A New Furostanol Saponin from Dioscorea futshauensis

A new furostanol saponin presenting moderate bioactivity of inducing morphological deformation of Pyricularia oryzae mycelia was isolated from Dioscorea futshauensis R.Kunth by bioactivity-guided fractionation. The structure was established as 26-O-β-D-glucopyranosyl-3β, 26-diol-23(S)-methoxyl-(25R)-furost-5,20 (22)-diene-3-O-[α-L-rhamnopyranosyl (1→2)-b-D-glucopyranosyl (1→3)]-β-D-glucopyranoside on the basis of chemical evidencesand spectral analysis, especially by 2D-NMR techniques.