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

The lipid extract of the marine sponge Luffariella cf. variabilis from Mayotte (Indian Ocean) has proven to be an extraordinarily rich source of a wide variety of unusual steroids belonging to the 5 alpha,8 alpha-epidioxy sterol family. Ten epidioxy sterols have been identified: 5 alpha,8 alpha-epidioxycholesta-6,22-dien-3 beta-ol, 5 alpha,8 alpha-epidioxycholest-6-en-3 beta-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 epimer (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 beta-ol and its epimer (24R), along with 5 alpha,8 alpha- epidioxy-24(xi)-methylcholesta-6,9(11),22-trien-3 beta-ol. Their structures were determined by nuclear magnetic resonance (H-1, C-13) and electron impact mass spectrometry. 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).