Mellatonin

Melatonin and Free Radicals _______________________ Melatonin is a very potent and efficient endogenous free radical scavenger. Pineal indolamine reacts with toxic hydroxyl radicals and can provide an immediate protection against oxidative damage to biomolecules within every cellular compartment. Melatonin acts as a primary non-enzymatic antioxidative defense against the destruction caused by hydroxyl free radicals. Melatonin and structurally related tryptophan metabolites are principally involved in the prevention of oxidative stress in a diverse range of organisms. Melatonin or treatments preserving the endogenous rythm of melatonin formation can retard the rate of ageing and the time of onset of age-related diseases. The activation of central excitatory amino acid receptors can suppress melatonin synthesis and is accompanied by a reduced detoxification rate of hydroxyl radicals. Aged animals and humans are melatonin-deficient and more sensitive to oxidative stress. New therapies investigating the effect of endogenous excitatory amino acid antagonists and stimulants of melatonin synthesis such as magnesium, may lead to therapeutic approaches for the prevention of diseases related to premature ageing. 18645 "Melatonin, Hydroxyl Radical-Mediated Oxidative Damage, and Ageing: A Hypothesis", Poeggeler, B., et al, Journal of Pineal Research, 1993;14:151-168. (Address: Russel J. Reiter, Department of Cellular and Structural Biology, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78284-7762, U.S.A.)