Garlic compounds protect vascular endothelial cells from oxidant injury

Oxygen radical injury and lipid peroxidation have been suggested as major causes of cancer, atherosclerosis and the aging process. We examined in vitro the effect of garlic on H2O2-induced oxidant injury in bovine pulmonary artery endothelial cells (PAEC). After overnight preincubation with Aged Garlic Extract (AGE, from Wakunaga Pharmaceutical Co., Ltd., Japan) or S-allyl cysteine (SAC), PAEC monolayers were exposed to H2O2 for 3 h. Cell viability (MTT assay), lactate dehydrogenase (LDH) release, and lipid peroxidation (TBA-RS) were measured to assess oxidant injury. AGE (1-4 mg/ml) pretreatment significantly reduced the loss of cell viability induced by 50-100 microM of H2O2. AGE and SAC exhibited dose dependent inhibition of both LDH release and TBA-RS production induced by 50 microM of H2O2. The results show that AGE and SAC can protect vascular endothelial cells from oxidant injury. Numerous garlic compounds could be involved in the antioxidant properties of garlic, while there could be some prooxidant compounds derived from garlic. It is important to keep an array of antioxidant compounds to develop good herbal preparation, like AGE.