Study on Relation between Antioxidant Activity of Extracts from Cyclocarya paliurus Leaves and Total Flavonoid Content

In September 2019, fresh Cyclocarya paliurus leaves were collected from 5-year trees in Suichang, Zhejiang province. Seven different extracts were isolated from them by different reagents. Experiments were conducted on scavenging DPPH, hydroxyl free radical and superoxide anion free radical of different extracts and total flavonoid content of different extracts were determined. The results showed that the extracts had scavenging effect on DPPH, the water extract after ethanol extraction had the strongest scavenging ability, the rate reached 91.29% with the concentration of 0.1 mg/mL. The ethanol extract had the strongest scavenging ability on hydroxyl free radical, the rate topped to 53.55% with concentration of 1 mg/mL. The scavenging rate of superoxide anion free radical of each extract was significantly lower than that of Vc. The total flavonoid content of water extract after ethanol extraction was the highest, 11.32%, followed by water extract, 10.94%. The content of flavonoid had extremely evident positive correlation with DPPH scavenging rate (r=0.602), evident positive with hydroxyl free radical scavenging rate (r=0.427) and positive with superoxide anion free radical scavenging rate (r=0.210).