Optimization of Microwave-assisted Extraction of Quercetin from Loquat Flowers by Response Surface Methodology and the Effects on Activity of Alcoholic Intoxication Enzyme

Quercetin was extracted from loquat flower dried in shade by microwave-assisted extraction with 60% ethanol as solvent.The effects of material-liquid ratio,microwave time and microwave power on quercetin extraction from loquat flower were studied.The Box-Behnken response surface method was used to optimize the extraction process by three factors and three levels.The results indicated that the optimum extraction conditions were solid-liquid ratio of 1∶15 (g/mL),microwave time of 25 min and microwave extraction power of 600 W;the extraction amount of quercetin from loquat flower was 8.26 mg/g. Quercetin from loquat flower was purified by HP-20 column chromatography,the purity of quercetin obtained was 64.87%. Infrared spectrum scans indicated that quercetin characteristic peaks existed at 1663,1611 and 1382 cm^-1.The effects of quercetin from loquat flower on the activities of ADH,ALDH and CAT in the process of alcoholic intoxication were investigated. The results for the test showed that the enzyme activities were all improved to a certain extent and the activation rates were 24.83%,29.18%,22.36%. Quercetin from loquat flower has certain activation effect on key enzymes in alcohol intoxication process,which provides certain theoretical basis for the development of natural product anti-alcoholism and food of auxiliary liver protection.