Comparative Research On Antioxidant Activity Of Some Kinds Of Natural Antioxidants And Antioxidant Healthy Function Of Tea Polyphenol

In order to select functional factors from fruits, vegetables and other plants as food and medicine, we determined the antioxidant activity with ferric reducing /antioxidant power assay(FRAP) established by Benzie and Strain. Tea polyphenol(TP), vitamin c, grape seed extract, extract of the fruit of Cornus Officinalis , ursolic acid etc. were selected in this research. Extract of the fruit of Cornus Officinalis and american ginseng were extracted in our own lab. In the extraction experiment of the fruit of Cornus Officinalis, optimal extracting parameters were selected by preliminary and orthogonal experiment. The results were as follows: alcohol 85%, extraction temperature 50℃,ultrasonic power 100W and time 30min.FRAP can be used to determine the total antioxidant activity of natural antioxidants. Antioxidant activity of single sample determined by FRAP showed that the effective concentration of antioxidant played a key role in antioxidant activity. The results showed that TP in lower concentration(0.01mg/mL) had a lower antioxidant activity than vitamin c. When the concentration reached 0.05mg/mL, the result of antioxidant activity was contrary. In the cooperative antioxidant research, TP with different concentration of EGCG was determined by FRAP. The result showed that it had the highest antioxidant activity when the concentration of EGCG in catechin was 40%-50%.The cooperative antioxidant activity of antioxidants related to the antioxidant activity of antioxidants themselves and the effective concentration of antioxidants. Firstly, when the effective concentration of antioxidants was low the cooperative antioxidant activity was weak, then it became stronger as the concentration increased until the maximum cooperative antioxidant activity. As the concentration went on increasing, the cooperative antioxidant activity would not increase.The animal experiment of antioxidant function was taken at the base of the determination of the total antioxidant activity by FRAP. It showed that the result of the animal experiment of antioxidant function of TP was positive. The calculated results proved that TP had good antioxidant activity and healthy function in scavenging free radicals and delaying aging.