Ultrasonic‐Assisted Ionic Liquid Extraction of Four Biflavonoids from Ginkgo biloba L.

Abstract

AbstractIn the study, four main biflavonoids (bilobetin (BIL), ginkgetin (GIN), isoginkgetin (IGIN) and sciadopitysin (SCI)) were extracted from Ginkgo biloba L. by ultrasonic‐assisted ionic liquid extraction (UAILE). The above four biflavonoids from Ginkgo biloba L. were simultaneously determined by the established high performance liquid chromatography (HPLC) approach. Next, three novel ionic liquids (ILs) were synthesized by one‐step method from benzoxazole and three acids or salts. The structure of ILs were characterized by elemental analysis, infrared spectroscopy and nuclear magnetic resonance. Moreover, the thermal stability of ILs was evaluated by thermogravimetric analysis. Through screening the extraction effect of 9 different ILs, [EPy]BF4 was screened as the optimal extraction agent. Through single factor and response surface analysis, the optimum extraction conditions of the four kinds of biflavonoids from Ginkgo biloba L. were further investigated. The optimum conditions were as follows: 0.148 mol/L IL concentration, 25 min extraction time, 1 : 14 g/ml solid‐liquid ratio, and 280 W ultrasonic power. The extraction rates of BIL, GIN, IGIN and SCI in Ginkgo biloba L. were 2.44 mg/g, 4.33 mg/g, 6.50 mg/g and 13.97 mg/g, respectively. Compared with ethanol‐UAE, infiltration extraction (IE) and percolation extraction (PE), UAILE not only could obtain more biflavonoids, but also could save the extraction time. In addition, the results of recovery test indicated that the recovered IL could be repeatedly extracted for 6 times. In general, three novel ILs were first synthesized in this study. The UAILE was first applied to extract the four biflavonoids in G. biloba L. This study provided a valuable reference for further investigation on G. biloba L.