Concurrent Extraction and Purification of Gentiopicroside from Gentiana scabra Bunge Using Microwave-Assisted Ethanol-Salt Aqueous Two-Phase Systems

A potential method called microwave-assisted aqueous two-phase extraction (MA-ATPE) was developed for concurrent extraction and purification of gentiopicroside from Gentiana scabra Bunge. Formation characteristics of aqueous two-phase system (ATPS) composed of ethanol and 25 kinds of salts were investigated; K2HPO4 (w/w, 21.71%) and ethanol (w/w, 40.72%) were determined to be the optimal compositions of ATPS. Response surface methodology based on Box-Behnken design was used to investigate the extraction conditions, the optimal parameters were summarized as follows: 80 degrees C of extraction temperature, 31 s of extraction time, 11:1 (mL/g) of liquid-to-solid ratio, 100 meshes of particle size and 806 W of microwave power. Under these conditions, the extraction yield of gentiopicroside was 65.32 +/- 0.24 mg/g with a recovery of 96.51%. Compared with other four methods, the purity of gentiopicroside in the crude extracts reached 17.16 +/- 0.25%, which was significantly higher than that of smashing tissue extraction, microwave assisted-extraction, ultrasonic-assisted extraction and heat reflux extraction, respectively. In addition, the phase-forming salt can be recyclable. Therefore, MA-ATPE was an excellent and alternative technique to the conventional extraction approaches of gentiopicroside.