AIM To study the activity of ecdysterone from Achyranthes bidentata Bl. (AB) promoting proliferation of osteoblast like (OB like) UMR106 cells and to determine its content in AB by HPLC method. METHODS Ecdysterone isolated from AB was cultured with OB like cells UMR106 together in vitro and the proliferation of OB like cells was determined by MTT assay. The chromatographic conditions for determining ecdysterone included an ODS column (250 mm×4 6 mm, 5 μm), a mobile phase consisting of a mixture of water acetontrile tetrahydrofuran (86∶11∶3), detection wavelength of 243 nm, and column temperature of 27℃. Phenacetin was used as the internal standard. RESULTS The ecdysterone from AB had significant activity promoting proliferation of OB like cells, the proliferation was promoted by 41% ( n =3). The average recovery of ecdysterone was 96 2% (RSD=2 1%), the calibration was linear in the range of 30～300 μg·mL -1 (γ=0 9998). CONCLUSION Ecdysterone was screened quickly by cultivating with OB like cells together in vitro . The HPLC method is accurate, fast and reproducible for the determination of ecdysterone in AB.
