Turnip (Brassica rapa L.) root ethanol extract (TRE) was prepared, and its chemical constituents were characterized by ultra-performance liquid chromatography and mass spectrometry. Thirteen glucosinolates (GSLs) were identified, comprising eight aliphatic, four indolic, and one aromatic compounds. The effects of these GSLs on bone formation were investigated in vitro by incubating human osteoblast-like MG-63 cells with TRE and then analyzing their viability, alkaline phosphatase (ALP) activity, collagen content, and mineralization and in vivo by administering TRE orally to normal young rats (500 mg/kg/day) and assessing subsequent changes in serum osteocalcin and bone microstructure in these animals. No TRE-related toxicity was found, and the levels of cell viability, ALP activity, collagen synthesis, and mineralization were significantly increased relative to the negative control. In particular, stimulatory effects on the differentiation of MG-63 cells were strongly enhanced as compared with a positive control (daidzein). Serum osteocalcin was also significantly increased, and some important bone microstructural parameters were improved in TRE-administered rats compared with their saline-administered counterparts. GSLs therefore appear to have a stimulatory effect on bone formation in both MG-63 cells and normal young rats. This is the first report on the usefulness of turnip root and its GSL compounds for bone formation.
Keywords: bone formation; bone microstructure; glucosinolate; human osteoblast-like cell; turnip.
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