Furostane-type steroidal saponins from the roots of Chlorophytum borivilianum

Four new furostanol steroid saponins, borivilianosides A-D (1-4, resp.), corresponding to (3β,5α,22R,25R)-26-(β-D-glucopyranosyloxy)-22- hydroxyfurostan-3-yl O-β-D-xylopyranosyl-(1 → 3)-O-β-D- glucopyranosyl-(1 → 4)-O-[α-L-rhamnopyranosyl-(1 → 2)]-β-D-galactopyranoside (1), (3β,5α,22R,25R)-26-(β-D- glucopyranosyloxy)-22-methoxyfurostan-3-yl O-β-D-xylopyranosyl-(1 → 3)-O-β-D-glucopyranosyl-(1 → 4)-O-[α-L-rhamnopyranosyl-(1 → 2)]-β-D-galactopyranoside (2), (3β,5α,22R,25R)-26-(β-D- glucopyranosyloxy)-22-methoxyfurostan-3-yl O-β-D-xylopyranosyl-(1 → 3)-O-[β-D-glucopyranosyl-(1 → 2)]-O-β-D-glucopyranosyl-(1 → 4)-β-D-galactopyranoside (3), and (3β,5α,25R)-26-(β-D- glucopyranosyloxy)furost-20(22)-en-3-yl O-β-D-xylopyranosyl-(1 → 3)-O-[β-D-glucopyranosyl-(1 → 2)]-O-β-D-glucopyranosyl-(1 → 4)-β-D-galactopyranoside (4), together with the known tribuluside A and (3β,5α,22R,25R)-26-(β-D-glucopyranosyloxy)-22-methoxyfurostan-3- yl O-β-D-xylopyranosyl-(1 → 2)-O-[β-D-xylopyranosyl-(1 → 3)]-O-β-D-glucopyranosyl-(1 → 4)-O-[α-L-rhamnopyranosyl-(1 → 2)]-β-D-galactopyranoside were isolated from the dried roots of Chlorophytum borivilianum SANT and FERN. Their structures were elucidated by 2D-NMR analyses (COSY, TOCSY, NOESY, HSQC, and HMBC) and mass spectrometry.