The Dangerous Hydroxyl Radical
The uncontrolled action of hydroxyl radicals the most damaging free radical by far can have devastating effects within the body. The hydroxyl radical is a third generation species of radical which is derived from hydrogen peroxide (HZ02), which, in turn, is derived from the superoxide radical through the action of the enzyme superoxide dismutase.
Hydrogen peroxide is reduced to hydroxyl radicals by the enzymes glutathione peroxidase and catalase in the presence of transition metals such iron or copper. The dangers of the hydroxyl radical has been highlighted by Dr. Reiter:
"If the function of radicals is to destroy molecules and tissues, then the hydroxyl radical would be the radical's radical. It reacts at diffusion rates with virtually any molecule found in its path including macromolecules such as DNA, membrane lipids, proteins, and carbohydrates. In terms of DNA, the hydroxyl radical can induce strand breaks as well as chemical changes in the deoxyribose and in the purine and pyrirnidine bases. ""Damaged proteins, many of them crucial enzymes in neurons, lose their efficiency and cellular function wanes. Protein oxidation in many tissues, including the brain, has been proposed as an explanation for the functional deficits associated with aging. "
The fact that melatonin is so much better at scavenging hydroxyl radicals than any other antioxidant is persuasive evidence that melatonin protects us against a wide variety of diseases and that its progressive depletion with advancing age contributes to aging and the diseases and disabilities associated with aging.
