Sylvain Petek

Institute of Research for Development | IRD · 195 - Marine Environmental Sciences Laboratory (LEMAR)

Guided by a "Chemistry First" approach using molecular networking, eight new bright-blue colored natural compounds, namely dactylocyanines A-H (3-10), were isolated from the Polynesian marine sponge Dactylospongia metachromia. Starting from ilimaquinone (1), an hemisynthetic phishing probe (2) was prepared for annotating and matching structurally r...

Four bicyclic and three pentacyclic guanidine alkaloids (1-7) were isolated from a French Polynesian Monanchora n. sp. sponge, along with the known alkaloids monalidine A (8), enantiomers 9-11 of known natural product crambescins, and the known crambescidins 12-15. Structures were assigned by spectroscopic data interpretation. The relative and abso...

Dactylospongia metachromia and Dactylospongia elegans collected from French Polynesia were studied with a particular focus on the variation of the diastereomeric ratio between ilimaquinone (4) and 5-epi-ilimaquinone (5). More than 100 samples, covering an area of 4100 km2, were studied to try to clarify this intriguing issue. Nuclear magnetic reson...

First georeferenced system of this type for the study of natural products, Cantharella provides a solution to access, share, analyze, sustain and refresh data, for a sustainable valorization. This tool ensures traceability of samples, from harvest to bioassays, through the various processes leading to the active compounds. The Open Source technolog...

Surveys of French Polynesian sponges were undertaken over many years to fill the gap in our knowledge of this group as a cornerstone for the conservation of marine biodiversity, and also to investigate potential new economical resources in French Polynesia. The website https://sponges-polynesia.ird.fr/ and this eBook, generated from the website, ar...

Chemical investigation of the South-Pacific marine sponge Suberea clavata led to the isola- tion of eight new bromotyrosine metabolites named subereins 1–8 (2–9) along with twelve known co-isolated congeners. The detailed configuration determination of the first representative major compound of this family 11-epi-fistularin-3 (11R,17S) (1) is descr...

Chemical investigation of the French Polynesia Monanchora sp. marine sponge led to the isolation and identification of one pentacyclic guanidine alkaloid crambescidin acid (1) along with four simple nitrogenous compounds, including one nucleoside thymidine (2) and three amino acid derivatives, namely phenylethylamine (3), tryptophan (4) and phenyla...

Extracts from 26 marine macroalgal species (11 Phaeophyceae, 7 Chlorophyta, and 8 Rhodophyta) sampled from the lagoons of Tahiti, Moorea, and Tubuai (French Polynesia) were tested for several biological activities. The red macroalga Amansia rhodantha exhibited the strongest antioxidant activities using four complementary methodologies (total phenol...

Four new brominated tyrosine metabolites, aplyzanzines C-F (1-4), were isolated from the French Polynesian sponge Pseudoceratina n. sp., along with the two known 2-aminoimidazolic derivatives, purealidin A (5) and 6, previously isolated, respectively, from the sponges Psammaplysilla purpurea and Verongula sp. Their structures were assigned based on...

Marine natural products isolated from the sponge Fascaplysinopsis cf reticulata, in French Polynesia, were investigated as an alternative to antibiotics to control pathogens in aquaculture. The overuse of antibiotics in aquaculture is largely considered to be an environmental pollution, because it supports the transfer of antibiotic resistance gene...

Six long chain polyunsaturated fatty acids 1-6 with varied unsaturation degrees were identified from the nonpolar fractions of Monanchora n. sp. marine sponge. Their structures were determined mainly by H NMR and HRMS spectroscopic data interpretations.

Six long chain polyunsaturated fatty acids 1-6 with varied unsaturation degrees were identified from the nonpolar fractions of Monanchora n. sp. marine sponge. Their structures were determined mainly by 1H-NMR and HRMS spectroscopic data interpretations.

The Cover Feature shows a ring‐distortion strategy applied to the marine natural product ilimaquinone. A chemically diverse library of molecules was synthesised that included rearrangements of the sesquiterpene moiety and original reorganisations of the quinone ring. Compounds were evaluated as quorum sensing inhibitors of Vibrio Harveyi, an econom...

Herein, we describe the isolation and spectroscopic identification of eight new tetrabrominated tyrosine alkaloids 2-9 from the Polynesian sponge Suberea ianthelliformis, along with known major compound psammaplysene D (1), N,N-dimethyldibromotyramine, 5-hydroxy xanthenuric acid, and xanthenuric acid. Cytotoxicity and acetylcholinesterase inhibitio...

Herein, we describe the isolation and spectroscopic identification of eight new tetrabrominated tyrosine alkaloids 2-9 from the Polynesian sponge Suberea ianthelliformis, along with known major compound psammaplysene D (1), N,N-dimethyldibromotyramine, 5-hydroxy xanthenuric acid, and xanthenuric acid. Cytotoxicity and acetylcholinesterase inhibitio...

We report herein a ring‐distortion strategy applied to marine natural substances ilimaquinone and 5‐epi‐ilimaquinone. A chemically diverse library of molecules was synthesised that included rearrangements of the sesquiterpene moiety and original reorganisations of the quinone ring. Chemoinformatic analyses evaluated the rise of structural diversity...

Recently, molecular networking has emerged as a promising computer-based approach to visualize and organize MS/MS data sets arising from complex mixtures. The success of this strategy relies on the availability and quality of MS/MS data for the annotation of the networks. In this study, MS/MS spectra of a well-tailored phishing probe were incorpora...

Two new acyclic bis-guanidine alkaloids, unguiculins B-C (2-3), were isolated from a French Polynesian sponge Monanchora n. sp. together with the known compound unguiculin A (1). Their structures were established by spectroscopic data interpretation and comparison with the literature. Unguiculins A-C displayed antiproliferative and cytotoxic effica...

10th European Conference on Marine Natural Products, Kolymbari, Crete, Greece

Marine sponges of the genus Suberea (order: verongida) are known to be prolific source of a large array of structurally diverse bromotyrosine alkaloids. These alkaloids are exceedingly abundant in verongida order.[1-3] In this work, eight new tetrabrominated tyrosine alkaloids were isolated from the French Polynesian sponge Suberea ianthelliformis,...

Sponges of the marine genus Suberea (order: verongidea) are known to produce a large array of structurally diverse brominated tyrosine alkaloids, which considered chemotaxonomical markers. eight new tetrabrominated tyrosine alkaloids were isolated from the French Polynesian sponge Suberea ianthelliformis, along with the known natural products psamm...

Over the past few decades, French Polynesian reefs have experienced a large algal bloom by two members of the Fucales, Sargassum pacificum and Turbinaria ornata, accompanied with reef degradation. This proliferation is a threat to the equilibrium of the coral reef ecosystem, and recently, other species of brown algae are growing significantly and a...

The Marquesas Islands have no longer a reef formation as they possessed before the Holocene. Despite an important variety of coastal and deep habitats in a rich plankton ocean environment, invertebrate richness is less than in other archipelagos of French Polynesia. Only a few taxonomic groups were studied; those species which are of significant si...

Seven 2,5-diketopiperazines (DKPs) were isolated from the Fijian marine sponge Acanthella cavernosa. NMR and circular dichroism (CD) comparison with synthetic L-L DKPs allowed us to determine unambiguously the L-L absolute configuration of the natural DKPs. This work initiated the setting up of an optical properties database of natural DKPs, includ...

Sponges are a rich source for investigation of bioactive small molecules. They have been mostly investigated for the search of new pharmacological models or therapeutic agents for the treatment of human diseases. Microorganisms can also represent a virulent pathogen for marine invertebrates such as sponges, which need to protect themselves against...

Informations about Cantharella, a pharmacochemical database of natural products

We report here on an extensive survey of sponges from French Polynesia, recording presence/absence and an estimate of local abundance on sites spread in the 5 group of islands of French Polynesia (viz. the Marquesas Islands, Windward and Leeward Islands (together making the Society Islands), Tuamotu and Australes islands. Sponge distributions withi...

Marine sponges are known to be prolific producers of a wealth of diverse secondary metabolites.1 One unique class of sponge-derived metabolites includes compounds that feature complex polycyclic guanidine alkaloid cores, most of which exhibit diverse biological activities. Members of this class of marine natural products have been isolated predomin...

Plakortides R–U, four new polyketide endoperoxides, have been isolated from the marine sponge Plakinastrella mamillaris. Their structures were elucidated on the basis of extensive NMR spectroscopic (1H and 13C, COSY, HSQC, HMBC, and ROESY) and MS analyses and by chemical methods. In addition, a new method for the unambiguous stereochemical elucidat...

This paper reports on a survey of sponges from the higher island reefs and slopes of the Marquesas and Society Islands Archipelagos, French Polynesia, recording presence/absence and an estimate of local abundance at 109 sites from six and eight islands within each archipelago, respectively. Sponge distributions within archipelagos were relatively h...

Cantharella est une base de données accessible par internet, qui a pour objectif de centraliser et pérenniser les différentes informations collectées lors de programmes de recherche s’intéressant aux substances naturelles. Cet outil collaboratif permet : - d’assurer une traçabilité des organismes de la récolte aux tests biologiques en passant par l...

In this paper we report the isolation and the molecular characterization of a new class of PPARγ ligands from the marine environment. Biochemical characterization of a library of 13 oxygenated polyketides isolated from the marine sponge Plakinastrella mamillaris allowed the discovery of gracilioether B and plakilactone C as selective PPARγ ligands...

Sponges of the family Dysideidae (Dictyoceratida) are renowned for their diversity of secondary metabolites, and its genus Lamellodysidea, particularly Lamellodysidea herbacea, is the most studied taxon biochemically. Despite its importance, the taxonomic status of L. herbacea—whether it is a distinct species or a species complex—has never been ass...

Pipestelides A-C (2-4) are three new NRPS-PKS hybrid macrolides containing uncommon moieties, isolated from the Pacific marine sponge Pipestela candelabra. Their structures were elucidated on the basis of spectroscopic data. These cyclodepsipeptides appear to be biosynthetically related to jaspamide (aka jasplakinolide) (1) by chemical modification...

We report the isolation and the structural elucidation of a family of polyhydroxylated steroids from the marine sponge Theonella swinhoei. Decodification of interactions of these family with nuclear receptors shows that these steroids are potent agonists of human pregnane-X-receptor (PXR) and antagonists of human farnesoid-X-receptor (FXR) with the...

Indole derivatives including bromoindoles have been isolated from the South Pacific marine sponges Rhopaloeides odorabile and Hyrtios sp. Their structures were established through analysis of mass spectra and 1D and 2D NMR spectroscopic data. Their potential inhibitory phospholipase A₂ (PLA₂), antioxidant and cytotoxic activities were evaluated. Th...

The compound haliclonacyclamine A was isolated from the Haliclona sponge at Solomon Islands. It acts as a powerful in vitro and in vivo anti-plasmodial agent against the chloroquine-resistant Plasmodium falciparum strain FCB1and Plasmodium vinckei petteri-infected mice, respectively.

Malaitasterol A, an unprecedented bis-secosterol, was isolated from a Solomon collection of Theonella swinhoei. The structure was elucidated on the basis of a combination of comprehensive 1D and 2D NMR analysis, high-resolution mass spectrometry and DFT (13)C chemical shift calculations. The biological characterization of malaitasterol A provided e...

The compound haliclonacyclamine A was isolated from the Haliclona sponge at Solomon Islands. It acts as a powerful in vitro and in vivo anti-plasmodial agent against the chloroquine-resistant Plasmodium falciparum strain FCB1and Plasmodium vinckei petteri-infected mice, respectively.

The finding of new PXR modulators as potential leads for treatment of human disorders characterized by dysregulation of innate immunity and with inflammation is of wide interest. In this paper, we report the identification of the first example of natural marine PXR agonists, solomonsterols A and B, from a Theonella swinhoei sponge. The structures w...

Bioassay-directed fractionation of South Pacific marine sponges of the genus Xestospongia has led to the isolation of a number of halenaquinone-type polyketides, including two new derivatives named xestosaprol C methylacetal 7 and orhalquinone 8. Chemical characterization of these two new compounds was achieved by extensive 1D and 2D NMR spectrosco...

The study of the n-butanol extract of the New Caledonian sponge Agelas dendromorpha led to the isolation and identification of three new pyrrole-2-aminoimidazole (P-2-AI) alkaloids, named agelastatins E (3) and F (4) and benzosceptrin C (5), together with 10 known metabolites, agelastatin A (1), agelastatin D (2), sceptrin (6), manzacidin A, tauroa...

Nine new cyclodepsipeptides, homophymines B-E (2-5) and A1-E1 (1a-5a), were isolated from the polar extracts of the sponge Homophymia sp. The new structures, featuring new polyketide-derived end groups, were determined by interpretation of NMR and MS data. The configurations of the new end groups was secured by the application of J-based configurat...

Investigation of the marine sponge Coscinoderma mathewsi led to the isolation of two novel nitrogen-containing cheilanthane sesterterpenoids, coscinolactams A and B, together with known suvanine. The structures were elucidated by extensive spectroscopic measurements including NOE experiments to deduce the stereochemistry. The natural compounds, as...

Investigation of the marine sponge Coscinoderma mathewsi led to the isolation of two novel nitrogen-containing cheilanthane sesterterpenoids, coscinolactams A and B, together with known suvanine. The structures were elucidated by extensive spectroscopic measurements including NOE experiments to deduce the stereochemistry. The natural compounds, as...

A new anti-HIV cyclodepsipeptide, homophymine A, was isolated from a New Caledonian collection of the marine sponge Homophymia sp. The structure of homophymine A was determined by interpretation of spectroscopic data, acid hydrolysis, and LC-MS analysis. Homophymine A contains 11 amino acid residues and an amide-linked 3-hydroxy-2,4,6-trimethylocta...

Three new diterpene alkaloids, agelasine J (3), agelasine K (4), and agelasine L (5), were isolated from the marine sponge Agelas cf. mauritiana collected in the Solomon Islands. The structures of these compounds were elucidated by physical data analyses. They displayed in vitro antimalarial activity against Plasmodium falciparum.

Agelasidae sponges have been widely investigated, but still represent a good source of new marine metabolites. 1 In the course of our survey of bioactive substances from marine sources we investigated different extracts of Agelas cf mauritiana course of our survey of bioactive substances from marine sources, we investigated different extracts of Ag...

Cette campagne « BSM-Fiji », programmée du 7 au 28 avril 2007 avait pour objectif d’échantillonner algues, éponges et ascidies pour des études de pharmacologie et d’analyse de la biodiversité de la région. Les récoltes ont été réalisées dans les provinces de Bua, Macuata (île de Vanua Levu), Cakaudrauve (atolls des Ringgold), Lomaiviti (îles de N’G...

The reaction between α-chloroglycidic esters 1 and magnesium iodide in the presence of an excess of active magnesium led to magnesium α-ketoester enolates 3. Some synthetic applications of these new reagents are reported.

Results are reported on the efficient regioselective C-mono and C-dideuteriation of iodomagnesium enolates derived from α-ketoesters in aliphatic and glucidic series using [D4]acetic acid as the best deuterium donor.

KDO8PS (3-deoxy-D-manno-2-octulosonate-8-phosphate synthase) and DAH7PS (3-deoxy-D-arabino-2-heptulosonate-7-phosphate synthase) are attractive targets for the development of new anti-infectious agents. Both enzymes appear to proceed via a common mechanism involving the reaction of phosphoenolpyruvate (PEP) with arabinose 5-phosphate or erythrose-4...

This manuscript presents work of design, synthesis and biological study of new molecules with antibiotic aimings. The 2 therapeutic targets that we chose are enzymes, namely: the KDO-8-phosphate synthetase and the DAH-7-phosphate synthetase. These proteins are of the same family of the phosphoenolpyruvate lyases, and respectively catalyses the aldo...

Ce manuscrit présente les travaux de conception, de synthèse et d'étude biologique de nouvelles molécules à visées antibiotiques. Les 2 cibles thérapeutiques qui ont été choisies sont des enzymes, à savoir : la KDO-8-phosphate synthétase et la DAH-7-phosphate synthétase. Ces protéines de la même famille des phosphoénolpyruvate lyases catalysent la...