Synergistic inhibitory effect of Icariside II with Icaritin from Herba Epimedii on pre-osteoclastic RAW264.7 cell growth

Increasing evidence shows the therapeutic superiority of herbal extracts in comparison to isolated single constituents. One of the reasons may be attributed to the synergy effect of compound combinations. Flavonoids from Herba Epimedii have been shown to have therapeutic effect against bone loss. Our previous study showed that Icariside II inhibited pre-osteoclast RAW264.7 growth. The aim of this study was to investigate whether the activity of Icariside II is synergized by other components of Herba Epimedii. The inhibitory activity of Icariside II was significantly enhanced in the presence of the extract of Herba Epimedii (EHE) at the ratio of 1:1, 1:5 and 1:10. Icaritin, another flavonoid constituent, was shown here to inhibit RAW264.7 growth in a dose-dependent manner. Further, we found that Icariside II, together with Icaritin, synergistically inhibited RAW264.7 growth. The synergistic effect is significant when the ratio of Icariside II and Icaritin was 10:1, 5:1, 1:1, 1:2, and 1:5, respectively. In conclusion, Icaritin were an active component. The inhibitory activity of Icariside II on pre-osteoclast RAW264.7 growth was synergized by Icaritin, which maybe contribute to the efficiency of Herba Epimedii extract on curing bone-related diseases, such as osteoporosis.