We performed the present study to investigate whether Rehmannia glutinosa Libosch (RG) extracts (RGX) and Eleutherococcus senticosus Max (ES) extracts (ESX) play any roles in bone metabolism. We examined cellular activities of bone cells by measurement of osteoblastic cell viability, osteoprotegerin (OPG) secretion from osteoblasts, osteoclastogenesis, and osteoclastic activity. There is no cytotoxicity from osteoblasts after treatment with RGX and ESX. The secretion of OPG from the osteoblasts showed marked increases after treatment with RGX and ESX. In addition, RGX and ESX treatment decreased the number of tartrate-resistant acid phosphatase-positive multinucleated cells and the resorption areas. RGX and ESX, when mixed at optimal ratios, induced synergic effects, in vitro. OPB, which showed synergic effects, is the extract of natural ingredients RG and ES mixed at a raw material weight ratio of 4 : 1. It can be suspected that extracts of RG and ES mixtures contains active ingredients involved in bone tissue metabolism and may be effective in improving osteoporosis.

• Seon-Yle Ko(Department of Pharmacology and Mechanism Research Institute, Department of Oral Biochemistry, School of Dentistry, Dankook University) Corresponding author
• Jung-Keun Kim(Department of Pharmacology and Mechanism Research Institute)
• Se-Won Kim(Department of Pharmacology and Mechanism Research Institute, Department of Dental Pharmacology, Schoof of Dentistry, Dankook University)
• Hae-Young Kim(Department of Pharmacokinetics, Research Institute, Oscotec Inc.)
• Byung-Eui Lee(Department of Herbal medicine, Research Institute, Oscotec Inc.)