Cytotoxic Sesterterpenes from Thai Marine Sponge Hyrtios erectus.

Four sesterterpenes, erectusolides B, C, D, and seco-manoalide-25-methyl ether, two 2-furanone derivatives, erectusfuranones A and B, together with thirteen known sesterterpenes, (6)-neomanoalide-24-acetate, two diastereomers of 24--methylmanoalide, luffariolide B, manoalide, (6)- and (6)-neomanoalide, seco-manoalide, scalarafuran, 12-acetylscalarolide, 12-epi--deacetyl-19-deoxyscalarin, 12-epi-scalarin, and 12--deacetyl-12-epi-scalarin, three indole alkaloids, 5-hydroxy-1-indole-3-carbaldehyde, hyrtiosine A, and variabine B, and one norterpene, cavernosine were isolated from the marine sponge . Their structures were determined by means of spectroscopic methods and the absolute configurations of the asymmetric centers were determined using the modified Mosher's method. The cytotoxic activities for the isolated compounds have been reported.