Bioactive Triterpene Glycosides from the Sea Cucumber <i>Holothuria fuscocinerea</i>

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-β-d-glucopyranosyl-(1→3)-β-d- glucopyranosyl-(1→4)-β-d-quinovopyranosyl-(1→2)-4-O-sodiumsulfato-β-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.