Bioactive triterpene glycosides from the sea cucumber Holothuria fuscocinerea.

Bioassay-guided fractionation of the active n-BuOH extract of the sea cucumber Holothuria fuscocinerea resulted in the isolation of three new triterpene glycosides, fuscocinerosides A (1), B (2), and C (3), along with two known glycosides, pervicoside C (4) and holothurin A (5), as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. Compounds 1-5 possess the same tetrasaccharide moiety, 3-O-methyl-beta-D-glucopyranosyl-(1-->3)-beta-D- glucopyranosyl-(1-->4)-beta-D-quinovopyranosyl-(1-->2)-4-O-sodiumsulfato-beta-D-xylopyranosyl, linked to C-3 of holostane triterpene aglycones that differ in their side chains and 17-substituents. Their structures were elucidated by extensive spectral studies as well as chemical evidence. All the glycosides showed in vitro cytotoxicity against two human tumor cell lines.