Chinese Medicine Of M. Dodecandrum Chemical Composition And Pharmacological Activity

The researches on Melastoma dodecandrum L. were reviewed at the beginning of this thesis, including plant source, chemical constituents, pharmacological activities and clinical applications. However as a Chinese herb, Melastoma dodecandrum L. has not been studied on its chemical constituents, not to mention the systematically physiological, biochemical and pharmacology study on it. So it should be done for its further exploitation.Firstly, the chemical constituents of Melastoma dodecandrum L. were preliminarily analysed and identified. The results showed that it has acidic components, steroids, steroid glycosides, flavonoid constituents, lactones, alkaloids, amino acids or peptides, saccharides and polysaccharides. The constituents and contents of amino acids in Melastoma dodecandrum L. have been studied. The sixteen amino acids were found in Melastoma dodecandrum L. The content of polysaccharides has been determined by UV-Vis spectrometry. Polysaccharide MDi was isolated and purified by decocting with water, followed by Sevage method, alcohol precipitation, DEAE-cellulose, gel filtration chromatography (Sephadex G-100). The structure of the polysaccharide purified has been determinated by the methods of TLC> UV> IR^ GC\ HPLC, periodate oxidation, Smith degration, etc. MDj is a kind of neutral heteropolysaccharide with many branches. It consists of Rha, Xyl, Ara, Man, Glc and Gal in a molar rate of 1:1.7:1.9:24.5:12.3:3.5. The average Mw is 3.1X103 . The effect of polyssacharideMDi to eliminate free radical 62"?> -OH and to peroxidize free radical of human erythrocyte membrane was studied for the first time. The results showed that polyssacharide MDi could eliminate O2"- and -OH (<250mg/L), compared to the control group(P<0.01). The result also showed that MDi could inhibit the lipid peroxidation of human erythrocyte membrane, compared to the control group (P<0.01). Finally, in this paper, the inhibitory effects of flavonoids of Melastoma dodecandrum L., quercetin and rutin on advanced glycation end products (AGE) ofhuman serum albumin (HSA) in vitro were studied for the first time. The results suggested that all of these flavonoids inhibited the formation of fluorescence AGE.