Physiological levels of tea catechins increase cellular lipid antioxidant activity of vitamin C and vitamin E in human intestinal Caco-2 cells

Abstract

Oxidative stress has been linked to the development of various chronic diseases. Vegetables and fruits, which contain polyphenols, were shown to have protective effects. (-)-Epigallocatechin-3-gallate (EGCG), a polyphenol abundant in tea, has been shown to have antioxidant activities in cellfree conditions and this study focused on the effect of cellular EGCG. Using an intestinal cell model to examine the oxidative stress induced by hydroxyl radicals, we report here that physiological concentrations (0.1-1 μM) of EGCG have dose-and incubation duration-dependent cell-associated lipid antioxidant activity (measuring malondialdehyde production). Vitamin E and vitamin C at 10-40 μM also showed cell-associated lipid antioxidant activities under shorter incubation durations. When EGCG was included in the incubation with vitamin E or C, more antioxidant activities were consistently observed than when vitamins were added alone. Catechin (widely present in fruits and vegetables) at 1 μM also significantly increased the antioxidant activity of vitamin E and C. Previous studies examining cell-associated activity of EGCG mainly focused on the 10-100 μM concentration range. Our results suggest that although the physiological level (0.1-1 μM) of dietary catechins is much lower than that of vitamins, they further contribute to the total antioxidant capacity even in the presence of vitamins.

Influence of the interactions between tea (Camellia sinensis) extracts and ascorbic acid on their antioxidant activity: analysis with interaction indexes and isobolograms

“…The synergistic effect of rosemary extract, tocopherol, BHA and AA was observed in the DPPH assay (Romano et al 2009). An additive or synergistic effect was also described for polyphenols and vitamins C and E in preventing lipid oxidation (Murakami et al 2003;Yeomans et al 2005;Intra & Kuo 2007). Significant synergism measured using the DPPH method was also found for four phenolic compounds of 'Ataulfo' mango pulp: chlorogenic, gallic, protocatechuic and vanillic acids.…”

Protictive effects of green tea and garlic on the morphological and oxidative stress changes of hippocampus in aged male and female albino rats

“…On the other hand, tea polyphenols have the ability to participate in vitamin E recycling [11]. Because of the presence of other antioxidant constituents in the green tea extract, it is more stable than pure epigallocatechingallate; one of the major constituents of green tea [12].…”

Upregulation of erythrocyte ascorbate free radical reductase by tea catechins: Correlation with their antioxidant properties

“…A study done to evaluate the relationship between tea catechins and ASC showed that tea catechins have the ability to increase cellular lipid antioxidant activity of vitamin C and vitamin E in human intestinal Caco-2 cells (Intra & Kuo, 2007).…”