Studies On Tea Catechins Oxypolymers And Its Biologic Activities

Research about the isolation,purification,analysis,physical and chemical properties,and biologic activities of tea catecliins (TC) has been done very systematically and deeply. But studies on tea catecliins oxypolymers (TCOP) have been just carried out .Very few studies on the transformation of TC to TCOP and relations between the structure and functions of TCOP have been found reported. Oxidizing was regarded to have negative effect on the biologic activities of TC in the past,but some recent researches illustrated that TCOP may have more significant activities than TC .This paper aimed at studying the effect of oxidizing on the biologic activities of TC and discussed the preparation,purification and analysis as well as biologic activities of TCOP. The main results were shown as follows:1 preparation,properties,separation and analysis of TCOPTCOP was prepared in the condition of acid and H2O2 as oxidize for the first time and the optimum preparation condition was founded.TCOP was stable in acidic or neutral solutions,but unstable in alkaline solutions;it was stable on Mg" and Al .but unstable on Pb-,Cu",Fe",Fe 4,Ba- and above 60C .Sunlight had little effect on its stability.Compared with TC,the content of total phenol of TCOP followed 19.45%,the pH value followed 1.27 . the redox potential went up 32mV,and the reduce ability and antioxidant value also followed. The content of theaflavins and thearubingins was 0.12% and 1.06% respectively,almost the same as TC.Sephadex LH-20 column and 101 large pore resin column were used to separate and purify TCOP. The results showed that both columns could separate the main fractions of TCOP from residue TC,caffeine and other small molecular substances,but the main fractions of TCOP couldn't separate from each other. Linear gradient and step gradient were combined to separate and analyze TCOP for the first time and the optimum condition was established.TCOP has absorption only at 280nm in Ultraviolet spectrum,that illustrated that it was not theaflavins. Infra-red spectrum showed that it has the basic structure of TC,but the hydroxyl was reduced . Mass spectrum showed that molecular weight range of the main fractions of TCOP was from 906.4 to 1962.4. which suggested that it might be dimer to pentamer of EGCG.'HNMR and "CNMR confirmed that it was mainly dimer to trimer of EGCG.and the main linkage was C4-C8.2 The biologic activities of TCOPExperiments about the inhibitory effect of TCOP on lipoxygenase and the auto-oxidizing of lipid.the clearing effect of TCOP on free radicals( . OH and O2 ),the influence of TCOP on the antioxidant system of mice were performed. It turned out that TCOP can inhibit the oxidizing of lard very significantly and its effect was not less than TC. TCOP and TC can clear free radicals ( . OH and O2") generated by different systems very effectively,the maximum clearing rate of TCOP and TC to . OH and O2- were 88.5% and 83.4%,92.1% and 96.6% respectively,and the rate constants of TCOP and TC to . OH were (1.4-2.8) X 1010M-1S-1 and 1.0X 1010M-1S-1 respectively. TC showed pro-oxidant effect when the concentration was above 500 u g/ml. but TCOP didn't show pro-oxidant effect;TCOP can activate red cell SOD and reduce the content of MDA of old mice very significantly;TCOP and TC can also inhibit the lipoxygenase,the IC50 values were 653 u g/ml and 202 u g/ml respectively.The toxicity test of TCOP and TC was carried out. The oral LD50 values of TCOP and TC for rat were found to be 6.40 g/kg and 2.64g/kg separately.The inhibitory or clearing effect of TCOP on nitrite was studied in pickles and imitating stomach condition. A remarkable effect of TCOP on inhibiting or clearing NaNO2 was shown.. The main mechanism was that TCOP could combine with NaNO2 directly .The immunomodulatory effects of TCOP were measured by delayed type hypersensitivity(DTH),phagocytosing method and LDH method. It was found that TCOP(Po,200mg/kg.d X 7d) can significantly intensify DTH caused by DNFB,and TCOP(Po,200mg/kg.d X30d) increa...