New furostanol glycosides from the rhizomes of Dioscorea futschauensis R. Kunth

Abstract

Two new furostanol glycosides, 26-O-beta-D-glucopyranosyl-3beta,26-dihydroxy-23(S)-methoxyl-25(R)-furosta-5,20(22)-dien-3-O-alpha-L-rhamnopyranosyl(1 --> 2)-[beta-D-glucopyranosyl(1 --> 3)]-beta-D-glucopyranoside (dioscoreside E, 1) and 26-O-beta-D-glucopyranosyl-3beta,26-dihydroxy-25(R)-furosta-5,20(22)-dien-3-O-alpha-Lrhamnopyranosyl(1 --> 2)-[beta-D-glucopyranosyl (1 --> 3)]-beta-D-glucopyranoside (prtotogracillin, 2), together with 11 known furostanol glycosides were isolated from the rhizomes of Dioscorea futshauensis R. Kunth. Their structures were elucidated on the basis of spectroscopic analysis (NMR and FABMS). Their anti-fungal activity against the plant pathogenic fungus Pyricularia oryzae and cytotoxic activity on K562 cancer cell line were evaluated in vitro.