Protective Effect of Epigallocatechin-3-Gallate in Hydrogen Peroxide-Induced Oxidative Damage in Chicken Lymphocytes

Epigallocatechin-3-gallate (EGCG) is one of the fundamental compounds in green tea. The present study was to evaluate the protective effect of EGCG in oxidative damage and apoptosis induced by hydrogen peroxide (H₂O₂) in chicken lymphocytes. Results showed that preincubation of lymphocytes with EGCG significantly decreased H₂O₂-reduced cell viability and apoptotic cells with DNA damage, restored the H₂O₂-dependent reduction in total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-PX), superoxide dismutase (SOD), glutathione (GSH), and glutathione disulfide (GSSG), and suppressed the increase in intracellular reactive oxygen species (ROS), nitric oxide (NO), nitric oxide synthesis (NOS), malondialdehyde (MDA), lipid peroxide (LPO), and protein carbonyl (Carbonyl). In addition, preincubation of the cells with EGCG increased mitochondrial membrane potential (MMP) and reduced calcium ion ([Ca²⁺]i) load. The protective effect of EGCG in oxidative damage in lymphocytes was accompanied by mRNA expression of SOD, Heme oxygenase-1 (HO-1), Catalase (CAT), GSH-PX, nuclear factor erythroid 2-related factor 2 (Nrf2), and thioredoxin-1 (Trx-1). As EGCG had been removed before lymphocytes were challenged with H₂O₂, the activation of genes such as Nrf2 and Trx-1 by preincubation with EGCG could be the main reason for EGCG to protect the cells from oxidative damage by H₂O_2. Since oxidative stress is an important mechanism of biological damage and is regarded as the reasons of several pathologies, the present findings may be helpful for the use of tea products to prevent oxidative stress and maintain healthy in both humans and animals.