ABSTRACT
Objective To optimize the process of extracting total saponins from Platycodon grandiflorum by orthogonal experimental design and central composite design-response surface method. Methods Independent variables were concentration of ethanol, reflux extraction time, reflux time and solvent fold. Dependent variables were extraction rate of total saponins in Platycodon grandiflorum and the yield of dry extract.Linear or nonlinear mathematic models were used to estimate the relationship between independent and dependent variables. Results The result of the orthogonal experimental design was 70%ethanol, 180 min for reflux, 6 fold of solvent and 2 times for extraction. The result of central composite design-response surface method was 70% ethanol, 140 min for reflux, 10 fold of solvent and 2 times for extraction. Conclusion The central composite design-response surface method is better than orthogonal experimental design in studying extraction process of Platycodon grandiflorum, which provides basis for feasibility of application of central composite design-response surface method in optimization of extraction process of Chinese traditional medicine.