Ulmosides A and B: flavonoid 6-C-glycosides from Ulmus wallichiana, stimulating osteoblast differentiation assessed by alkaline phosphatase.

Chemical investigation of Ulmus wallichiana stem bark resulted in isolation and identification of three new compounds (2S,3S)-(+)-3',4',5,7-tetrahydroxydihydroflavonol-6-C-beta-D-glucopyranoside (1), (2S,3S)-(+)-4',5,7-trihydroxydihydroflavonol-6-C-beta-D-glucopyranoside (3) and 3-C-beta-D-glucopyranoside-2,4,6-trihydroxymethylbenzoate (8), together with five known flavonoid-6-C-glucosides (2, 4-7). Their structures were elucidated using 1D and 2D NMR spectroscopic analysis. The absolute stereochemistry in compounds 1 and 3 were established with the help of CD data analysis and comparison with the literature data analysis. All the isolated compounds (1-8) were assessed for promoting the osteoblast differentiation using primary culture of rat osteoblast as an in vitro system. Compounds 1-3 and 5 significantly increased osteoblast differentiation as assessed by alkaline phosphatase activity.