Novel acylated saponins from Montbretia (Crocosmia crocosmiiflora). Isolation of saponins and the structures of crocosmiosides A, B and H.

Nine novel triterpenoid saponins, named crocosmiosides A-I, were isolated from the corms of montbretia (Crocosmia crocosmiiflora N. E. BR., Iridaceae). Among those saponins, the structures of crocosmiosides A (1), B (2) and H (3) were determined on the basis of spectral and chemical evidence. They are unique acylated saponins which have 2, 9, 16-trihydroxypalmitic acid glycoside as the acyl moiety, and their structures were elucidated as polygalacic acid-3-{α-L-arabinopyranosyl-(1→6)-β-D-glucopyranosido}-28-{2-O-[β-D-apio-D-furanosyl-(1→4)-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl]-4-O-(9-hydroxy-16-α-L-rhamnopyranosyloxy-2-β-D-xylopyranosyloxyhexadecanoyl)-β-D-fucopyranoside} (1), polygalacic acid-3-{α-L-arabinopyranosyl-(1→6)-β-D-glucopyranosido}-28-{2-O-[β-D-apio-D-furanosyl-(1→4)-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl]-4-O-(9, 16-dihydroxy-2-β-D-xylopyranosyloxyhexadecanoyl)-β-D-fucopyranoside} (2) and polygalacic acid-3-{α-L-arabinopyranosyl-(1→6)-β-D-glucopyranosido}-28-{2-O-[β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl]-4-O-(9-hydroxy-16-α-L-rhamnopyranosyloxy-2-β-D-xylopyranosyloxyhexadecanoyl)-β-D-fucopyranoside} (3), respectively.