Brasiliquinones A–C, new cytotoxic benz[a]anthraquinones with an ethyl group at C-3 from actinomycete Nocardia brasiliensis

Abstract

Three new cytotoxic benz[a]anthraquinones with an ethyl group at C-3, brasiliquinones A–C 1–3, have been isolated from the actinomycete Nocardia brasiliensis IFM 0089, and their structures elucidated on the basis of spectroscopic data and by chemical means. Brasiliquinone A 1 is the first benz[a]anthraquinone possessing ristosamine as an O-glycoside moiety, while brasiliquinones B 2 and C 3 correspond to the aglycone of 1 and the 8-O-methyl derivative of 2, respectively.