A series of new 5,6-epoxysterols from a Chinese sponge Ircinia aruensis

Chromatographic separation of the ethanolic extract of the marine sponge, Ircinia aruensis, resulted in the isolation and characterization of six new sterols. 5α,6α-Epoxy-26,27-dinorergosta-7,22-en-3β-ol (1), 5α,6α-epoxycholesta-7,22-en-3β-ol (2), 5α,6α-epoxyergosta-7,24(28)-en-3β-ol (3), 5α,6α-epoxyergosta-7-en-3β-ol (4), 5α,6α-epoxystigmasta-7,22-en-3β-ol (5), 5α,6α-epoxystigmasta-7-en-3β-ol (6). The structures of the new compounds were determined on the basis of extensive spectroscopic data (IR, MS, 1H and 13C NMR, HMQC, and HMBC) analyses. The cytotoxic of 1–3 toward a limited panel of cancer cell lines is also reported.