Tea Catechins Protect against Lead-Induced ROS Formation, Mitochondrial Dysfunction, and Calcium Dysregulation in PC12 Cells

Abstract

Recent studies have shown that lead causes oxidative stress by inducing the generation of reactive oxygen species (ROS) and reducing the antioxidant defense system of cells, which suggests that antioxidants may play an important role in the treatment of lead poisoning. The present study was designed to elucidate whether tea catechins had any protective effects on altered oxidative stress parameter in PC12 cells exposed to lead. The experimental results showed that lead decreased PC12 cell viability and induced a rapid elevation of [Ca(2+)](i), which was followed by an accumulation of ROS and a decrease of mitochondrial membrane potential (MMP). Treatment by tea catechins significantly increased cell viability, decreased intracellular Ca(2+) levels and ROS formation, and improved MMP in PC12 cells exposed to lead. The galloylated catechins showed a greater effect on ROS formation and mitochondrial dysfunction than that of nongalloylated catechins, which was similar to the result of their scavenging ability on free radical. In view of the time course of ROS formation and mitochondrial dysfunction and their correlation, our results also suggested that the beneficial effects of tea catechins on MMP are related, at least in part, to its ability to scavenge ROS in PC12 cells exposed to 100 microM Pb(2+). The present results suggest that tea catechins supplementation may play a role for modulating oxidative stress in PC12 cells exposed to lead.

High-Molecular-Weight Polyphenols from Oolong Tea and Black Tea: Purification, Some Properties, and Role in Increasing Mitochondrial Membrane Potential

“…The protective effect of tea catechins is related to their scavenging ability. 31) We also found that galloylated catechins (ECG and EGCG) increased mitochondrial membrane potential more than nongalloylated catechins (EC and EGC) in Fig. 7.…”

Potential for preventive effects of cocoa and cocoa polyphenols in cancer

“…EC reduced the cytotoxicity induced by t-BOOH , Martín et al, 2010b) and 9 conferred a protection against oxidative stress by preventing t-BOOH-induced increase of ROS, malondialdehyde, GPx and GR activities as well as the decrease of GSH in HepG2 cells (Martín et al, 2010b, Murakami et al, 2002. EC also protected cells from oxidative insults by preventing hydroxyl radical formation in the presence of copper (Azam et al, 2004), and played a role in modulating oxidative stress in lead-exposed cells through the downregulation of ROS generation, decrease of intracellular calcium and prevented the alteration of the mitochondrial membrane potential (Chen et al, 2002, Chen et al, 2003. Moreover, EC and one its major Similarly, a hexameric procyanidin fraction isolated from cocoa interacted with Caco-2 cell membranes preferentially at the water-lipid interface without affecting their integrity, and it inhibited the deoxycholic (DOC)-induced cytotoxicity, oxidant generation, NADPH oxidase 12 activation, loss of monolayer integrity and DOC-triggered increase in cellular calcium (Da Silva et al, 2012, Erlejman et al, 2006.…”

The Health Effects of Tea Polyphenols and Their Antioxidant Mechanism

“…In view of the time course of ROS formation and mitochondrial dysfunction and their correlation, our results also suggested that the beneficial effects of tea catechis on MMP are related, at least in part, to its ability to scavenge ROS in PC12 cells exposed to 100 µM Pb ++ . The present results suggest that tea catechins supplementation may play a role for modulating oxidative stress in PC12 cells exposed to lead [53].…”