Two new flavonol glycosides from Epimedium koreanum Nakai

Abstract

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-(γ-hydroxyl-γ,γ-dimethyl)-propyl-3-O-α-l-rhamnopyranosyl-flavonol-7-O-β-d-glucopyranoside (1) and 5-hydroxyl-4′-methoxy-8-(γ-methoxy-γ,γ-dimethyl)-propyl-3-O-β-d-glucopyranosyl(1 → 3)-α-l-rhamnopyranosyl-flavonol-7-O-β-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.

Keywords:

• Epimedium koreanum Nakai
• icarisid B
• icarisid C
• UMR106
• proliferation
• ALP

Acknowledgements

This work was supported by the National Science Foundation of China (NSFC Ref. 30418007) and the Research Grants Council of Hong Kong (RGC Ref. N_PolyU536/04). The authors are grateful to Professor Qi-Shi Sun, Shenyang Pharmaceutical University, for the identification of the plant of E. koreanum Nakai and the Shanghai Institute of Materia Medica of Chinese Academy of Science for HR-ESI-MS experiments. Thanks are also extended to Mr Haiyang Yu for UV and IR, Mr Weihua Jiao and Ms Ping Weng for optical rotations, Mr Jin-Hui Huang for NMR, and Ms Ling Li for ESI-MS.