Red yeast rice stimulates osteoblast proliferation and increases alkaline phosphatase activity in MC3T3-E1 cells

Red yeast (Monascus purpureus) is used as a traditional hypocholesterolemic dietary food component in Asia due to its bioactive component, lovastatin. Recently, new evidence suggesting that the statins in red yeast enhance bone formation has been reported, but more research is still needed in order to support these claims of osteogenic effects. Therefore, in this study, we hypothesized that red yeast rice (in which red yeast is fermented) can improve osteogenic function through osteoblast cell proliferation and differentiation. We studied the effect of methanol extract of red yeast rice powder (RYRP) on osteoblast proliferation and differentiation by measuring mitochondrial enzyme activity and bone marker alkaline phosphatase (ALP) activity, respectively. Osteoblast-like MC3T3-E1 cells were cultured in various concentrations of RYRP methanol extract (0.001-1 mg/mL) during the osteoblast differentiation period (1, 5, 10, and 15 days). As measured by 3-[4,5-dimethylthiazol-2-y]-2,5-diphenyltetrazolium bromide assay, RYRP extracts stimulated cell proliferation during a 24-hour period, compared to cooked white rice powder extract. The most pronounced effect was observed at the concentration range between 0.075 and 0.1 mg/mL. This RYRP stimulatory effect for cell proliferation was observed during the whole osteogenic period. Cellular (synthesized) ALP activity was increased at a RYRP extract concentration of 0.075 mg/mL during 15 days of culture, but the medium (secreted) ALP activity did not show any significant change. This cellular ALP activity stimulation by RYRP extract was confirmed by the staining of ALP activity on cell matrix layers for matrix calcification. The results imply that RYRP extract may increase osteogenic effect by stimulating cell proliferation and ALP activity in osteoblastic cells.