Functional analysis of 70% ethanolic extract of akar kelembak (Rheum officinale Baill.) on 3t3 L1 preadipocyte cell lines in osteogenic medium

Compounds with estrogen receptor modulation activity are necessary to treat osteoporosis by increasing osteoblast formation and activity. Anthraquinone and stilbene compounds from genus Rheum have been reported to exert modulation activity toward estrogen receptors. This research aimed to reveal osteoblastogenesis activity of an Indonesian native plant, akar kelembak (Rheum officinale Baill.) that extracted with 70% ethanol. The extract then tested on 3T3 L1 preadipocyte cell lines cultured in osteogenic differentiation medium with concentrations of extract of 25, 50, 75, 100, and 125 μg/mL. The differentiation of these cells was marked by alkaline phosphatase (ALP) staining. The ALP level decrease progressively at 75, 100, and 125 μg/mL. No mineralized nodules or positive alizarin red staining was observed. mRNA expression level of osteoblastic markers was detected by Reverse Transcriptase PCR (RT PCR) for Runx2 and BMP-2,estrogen receptor α (ER α) and β (ER β). The results indicate that the key regulator genes of osteogenesis differentiation, Runx2 and BMP-2, tend to increased, while ER α and ER β tend to decreased, in a dose-dependent manner. It was suggested that osteogenic differentiation was best stimulated at concentration of 50 μg/mL based on the increase of alkaline phosphatase level as well as mRNA level of Runx2 and BMP-2, while mRNA level of ER α was decreased.