Aspalathin from Aspalathus linearis (rooibos) reduces osteoclast activity and increases osteoblast activity in vitro

Bone remodelling in a healthy body is in constant balance, maintaining an adaptive and robust skeletal system. In osteoporosis this balance is disrupted with the rates of osteoclastic bone resorption exceeding osteoblastic bone formation, resulting in lower bone mineral density. Rooibos tea, is a popular South African drink made from Aspalathus linearis leaves grown in the Western Cape. This tea is rich in phenolic compounds which have been widely investigated in recent years as a potential treatment for many ailments. In this study, aspalathin, a phenolic compound found exclusively in rooibos, increases osteoblast formation and function including increased osteoblast marker expression and mineralisation. In addition, aspalathin decreased differentiation and function of osteoclasts as well as reducing osteoclast formation in an osteoclast/osteoblast co-culture model. These results illustrate bone-protective effects of aspalathin in vitro through the reduction of osteoclast activity and promotion of osteoblast activity, with potential applications in the maintenance of bone density.