Analysis Of Chemical Constituents And Antioxidation Activity In Zijuan Tea

Zijuan tea is a unique kind of Yunnan large leaf species tea with the characteristic purple buds, leaves and stems. Researches showed that the antihypertensive effect of Zijuan tea is superior to other big leaf species green tea. In addition, the high content of anthocyanidin in Zijuan tea enhanced its abilities of anti-obesity, antioxidation, and antiradiation. Therefore, it was beneficial for sub healthy people or people who worked with computer for long time.In this paper, the chemical components and their antioxidant activity in Yunnan Zijuan sun-dried green tea, common larged-Ieaves tea and other species were analyzed. The content of major tea polyphenols and alkaloids were detected by HPLC; other components related to its quality, such as water extract, total amino acids, total flavonoids and total anthocyanidin were determined by the national standard methods; the antioxidant activity was detected by DPPH method.HPLC was used to detect the total of eleven compounds belonging to polyphenols and alkaloids in Zijuan green tea, common larged-Ieaves tea, and other species. Mobile phase was 0.17% Acetic acid in water and Acetonitrile, eluting with gradient solvent, flow rate was 1.0 mL/min, and the column was kept 30?, the detection wavelength was 280 nm, then the reference correlation coefficient of linear regression of equation was between 0.9994-1, the accuracy and precision of the method was between 89-105%.The water extraction of Zijuan tea and regular tea leaves was measured according to the national standard (GB/T 8305-2002) method, spectrophotometry was used to determine the total content of free amino acids, total flavonoids, and total anthocyanins of Zijuan drying green tea and conventional large leaf teas, the results showed that the total content of free amino acids and flavonoid just varied a little, however the content of anthocyanin varied greatly among "Zijuan" and several other big-leaf tea, the content in "Zijuan" was about 6 times of other types of tea.The method of DPPH was used to detect the antioxidant activity of Yunnan "Zijuan" drying green tea, regular tea leaves and non Yunnan large leaf tea. Vitamin C was used as positive control, the results showed, when the concentration of tea extraction of "ZiJuan" was 0.1 mg/mL, the inhibition rate of DPPH was the largest, which was up to about 89.82%, however when the tea sample was taken placed by non-Yixian County in Yunnan large leaf tea, the inhibition rate of DPPH was the lowest, only 58.48%. As following, the half clearance rate of DPPH of teas was measured, the results showed, the minimum value of IC50 was Zijuan, is 0.03 mg/mL, while IC50 of Yixian County Roasted was 0.071 mg/mL, IC50 of Vc was 0.02 mg/mL. This experiment showed that green tea has good antioxidant activity; however, Zijuan has the strongest antioxidant activity.