The correlation of Salvia miltiorrhiza extract-induced regulation of osteoclastogenesis with the amount of components tanshinone I, tanshinone IIA, cryptotanshinone, and dihydrotanshinone.

Tanshinone I, tanshinone IIA, cryptotanshinone, and dihydrotanshinone are compounds that have been isolated from the root of Salvia miltiorrhiza (SM), which is also known as "Danshen." The SM extract has been used successfully in China for treating postmenopausal syndrome. Furthermore, it was previously reported that SM had inhibitory effect on osteoporosis in ovariectomized rats. Another study reported that the four components, tanshinone I, tanshinone IIA, cryptotanshinone, and dihydrotanshinone, prevented osteoclast function in an in vitro system. However, there are no reports of a correlation between SM and its components on osteoporosis and osteoclast function. This study was undertaken to examine the effect of SM on osteoclastogenesis and osteoblast differentiation, which are two important markers of the bone physiology. Through a rapid, sensitive and specific isocratic liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitative determination of four diterpenoids, tanshinone I, tanshinone IIA, cryptotanshinone, and dihydrotanshinone in SM, the authors tried to correlate the amount of tanshinone compounds in SM into the antiosteoclast activity. The SM fraction (methanol and ethanol isolated) with a low concentration of tanshinone IIA (1 mug/mL) had no effect on the alkaline phosphotase activity (osteoblast differentiation), but completely inhibited osteoclastogenesis. Although the tanshinone compound itself showed similar effects, the concentrations of commercially available tanshinone (diterpenoids, tanshinone I, tanshinone IIA, cryptotanshinone, and dihydrotanshinone) needed for antiosteoclast activity was almost 1000 times more than that of tanshinone in SM fraction. This suggests that there are other unknown compounds in the SM extract that have a synergistic effect with tanshinone. These results also suggest that tanshinone can be a good marker compound to explain the antiosteoporotic function of SM.