Process Biochemistry 39 (2004) 1525–1531 Epicatechin effect on oxidative damage induced by tert-BOOH in isolated hepatocytes of fasted rats V.Valls-Bellés, P. González, P. Muñiz ∗ Area Bioqu´ımica y Biolog´ıa Molecular, Dpto Biotechnolog´ıa y Ciencia de los Alimentos, Facultad de Ciencias, Universidad de Burgos, Plaza de Misael Bañuelos s/n, 09001 Burgos, Spain Received 10 February 2003; received in revised form 6 June 2003; accepted 5 July 2003 Abstract There is currently considerable interest in the study of cytoprotective effects of natural antioxidants against oxidative stress. However, the cellular response to oxidative stress of the antioxidants may be compromised under conditions of dietary restriction. Therefore, the objective of the present study was to investigate the ability of the (−)-epicatechin, a polyphenol with powerful antioxidant properties in vitro, to attenuate oxidative stress-induced cell damage and to understand the mechanism of its protective action in hepatocytes from overnight fasted rats. Oxidative stress in isolated hepatocytes was induced using tert-butylhydroperoxide and the cellular responses in the form of cell membrane damage, lipid peroxidation and levels of endogenous antioxidants assessed. The results provide evidence that in fasted rat hepatocytes, subjected to oxidative stress, epicatechin inhibits cell membrane damage. In addition, lipid peroxidation and superoxide dismutase and catalase activities return to their control condition. The levels of glutathione peroxidase and glutathione, however, were not significantly different from those without treatment with epicatechin, suggesting that the epicatechin influence on these intracellular antioxidants is not the mechanism of protection. © 2003 Elsevier Ltd. All rights reserved. Keywords: Epicatechin; Antioxidant enzymes; GSH; Lipid peroxidation; Fasted rats 1. Introduction There has been growing of evidence that reactive oxy- gen species (ROS) are implicated as a major cause of cellu- lar injuries in a vast variety of clinical abnormalities [1,2]. ROS are produced in living cells as a result of normal cell metabolism but when not adequately removed or formed ad- ditionally in the cells by exogenous sources, oxidative stress may occur [3]. Excessive generation of ROS can modify and damage DNA, carbohydrates, proteins, and polyunsat- urated fatty acids in cells. This oxidative injury has been reported to develop according to a general pattern that ba- sically involves free thiol oxidation and appearance of pro- tein disulphides, depletion of ATP pool, elevation of free cytosolic calcium, increase in plasma membrane permeabil- ity, increase in plasma membrane peroxidation, release of cytosolic components, and induction of DNA [4]. ∗ Corresponding author. Tel.: +34-6-947258800x8210. E-mail address: pmuniz@ubu.es (P. Muñiz). The organic hydroperoxide, tert-butylhydroperoxide (tert-BOOH), is a useful model compound for the study of mechanisms of oxidative cell injury [5,6]. Organic hy- droperoxides form as a result of oxygen addition to alkyl radicals and/or by hydrogen atom abstraction from peroxyl radicals [7]. One of the ways to prevent ROS-mediated cellular injuries is to increase or fortify the endogenous defence capacity against oxidative stress through dietary or pharmacological intake of antioxidants. Many studies have investigated the antioxidant effects of flavonoids and phenolic compounds in the context of a variety of cell functions [8–11]. The cytoprotective effects of flavonoids is know and these effects have been attributed to their antioxidant properties either through their reducing capacities or though their influence on intracellular redox status [12,13]. Furthermore, studies have claimed in general to show a correlation between high consumption of flavonoid antioxidants and reduced risks of diseases [14–17]. Given the possibility that some polyphenol supplements and sources could be detrimental, there is a need to perform 0032-9592/$ – see front matter © 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0032-9592(03)00292-9