The optimum conditions for the extraction of bioactive alkaloids and antioxidants from rhizome coptidis were determined by using response surface methodology (RSM). A small central composite design (SCD) was employed to investigate the effect of 3 process variables such as extraction time (3–7 h), ethanol concentration (0–100%), and solvent to sample ratio (25–45 mL/g) during extraction process. Analysis of variance showed a high significance of fitted model which indicated the model is reliable for prediction. The optimal conditions for alkaloids and antioxidant ability were obtained using ridge analysis, and under the optimum conditions the corresponding predicted response values for berberine content, palmatine content, and antioxidant ability were 747.2 μg berberine chloride equivalent/mL, 168.34 μg palmatine chloride equivalent/mL, and 2.99 mmol/L Trolox equivalent, respectively, which well agreed with predicted values, indicating the success of RSM in optimizing the extraction conditions.
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