| With the improvement of socical economy and human's living standard and the aging of population, "Health" is becoming the most important topic in the world. Ampelopsis grossedentata belongs to Ampelopsis Michx of Vitaceae. The tender stems and leaves have been made into a healthy drink which is called "mystic tea" with a long history of several hundred years among Yao and Zhuang nationality in China.Dihydromyricetin (DMY) and Myricetin were isolated from the leaves and stems in A. grossedentata previously, but experiments show that some constituents haven't yet been isolated from it . At the same time , the antioxidation and stability of DMY haven't been reported before. In this paper, the constituents of A. grossedentata were studied and eight compounds were isolated from it; The methods were established to determine the content of DMY and total flavonids in A. grossedentata .The relationships between the main constituents and seasons were studied. The morphologic dissection of A. grossedentata was also studied. The value of this research resides not only in providing scientific basis of exploring and cultivating A. grossedentata, but also in plugging the gaps in the research of Ampelopsis genus. The results were as follows:1. Studies on chemical constituents.Eight compounds isolated from petroleum extracts, water extracts and ethanol extracts of A. grossedentata by column chromatography were characterized as dihydromyricetin (wl), myricetin (w2), hesperitin ( I ) dihydroquercetin (II) kaempferol (III), apigenin (IV ), 3 -sitosterol, (V), oleanolic acid (VI), respectively,on the basis of physical and chemical evidences and spectroscopic analysis. Among these compounds, I , II, III, IV, V and VI were obtained from this plant for the first time.2. Studies on content of main constituents:1) A method of Differential spectrophotometry was set up to determine the total content of flavonoids(TCF) in A. grossedentata at wavelength of 318nm.The referenceswas DMY. The content of TCF showed different numerical values in samples from different districts in different seasons.The content of TCF in the leaves of A. grossedentala collected in May was the highest as 41.2-45.4%, then decrease gradually, the lowest as 19.1-19.7% in winter. It was three- four times that of in the stems.2) A method of HPLC was set up to assay the content of DMY in A. grossedentala . Chromalographic conditions were: using Lichrospher C18 column (150 mmx4.6 mm) , 25% methanol containing 0.1 % phosphoric acid as mobile phase with 1.0 mL/min of flow rate, delecting at 290 nm . The column temperature was at 25 C and injection volume was 20uL. The content of DMY in samples was different according to different seasons. The content of DMY in the leaves of A. grossedentala collected in May was the highest as 27.9-31.2%. It was three four times that of in the stems. The content of DMY was in the order of Jianghua > Zhangjiajie > Zhuzhou.3. Studies on antioxidation of main constituents:1) The effect of TCF on the scavenging activity on superoxide anion radical induced by xanthine-xanthine oxidase and the activity of TCF on antilipid-peroxidation of liver tissue homogenate and mitochondria induced by Cys -Fe2+ and VitC -Fe2+ were studied by using spectropholometry. The results showed TCF could significantly inhibit the superoxide anion radical, the IC50 was 14.7 u g/mL and the lipid peroxidation of liver homogenate and mitochondria induced by auto-oxidation and Cys - Fe +, the EC50 were 9.4 u g /mL, 38.1 u g/mL ,respectively. The inhibition exhibited concentration-dependent manner. It is indicated that TCF is the scavenger of oxygen free radicals and is capable of prophetically antagonizing against the oxidative injury by superoxide anion.2) The antilipid-peroxidation of DMY on heart, liver, brain tissue homogenate and mitochondria was measured by determining the content of malondialdehyde(MDA) induced by Vi tC-Fe2+Cys -Fe2+, H2O2-Fe2+ using spectrophotometry. The results showed DMY could inhibit the li...
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