Radical Scavenging of White Tea and Its Flavonoid Constituents by Electron Paramagnetic Resonance (EPR) Spectroscopy

• Published in: Journal of agricultural and food chemistry Vol. 62; no. 25; pp. 5743 - 5748
• Main Authors: Azman, Nurul A. M, Peiró, Sara, Fajarí, Lluís, Julià, Luis, Almajano, Maria Pilar
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 25.06.2014; American Chemical Society, Books and Journals Division
• Subjects: antioxidant activity; buds; Camellia sinensis - chemistry; catechin; electron paramagnetic resonance spectroscopy; Electron Spin Resonance Spectroscopy - methods; epicatechin; epigallocatechin; ferulic acid; Flavonoids - chemistry; free radical scavengers; Free Radical Scavengers - chemistry; leaves; methanol; Oxidation-Reduction; oxidative stress; Plant Extracts - chemistry; white tea; white tea; radical scavenging; spin trap; antioxidant activity; EPR
• ISSN: 0021-8561; 1520-5118; 1520-5118
• DOI: 10.1021/jf501707p

White tea (WT) presents high levels of catechins, which are known to reduce oxidative stress. WT is the least processed tea, unfermented and prepared only from very young tea leaves. The subject of this paper is the use of the spin trap method and electron paramagnetic resonance (EPR) spectroscopy as the analytical tool to measure, for the first time, the radical scavenging activity of WT and its major catechin components, epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC), and epigallocatechin-3-gallate (EGCG), against the methoxy radical, using ferulic acid as antioxidant pattern. The antioxidant activity has been measured by the decrease of the intensity of the spectral bands of the adduct DMPO–OCH3 in the EPR with the amount of antioxidant in the reactive mixture. Tea leaves and buds were extracted with waterless methanol. It has been proved that tea compounds with more antiradical activity against methoxy radical are those with the gallate group, EGCG and ECG.