Technological Optimization For Extraction Of Polyphenols From Burdock And Assessment Of Their Antioxidant Activity

Burdock is a kind of vegetable with medicinal and health value, and its active ingredients-polyphenols and flavonoids are hot spots of domestic and overseas research which being widely found in fruits and vegetables as secondary metabolites with good biological activity. As natural antioxidants, polyphenols and flavonoids have been widely used in food and medicine.The microwave-assisted, ultra high pressure-assisted, ultrasonic-assisted extraction process of polyphenols from burdock were studied by the response surface methodology. The results showed that microwave method got the highest yield of polyphenols and flavones, ultra high method the next, and ultrasonic method got the lowest yield. The optimal extraction conditions were the presence of microwave power 140 W, 72% ethanol solvent, extraction time 2.5 minutes and liquid ratio 1:36 g/mL, under the optimal conditions, the yield of total phenols and flavones from burdock reached(129.68±1.652) mg/g and(23.46±0.275) mg/g respectively.To evaluate the antioxidant activity of polyphenols and flavones extract of burdock, five kinds of systems were employed for the experiment. The results indicated that polyphenols and flavones extract of burdock showed a very strong total antioxidant capacity, DPPH radical(IC50 0.63±0.057mg/mL) and hydroxy free radicals(IC50 0.74±0.081mg/mL) scavenging activity, a strong ferric reducing ability and ferrous ions chelating activity(IC50 5.31±0.592mg/mL). As a kind of natural antioxidant, burdock has development value extremely.The compositions was identified by ultra performance liquid chromatography, and 4 compounds were characterized. They were quercetin, chlorogenic acid, caffeic acid, and ferulic acid. The research provides the theoretical basis for the development of antioxidant activity of burdock component and also provides a new way to develop and utilize burdock reasonably.