Chlorogenic Acid Promotes Bone Remodelling by Regulating ALP, OCN, OPG/RANK-L

Objectives: Bone regeneration is being considered as a therapeutic modality for alveolar bone resorption. Phenolic antioxidants such as chlorogenic acid, ascorbic acid and quercetin have been suggested as modulators of bone remodelling. However, no comprehensive study has been performed to assess their effect on osteoblast activities. We aimed to compare the effects of chlorogenic acid, ascorbic acid and quercetin on MC3T3-E1 preosteoblasts. Methods: MC3T3-E1 preosteoblasts were cultured in aMEM Medium containing various concentrations of test compounds (chlorogenic acid, ascorbic acid and quercetin). Dose-dependent (0.01mM, 0.1mM, 1mM and 10mM) and time-dependent (0-72h) tests were performed using standard methodology. Cellular viability was evaluated by MTT colorimetric assay at 570nm. Gene expressions of ALP, OCN, OPG and RANK-L at mRNA level were determined by quantitative real-time qPCR. Alkaline phosphatase activity of the culture supernatant was quantified by the absorbance at 450nm. Results: In general, chlorogenic acid increased the gene expression of ALP between the intervals from 24 to 72 hours. Both chlorogenic acid and ascorbic acid similarly enhanced OCN gene expression in dose- and time-dependent experiments. The OPG/RANK-L ratio was down-regulated in first 24 hours and then up-regulated after 48 hours. At 1mM chlorogenic acid had 50% (p<0.001) and 67% (p<0.001) higher alkaline phosphate activity of MC3T3-E1 cells than ascorbic acid at 6 hours and 24 hours respectively. This suggested that osteogenesis was facilitated through suppressing RANKL expression in chlorogenic acid and ascorbic acid promoted bone formation mainly by increasing OPG expression at later stage (72 hours) while quercetin did not show any significant effect in these gene expressions. Conclusions: Chlorogenic acid promotes bone remodelling on MC3T3-E1 by regulating ALP, OCN and OPG/RANK-L gene expressions at specific concentration. Present study demonstrates the promising activity of chlorogenic acid as a bone remodelling agent for the treatment of bone resorption seen in major dental diseases.