Osteoblastic differentiation bioassay and its application to investigating the activity of fractions and compounds from Psoralea corylifolia L.

A cell differentiation bioassay measuring alkaline phosphatase activity was developed using osteoblast-like UMR 106 cell line as a model. The effect of fractions and compounds of Psoralea corylifolia L. extract on osteoblastic differentiation was investigated. The fractions or compounds were co-cultured with cells for 48 h, the cellular ALP activity was then measured. The crude ethanol extract of Psoralea corylifolia L. increased ALP activity by 39.5% at a concentration of 0.1 mg/ml, and the activity was concentrated in the ethyl acetate fraction, which produced a maximum ALP activity increase of 38.2%. A significant activity was observed for a flavonoid, corylin, providing 30.0% increment in ALP. These effects suggest that Psoralea corylifolia L. extract, its ethyl acetate fraction and corylin would stimulate bone formation.