine and five known alkaloids: protopine, norsanguinarine, dihydrosanguinarine, 6-methoxydihydrosanguinarine and oxysanguinarine. Among the five of the alkaloids tested, simplicifolianine showed the most potent antiplasmodial activities against the Plasmodium falciparum strains, TM4/8.2 (chloroquine-antifolate sensitive strain) and K1CB1 (multidrug resistant strain) with IC50 values of 0.78 μg/mL and 1.29 μg/mL, respectively. The compounds tested did not show any significant cytotoxicity activities against human oral carcinoma KB cells and normal Vero cells of African kidney epithelial cells. This study validated the traditional uses of the plant for the treatment of malaria and identified a new alkaloid, simplicifolianine as a potential antimalarial drug lead.
Cationic Peptidomimetic Amphiphiles Having a N-Aryl- or N-Naphthyl-1,2,3-Triazole Core Structure Targeting Clostridioides (Clostridium) difficile: Synthesis, Antibacterial Evaluation, and an In Vivo C. difficile Infection Model
Publisher: MDPI AG
Date: 26-07-2021
DOI: 10.3390/ANTIBIOTICS10080913
Abstract: Clostridioides (also known as Clostridium) difficile is a Gram-positive anaerobic, spore producing bacterial pathogen that causes severe gastrointestinal infection in humans. The current chemotherapeutic options are inadequate, expensive, and limited, and thus inexpensive drug treatments for C. difficile infection (CDI) with improved efficacy and specificity are urgently needed. To improve the solubility of our cationic hiphilic 1,1′-binaphthylpeptidomimetics developed earlier that showed promise in an in vivo murine CDI model we have synthesized related compounds with an N-arytriazole or N-naphthyltriazole moiety instead of the 1,1′-biphenyl or 1,1′-binaphthyl moiety. This modification was made to increase the polarity and thus water solubility of the overall peptidomimetics, while maintaining the aromatic character. The dicationic N-naphthyltriazole derivative 40 was identified as a C. difficile-selective antibacterial with MIC values of 8 µg/mL against C. difficile strains ATCC 700057 and 132 (both ribotype 027). This compound displayed increased water solubility and reduced hemolytic activity (32 µg/mL) in an in vitro hemolysis assay and reduced cytotoxicity (CC50 32 µg/mL against HEK293 cells) relative to lead compound 2. Compound 40 exhibited mild efficacy (with 80% survival observed after 24 h compared to the DMSO control of 40%) in an in vivo murine model of C. difficile infection by reducing the severity and slowing the onset of disease.
Mallopenins A–E, Antibacterial Phenolic Derivatives from the Fruits of Mallotus philippensis
Publisher: American Chemical Society (ACS)
Date: 18-07-2019
DOI: 10.1021/ACS.JNATPROD.9B00182
Abstract: The chromatographic separation of the components of the acetone extract of
Studies towards the synthesis of polyhydroxylated pyrrolidine alkaloids isolated from Broussonetia kazinoki (moraceae)
Publisher: Elsevier BV
Date: 12-2022
The synthesis of carbon linked bis-benzylisoquinolines using Mizoroki-Heck and Sonagashira coupling reactions
Publisher: Elsevier BV
Date: 2009
An assessment of the Bhutanese traditional medicine for its ethnopharmacology, ethnobotany and ethnoquality: Textual understanding and the current practices
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.JEP.2013.04.030
Abstract: : This study involves the assessment of the Bhutanese traditional medicine (BTM) which was integrated with the mainstream biomedicine in 1967 to provide primary health care services in the country. It caters to 20-30% of the daily out-patients within 49 traditional medicine units attached to 20 district modern hospitals and 29 Basic Health Units in the country. : This study presents the ethnopharmacological, ethnobotanical and the ethnoquality concepts in relation to mainstream Tibetan medicine and describes the current practices of BTM. : Experienced BTM practitioners (Drung-tshos and Smen-pas) were selected using a convenience s ling method and were interviewed using an open questionnaire followed by informal discussions. The corpus of BTM, Tibetan and scientific literature was obtained and the information on ethnopharmacological, ethnoquality and ethnobotanical concepts and current practices of BTM was extracted. : This study found that the BTM shares many similarities in terms of materia medica, pharmacopoeia and the principles and concepts of ethnopharmacology and ethnobotany with its mainstream Tibetan medicine. However, the resourceful Bhutanese Drung-tshos and Smen-pas have adapted this medical system based on the local language, culture, disease trend, health care needs and their familiarity with the locally available medicinal ingredients making it particular to the country. A number of notable distinctions observed in the current practices include a code of classification of diseases (only 79 of 404 types of disorders recognized), formulations (currently used only 103 of thousands formulation types), usage of medicinal plants (only 229 species of thousands described) and selected treatment procedures (golden needle and water therapy). This BTM was found to cater to 20-30% of daily out-patients visiting 49 modern hospitals and basic health units in the country. : The BTM has been evolved from the Tibetan medicine. While the pharmacopoeia, ethnopharmacology, ethnobotany and the ethnoquality aspects shares commonalities with the mainstream Tibetan medicine, there are some practices unique to BTM. Such uniqueness observed in the current practices of BTM include formulations, medicinal plants collection and usage, and the treatment procedures including golden needle and water therapy. This could be a promising source of information for the rediscovery of useful remedies, the development of modern phytotherapeutics and the establishment of efficient quality control measures.
Rhodium-catalysed tetradehydro-Diels–Alder reactions of enediynes via a rhodium-stabilized cyclic allene
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC04390G
Abstract: Room temperature Rh-catalysed tetradehydro-Diels–Alder reaction via an unusual Rh-stabilised allene.
The Chemical Synthesis of the 1-C-Alkyl Substituted Pyrrolidine and Piperidine Iminosugar Natural Products and their Analogues
Publisher: Bentham Science Publishers Ltd.
Date: 12-2023
DOI: 10.2174/1385272827666230124150741
Abstract: A review of the chemical synthesis of the 1-C-alkyl substituted pyrrolidine and piperidine iminosugar natural products and their analogues (where the alkyl chain comprises two or more carbons) is provided. These syntheses can be grouped into nine different synthetic strategies that share a common approach toward installing the alkyl substituent. These include nucleophilic addition to aldimines Grignard additions to glycosylamines, cyclic imides, and carbohydrates Weinreb ketone synthesis nucleophilic addition to cyclic nitrones the Overmann rearrangement the allylation of hemiaminals and the Petasis borono-Mannich reaction. The broussonetine alkaloids have proven popular synthetic targets to develop new synthetic methods and verify these target molecules' structures and stereochemistry.
Influence of Plantlet Age and Different Soilless Culture on Acclimatization of Stemona curtisii Hook.f.
Publisher: Science Alert
Date: 15-10-2012
Highly diastereoselective synthesis of enantioenriched anti-α-allyl-β-fluoroamines
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CC02765C
Abstract: A highly diastereoselective synthesis (dr = 99 : 1 97 : 3) of enantioenriched anti -α-allyl-β-fluoroamines (ee = 86–92%) has been developed involving a highly diastereoselective Petasis allyl borono-Mannich reaction of ( S )- or ( R )-α-fluoroaldehydes.
Dasymaschalolactams A–E, Aristolactams from a Twig Extract of Dasymaschalon dasymaschalum
Publisher: American Chemical Society (ACS)
Date: 29-10-2019
DOI: 10.1021/ACS.JNATPROD.9B00506
Abstract: Five new aristolactam alkaloids (
Stereoselective synthesis of two new trihydroxylated pyrrolidines using a meyer-schuster rearrangement
Publisher: Informa UK Limited
Date: 15-08-2011
Structure elucidation of cyclohexene (9Z)-octadec-9-enyl ethers isolated from the leaves of Uvaria cherrevensis (Annonaceae)
Publisher: Elsevier BV
Date: 04-2019
Synthesis of benzo[c]chromen-6-ones via novel cyclic aryl-Pd(II)-ester enolate intermediates
Publisher: Elsevier BV
Date: 11-2007
Intramolecular versus intermolecular oxidative couplings of ester tethered di-aryl ethers
Publisher: Elsevier BV
Date: 11-2007
The synthesis of 2′, 2′-bis-benzylisoquinolines and their cytostatic activities
Publisher: Elsevier BV
Date: 11-2007
Microwave‐Assisted Facile Synthesis and Crystal Structure of cis‐9,10,11,15‐Tetrahydro‐9,10[3′,4′]‐furanoanthracene‐12,14‐dione
Publisher: Informa UK Limited
Date: 03-2006
Desmoschinensisflavones A and B, two rare flavones having a hybrid benzyl benzoate ester-flavone structural framework from Desmos chinensis Lour
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0RA09985F
Abstract: Two rare flavones having a hybrid benzyl benzoate ester-flavone structural framework, desmoschinensisflavones A and B ( 1 and 2 ), together with 12 known compounds ( 3–14 ) were isolated from Desmos chinensis (red flower).
Fimbricalyx A, a novel phenanthrenone derivative having a rare 2H-benz[e]inden-2-one substructure
Publisher: Elsevier BV
Date: 04-2013
Uvarialuridols A-C, three new polyoxygenated cyclohexenes from the twig and leaf extracts of Uvaria lurida
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.FITOTE.2019.104340
Abstract: The first phytochemical investigation of Uvaria lurida resulted in the isolation and identification of three new polyoxygenated cyclohexenes, (+)-(1R,2S,3R,6S)-uvarialuridols A-C (1-3), together with 10 known compounds (4-13). All new structures were elucidated by spectroscopic methods and HRESIMS. The absolute configurations of compounds 1 and 5 were confirmed by X-ray diffraction analysis using Cu Kα radiation. The absolute configurations of compounds 2-4 were identified from comparisons of their specific rotations and ECD spectra with those of known compounds. Compound 11 showed α-glucosidase inhibitory activity with an IC
Copper-mediated cyclization-halogenation and cyclization-cyanation reactions of β-hydroxyalkynes and o -alkynylphenols and anilines
Publisher: American Chemical Society (ACS)
Date: 21-04-2010
DOI: 10.1021/JO1005119
Abstract: The CuX (X = I, Br, Cl, CN)-mediated cyclization-halogenation and cyclization-cyanation reactions of beta-hydroxyalkynes and o-alkynylphenol and -aniline derivatives give rise to 3-halo- and 3-cyanofuro[3,2-b]pyrroles, 3-iodo-, 3-bromo-, and 3-cyanobenzofurans, and 3-cyanoindoles, respectively.
MODEL STUDIES TOWARDS THE TOTAL SYNTHESIS OF THE STEMONA ALKALOID 1-HYDROXYPROTOSTEMONINE: SYNTHESIS OF ENT-1-HYDROXYSTEMOAMIDE
Publisher: The Japan Institute of Heterocyclic Chemistry
Date: 2011
DOI: 10.3987/COM-11-S(P)8
Gold- and Silver-Catalysed Cyclisation Reactions of β-Amino Allenes
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CH18197
Abstract: Herein we report the formation of pyrrolines and tetrahydropyridines from the cyclisation reactions of β-amino allenes by both AuI and AgI catalysts in yields ranging from 5 to 70 %. AuI catalysts favour a 5-endo-dig cyclisation before rapid rearrangement to the 5-exo-dig product, while AgI favours a 6-endo-trig cyclisation. We also report the first known Ag2O catalysed cyclisation reaction of an allene which occurred in good yield (61 %).
Ethnobotanical authentication and identification of Khrog-sman (Lower Elevation Medicinal Plants) of Bhutan
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.JEP.2011.01.034
Abstract: The Bhutanese form of g.so-ba-rig-pa medicine, which is a scholarly medical system, belongs to a larger system of medicinal corpus that spreads from Mongolia to India. It uses medicinal plants as a bulk ingredient but only 'Higher Elevation Medicinal Plants' have been botanically identified so far. Our study reports the botanical identification of 'Lower Elevation Medicinal Plants' and their ethnomedical uses. To botanically identify the 'Lower Elevation Medicinal Plants' used in Bhutanese traditional medicine. A five stage process was conducted which consisted of: (1) a survey of specialized ancient ethnomedical literatures (Pharmacopoeias and formularies) (2) freely listing the 'Lower Elevation Medicinal Plants' reported in the ancient Bhutanese medical texts and translating their ethnomedical uses in equivalent terms of English (3) making field visits, collecting herbarium specimens and photographs, and spot identification of plants (4) double blind testing of Bhutanese traditional medicine practitioners for authentication and standardization of Bhutanese g.so-ba-rig-pa names (5) organising workshops for open forum discussions on medicinal plants involving Traditional Physicians and other professional participants of the relevant areas. We identified the botanical names of 113 'Lower Elevation Medicinal Plants' belonging to 68 families and 104 genera. Out of 113 medicinal plant species identified, 92 species are currently used in Bhutan and the remaining 21 species were not used in the current formulation, but described in the Bhutanese traditional medical texts. The identification of these 21 species was achieved both ethnomedically and botanically for the first time. Out of the 28 plant species that are currently imported from India, we found for the first time, even to the knowledge of Traditional Physicians, that 16 of them are actually growing abundantly in Bhutan. Among the plant parts collected, seeds were the most prominent followed by fruits and then roots. Our study identified 113 'Lower Elevation Medicinal Plants' out of which 92 of them are used daily in formulating 102 multi-ingredient prescription medicines in Bhutan.
Phytochemical Studies on Stemona aphylla: Isolation of a New Stemofoline Alkaloid and Six New Stemofurans
Publisher: American Chemical Society (ACS)
Date: 02-12-2010
DOI: 10.1021/NP100668S
Abstract: A new stemofoline alkaloid, (2'S)-hydroxy-(11S,12R)-dihydrostemofoline (3), new stemofurans M-R (8-13), and known compounds stemofoline (1), (2'S)-hydroxystemofoline (2), stemofuran E (4), stemofuran F (5), stemofuran J (6), and stilbostemin F (7) have been isolated from the root extracts of Stemona aphylla. The structures and relative configurations of these new compounds have been determined by spectroscopic data interpretation and from semisynthetic studies. These natural and semisynthetic alkaloids were tested for acetylcholinesterase inhibitory activities and were found to be 10-20 times less active than 1',2'-didehydrostemofoline itself. Stemofurans 4, 6, 8, 11, and 13 were tested for their antibacterial and antifungal activities. Three of these showed antibacterial activities against MRSA with MIC values of 15.6 μg/mL.
Palladium-catalysed enantio- and regioselective (3 + 2) cycloaddition reactions of sulfamidate imine-derived 1-azadienes towards spirocyclic cyclopentanes
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3SC01510F
Abstract: Formation of valuable spiroheterocycles with multiple contiguous stereogenic centres from palladium-catalysed enantioselective (3 + 2) cycloaddition reactions of sulfamidate-derived azadienes and vinylcyclopropanes.
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