Four new ursane‐type saponins from Morina nepalensis var. alba

Four new ursane‐type saponins, monepalosides C–F, together with a known saponin, mazusaponin II, were isolated from Morina nepalensis var. alba Hand.‐Mazz. Their structures were determined to be 3‐ O ‐α‐ L ‐arabinopyranosyl‐(1 → 3)‐&[alpha;‐ L ‐rhamnopyranosyl‐(1 → 2)]‐α‐ L ‐arabinopyranosylpomolic acid 28‐ O ‐β‐ D ‐glucopyranosyl‐(1 → 6)‐β‐ D ‐glucopyranoside (monepaloside C, 1 ), 3‐ O ‐α‐ L ‐arabinopyranosyl‐(1 → 3)‐&[alpha;‐ L ‐rhamnopyranosyl‐(1 → 2)]‐β‐ D ‐xylopyranosylpomolic acid 28‐ O ‐β‐ D ‐glucopyranosyl‐(1 → 6)‐β‐ D ‐glucopyranoside (monepaloside D, 2 ), 3‐ O ‐α‐ L ‐arabinopyranosyl‐(1 → 3)‐&[beta;‐ D ‐glucopyranosy‐(1 → 2)]‐α‐ L ‐arabinopyranosylpomolic acid 28‐ O ‐β‐ D ‐glucopyranosyl‐(1 → 6)‐β‐ D ‐glucopyranoside (monepaloside E, 3 ) and 3‐ O ‐β‐ D ‐xylopyranosylpomolic acid 28‐ O ‐β‐ D ‐glucopyranoside (monepaloside F, 4 ) on the basis of chemical and spectroscopic evidence. 2D NMR techniques, including 1 H– 1 H COSY, HMQC, 2D HMQC‐TOCSY, HMBC and ROESY, and selective excitation experiments, including SELTOCSY and SELNOESY, were utilized in the structure elucidation and complete assignments of 1 H and 13 C NMR spectra. Copyright © 2002 John Wiley & Sons, Ltd.