Optimization of extraction of total flavonoids from Drynaria rhizome, and its effect on osteoclast differentiation

Abstract

Purpose: To optimize the extraction parameters for total flavonoids of Drynaria rhizome, and determine their effect on osteoclast differentiation and bone resorption in vitro. Methods: A 5-level 3-factor central composite design was applied to the optimization of extract yield of total flavonoids from Drynaria rhizome. Response Surface Methodology (RSM) design was used to optimize total flavonoids extraction from Drynaria rhizome. The independent factors included extraction temperature (A), extraction time (B) and liquid: solid ratio (C). Moreover, NFATc1, DC-STAMP, cathepsin K and MMP-9 mRNA expressions were determined. Results: Values obtained were fitted into a second-order polynomial equation with multiple regression analysis using a statistical method. Analysis of variance results indicate that the independent variables influenced total flavonoid extraction from Drynaria rhizome. The optimal conditions for extraction yield were extraction temperature of 75 oC, extraction time of 100 min, and liquid: solid ratio of 107:1. The yield of 5.38 ± 0.62 % was consistent with these optimized conditions, which was an indication of the accuracy of the model. Experiments revealed that total flavonoids from Drynaria rhizome regulated the expression levels of NFATc1, DC-STAMP, cathepsin K and MMP-9 mRNA Conclusion: This study has successfully optimized the extraction yield of total flavonoids from Drynaria rhizome. The total flavonoids inhibit osteoclast differentiation and bone resorption. Thus, they may be beneficial in the treatment of bone diseases.