| Nowadays losing weight has become a topic of great concern when obesity group are increasing continuously. Looking for efficient lipid-lowering drugs has become the common aspiration of the medical profession. A wide variety of lipid-lowering diet pills on the market today, but most of them are chemicals, and some of them can obviously bring side effects. Now, more and more people turn our gaze to the development and utilization of natural lipid-lowering diet pills.Tea as a natural drink has thousands of years of drinking history. Several study showed Oolong tea has beneficial effects on weight control. As a calorie-free beverage, Oolong tea can be a method to weight control.In this thesis, Oolong tea polyphenols, EGCG and EGCG3"Me which were pre-prepared were studied on their effect on reducing weight and fat. By the study of the effect on reducing weight and fat of nutritional obese rats, inhibition on a-amylase activity, inhibition of proliferation and differentiation of3T3-L1preadipocyte, the effect of Oolong tea polyphenols and tea catechins on reducing weight and fat has been proved.1. The separation and purification of Oolong tea polyphenols. From certain variety of Oolong tea polyphenols, Oolong tea polyphenols, EGCG and EGCG3"Me monomers were obtained respectively by macroporous adsorption resin. Firstly, appropriate macroporous adsorption resin were selected to adsorb Oolong tea polyphenols, after pured by water to remove caffeine, ethanol was used for desorption, and Oolong tea polyphenols with high purity and high content of ester tea catechins were obtained. Then, Oolong tea polyphenols were purified by different macroporous adsorption resin, after eluted with ethanol different fractions were collected, and EGCG and EGCG3"Me monomers purity higher than95%were obtained.2. The effect of Oolong tea polyphenols on reducing weight and fat of nutritional obese rats. SD rats weight of about50g were randomly divided into normal control group, the obese control group, and Oolong tea group. The normal control group were fed with normal diet, the obese control group and oolong tea group were fed with high fat diet. Oolong tea group were given sample by gavage, the normal control group and obese control group were given distilled water. Experimental rats were killed after7weeks, the serum and liver tissue were obtained to determine four items of blood-lipid (TC, TG, HDL-C and LDL-C), lipase, SOD enzymes and MDA, etc. The experimental results showed that oolong tea polyphenols can improve various biochemical indexes of obese rats significantly, it can make each index of Oolong tea group better than obese control group, and close to normal control group, which showed significant effect of reducing weight and fat.3. The inhibition of a-amylase activity and fluorescence quenching effect of Oolong tea polyphenols. The inhibition effect of Oolong tea polyphenols, EGCG and EGCG3"Me monomers on a-amylase activity, and the fluorescence quenching effect between the sample and a-amylase were studied. By the measurement of the content of maltose by DNS method, the a-amylase activity was determine indirectly, and the inhibition rate and type of sample inhibitor for a-amylase activity were also determined. It showed that the inhibition effect of Oolong tea polyphenols and EGCG on a-amylase activity were competitive inhibition, for EGCG3"Me was noncompetitive inhibition. By the determination of ultraviolet spectrophotometer, the effect of three samples on α-amylase all showed the structure change and red shift. By fluorescence spectrophotometer, the3D fluorescence map of a-amylase and the effect of sample on the structure of a-amylase were analysed, and further analysis of the quenching effect type of the sample on the enzyme was also made. It showed that the three samples have good inhibition and quenching effect on a-amylase.4. The inhibition effect of Oolong tea polyphenols on the proliferation and differentiation of3T3-L1preadipocyte. the effect of Oolong tea polyphenols and tea catechins on reducing weight and fat has been studied. By cell culture and MTT assay, the proliferation of3T3-L1preadipocyte at24h,48h,72h and96h after different samples were added was determined. And by adding samples when adding insulin, DEX, and IBMX to induce cell differentiation into adipocytes, to test the inhibition effect of samples on the conversion of preadipocytes to adipocytes, and the effect on the content of fat in the adipocytes which had been differentiated. It showed that the three samples all have good inhibition effect on the proliferation and differentiation of3T3-L1preadipocyte... |
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