Optimal Extraction of Main Constituents from Radix Scrophulariae Based on Response Surface Methodology

Objective: To optimize the extraction process of Radix Scrophulariae. Methods: A gradient HPLC method was established for the determination of aucubin, harpagide, harpagoside, acetoside, angroside C and cinnamic acid in Radix Scrophulariae(Xuanshen). The effects of methanol concentration, extraction time and ratio of solid to liquid on the extraction effciency of three iridoid glycosides and three phenylpropanoid in Radix Scrophulariae were investigated. The extraction parameters were optimized with Response Surface Methodology on the basis of single factor experiments using a three-factor and three-level Box-Behnken center united design. Results: The results showed that the optimum conditions of extraction were: concentration of methanol 88.15%, ratio of solid to liquid 1:36.23, extraction time 25.65 min. The predicted extraction area of six constituents was 3.12×106, and the practical extraction area was 3.11 ×106. The RSD between the practical and the predicted values was less than 1%. Conclusion: Box-Behnken Design-Response Surface Methodology can efficiently predict the optimum extraction process of Radix Scrophulariae.