Isolation and identification of flavonoids from Epimedium koreanum and their effects on proliferation of RAW 264.7 cell line

Objective: To study the antiosteoporosis activity of flavonoids isolated from Epimedium koreanum. Methods: The compounds were separated by column chromatography with silica gel and Sephadex LH-20 and identified by spectral analysis (ESI-MS, ¹H-NMR, and ¹³C-NMR), respectively. MTT Assay was used to investigate the effects of the compounds on proliferation of preosteoclast RAW 264.7 cell line in vitro. Results: Five compounds were isolated from the ethyl acetate extract of the aerial part of E. koreanum. Their structures were identified as icariin (I), baohuoside II (II), epimedokoreanin B (III), baohuoside I (IV), and hyperoside (V). The results indicated that compound II could promote the proliferation of RAW 264.7 cell line at concentrations of 0.1-100 μmol/L. Compound I at concentrations of 0.1-100 μmol/L could inhibit the proliferation of RAW 264.7 cell line and turned to stimulate the proliferation of RAW 264.7 cell line as concentration increased. Compound III at concentrations of 1.0 and 10 μmol/L had no effect on the proliferation, but significantly inhibited the proliferation of RAW 264.7 cell Line at other concentrations. Except individual concentration, compounds IV and V at concentrations of 0.1-100 μmol/L significantly inhibited the proliferation of RAW 264.7 cell line. Conclusion: The effects of flavonoids on the proliferation of RAW 264.7 cell line are bi-directional, depending on concentrations and their chemical structures. The osteoporsis may be controlled by E. koreanum through inhibiting the proliferation and differentiation of preosteoclast.