Enhancement of antioxidant defense system by epigallocatechin-3-gallate during bleomycin induced experimental pulmonary fibrosis

Abstract

Oxidative stress resulting from an imbalance between radical-generating and radical scavenging systems plays an important role in the pathogenesis of pulmonary fibrosis. Epigallocatechin-3-gallate (EGCG), a polyphenol and a major component of green tea, possess a potent antioxidant property. This study was designed to evaluate the potential antioxidative activity of EGCG in the plasma and lungs during bleomycin induced experimental pulmonary fibrosis. Intratracheal administration of bleomycin (6.5 U/kg body weight) to rats resulted in significant reduction of body weight, enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase) and non-enzymic antioxidants (reduced glutathione, vitamin C, vitamin E and vitamin A). Elevations in lung W/D (wet weight/dry weight) ratio, hydroxyproline content was observed with a synchronized increase in lipid peroxidation markers (thiobarbituric acid reactive substances and hydroperoxides). Intraperitoneal administration of EGCG at a dose of 20 mg/kg body weight significantly improved the body weight, enzymic and non enzymic antioxidants and considerably decreased the W/D ratio, hydroxyproline and lipid peroxidation marker levels. Histological observations also correlated with the biochemical parameters. Thus, this study confirms the beneficial use of EGCG in alleviating the oxidative stress induced during pulmonary fibrosis. © 2008 Pharmaceutical Society of Japan.