title: Isolation and purification of two antioxidant isomers of resveratrol dimer from the wine grape by counter-current chromatography.
abstract: Resveratrol dimers belong to a group of compounds called stilbenes, which along with proanthocyanidins, anthocyanins, catechins, and flavonols are natural phenolic compounds found in grapes and red wine. Stilbenes have a variety of structural isomers, all of which exhibit various biological properties. Counter-current chromatography with a two-phase solvent system composed of n-hexane/ethyl acetate/methanol/water (2:5:4:5, v/v/v/v) was applied to isolate and purify stilbene from the stems of wine grape. Two isomers of resveratrol dimers trans-ε-viniferin and trans-δ-viniferin were obtained from the crude sample in a one-step separation, with purities of 93.2 and 97.5%, respectively, as determined by high-performance liquid chromatography. The structures of these two compounds were identified by (1) H and (13) C NMR spectroscopy. In addition, their antioxidant activities were assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The antioxidant activities of trans-δ-viniferin were higher than that of trans-ε-viniferin in this model. This work demonstrated that counter-current chromatography is a powerful and effective method for the isolation and purification of polyphenols from wine grape. Additionally, the DPPH radical assay showed that the isolated component trans-δ-viniferin exhibited stronger antioxidant activities than trans-ε-viniferin and a little bit weaker than vitamin E at the same concentration.
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi'an, China.|Department of Chemistry, Zhejiang University, Hangzhou, China.
authors.forename: Qingjun
authors.initials: Q
authors.lastname: Kong
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi'an, China.
authors.forename: Xueyan
authors.initials: X
authors.lastname: Ren
authors.affiliation: Department of Chemistry, Zhejiang University, Hangzhou, China.
authors.forename: Ruilin
authors.initials: R
authors.lastname: Hu
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi'an, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Yin
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi'an, China.
authors.forename: Guoshan
authors.initials: G
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, Zhejiang University, Hangzhou, China.
authors.forename: Yuanjiang
authors.initials: Y
authors.lastname: Pan
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification*; D003377:Countercurrent Distribution; D019281:Dimerization; D000077185:Resveratrol; D013237:Stereoisomerism; D013267:Stilbenes / Q000737:chemistry / Q000302:isolation & purification*; D027843:Vitis / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
chemical_list: D000975:Antioxidants; D013267:Stilbenes; D000077185:Resveratrol
keywords: Antioxidant; Counter-current chromatography; Isomers; Wine grapes