Osteogenic constituents from Pterospermum acerifolium Willd. flowers

Phytochemical investigation of ethanol extracts of the Pterospermum acerifolium flowers led to the isolation and identification of two new flavones, 4'-(2-methoxy-4-(1,2,3-trihydroxypropyl) phenoxy luteolin (1) and 5,7,3'-trihydroxy-6-O-β-D-glucopyranosyl flavone (2), and one new lactone, 3,5-dihydroxyfuran-2(5H)-one (3) along with 14 known compounds (4-17). The structure of compounds 1-17 was established based on MS, 1D and 2D NMR, spectroscopic analysis. Eight of these compounds (1-6, 8 and 9) were assessed for osteogenic activity by using primary cultures of rat osteoblast. The compounds 1, 3 and 4 significantly stimulated osteoblast differentiation and mineralization as evident from a marked increase in expression of alkaline phosphatase and alizarin red-S staining of osteoblasts.