Isolation, Purification And Bioactivity Analysis Of Oxidation Products Of Catechins

People pay more attention to the biological activity of oxidation products of catechins increasingly. Scholars home and abroad have done many researches on them. In this paper, column chromatography and preparative HPLC were uesed to separate oxidation products of catechins, the structures of fractions are identified, and the bioability was analyzed. The results of study show:Column chromatography was used to separate oxidation products of catechins produced in alkalescence condition. Tea oxidation products were fractionated by MCI GEL CHP20P column with 10% step-wise elution of H2O containing increasing proportions of MeOH from 10% to 70% and Sephadex LH-20 column with 10% step-wise elution of H2O containing increasing proportions of acetone from 20% to 60%. Oxides with different polaritis were seperated. Thesse two eluting system can separate catechins and oxides, and different oxides with close polarities availably. M6, S7 and S10 were collected in this part of experiment, which contained oligomers of catechins.M6, S7 and S10 were applied to a column of OBD(C18) with H2O containing acetonitrile. After purification, M6-2, S7-1, S7-2, S10-1 and S10-2 were get. According to the results of MS and NMR analysis and refer to literatures, the structures of these substance s were determined, M6-2 was Kaempferol-3-O-β-D-glucoside, and S7-1 was dipolymer of EGCG linked at the B-rings through a C-C bond, S7-2 were GCG, S10-1 were epitheaflagallin-3-O-gallate, S10-2 were theaflavin-3-gallate.The bioability of oxides P and fraction S7 on total antioxidation(T-AOC) and radicals scavenging of OH·, O2-·were tested. The results showed the bioactivity of oxide and S7 were active. Significant difference analysis showed that, the T-AOC of P was significantly higher than that of 98%TP and EGCG, the ability of scavenging OH·of it was significantly higher than that of EGCG, 98%TP and 80%TFs, and the ability of scavenging O2-·of it was significantly higher than that of 80%TFs. The T-AOC of S7 was significantly higher than that of EGCG, the ability of scavenging OH·of it was significantly higher than that of EGCG and 98%TP, it was equal to 80%TFs. And the ability of scavenging O2-·of S7 was significantly higher than that of 80%TFs.