Novel linear C22-sesterterpenoids from sponge Ircinia formosana

Four unprecedented C-22-sesterterpenes, irciformonins A-D (1-4), have been isolated from the marine sponge Ircinia formosana, collected off the coast of eastern Taiwan. The structures of the isolated metabolites were established on the basis of extensive spectral analysis, primarily 1- and 2D-NMR. Compounds 3 and 4 exhibited significant cytotoxicity against human colon (WiDr) tumor cells. (c) 2006 Elsevier Ltd. All rights reserved.