| In recent years, polysaccharides receive more and more attention. Researchers are eager to find more active and effective polysaccharides from natural products, especially those aim at refractory diseases, such as tumor, cardiovascular diseases, etc. Hsian-tsao (Mesona Procumbens Hemsl) is a Chinese traditional herb with heat-clearing and life-prolonging function. Polysaccharides extracted from Mesona Procumbens Hemsl(PMPH) is a kind of active element. The deepgoing research on PMPH has great exploitative potential and practical significance.In this research, we used H2O2 as oxidative damaging agent to observe the antioxidative effect of PMPH in vitro, and its action mechanism was also preliminarily explored.1.Effect of PMPH on lipid peroxidation and the activities of antioxidative enzyme SOD and GSH-px in rat liver homogenateSD rats were killed by cut off necks. Their livers were retrieved promptly and then made into 5% liver homogenate. 20 test tubes, contained 2ml of 5% liver homogenate each, were divided into 4 groups randomly: control group, PMPH treated group 1 (Img/ml), PMPH treated group II (2.5mg/ml), PMPH treated group III (5mg/ml). Each group had 5 tubes. After adding 2ml PMPH solution with different concentration (salt solution in control group) and 200 u 1 3% H2O2 solution to each tube, the tubes were incubating at 37癈 for 6 hours with shaking. The content of MDA and the activities of SOD and GSH- px were measured in the compound afterwards. Added 5% liver homogenate, 2ml 2.5mg/ml PMPH solution and 200 u I 3% H2O2 solution to another 20 tubes, and alsodivided into four groups randomly. After incubating for 3h, 6h, 12h and 24h respectively, MDA content was measured with the same method.The results showed that PMPH could dramatically reduce the production of MDA content induced by H2O2 in rat liver homogenate, which is dose-dependent in certain PMPH concentration range. The 5mg/ml PMPH could reduce the concentration of MDA by 50%, suggesting relatively strong antioxidation capability. The results also showed that the inhibition rates of 2.5mg/ml PMPH, which were conserved with the rat liver homogenate and H2C>2 incubating for 3,6,12 and 24h, respectively, were all over 40%. Moreover, PMPH could remarkably increase the activity of GSH-px(p<0.01) in rat liver homogenate, while the SOD activity showed no change. Since there was a significantly negative relativity between the GSH-px activity and the production of MDA(p<0.01) , our results indicated that the role of PMPH to reduce MDA is closely related to the activity of GSH-px in rat liver homogenate.2.The effect of PMPH on H2O2-induced DNA damage of primary cultured spleen lymphocytesWe employed a novel technique of single cell gel electrophoresis (SCGE, comet assay) to measure the DNA damage of different concentration H2O2 solution to primary cultured spleen lymphocytes and the protection role of PMPH. Primary spleen lymphocytes were cultured for 24h, and divided into 4 groups randomly. Each group had 3 tubes. Added 25 u 1 H2O2 of different concentration to each tube to make the final concentration of 25 u mol/L, 50 u mol/L and 125 u mol/L respectively(added same volume of PBS solution into blank tubes), treated at 4'C for 20 minutes, then harvested cells and subjected to SCGE.Primary spleen lymphocytes were divided into 6 groups randomly. PMPH treated groups were pre-treated with different concentration of PMPH for 60 min (RPMI1640 culture medium in control groups), and then treated with 50 u mol/L H2O2 for 20 min. The treated cells were subjected to SCGE and analyzed by using confocal microscope. The total length of DNA comet and the percentage of cells with migrated DNA were measured.The results showed that H202 could cause severe DNA damage in primary cultured spleen lymphocytes. With higher concentration, the damage of DNA would be worse and the total length of DNA comet and the percentage of cells with migrated DNA both grew dramatically (PO.05). But PMPH could reduce the DNA damage induced by H2O2. In the range o...
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