Studies On Screening And Extraction&Isolation Of Active Components For Lipid-lowering And Anti-Obesity From Qingzhuan Tea

Qingzhuan tea belongs to dark tea. It was made by pile-fermentation and repression based on Laoqing tea as raw material, mainly in Xianning areas of Hubei province. It has a history of over one hundred years and is a kind of necessary natural healthy drink in Northwest China and regions with high fat and energy diets. Animal experiments showed that:Qingzhuan tea has evident weight-loss, anti-obesity, lipid-lowering and antioxidant effects on rats. To further explore the mechanism of lipid-lowering and anti-obesity effect of Qingzhuan tea, this article first studied on the main ingredients and capacities of scavenging free radicals of Qingzhuan Tea. Then many fractions were extracted with different polar solvents and separated by Selphadex LH-20 column chromatography from Qingzhuan tea. The effect of all the fractions on a-amylase and lipase enzyme activity was measured to select the active components with the strongest inhibiting on the two enzymes.1 Study on the main ingredients and capacities of scavenging free radicals of Qingzhuan Tea1.1 Analysis about the main ingredients of Qingzhuan TeaThe main ingredients of green tea, green brick tea and Qingzhuan teas stored different years (stored for 11 years, stored for 2 years and new) were determined by colorimetry and HPLC. The results showed that only the contents of polysaccharides and theabrowns in Qingzhuan tea were higher than green brick tea and green tea. The longer Qingzhuan tea was stored, the higher the contents of polysaccharides and theabrowns in it were, the lower the contents of the other ingredients.1.2 Study on capacities of scavenging free radicals of Qingzhuan TeaThe capacities of scavenging O2- and·OH free radicals were respectively tested by methods of the xanthine oxidase and D-deoxyribose-iron system. The results showed that the capacities of scavenging O2- free radicals and scavenging·OH free radicals of tea liquors with low concentrations were:green tea>green brick tea>Qingzhuan tea; but the capacities of scavenging·OH free radicals of tea liquors with high concentrations were: Qingzhuang tea>green brick tea>green tea. The longer Qingzhuan tea was stored, the better the capacities of scavenging O2- and·OH free radicals were.1.3 The correlation analysis between the capacities of scavenging free radicals of the tea liquors and the contents of their main ingredientsThe analysis results indicated that:the correlativities of capacities of scavenging·OH free radicals of the tea liquors with low concentrations or O2- free radicals and the contents of water extracting, amino acids, polyphenols, catechins, flavones, thearubigins, theanine, coffein were positive significantly. The correlativities of the capacity of scavenging·OH free radicals of tea liquors with high concentrations and the content of polysaccharides and theabrowns were positive significantly.2 Study on screening active components for lipid-lowering and anti-obesity from Qingzhuan tea2.1 Analysis about the main active ingredients of different fractions of Qingzhuan teaWater extraction, chloroform fraction, ethyl acetate fraction, n-butanol fraction, precipitation fraction and the remaining water fraction were obtained by extracting with different polar solvents from Qingzhuan tea. The main ingredients of all fractions were determined by colorimetry and HPLC. The results showed that:caffeine accounted for 70.55% in chloroform fraction; polyphenols, catechins and flavonoids separately accounted for 78.72%,33.14% and 5.63% in ethyl acetate fraction; polyphenols, sugar, flavonoids and theanine separately accounted for 31.09%,15.56%,8.34% and 1.29% in n-butanol fraction; polysaccharides was the main ingredient in precipitation fraction; the remaining water fraction contained many ingredients with different contents.2.2 The effect of Qingzhuan Tea fractions on a-amylase and pancreatic lipase activityThe effect of all fractions on a-amylase and lipase enzyme activity were tested by iodine-starch colorimetry and triglyceride turbidimetry separately. The result of comparing the size of the relative enzyme activity at different concentrations and hemi-inhibitory concentration showed that:ethyl acetate fraction was the best active part in inhibiting a-amylase, its IC50 was 4.48mg/ml; n-butanol fraction was the best active part in inhibiting lipase enzyme, its IC50 was 2.90mg/ml.2.3 The effect of isolates of ethyl acetate fraction and n-butanol fraction on a-amylase and pancreatic lipase activityEight different components were respectively obtained by using Selphadex LH-20 column chromatography from ethyl acetate fraction and n-butanol fraction. The effect of all isolates on a-amylase and lipase enzyme activity were tested by iodine-starch colorimetry and triglyceride turbidimetry separately. The result showed that:50% acetone elutions from ethyl acetate fraction and n-butanol fraction had the strongest inhibition on a-amylase, their IC50 were respectively 0.37mg/ml and 0.29mg/ml; n-butanol fraction had the strongest inhibition on lipase enzyme, its IC50 was 2.90mg/ml.