New furostanol saponins from Allium ascalonicum L.

An analysis of the polar extracts from Allium ascalonicum L. led to the isolation of two new furostanol saponins (compound 1 and 2) and two known furostanol saponins (compound 3 and 4). On the basis of 1D and 2D NMR (including 1 H, 13 C NMR, 1 H 1 H COSY, HSQC, TOCSY, HMBC, and NOESY), FAB‐MS spectrometry, and chemical methods, their structures were elucidated as (25 R )‐26‐ O ‐β‐ D ‐glucopyranosyl‐22‐hydroxy‐5α‐furost‐2‐one‐3β, 5, 6β, 26‐tetraol‐3‐ O ‐α‐ L ‐rhamnopyranosyl‐(1→2)‐β‐ D ‐glucopyranoside (ascalonicoside C, 1), (25 R )‐26‐ O ‐β‐ D ‐glucopyranosyl‐22‐methoxy‐5α‐furost‐2‐one‐3β, 5, 6β, 26‐tetraol‐ 3‐ O ‐α‐ L ‐rhamnopyranosyl‐(1→2)‐β‐ D ‐glucopyranoside (ascalonicoside D, 2), (25 R )‐26‐ O ‐β‐ D ‐glucopyranosyl‐22‐hydroxy‐5‐ene‐furostan‐3β, 26‐diol‐3‐ O ‐α‐ L ‐rhamnopyranosyl‐(1→4)‐α‐ L ‐rhamnopyranosyl‐(1→4)‐[α‐ L ‐rhamnopyranosyl‐(1→2)]‐β‐ D ‐glucopyranoside (dichotomin, 3), and (25 R )‐26‐ O ‐β‐ D ‐glucopyranosyl‐22‐hydroxy‐5‐ene‐furostan‐3β, 26‐diol‐3‐ O ‐α‐ L ‐rhamnopyranosyl‐(1→2)‐[α‐ L ‐arabinofuranosyl‐(1→4)]‐β‐ D ‐ glucopyranoside (parisaponin I, 4). Copyright © 2007 John Wiley & Sons, Ltd.