Biol. Pharm. Bull. 29(9) 1820—1824 (2006)

product containing a catechol group with an a ,b-unsaturated carboxylic acid chain (Fig. 1), is a widespread phenolic acid, naturally found in many agricultural products such as fruits, vegetables, wine, olive oil, and coffee. Caffeic acid has been reported to possess a wide spectrum of biological effects such as antioxidant activity, inhibition of enzyme activities (lipoxygenase, glutathione S-transferase, xanthine oxidase), antitumor activity, anti-inflammatory effect, and inhibition of HIV replication. More recently, caffeic acid has been demonstrated to modulate cellular response on oxidative challenge. Reactive oxygen species (ROS) are known to cause oxidative modification of DNA, proteins, lipids and small cellular molecules. ROS are associated with tissue damage and are the contributing factors for inflammation, aging, cancer, arteriosclerosis, hypertension and diabetes. The cells have developed a variety of antioxidant defense mechanisms against ROS. Enzymatic defense mechanisms involve superoxide dismutase, which catalyzes dismutation of superoxide anion to hydrogen peroxide, catalase, which converts hydrogen peroxide into molecular oxygen and water, and glutathione peroxidase, which destroys toxic peroxides. In the present study, we have investigated the protective effect of caffeic acid on cell damage induced by hydrogen peroxide and the possible mechanism of cytoprotection.