Abstract

The health promoting properties of catechins and anthocyanins have been of great interest to researchers in the recent past due to their significant in vitro and in vivo antioxidant activities. Most research on anthocyanins has been based on berry anthocyanins. These potentially health enhancing pigments are also found in some Kenyan tea cultivars. An in vitro study was carried out to determine the effects of pure catechins (EGCG and EC) and tea anthocyanin extract from cultivar TRFK 306/1 on t-Butylhydroperoxide (t-BHP) induced oxidatively stressed HEK 293 cells. The effects of the catechins and tea anthocyanin extract on untreated cells (without t-BHP) cells and cells treated (with t-BHP, 500 µM) were determined by measuring cytotoxicity (lactate dehydrogenase (LDH) leakage from the cells) and depletion of cellular glutathione (GSH). Cells were preincubated with the antioxidants for 30 min before addition of t-BHP (500 µM) and additional incubation for 6 h. The results showed that epigallocatechin gallate (EGCG) and epicatechin (EC) as well as tea anthocyanin extract significantly (p<0.001) attenuated t-BHP induced LDH leakage in a concentration dependent manner in treated cells. One way ANOVA analysis showed significant (p<0.001) differences in the various effective concentrations of the catechins and tea anthocyanin extract used. Intracellular GSH content was also increased in a dose dependent manner. From these results, it is concluded that anthocyanin rich tea from selected Kenyan cultivars may have cytoprotective effects against oxidative stressors.

Key words: Anthocyanins, catechins, oxidative stress, lactate dehydrogenase, glutathione, t-BHP, attenuate, antioxidant, reactive oxygen species (ROS).