Two novel furostanol saponins from Ophiopogon japonicus

Two novel furostanol saponins were isolated from the fresh tubers of Ophiopogon japonicus. Comprehensive spectroscopic analysis allowed the chemical structures of the compounds to be assigned as (25R)-26-[(O-beta-d-glucopyranosyl-(1 --> 2)-beta-d-glucopyranosyl)]-22alpha-hydroxyfurost-5-ene-3-O-beta-d-xylopyranosyl-(1 --> 4)-O-[alpha-l-rhamnopyranosyl-(1 --> 2)]-beta-d-glucopyranoside (1, ophiopogonin F) and (25R)-26-[(O-beta-d-glucopyranosyl-(1 --> 6)-beta-d-glucopyranosyl)]-22alpha-hydroxyfurost-5-ene-3-O-beta-d-xylopyranosyl-(1 --> 4)-O-[alpha-l-rhamnopyranosyl-(1 --> 2)]-beta-d-glucopyranoside (2, ophiopogonin G). The rare furostanol saponins with two glucosyl residues at C-26 position were isolated from the natural source for the first time.