Response surface methodology optimised solvothermal system enables an efficient extraction of echinacoside and oleuropein from Syringa pubescens Turcz

Introduction Syringa pubescens Turcz. was reported to be abundant in the Funiu Mountains of Henan Province and can be used to treat hepatitis and cirrhosis. In order to develop and utilise the resource, a fast and simple technique to extract bioactive compounds is needed. Objectives Our aims were to provide an extraction technique of glycosides from S. pubescens and study the antioxidant activity of this material. Methods Box–Behnken design (BBD) was employed with three factors at three levels. The process parameters such as ethanol concentration (X1), temperature (X2), and solvent–solid ratio (X3) could significantly influence efficiency and yield of target compounds. High‐performance liquid chromatography (HPLC) was used to determine the content of glycosides. DPPH (α,α‐diphenyl‐β‐picrylhydrazyl), ABTS (2,2'‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) and reducing power were used to evaluate the antioxidant activity of S. pubescens extract. Results The optimal parameters for the maximal extraction yield were obtained with ethanol concentration of 68%, temperature of 89°C, solvent–solid ratio of 46 mL/g, and time of 20 min. The S. pubescens extract showed strong antioxidant properties in vitro. Conclusion The findings indicated the potential application of solvothermal extraction method to extract bioactive compounds from S. pubescens Turcz. Furthermore, the S. pubescens extract could be used as an important resource of antioxidant activity. Solvothermal extraction technique is an efficient, simple, and fast technique. Optimization of the solvothermal process was performed using response surface methodology. The antioxidant activity of S. pubescens Turcz. extract was evaluated in vitro.