Effects of tea catechins, epigallocatechin, gallocatechin, and gallocatechin gallate, on bone metabolism.

In this study, three tea catechins, epigallocatechin (EGC), gallocatechin (GC), and gallocatechin gallate (GCG), were investigated for their effects on bone metabolism. The effects of the tea catechins on bone formation were evaluated using cultured rat osteoblast-like osteosarcoma cell line UMR-106. EGC stimulated alkaline phosphatase activity significantly at concentrations of 10 and 20 microM. The amount of mineralization also increased significantly with EGC. On another cell culture platform, EGC significantly inhibited osteoclast formations from RAW 264.7 cells upon receptor activation of nuclear factor-kappaB ligand induction on the fourth day of treatment, at a concentration of 10 microM. EGC also dose-dependently inhibited the mRNA expression of tatrate-resistant acid phosphatase. GC and GCG could decrease osteoclastogenesis at 20 microM. The present study illustrated that the tea catechins, EGC in particular, had positive effects on bone metabolism through a double process of promoting osteoblastic activity and inhibiting osteoclast differentiations.