RESUMO
An abundant sponge of the order Bubarida was selected for further chemical investigation following biological and chemical screening of sponges collected from Futuna Islands in the Indo-Pacific. Ten new nitrogenous bisabolene derivatives were isolated and identified: the monomeric theonellin formamide analogues named bubaridins A-F (1-6) with unusual oxidised linear chains, and the first isocyanide/formamide dimeric and cyclised bisabolenes 7-9. The structure elucidation of these nitrogenous bisabolenes involved HRESIMS, NMR, and ECD analyses, and the chiral compounds were found to be racemates. A biosynthetic hypothesis for the production of these metabolites is proposed and some chemotaxonomic considerations are discussed. Furthermore, the antimicrobial and antitumoral activity were evalutated and the trans-dimer theonellin isocyanide (7) was shown to exhibit potent and selective antifungal activity.