Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Chemistry a European Journal 8989-8994 ab initio calculations antibiotics arsenic mass spectrometry natural products 2006 fdi:010055024 ENG Chemistry a European Journal 0947-6539 CC:0002427935-0009 35 10.1002/chem.200600783 https://www.documentation.ird.fr/hor/fdi:010055024 https://www.documentation.ird.fr/intranet/publi/depot/2012-04-05/010055024.pdf 12 Horizon (IRD) 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 northeastern 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. 035