The relative antioxidant activity and steric structure of green tea catechins – A kinetic approach. (15th August 2018)

• Record Type: Journal Article
• Authors: Yang, Hong; Xue, Xuejia; Li, Huan; Apandi, Siti Norasikin; Tay-Chan, Su Chin; Ong, Seng Poon; Tian, Edmund Feng
• Is Part Of: Food chemistry. Volume 257(2018)
• Page Start: 399
• Page End: 405
• Publication Date: 2018-08-15
• Subjects: Antioxidant activity -- Green tea catechins -- Stereochemistry; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2018.03.043
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Relative antioxidant activity of 4 pairs of green tea catechins were studied. Steric impact within each pair of epimers was discussed. The ease of forming the dimeric products determined the antioxidant kinetics. Abstract: There are eight most abundant green tea catechins (GTCs) existing in four pairs of eipimers, and carbon-3 configuration represents the only steric difference within each pair. This study aimed to use a new kinetic approach to elucidate the effect of stereochemical changes on the antioxidant activity. A mixture of eight GTCs was treated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) prepared in a series of concentrations, their relative reaction rates towards scavenging DPPH were revealed by the recently introduced parameter, i.e. Dm . The 3- R configuration in (−)-epicatechin, (−)-epigallocatechin and (−)-epigallocatechin gallate gave lower Dm values demonstrating faster kinetics as opposed to their 3- S counterparts, with the only exception of the pair of (−)-catechin gallate and (−)-epicatechin gallate in which 3- S configuration was faster. These results suggested that the kinetic approach adopted in this study could reflect the different antioxidant activity of GTCs attributed by minor steric changes.