title: Antioxidant phenolic compounds from Pu-erh tea.
abstract: Eight compounds were isolated from the water extract of Pu-erh tea and their structures were elucidated by NMR and MS as gallic acid (1), (+)-catechin (2), (−)-epicatechin (3), (−)-epicatechin-3-O-gallate (4), (−)-epigallocatechin-3-O-gallate (5), (−)-epiafzelechin- 3-O-gallate (6), kaempferol (7), and quercetin (8). Their in vitro antioxidant activities were assessed by the DPPH and ABTS scavenging methods with microplate assays. The relative order of DPPH scavenging capacity for these compounds was compound 8 > compound 7 > compound 1 > compound 6 > compound 4 ≈ compound 5 > compound 2 > VC (reference) > compound 3, and that of ABTS scavenging capacity was compound 1 > compound 2 > compound 7 ≈ compound 8 > compound 6 > compound 5 > compound 4 > VC (reference) > compound 3. The results showed that these phenolic compounds contributed to the antioxidant activity of Pu-erh tea.
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.
authors.forename: Hai Ming
authors.initials: HM
authors.lastname: Zhang
authors.forename: Cheng Fang
authors.initials: CF
authors.lastname: Wang
authors.forename: Sheng Min
authors.initials: SM
authors.lastname: Shen
authors.forename: Gang Li
authors.initials: GL
authors.lastname: Wang
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.forename: Zi Mu
authors.initials: ZM
authors.lastname: Liu
authors.forename: Yong Yan
authors.initials: YY
authors.lastname: Wang
authors.forename: Shu Shan
authors.initials: SS
authors.lastname: Du
authors.forename: Zhi Long
authors.initials: ZL
authors.lastname: Liu
authors.forename: Zhi Wei
authors.initials: ZW
authors.lastname: Deng
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D052160:Benzothiazoles / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000493:pharmacokinetics; D005419:Flavonoids / Q000737:chemistry; D016166:Free Radical Scavengers / Q000032:analysis; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D010851:Picrates / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D004365:Drugs, Chinese Herbal; D005419:Flavonoids; D016166:Free Radical Scavengers; D010636:Phenols; D010851:Picrates; D013451:Sulfonic Acids; D013662:Tea; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C004931:1,1-diphenyl-2-picrylhydrazyl