Anti-Osteoclastic Activity of Artemisia capillaris Thunb. Extract Depends upon Attenuation of Osteoclast Differentiation and Bone Resorption-Associated Acidification Due to Chlorogenic Acid, Hyperoside, and Scoparone

The present study attempts to elucidate the anti-osteoporotic activity of Artemisia capillaris Thunb. in the form of anti-osteoclastic effect and responsible bioactive compounds. The contents of chlorogenic acid, caffeic acid, hyperoside, isoquercitrin, isochlorogenic acid A, and scoparone in Artemisia capillaris hydroethanolic extract (ACHE) were 38.53, 0.52, 4.07, 3.03, 13.90, and 6.59 mg/g, respectively. ACHE diminished osteoclast differentiation and bone resorption due to chlorogenic acid, hyperoside, and scoparone. In addition, ACHE attenuated acidification as well as reducing tumor necrosis factor receptor-associated factor 6 (TRAF6) expression and its association with vacuolar H⁺-adenosine triphosphatase (V-ATPase). Furthermore, chlorogenic acid, hyperoside, and scoparone from A. capillaris abrogated the association of V-ATPase with TRAF6, suggesting that the blockage of bone resorption by A. capillaris was partially mediated by reducing acidification through down-regulating interaction of V-ATPase with TRAF6 due to scoparone as well as chlorogenic acid and hyperoside. These results imply that the anti-osteoclastic effect of A. capillaris through down-regulating osteoclast differentiation and bone resorption may contribute to its anti-osteoporotic effect.