Inhibitory activity of the ethyl acetate fraction from Viscum coloratum on bone resorption.

The effects of four fractions, a hexane fraction, an ethyl acetate fraction, an n-butanol fraction and a water fraction, from a water extract of Herba Visci were investigated to find the fraction, in in vitro experiments, with the greatest ability to inhibit the formation of osteoclast-like multinucleated cells from mouse bone marrow cells and also to inhibit Ca-45 release from a mouse parietal bone organ culture system. The ethyl acetate fraction was able to inhibit the formation of osteoclast-like cells in a dose-dependent manner and was also able to potently inhibit the release of Ca-45 even at a low concentration. Therefore, a further in vivo experiment was performed to determine if the ethyl acetate fraction had antiosteoporotic activity. It was found to inhibit the decreases in total and cancellous bone mineral density, in cancellous and cortical bone mineral content as well as in cortical bone thickness and in the X-axis strength index of tibiae of ovariectomized rats. The principle constituents of the ethyl acetate fraction were determined to be (+)-syringaresinol O-beta-glucopyranoside, 2-homoeriodictyol 7-O-glucoside and viscumneoside I by HPLC analysis.