Study On Extraction And Identification Of Flavonoids In Leaves Of Corylus Heterophylla Fisch

Corylus heterophylla (hazel) belonging to the genus of Corylus from Betulaceaefamily and now widely distributed in Hebei, Shandong, Henan and Shaanxi Province ofChina. There are abundant in wild hazel resource in China, and most of the resources areCorylus heterophylla Fisch.. Corylus heterophylla Fisch. leaves are rich in flavonoids,while few studies of flavonoids in Corylus heterophylla Fisch. leaves were reported. Thisstudy focused on compounds analyses and evaluating antioxidant activity of flavonoids inCorylus heterophylla Fisch. leaves, and hoped to provide a reliable basis for furtherdevelopment of this plant.This study is made up of four parts:(1) Microwave-assisted extraction (MAE) technique was developed for extraction offlavonoids from Corylus heterophylla Fisch. leaves. Several influential parameters of theMAE procedure (concentration of ethnol, material to solvent ratio, microwave temperature,microwave power and irradiation time) were investigated. The optimal extraction (themaximum yield of flavonoids) with MAE was achieved using a55%(v/v) ethanol solution,with a ratio of material and extraction solvent of1:35(g: mL), together with a microwavetreatment for5min and a microwave power of300W at80℃.(2) By comparing static adsorption and desorption ability of eight kinds ofmacroporous resin, the D101macroporous resin showed the best adsorption and desorptionability. The flow of the sample solution, pH value of adsorption solution, pH value ofelution agent, the elution agent (ethanol) concentration and the volume of eluton agent werestudied by using dynamic adsorption and desorption. The best conditions for purificationwere as follows: adsorption solution flow rate is2BV/h, pH value of adsorption solution is4, pH value of elution agent (ethanol) is4, elution agent concentration of70%and avolume of3BV. Under the proposed conditions, the content of flavonoids in the purifiedincreased to57.4%in comparison with the crude flavonoids.(3) Qualitative and quantitative analysis of all compounds in the purified flavonoidsextract was carried out by using high performance liquid chromatography coupled withtandem mass spectrometry (HPLC-MS/MS). A total twelve compounds were found inCorylus heterophylla Fisch. leaves, of which eleven compounds were reported for the firsttime, including epicatechin (41.45±1.87μg/g, dry weight), chlorogenic acid(3-caffeoylquinic acid,389.00±17.15μg/g), syringetin-3-O-glucoside (6169.78±209.73μg/g), salvianolic acid C (443.37±21.07μg/g), chrysoeriol-6-C-glucoside (206.81±10.07μg/g), hyperoside (quercetin-3-O-galactoside,154.44±7.63μg/g), quercitrin (quercetin-3-O-rhamnoside,937.15±40.86μg/g), laricitrin-3-O-galactoside (17.27±0.82μg/g), Malvidin-3-O-glucoside (202.74±10.04μg/g), laricitrin-3-O-glucoside (101.27±4.99μg/g), kaempferol-3-O-rhamnoside (112.37±4.77μg/g).(4) The cellular antioxidant activities (CAA) of flavonoids in Corylus heterophyllaFisch. leaves were evaluated using cell model. The results showed that the flavonoids inCorylus heterophylla Fisch. leaves were not cytotoxic, which did not significant inhibitionto the growth of HT-29cells and RAW264.7cells. These flavonoids also showed strongscavenging activities to cellular reactive oxygen species (ROS) in both HT-29cells andRAW264.7cells. In addition, the antioxidant activities of flavonoids were evaluated usingchemical methods. And compared with synthetic antioxidants such as ascorbic acid (Vc),the flavonoids from Corylus heterophylla Fisch. leaves had weaker capacity on totalantioxidant ability, superoxide anion scavenging activity, and DPPH redical scavengingactivity, but stronger capacity of scavenging on hydroxyl radical and lipoprotein and lipidof yolk.