Two new flavonol glycosides from Epimedium koreanum Nakai.

Two new flavonol glycosides, named icarisid B (1) and icarisid C (2), along with seven known flavonol glycosides were isolated from the bioassay-directed fractions of the aqueous extract of Epimedium koreanum Nakai. The structures of the two new compounds were established on the basis of chemical and spectroscopic methods (ESI-MS, 1D, and 2D NMR) as 5-hydroxyl-4'-methoxy-8-(gamma-hydroxyl-gamma,gamma-dimethyl)-propyl-3-O-alpha-L-rhamnopyranosyl-flavonol-7-O-beta-D-glucopyranoside (1) and 5-hydroxyl-4'-methoxy-8-(gamma-methoxy-gamma,gamma-dimethyl)-propyl-3-O-beta-D-glucopyranosyl(1 --> 3)-alpha-L-rhamnopyranosyl-flavonol-7-O-beta-D-glucopyranoside (2), respectively. All the nine compounds were tested for their effects on proliferation and alkaline phosphatase (ALP) activity using UMR106 cells. As a result, five compounds showed stimulating effects on both the proliferation and ALP activity, which suggested that they might be used as potential leading compounds to cure osteoporosis.