Ionic Liquid Based Ultrasonic-Assisted Extraction of Oleanolic Acid from Grape Seeds

Abstract

Ionic liquid based ultrasonic-assisted extraction (ILUAE) was successfully applied to extract Oleanolic acid (OA) from grape seeds. Different kinds of 1-alkyl-3-methylimidazolium ionic liquids with different kinds of cations and anions were studied and 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) solution was selected as extractants. The optimal conditions of ILUAE were determined by single factor experiments and Box-Behnken design as follows: [C4mim]Cl concentration of 0.7 mol/L, extraction time of 4 h, liquid-solid ratio of 15:1 mL/g, ultrasonic power of 195 W, the ultrasonication time of 13 min, and extraction temperature of 48℃·min. The extraction yield of OA was 13.4 mg/g, which is well in close agreement with the value predicted by the model. Compared with the regular ultrasonic-assisted extraction (UAE), the proposed approach exhibited 1.64 times higher efficiency, which indicated that ILUAE has a broad prospect for sample preparation of the bioactive compounds.