Six new ergosterols from the marine-derived fungus Rhizopus sp.

Six new ergosterols, including 3beta-hydroxyl-(22E, 24R)-ergosta-5,8,22-trien-7,15-dione (1), 3beta-hydroxyl-(22E, 24R)-ergosta-5,8,14,22-tetraen-7-one (2), 3beta,15beta-dihydroxyl-(22E, 24R)-ergosta-5,8(14),22-trien-7-one (3), 3beta,15alpha-dihydroxyl-(22E, 24R)-ergosta-5,8(14),22-trien-7-one (4), 3beta-hydroxyl-(22E, 24R)-ergosta-5,8(14),22-trien-7,15-dione (5), and 5alpha,8alpha-epidioxy-23,24(R)-dimethylcholesta-6,9(11),22-trien-3beta-ol (6), have been isolated from the marine-derived fungus Rhizopus sp., along with four known ones (7-10). The structures of the new compounds were determined on the basis of extensive spectroscopic data. All compounds were evaluated for their cytotoxic activities on P388, A549, HL-60, and BEL-7420 cell lines by the MTT and SRB methods.