The production of hemolysis in tocopherol-deficient rats by injection of compounds related to alloxan has been studied. Alloxantin had the same hemolytic action as alloxan; dialuric acid was about twice, ninhydrin about six times as effective as alloxan. Alloxanic acid had no hemolytic action. In tocopherol-treated rats no hemolysis was observed after the injection of alloxantin, dialuric acid and ninhydrin, as well as of alloxan.
Hemolysis of red blood cells obtained from tocopherol-deficient rats could be produced in vitro by dialuric acid and to a lesser extent by alloxantin but not by alloxan or ninhydrin. In the presence of cysteine, glutathione or ascorbic acid, alloxan reacted as dialuric acid. The three reducing agents themselves hemolyzed the cells of deficient rats although to a much lesser extent than did dialuric acid. The red blood cells of tocopherol-treated rats were resistant to hemolysis in vitro as in vivo by all the above hemolyzing compounds. Addition of tocopherol to the reaction mixture protected the cells of deficient animals against the hemolytic action of dialuric acid. The tocopherol was more effective when it was incubated with the cells before the dialuric acid was added.
It is proposed that the hemolysis is linked with the reversible oxidation-reduction system of dialuric acid and alloxan, the actual hemolyzing agent being an intermediate of this reaction. Cysteine, glutathione and ascorbic acid, which are readily oxidized by molecular oxygen may form similar intermediates. The protective action of tocopherol is a function of the red blood cell and may best be explained as an antioxidant effect.