Solanum incanum and S. heteracanthum as sources of biologically active steroid glycosides: Confirmation of their synonymy

Abstract A new spirostanol saponin ( 1 ), along with four known saponins, dioscin ( 2 ), protodioscin ( 3 ), methyl-protodioscin ( 4 ), and indioside D ( 5 ), and one known steroid glycoalkaloid solamargine ( 6 ) were isolated from the two synonymous species, Solanum incanum and S. heteracanthum . The structure of the new saponin was established as (23 S ,25 R )-spirost-5-en-3β,23-diol 3- O -{β- d -xylopyranosyl-(1→2)- O -α- l -rhamnopyranosyl-(1→4)-[ O- α- l -rhamnopyranosyl-(1→2)]-β- d -glucopyranoside}, by using a combination of 1D and 2D NMR techniques including 1 H, 13 C, COSY, TOCSY, NOESY, HSQC and HMBC experiments and by mass spectrometry. The compounds 1 , 3 , 4 and 5 were evaluated for cytotoxicity against five cancer cell lines and for antioxidant and cytoprotective activity.