Abstract:
In this paper, ursolic acid was extracted from the roots of
Rosa multiflora Thunb by ultrasonic−microwave−assisted extraction, and the optimum extraction and purification conditions were determined. The extraction process of ursolic acid was optimized by response surface methodology. The best conditions for separation and purification of ursolic acid were obtained by defatting, decolorizing, acid base precipitation and gel column chromatography. The products were identified by ultraviolet spectroscopy (UV), infrared spectroscopy (IR),
1H NMR and
13C NMR. The results showed that the yield of ursolic acid could reach 2.64% under the conditions of ultrasonic power 50 W, microwave power 310 W, extraction time 2.4 min, liquid−solid ratio 20∶1 mL/g, microwave extraction time 15 min and extraction temperature 55℃. When the amount of petroleum ether was 0.2 times of the volume of extract, 2 times of degreasing, 0.04 g/mL of active carbon, 3 times of decolorization; the pH value of alkali precipitation was 12; the acid precipitation pH value was 4; when ursolic acid crude product was separated from dextran gel LH-20 for two times, the purity of ursolic acid after recrystallization was over 97%, achieving a better separation effect.