title: Preparation of A-type proanthocyanidin dimers from peanut skins and persimmon pulp and comparison of the antioxidant activity of A-type and B-type dimers.
abstract: We have established a simple method for preparing large quantities of A-type dimers from peanut skin and persimmon for further structure-activity relationship study. Peanut skins were defatted with hexane and oligomeric proanthocyanidins were extracted from it with 20% of methanol, and the extract was fractionated with ethyl acetate. Persimmon tannin was extracted from persimmon with methanol acidified with 1% hydrochloric acid, after removing the sugar and small phenols, the high molecular weight persimmon tannin was partially cleaved with 6.25% hydrochloric acid in methanol. The ethyl acetate fraction from peanut skins and persimmon tannin cleaved products was chromatographed on AB-8 macroporous resin followed by Toyopearl HW-50F resin to yield about 378.3mg of A-type (epi)catechin (EC) dimer from 1 kg dry peanut skins and 34.3mg of A-type (epi)catechin-3-O-gallate (ECG) dimer and 37.7 mg of A-type (epi)gallocatechin-3-O-gallate (EGCG) dimer from 1 kg fresh persimmon fruit. The antioxidant properties of the A-type and B-type dimers were compared in five different assays, namely, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical, hydroxyl radical, lipid peroxidation in mice liver homogenate and erythrocyte hemolysis in rat blood. Our results showed that both A-type and B-type dimers showed high antioxidant potency in a dose-dependent manner. In general, B-type dimers showed higher radical scavenging potency than A-type ones with the same subunits in aqueous systems. But in tissue or lipid systems, A-type dimers showed similar or even higher antioxidant potency than B-type ones.
authors.affiliation: College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xiao-Qian
authors.initials: XQ
authors.lastname: Dong
authors.affiliation: College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zou
authors.affiliation: College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Zhen-Zhen
authors.initials: ZZ
authors.lastname: Ge
authors.affiliation: College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Du
authors.affiliation: College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Environment Correlative Food Science, Huazhong Agricultural University, Ministry of Education, China. Electronic address: lichmyl@mail.hzau.edu.cn.
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Li
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D010367:Arachis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D019281:Dimerization; D029788:Diospyros / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D005638:Fruit / Q000737:chemistry; D017665:Hydroxyl Radical / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D044945:Proanthocyanidins / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D012639:Seeds / Q000737:chemistry; D013329:Structure-Activity Relationship; D013634:Tannins / Q000737:chemistry
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D044945:Proanthocyanidins; D013634:Tannins; C013221:proanthocyanidin; D017665:Hydroxyl Radical; D002392:Catechin
keywords: A-type dimers; Antioxidant activity; B-type dimers; Preparation