Abstract
Catechins, such as catechin, epicatechin (EC), epigallocatechin (EGC) and epigallocatechin gallate (EGCG), are polyphenols contained in green tea. Catechins exhibits various biological functions including antioxidative activities; however, the effects of catechins on bone metabolism are still unclear.
We have reported that EGCG and methylated EGCG (EGCG3’’Me), methylated derivative of EGCG, exerted the bone protective effects against an experimental periodontitis model.
Both EGCG and EGCG3’’Me inhibited osteoclast differentiation and bone resorption. In osteoblasts, EGCG and EGCG3’’Me directly attenuated IκB kinase (IKK) activity, leading to the inhibition of osteoclast differentiation through the decreased production of prostaglandin (PG) E2 and receptor activator of NF-κB ligand (RANKL).
We further showed that EGCG and EGCG3’’Me suppressed LPS-induced bone resorption of alveolar bone in an experimental periodontitis model.
The intake of EGCG has also shown to inhibit the estrogen deficiency-induced bone loss in ovariectomized animal model. Since it is the important issues to prevent the bone loss in super-aging society, catechins are the candidates for the prevention of bone-related diseases. This review described the effects of catechins on bone diseases including periodontitis and postmenopausal osteoporosis.