Study On Chemical Constituents Of Pu'er Tea

Pu-erh tea is a special Chinese tea produced by using tea leaves from Yu nnan tea variety and a special post-fermentation processing. The numerous heal th benefits of pu-erh tea, such as hypolipidemic, antioxidant, antibacterial activ-ities and so on. The chemical compounds of Pu-erh tea were isolated and ide-ntified by using moden chromatogram and spectrum technology, such as "H-N MR, 13C-NMR and mass spectrum. Nineteen compounds were isolated from Pu-erh tea by using chromatogrammethod and the struetures of them were deduce d from their spectral data as follows:gallic acid(1), (+)-catechin(2), (-)-epicatec-hin(3), (-)-galloeatechin(4), (-)-epigallocatechin(5), (-)-epicatechin-3-O-gallate(6), (-)-epigallocatechin-3-O-gallate(7), rutin(8), kaempferol-3-0-β-D-rutinoside(9), kae-mpferol-3-O-(3-D-glucopyranoside(10), kaempferol(11), quercetin(12), quercetin3-O-β-D-glucopyranoside(13), dihydromyricetin(14), caffeine(15), myricetin(16), (-)-gallocatechingallate(17), taxifolin(18), chlorogenic acid (19).In this study, Pu-erh tea was fractionated by organic solvents including petroleum ether, methylene chloride, ethyl acetate, n-butanol. Meanwhile, compared with ascorbic acid, the antioxidant activity of the four polarity parts extracted was evaluated by scavenging DPPH radical, hydroxyl radical, and total reduction capability. The highest antioxidate activity was shown in the ethyl acetate part, when the concentration reached 0.5 g/L, the clearance rate to DPPH radical and hydroxyl radical was 80.19% and 83.55% respectively, when the concentration reached 1 g/L, total reduction capability was 1.62. Escherichia coli, Staphyloccocus aureus, Monilia albican and Bacillus subtilis were used to study the antibacterial activity of the four polarity parts. As a result, dichloromethane extraction part, ethyl acetate extraction part and n-butyl alcohol extraction part have showed good antibacterial activity on S. aureus, ethyl acetate extraction part had hghest antibacterial activity and its minimal inhibitory concentration was 1 g/L.Flavone compounds are the mainly functional components of Pu-erh tea. In this paper, three kinds of MOFs materials were synthesized to adsorb flavonoids from Pu-erh tea and studied the effect of different conditions on the adsorption capacity and desorption rate. The results showed that MIL-101-Fe had maximum adsorption capacity and the effect of desorption was best among three kinds of MOFs materials, the largest adsorbing and desorption capacity was 10.16 mg/g and 8.29mg/g, respectively.