Sesquiterpene isocyanides, isothiocyanates, thiocyanates, and formamides from the Thai sponge Halichondria sp.

Nine new nitrogenous sesquiterpenes (1–9) were isolated together with 11 known compounds (10–20) from the Thai marine sponge Halichondria sp. The structures of the isolated compounds were determined on the basis of extensive NMR studies and high-resolution MS measurements as well as comparison with literature data. Sixteen of these metabolites were evaluated for cytotoxic activity against six tumor cell lines.