Peripheral non-enzymatic antioxidant changes with human aging: a selectivestatus report

Oxidative stress is thought to be involved in the aging process in aerobic organisms and to play a role in the pathogenesis of several disease states. Since free radicals are extremely reactive, shortly half-lived and therefo re very difficult to measure directly, oxidative stress has been mainly stu died through the search of indirect biomarkers of free radical-induced dama ge. In aerobic organisms, oxidative damage to tissues and organs is prevent ed by a network of defenses which includes antioxidant and repairing enzyme s as well as small molecules with scavenging ability, such as antioxidant v itamins. For these reasons, the assay of antioxidant Vitamins and of small molecular free radical scavengers in biological milieus may be used, if app ropriately performed, to quantify the defense status against oxidative dama ge and to provide an indirect estimate of free radical production in aging humans. Since several conflicting data have been reported in this area, thi s review is aimed to summarize the existing evidence and possible faults of the research focusing on the role of plasma concentrations of small-molecu lar, non-enzymatic antioxidants in the process of senescence in healthy hum ans.