Studies On Extraction, Component And Bioactivity Of Polyphenols Oxide From Pu'er Tea

Pu'er tea is post fermented tea, a special tea with much market-developingpotential in China. The method of extraction and isolation of polyphenol Oxides fromPu'er tea was studied in my project; also we studied its effect on rat's blood lipids andantioxidant capacity. This is the first experiment on the material of Yunnan wild tearaw. In order to study it comprehensively, evaluate it scientifically, and provideintensive processing technology and industrial development theories. Also we mayguide the development of functional foods, the consumers' choice and the teaconsumer market.1. Study on extraction technology of polyphenol oxides and main qualitycomponent from Pu'er teaThe influence of pH value of solvent, temperature, heating time and ratio of teato solvent on extraction rate of TBS was studied. The results showed that allparameters affected the extraction rate noticeably, and the effects of last threeparameters was extremely remarkable. The order of importance was: ratio of tea tosolvent＞temperature＞heating time＞pH value of solvent. The optimized parameterswere: using pH=7 water solution as extract solvent, the ratio of tea to solvent was 1:30,and extracting at 100℃for 20min.Fermentation was the main influence factor of Pu'er tea quality. Pu'er teachemical contents had much difference with its material raw. Tea polyphenol, gallicacid, amino acids (in particular theanine) was much lower in Pu'er tea, while TFS,TRS, TBS and soluble sugar content was higher than the drying green tea. The maincatechins of Pu'er tea were simple catechins, while the drying green tea catechinswere complex catechins. The distribution of gallic acid, theanine and caffeine in Pu'ertea polyphenol oxides was quit difference. Gallic acid was found primarily in the TFS,while theanine in the TRS and TBS, and Caffeine in the TFS and TRS.2. Study on Pu'er tea and its polyphenol oxides on reducing blood lipidsUsing the drying green tea extraction (GE) as a control, hyperlipidemia modelmice were intragastric Infusion with different dose of TFS, TRS, TBS, PE and GE for40 days. After last administration, he mice were fasted at least 10 hours, and then theywere sacrificed by cervical dislocation, serum was prepared from blood obtained ineye vein cluster and TC,TG,HDL-C,MDA and SOD were assayed; The liver washomogenized in physiology saline and TC, TG, MDA and SOD were assayed. Theresults were showed:(1) Pu'er tea and its polyphenol oxides can be effectively regulated preventivehigh fat mice serum lipid level. TBS with medi-dose, high-dose and each dose of PE could remarkably decrease the content of TC; TRS, TBS and PE at all doses couldsignificantly lower the content of TG, the effect of Pu'er tea was better than itspolyphenol oxides; All the tasted samples could increase HDL-C contents of serumsignificantly except PE medi-dose and low dose, and the effect of TFS, TRS wasbetter than others.(2)The regulative effect on high-fat mice liver of Pu'er tea and its polyphenoloxides was mainly reflected in the decreased of TG, TC content; Each dose of TRSand PE could prevent the increase of TC content effectually on the liver of high-fatmice, and all doses of tasted samples except high dose of TRS could significantlyreduced liver triglyceride content of high-fat diet mice, and the effect of PE was betterthan its polyphenol oxides. The liver biopsy of high-fat group showed that: theexperimental groups can be effective in preventing the disappear extent of high-cellsof normal liver structure.(3)The Green tea had more effect on reducing blood lipids than Pu'er tea. As theGE group had the lowest content of TC and TG, and GE can reduce the TC contentmuch more significantly than other samples.3. The effect of Pu'er tea and its polypheuol oxides on antioxidant abilityThe antioxidant activity of TFS, TRS, TBS, TA and green tea extracts wasstudied. The results showed:(1)Pu'er tea and its polyphenol oxides can significantly enhance the preventivehigh-fat mouse serum and liver antioxidant function. PE group, TBS medi-dose,high-dose groups, TFS medi-dose group could significantly increase the SOD activityof serum, and all the samples could significantly raise the SOD activity of liver. Allthe test groups can significantly reduce the content of MDA in serum, and TRS hadthe most significant impact, but only high-dose of PE could effectively reduce thecontent of MDA significantly in the liver.(2)Pu'er tea and its polyphenol had strong activity in vitro oxides of O₂·-radicalscavenging. The removal of oxygen-free radicals ingredients mainly concentrated inthe TFS, the order of removing ability was: TFS＞TRS＞TBS＞PE.(3) The antioxidant activity of Green tea was better than the Pu'er tea. Mainlybecause of that it can significantly improve the SOD activity and lower MDA contentof preventive high fat mice in the body, and its strong scavenging capacity of O₂·^-.