Garlic inhibits free radical generation and augments antioxidant enzyme activity in vascular endothelial cells

Oxygen free radicals have been implicated in mediating various pathological processes such as ischemia, inflammatory diseases, diabetes, and atherosclerosis. The antioxidant enzymes-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX)-play an important role in scavenging oxidants and preventing cell injury. Aged Garlic Extract (AGE) has been shown to prevent oxidant-induced injury of endothelial cells. The present study determined the effects of AGE on the generation of hydrogen peroxide (H2O2) and superoxide anion (O-2(.)) and the activity of three antioxidant enzymes in bovine pulmonary artery endothelial cells (PAEC). Confluent monolayers of PAEC were incubated with AGE, and oxidative stress was triggered by hypoxanthine and xanthine oxidase or H2O2. AGE exhibited both concentration- and time-dependent suppression of H2O2 and O-2(.) generation, and it also significantly increased the activities of SOD, CAT and GPX. The results suggest that AGE may be an effective antioxidant in preventing or treating disorders related to endothelial cell injury associated with free radicals. (C) 1998 Elsevier Science Inc.