Isolation of bioactive 5 alpha,8 alpha-epidioxy sterols from the marine sponge Luffariella cf. variabilis

The lipid extract of the marine sponge Luffariella cf. variabilis from Mayo tte (Indian Ocean) has proven to be an extraordinarily rich source of a wid e variety of unusual steroids belonging to the 5 alpha,8 alpha-epidioxy ste rol family. Ten epidioxy sterols have been identified: 5 alpha,8 alpha-epid ioxycholesta-6,22-dien-3 beta-ol, 5 alpha,8 alpha-epidioxycholest-6-en-3 be ta-ol, 5 alpha,8 alpha-epidioxy-24(xi)-methylcholesta-6,22-dien- 3 beta-ol, 5 alpha,8 alpha-epidioxy-24(S)-methylcholest-6- en-3 beta-ol and its epime r (24R), 5 alpha,8 alpha-epidioxy- 24(S)-ethylcholesta-6,22-dien-3 beta-ol and its epimer (24R), 5 alpha,8 alpha-epidioxy-24(S)-ethylcholest-6-en- 3 b eta-ol and its epimer (24R), along with 5 alpha,8 alpha- epidioxy-24(xi)-me thylcholesta-6,9(11),22-trien-3 beta-ol. Their structures were determined b y nuclear magnetic resonance (H-1, C-13) and electron impact mass spectrome try. The mixture of the 10 steroids showed inhibitive activity against the human T-cell leukemia/lymphotropic virus type I (HTLV-I) and also displayed cytotoxic activity against the human breast cancer cell line (MCF7WT).