Comparative studies on the antioxidant capacities and catechin profiles of conventional and organic green tea

Abstract

As one of the most consumed beverages worldwide, green tea has been extensively studied for its wide array of health benefits. In this study, the composition of active compounds and antioxidative activity was analyzed using various antioxidant assay systems and compared between organic green tea (OGT) and conventionally grown green tea (CGT). OGT extract was prepared in the same way as CGT with the exception of fertilizer and insecticide, which were used only for CGT preparation. There were no significant differences in total polyphenol content and antioxidant activity tested against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radicals and 1,1-diphenyl-2-picrylhydrazyl radicals. In addition, the antioxidant activities shown with both assays were highly correlated with the polyphenol contents (r(2) > 0.99). No significant differences were observed in the cellular antioxidant activity assay using HepG2 cells (P > 0.05). However, substantially higher concentrations of catechins, especially epigallocatechin-3-gallate, were found in the OGT (7.64 vs 5.54/100 mg extract). Thus, OGT could be considered as a potent and safe antioxidative resource, being free of both fertilizer and herbicide uses. However, the advantages of OGT should be further optimized to provide a wide range of physiological effects, considering the price of production and parallel amounts of the active ingredients in CGT.