Therapeutic effect of aqueous-extract from a traditional Chinese medical herb Drynaria fortunei on rat experimental model of alveolar bone resorption Influence of prenylation at C-8 of ring A of flavonoid on bioactivity of parent compound Research on effect of Sargentodoxae caulis on activity of osteoclasts and proliferation differentiation of osteoblasts Comparative study on effect of 8-prenlynaringenin and narigenin on activity of osteoclasts cultured in vitro