Reported here is the first polyarsenic compound ever found in nature. Denominated arsenicin A, it was isolated along a bioassay-guided fractionation of the organic extract of the poecilosclerid sponge Echinochalina bargibanti collected from the north-eastern coast of New Caledonia. In defining an adamantine-type polyarsenic structure for this compound, deceptively simple NMR spectra were complemented by extensive mass spectral analysis. However, it was only the synthesis of a model compound that provided the basis to discriminate structure 4 from other spectrally compatible structures for arsenicin A; to this end, a comparative ab initio simulation of IR spectra for the natural and the synthetic compounds was decisive. Arsenicin A is endowed with potent bactericidal and fungicidal activities on human pathogenic strains. All this may revive pharmacological interest in arsenic compounds while prompting us to rethink the arsenic cycle in nature.

No abstract

Five new amino acid derivatives were isolated from the New Caledonian sponge Jaspis carteri, together with known bengamides A and B. The structures of the new compounds were determined by interpretation of their spectral data and by comparison with spectral data of known bengamides. Compounds 4−7 are simply the tridecanoate and pentadecanoate analogues of the original bengamides A and B, whereas compound 8 is a caprolactam formamide derivative of bengamide B.

The structure of title compound (I) is assigned by NMR and mass spectroscopy and supported by a comparative ab initio simulation of IR spectra for the natural compound and synthetic analogues. -(MANCINI*, I.; GUELLA, G.; FROSTIN, M.; HNAWIA, E.; LAURENT, D.; DEBITUS, C.; PIETRA, F.; Chem. Eur. J. 12 (2006) 35, 8989-8994; Lab. Chim. Bioorg., Univ. Trento, I-38050 Povo-Trento, Italy; Eng.) -Nuesgen 14-214

Ciguatera is the most common food poisoning found in the tropical and subtropical areas, acquired by the consumption of marine products. A lot of work concerning its etiology, its epidemiology and its clinical effects, as well as the discovery of the toxins involved, the description of their transfer, the study of their structure and the analysis of their pharmacological effects, have allowed a better understanding of the ciguateric phenomenon. Ciguatera is known to be due to benthic dinoflagellates belonging to the Gambierdiscus gender, in particular G. toxicus. Under specific conditions, this microalga produces gambier-toxins, toxins which are the precursors of other toxins, the ciguatoxins. However, the factors supporting this production are still poorly known, and the implication of others dinoflagellates, cyanophytes or bacteria have been suspected. In contrast, the fish species responsible for the transmission of ciguatera are globally well identified. The clinical symptoms of the intoxication are now well described. They mainly include digestive, neurological and cardiovascular disorders whose preponderance varies according to the nature of the toxins involved, since toxin structures are different between one ocean and the other. The ciguateric intoxication tends to be exported towards non endemic areas where it is still misdiagnosed. No specific antidote exists to date, and it is only by symptomatic or palliative treatments that ciguatera is currently treated.