Synergistic effect of trace elements and flavonoids from Epimedium koreanum Nakai on primary osteoblasts

Several trace elements, particularly, manganese (Mn) and zinc (Zn), are essential in bone metabolism as cofactors for specific enzymes. It has been reported that there exists the relationship between osteoporosis and trace element-deficiency and the efficacy of Ca, Mn and Zn supplementation on spinal bone mineral density in postmenopausal women. Traditional Chinese medicines (TCM), such as Herba epimedii, were proved to be effective for prevention of osteoprosis in vivo; however, the efficacy of the main constituents and/or crude extract was not ideal in vitro, which suggested that they may work in another way. The purpose of the present study was to examine whether the combination of icariin and total flavonoids (TF) from Herba epimedii with mineral elements, which were abundant in Herba epimedii, would have a more beneficial effect on the viability and differentiation of primary osteoblasts than either agent alone, and to analyze the dada for a possible synergistic, additive or antagonistic effect. The combinations of 10 μmol/L Zn, Ca and Mn with icariin and total flavonoids greatly improved the cell viability and meanwhile dramatically enhanced the alkaline phosphatase activity as compared to each agent alone. On the other hand, an increased cell growth inhibition was also observed by combining 0.1 μmol/L, 1 μmol/L Zn with 10 μmol/L icariin, and 10 μmol/L Mn with 0.06 μg/mL total flavonoids. Meanwhile a decreased alkaline phosphatase activity was also found in several icariin-Zn/Mn and total flavonoids-Zn/Ca/Mn combinations. These results suggested that mineral elements (Zn, Ca, Mn) greatly enhanced the efficacy of icariin and total flavonoids from Herba epimedii on the viability and differentiation of primary osteoblasts by certain combinations. Supported by the National Natural Science Foundation of China, the Research Grants Council of Hong Kong Joint Research Scheme (Grant No. 30418007), and Key Lab Funding Scheme of Shenzhen Municipal Government