ORCID Profile
0000-0002-5708-1409
Current Organisation
University of Galway
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Publisher: MDPI AG
Date: 20-07-2018
DOI: 10.3390/MD16070242
Abstract: Two new zoanthamine alkaloids, namely 3-acetoxynorzoanthamine (1) and 3-acetoxyzoanthamine (2), have been isolated from the zoantharian Zoanthus cf. pulchellus collected off the coast of the Santa Elena Peninsula, Ecuador, together with three known derivatives: zoanthamine, norzoanthamine, and 3-hydroxynorzoanthamine. The chemical structures of 1 and 2 were determined by interpretation of their 1D and 2D NMR data and comparison with literature data. This is the first report of zoanthamine-type alkaloids from Zoanthus cf. pulchellus collected in the Tropical Eastern Pacific. The neuroinflammatory activity of all the isolated compounds was evaluated in microglia BV-2 cells and high inhibitory effects were observed in reactive oxygen species (ROS) and nitric oxide (NO) generation.
Publisher: Elsevier BV
Date: 12-2017
Publisher: MDPI AG
Date: 05-01-2022
DOI: 10.3390/MD20010052
Abstract: Sponges are at the forefront of marine natural product research. In the deep sea, extreme conditions have driven secondary metabolite pathway evolution such that we might expect deep-sea sponges to yield a broad range of unique natural products. Here, we investigate the chemo ersity of a deep-sea tetractinellid sponge, Characella pachastrelloides, collected from ~800 m depth in Irish waters. First, we analyzed the MS/MS data obtained from fractions of this sponge on the GNPS public online platform to guide our exploration of its chemo ersity. Novel glycolipopeptides named characellides were previously isolated from the sponge and herein cyanocobalamin, a manufactured form of vitamin B12, not previously found in nature, was isolated in a large amount. We also identified several poecillastrins from the molecular network, a class of polyketide known to exhibit cytotoxicity. Light sensitivity prevented the isolation and characterization of these polyketides, but their presence was confirmed by characteristic NMR and MS signals. Finally, we isolated the new betaine 6-methylhercynine, which contains a unique methylation at C-2 of the imidazole ring. This compound showed potent cytotoxicity towards against HeLa (cervical cancer) cells.
Publisher: American Chemical Society (ACS)
Date: 22-10-2020
Publisher: MDPI AG
Date: 11-02-2018
DOI: 10.3390/MD16020058
Publisher: American Chemical Society (ACS)
Date: 24-04-2019
DOI: 10.1021/ACS.JNATPROD.9B00173
Abstract: In the search for bioactive marine natural products from zoantharians of the Tropical Eastern Pacific, four new tyrosine dipeptides, named val iamides A-D (1-4), were isolated from Antipathozoanthus hickmani, and two new tyramine derivatives, 5 and 6, from Parazoanthus darwini. The phenols of all six tyrosine derivatives are substituted by bromine and/or iodine atoms at the ortho positions of the hydroxyl. The planar structures of these aromatic alkaloids were elucidated from 1D and 2D NMR experiments in combination with HRESIMS data, and the absolute configurations of 1-4 were deduced from comparison between experimental and calculated electronic circular dichroism spectra. As halogenated tyrosine derivatives could represent chemotaxonomic markers of these genera, we decided to undertake the first chemical investigation of another species, Terrazoanthus cf. patagonichus. As expected, no halogenated metabolite was evidenced in the species, but we report herein the identification of two new zoanthoxanthin derivatives, named zoamides E (7) and F (8), from this species. Antimicrobial and cytotoxicity bioassays revealed that val iamide B (2) displayed moderate cytotoxicity against the HepG2 cell line with an IC
Publisher: Informa UK Limited
Date: 30-11-2018
Publisher: MDPI AG
Date: 30-05-2019
DOI: 10.3390/MD17060319
Abstract: So far, the Futuna Islands located in the Central Indo-Pacific Ocean have not been inventoried for their ersity in marine sponges and associated chemical ersity. As part of the Tara Pacific expedition, the first chemical investigation of the sponge Narrabeena nigra collected around the Futuna Islands yielded 18 brominated alkaloids: seven new bromotryptamine derivatives 1–7 and one new bromotyramine derivative 8 together with 10 known metabolites of both families 9–18. Their structures were deduced from extensive analyses of nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) data. In silico metabolite anticipation using the online tool MetWork revealed the presence of a key and minor biosynthetic intermediates. These 18 compounds showed almost no cytotoxic effect up to 10 µM on human neuroblastoma SH-SY5Y and microglia BV2 cells, and some of them exhibited an interesting neuroprotective activity by reducing oxidative damage.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1OB02297K
Abstract: Ten nitrogenous bisabolene derivatives where isolated and structurally characterised from a Bubarida sponge collected in Futuna islands. An isocyanide bisabolene dimer showed potent antifungal activity.
Publisher: Elsevier BV
Date: 12-2020
Publisher: American Chemical Society (ACS)
Date: 06-07-2020
Publisher: American Chemical Society (ACS)
Date: 23-03-2017
DOI: 10.1021/ACS.ORGLETT.7B00369
Abstract: The first chemical study of the common species Terrazoanthus onoi, present off the coast of Ecuador, led to the identification of a new family of 2-aminoimidazole alkaloids named terrazoanthines A-C (1-3). Homologues 1 and 2 feature an unprecedented 6-(imidazol-5-yl)benzo[d]imidazole. Acyl substitution pattern and complete configurational assignments were deduced from comparison between experimental and theoretical
Publisher: Elsevier BV
Date: 09-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9NP00043G
Abstract: The dazzling marine zoantharians represent a reservoir of chemical ersity that remains to be unveiled. These fragile animals have so far been found to harbour the highly bioactive palytoxins or zoanthamines but also the harmless ecdysteroids or zoanthozanthins.
Publisher: American Chemical Society (ACS)
Date: 22-10-2021
Publisher: Springer Science and Business Media LLC
Date: 08-05-2018
DOI: 10.1038/S41598-018-25086-4
Abstract: Zoantharians represent a group of marine invertebrates widely distributed from shallow waters to the deep sea. Despite a high ersity and abundance in the rocky reefs of the Pacific Ocean, very few studies have been reported on the ersity of this group in the Tropical Eastern Pacific coasts. While molecular techniques recently clarified some taxonomic relationships within the order, the taxonomy of zoantharians is still highly challenging due to a lack of clear morphological characters and confusing use of different data in previous studies. Our first insight into the zoantharian ersity at El Pelado Marine Protected Area - Ecuador led to the identification of six species: Terrazoanthus patagonichus Terrazoanthus sp. Antipathozoanthus hickmani Parazoanthus darwini Zoanthus cf. pulchellus and Zoanthus cf. sociatus . A metabolomic approach using UHPLC-HRMS was proven to be very efficient as a complementary tool in the systematics of these species and specialized metabolites of the ecdysteroid and alkaloid families were identified as key biomarkers for interspecific discrimination. These results show good promise for an application of this integrative approach to other zoantharians.
Publisher: MDPI AG
Date: 03-07-2018
DOI: 10.20944/PREPRINTS201807.0046.V1
Abstract: Two new zoanthamine alkaloids, namely 3-acetoxynorzoanthamine (1) and 3-acetoxyzoanthamine (2), have been isolated from the zoantharian Zoanthus cf. pulchellus collected off the coast of the Peninsula of Santa Elena & ndash Ecuador, together with three known alkaloids zoanthamine, norzoanthamine and 3-hydroxynorzoanthamine. The chemical structures of 1 and 2 were determined by interpretation of their 1D and 2D NMR data and comparison with literature data. This is the first report of zoanthamine-type alkaloids from Zoanthus cf. pulchellus collected in the Tropical Eastern Pacific. The neuroinflammatory activity of all the isolated compounds were evaluated in microglia BV-2 cells and high inhibitory effects were observed in ROS and NO generation.
Publisher: MDPI AG
Date: 29-10-2019
DOI: 10.3390/MOLECULES24213890
Abstract: As part of an ongoing program to identify new bioactive compounds from Irish marine bioresources, we selected the subtidal sponge Spongosorites calcicola for chemical study, as fractions of this species displayed interesting cytotoxic bioactivities and chemical profiles. The first chemical investigation of this marine species led to the discovery of two new bisindole alkaloids of the topsentin family, together with six other known indole alkaloids. Missing the usual central core featured by the representatives of these marine natural products, the new metabolites may represent key biosynthetic intermediates for other known bisindoles. These compounds were found to exhibit weak cytotoxic activity against HeLa tumour cells, suggesting a specificity towards previously screened carcinoma and leukaemia cells.
Publisher: MDPI AG
Date: 26-09-2019
DOI: 10.3390/MICROORGANISMS7100394
Abstract: Much recent interest has arisen in investigating Streptomyces isolates derived from the marine environment in the search for new bioactive compounds, particularly those found in association with marine invertebrates, such as sponges. Among these new compounds recently identified from marine Streptomyces isolates are the octapeptidic surugamides, which have been shown to possess anticancer and antifungal activities. By employing genome mining followed by an one strain many compounds (OSMAC)-based approach, we have identified the previously unreported capability of a marine sponge-derived isolate, namely Streptomyces sp. SM17, to produce surugamide A. Phylogenomics analyses provided novel insights on the distribution and conservation of the surugamides biosynthetic gene cluster (sur BGC) and suggested a closer relatedness between marine-derived sur BGCs than their terrestrially derived counterparts. Subsequent analysis showed differential production of surugamide A when comparing the closely related marine and terrestrial isolates, namely Streptomyces sp. SM17 and Streptomyces albidoflavus J1074. SM17 produced higher levels of surugamide A than S. albidoflavus J1074 under all conditions tested, and in particular producing -fold higher levels when grown in YD and 3-fold higher levels in SYP-NaCl medium. In addition, surugamide A production was repressed in TSB and YD medium, suggesting that carbon catabolite repression (CCR) may influence the production of surugamides in these strains.
Publisher: Elsevier BV
Date: 09-2018
No related grants have been discovered for Olivier THOMAS.