Vitamin B6 Compounds are Capable of Reducing the Superoxide Radical and Lipid Peroxide Levels Induced by H2O2 in Vascular Endothelial Cells in Culture

Pyridoxamine, pyridoxine, and pyridoxal phosphate were tested to examine if they have antioxidant properties. Endothelial cells exposed to 0.5 mM H2O2 for 2 hours increased the superoxide anion and lipid peroxide levels as biomarkers of oxidative stress. The increase of superoxide was mainly due to the activation of NADPH-oxidase by H2O2. Preincubation of the endothelial cells with 0.1 or 1.0 mM of pyridoxamine or pyridoxal phosphate for one-half hour before H2O2 exposure significantly reduced the superoxide and lipid peroxide compared to the cells exposed to H2O2 only. Preincubation of the cells with 0.1 or 1.0 mM of pyridoxine also significantly reduced the lipid peroxide but did not significantly affect the superoxide level unless the preincubation time was extended to 24 hours. The prostacyclin release by endothelial cells was also significantly inhibited by H2O2. However, the preincubation of endothelial cells with 1.0 mM of pyridoxamine, pyridoxine, or pyridoxal phosphate did not prevent that inhibition. These results indicate that pyridoxamine, pyridoxine, and pyridoxal phosphate acted as antioxidants and reduced the superoxide and lipid peroxides induced by H2O2, but did not protect the cells from the effects directly related to H2O2 itself.