Vitamin E (alpha-tocopherol) enhances arachidonic acid release in rat heart myoblastic cells through the activation of cytosolic phospholipase A2

Antioxidant modulation of oxidant-stimulated uptake and release of arachidonic acid in eicosapentaenoic acid-supplemented human lymphoma U937 cells

Omega-3 polyunsaturated fatty acids (PUFA) are increasingly finding use as treatments for a variety of medical conditions. PUFA supplementation can, however, result in increased oxidative stress causing elevated turnover rate of membrane phospholipids, impairment of membrane integrity and increased formation of inflammatory mediators. The aim of this study was to determine which antioxidant compounds were most effective in ameliorating the stimulation of phospholipid turnover by oxidative stress. U937 cells were supplemented with eicosapentaenoic acid and either ascorbic acid, alpha-tocopherol, beta-carotene or astaxanthin prior to being challenged with oxidant. Although all antioxidants were found to be effective in decreasing oxidant-stimulated peroxide formation, only alpha-tocopherol significantly decreased oxidant-stimulated release of 3H-labeled arachidonic acid (AA), while ascorbic acid markedly increased release. All antioxidants except alpha-tocopherol decreased oxidant-stimulated 3H-AA uptake. Our data suggest that antioxidants are not equally effective in combating the effects of oxidative stress upon membrane phospholipid turnover, and that optimal protection will require mixtures of antioxidants.