Two new flavonol glycosides from Otostegia limbata BENTH.

A BuOH-soluble part of the methanolic extract from the roots of Otostegia limbata yielded two new flavonol glycosides; kaempferol 3-O-[beta-D-glucopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->3)]-[beta-D-glucopyranosyl-(1-->4)]-alpha-L-rhamnopyranoside]-7-O-[alpha-L-rhamnopyranoside] (1) and kaempferol 3-O-[beta-D-glucopyranosyl-(1-->4)-beta-D-6'''''[4-hydroxy (E)-cinnamoyl]glucopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-alpha-L-rhamnopyranoside]-7-O-[alpha-L-rhamnopyranoside] (2). The structures of these compounds were elucidated by spectroscopic and chemical means. To the best of our knowledge, these are the largest flavonoids derivatives described so far from the genus Otostegia.