Study On The Antioxidantive Activities And Detection Method For Bleeding Sap Of Xinjiang Grape Tree

Objective: To establish a convenient method for determine the antioxidant activities of water-soluble substances, by which to detect and compare the antioxidant activity of bleeding sap of grape tree from different region of xinjiang. And study the physic-chemical characteristics of those bleeding sap which have the significant antioxidant activity. Method: (1) The hydroxyl radical(·OH) produced by the reacting of Mn²⁺and H₂O₂ oxidized rapidly the chelating substance of PAR-Mn²⁺ ,the absorption of that substance at the wavelength of 500nm could be decreased simultaneously, be used to measure the amount of (·OH) produced indirectly (PAR method) .With selecting of pH value, [PAR],[Mn²⁺ ] and [H₂O₂] of reacting system ,the optimized experimental condition were developed and the recurrence of new method was verified .The feasibility of the method was evaluated by detecting the (·OH) scavenging capability of ascorbic acid ,compared with DPPH·method and hydroxyl radical reagent kit. (2) The physic-chemical characteristics were studied; The·OH and the superoxide anion radical (O2-·) scavenging capability of bleeding sap of grape tree from different region of xinjiang were investigated by the new method and the Superoxide anion radical reagent kit.;(3) The antioxidant activity of bleeding sap from Hetian red grape tree was observed , after initial management and in different temperature. The antioxidant activity of bleeding sap after extracting with different organic solvents were obtained. (4) Quantitative characterization analysis was made on the antioxidant activity of bleeding sap from Hetian red grape tree. Results: (1) The PAR method showed stable, simple, rapid and convenient , can be used as one of the method to selecting the water soluble antioxidants. The IC50 of ascorbic acid measured with three methods were 0.013 mg·mL-1 for PAR method, 0.005 mg·mL-1 for DPPH·method, 0.200 mg·mL-1 for hydroxyl radical reagent kit, respectively. (2) The bleeding sap of grape trees showed weak acidity; the absorption of samples at wavelength 250-270nm were low but the sample of Hetian red grape tree was the highest ; The samples from the Hetian, Atushi grape tree showed strong absorption at 205nm and 215nm ; There were differences in antioxidant activities of bleeding sap of grape trees among the different places. The ratio of scavenging on·OH of those samples from Hetian, Atushi, Kashi, Tulufan were 73.36%, 57.15%, 50.58% , and 32.45 %, vitamin C (0.01 mg·mL-1) was 33.28%,respectively .And the ratio of scavenging on O2-·were 24.79%,27.78%,29.81%,18.82%,vitamin C (0.15 mg·mL-1) was 44.19%;The scavenging capability of bleeding sap of the Hetian red grape tree have showed strong thermal stability;After extracting the bleeding sap of the Hetian red grape tree with aether,petroleum ether , the scavenging capability of the inorganic part on·OH were 67.71%,70.14%,respectively. (4) There were saccharide and triterpenoid saponin in the bleeding sap of the Hetian red grape tree, the physic-chemical characteristics of bleeding sap of grape tree were different from the flavonoid and the common substances from the grape. Conclusion : (1) In PAR method ,Mn²⁺-H₂O₂ system could produce the more·OH, can be used to determine the scavenging ability of antioxidants. (2) The bleeding sap of grape tree have strong scavenging activity on·OH but low to O2-·; Antioxidant activity of them were different in different kinds of grapes, region and the climate, among them the activity of bleeding sap of the Hetian red grape tree was the highest. (3) There were low influence of temperature to scavenging activity on·OH ,the bleeding sap of Hetian red grape tree showed strong thermal stability. The antioxidants from the sample showed high polarity, the main property of that substances were different from the common antioxdants, to determine the concrete chemical ingredients of bleeding sap of grape tree , a further study is needed.