Céline Moriou

Unprecedented Stylissazoles A–C from Stylissa carteri: Another Dimension for Marine Pyrrole‐2‐aminoimidazole Metabolite Diversity

Theirintriguingdimeric polycyclic ring systems that were isolated during thelast years revealed their elaborate structures and moleculardiversity which arise from a variety of modes of dimerizationand polycyclization. Structurally, it is assumed that thesemetabolites arise from the crucial intermediates clathrodin,

Quorum sensing inhibitors from Leucetta chagosensis Dendy, 1863

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. Micro‐organisms can also represent a virulent pathogen for marine invertebrates such as sponges, which need to protect themselves against these microbes. Sponges self defence mechanisms involving dialogue molecules thus represent a pertinent research track for potent anti‐infective and anti‐biofilm activities such as quorum sensing inhibitors (QSIs). The investigation of the QSI crude extract of Leucetta chagosensis Dendy, 1863 led to the isolation of three new alkaloids, isonaamine D, di‐isonaamidine A and leucettamine D, along with the known isonaamine A and isonaamidine A. Isonaamidine A and isonaamine D were identified as inhibitors of the three quorum sensing pathways of Vibrio harveyi (CAI‐1, AI‐2 and harveyi auto inducer), but isonaamidine A displayed the strongest activity on AI‐2 biosensor. Both compounds are new examples of natural QSIs of V. harveyi. These results outline the importance of these secondary metabolites for their producing organisms themselves in their natural environment, as well as the potential of the marine resource for aquaculture needs.

Netamines O-S, Five New Tricyclic Guanidine Alkaloids from the Madagascar Sponge Biemna laboutei, and Their Antimalarial Activities.

In our continuing program to isolate new compounds from the Madagascar sponge Biemna laboutei, five new tricyclic guanidine alkaloids, netamines O – S (1–5, resp.), have been identified together with the known compounds netamine E (6) and mirabilin J (7). The structures of all new netamines were assigned on the basis of spectroscopic analyses. Their relative configurations were established by analysis of ROESY data and comparison with literature data. Netamines O, P, and Q, which were isolated in sufficient quantities, were tested for their cytotoxic activities against KB cells and their activities against the malaria parasite Plasmodium falciparum. Netamines O and Q were found to be moderately cytotoxic. Netamines O, P, and Q exhibited antiplasmodial activities with IC50 values of 16.99±4.12, 32.62±3.44, and 8.37±1.35u2005μM, respectively.

Metabolomics approach to chemical diversity of the Mediterranean marine sponge Agelas oroides

Abstract The Mediterranean marine sponge Agelas oroides is known to contain a large quantity of oroidin, a deterrent, antifouling and antibiofilm pyrrole-2-aminoimidazole. In contrast with other tropical specimens, the chemical composition of Mediterranean Agelas oroides is surprisingly relatively poor in other related metabolites. In the course of finding novel marine natural products, LC-MS based metabolomics study of the Mediterranean Agelas oroides, however, revealed that next to the major compound oroidin, the sponge contains in fact a great diversity of known pyrrole-imidazole alkaloids in minute amounts. Here, we describe identification of 13 known oroidin class alkaloids along with one new monobromoagelaspongin (24). Five betaines and one amine were also identified from the aqueous fraction. One of those compounds (−)-equinobetaine B (30) was found to be an enantiomer of the known natural product (+)-equinobetaine B.

Unguiculins A-C: cytotoxic bis-guanidine alkaloids from the French Polynesian sponge, Monanchora n. sp

Abstract 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 efficacy against several human cancer cells with IC50 values in the micromolar range.

C2′-F Stereoconfiguration As a Puckering Switch for Base Stacking at the Dinucleotide Level

Fluorine configuration at C2 of the bis(2-fluorothymidine) dinucleotide is demonstrated to drive intramolecular base stacking. 2-β F-Configuration drastically reduces stacking compared to the 2-α series. Hence, base stacking emerges as being tunable by the C2-F stereoconfiguration through dramatic puckering variations scrutinized by NMR and natural bond orbital analysis. Accordingly, 2-β F-isomer photoreactivity is significantly reduced compared to that of the 2-α F-isomer.