| Green tea, without fermentation, is the richest in natural products among other types of tea. Modern research has shown that tea polyphenols (TPs) which are the most abundant secondary metabolites of tea are active in anti-oxidation, anti-inflammation, anti-cancer, anti-bacterial, anti-diabetes and beneficial in cardiovascular disease, etc. The extraction and separation processes of TPs were optimized in this study. This will provide efficient and environmental processes for tea industrial production, make full use of the crude and unsalable tea, and improve the quality of polyphenols products. Lee et al found that green tea polyphenol extracts could operate protective effects against ethanol-induced acute gastric mucosal damages in rats. The present study was designed to evaluate the efficacy of TPs in protecting against multiple factors-induced chronic gastritis mucosa damages and to elucidate the possible underlying mechanisms. It will provide reference and basis for further study, development and utilization of green tea.The main contents and findings were as follows:1. The contents of six catechins (GC, EGC, C, EGCG, ECG and EC) and limited composition caffeine(CAF) were investigated by HPLC method with Hanbon BenetnachTM C18 column (5 μm× 4.6 mm×250 mm) at 30 ℃ and the UV detection wavelength was 280 nm. The mobile phase was methanol-water-phosphorus acid (28:72:0.1, v/v/v) isocratic elution system, and the flow rate was 0.8 mL·min-1. The results showed that the linear ranges of GC, EGC, C, EGCG, ECG, EC and CAF were 0.10～1.00,0.16～1.00,0.10～1.00,0.05～0.50,0.10～1.50,0.10～2.00 and 0.02-1.00 mg·mL-1 respectively, and the correlation coefficients were ranged from 0.9984～ 0.9999. The average recoveries of the two most abundant compositions EGCG and CAF were 100.89% and 99.07%, respectively. The resolutions of the six object components were more than 2, except GC. The method was simple, rapid, accurate, reproducible and ideal for routine analysis of catechins and CAF.2. The extraction processes of green tea polyphenols with ethanol and ultrasound-assisited water were optimized by response surface analysis methodology based on single factor test, respectively. The optimum extraction process of green tea polyphenols with ethanol was as follows:ratio of solid to liquid was 1:20, extraction time was 43 min, ethanol concentration was 65%, particle size was 80 mu. The yield of TPs was 100.12% under the described conditions. The optimum extraction process of TPs with ultrasound-assisited water was as follows:ultrasonic power was 480 W, ratio of solid to liquid was 1:20, the pH of water was 2, particle size was 80 mu, extraction time was 30 min. The yield of TPs was 77.89% under the described conditions.3. The method of isolation and purification of TPs without CAF was established. Macroporous resin LX-8 was selected by static absorption and desorption experiments. Then, the sampling conditions of TPs purification process were optimized through L9 (34) orthogonal test. The optimum process was as follows:resin-column ratio was 1:10, sample concentration was 0.02 g·mL-1, pH was 5, the sampling amount was 52 BV, and the flow was 1 mL·min-1. The elution conditions were investigated and determined:the elution flow was 2 BV·h-1,the resin column was eluted with 28 BV water,20 BV 10% ethanol and 14 BV 70% ethanol in turn. The fraction of 70% ethanol eluent was collected and dried, and by that process decaffeinated TPs products were got. The final product TPs was 99.93% in content after separation, in which EGCG was 64.14%, and CAF wasn’t detected. The process was simple only using a single separation of a resin column, cheap, environmental and practical for industrial product, and suitable for TPs used in food, drug and daily necessities.4. The efficacy of TPs in protecting against multiple factors-induced chronic gastritis mucosa damages in rats was tested by the whole pharmacological experiment in vivo. The general situation of gastric mucosa of rats was evaluated by gross anatomy observation and gastric lesion area. The histological changes and surface morphological changes of gastric mucosa of rats were evaluated with pathological section and observation under scanning electron microscopy. The results showed that TPs obviously relieved mucosal folds flatten, red and edema, erosion and defects in rats with chronic gastritis in the macroscopic; and improved the damage situations and repaired gastric mucosa in rats with chronic gastritis in microscopic, like pyknosis, hemorrhage, infiltration of inflammatory cells, loosely arranged cells in lamina propria, deformation and desquamation of mucosal epithelial cell, etc. The middle-dose and high-dose TPs could significantly reduce the gastric lesion areas in rats with chronic gastritis (P<0.5), and the effects of the middle-dose TPs was better than the effects of the high-dose TPs in microscopic observation.5. To elucidate the possible underlying mechanisms of TPs in protecting against multiple factors-induced chronic gastritis mucosa damages in rats, the content of MDA, SOD, NO and PGE2 were detected with the kits. The results showed that the middle-dose and high-dose TPs significantly decreased MDA levels and increased SOD activities in stomach tissues of rats with chronic gastritis (P<0.5). Further, the two groups significantly increased NO and PGE2 levels in stomach tissues of rats with chronic gastritis (P<0.5), and the middle-dose TPs group showed highly significant when compared with the model group(P<0.01). The mechanisms could be related to SOD activities and MDA contents in stomach tissue of rats through enhancing the antioxidant defense, in part. And the other possible mechanisms could be elevating the contents of NO and PGE2 through cytoprotection, affecting microcirculation and secretion of the gastric mucosa.
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