Hydroperoxysterols from the tunicate Eudistoma sp.

Two 27C hydroperoxysterols, 7beta-hydroperoxycholesterol (1) and its stereoisomer 7alpha-hydroperoxycholesterol (2), were isolated from the lipophilic extracts of a Formosan tunicate belonging to the genus Eudistoma. The structures of sterols 1 and 2 were elucidated on the basis of extensive spectral data analyses. Cytotoxicity of sterols 1 and 2 against a limited panel of cancer cell lines is also described. Sterol 1 show weak inhibitory effects on human neutrophil elastase release.