BIOLOGY OF FREE-RADICAL SCAVENGERS - AN EVALUATION OF ASCORBATE

Reactive free radical species (R.) arc associated with several forms o f tissue damage and disease, and also with the process of aging. Prote ction is thought to be available in the form of endogenous compounds t hat react with and thereby ''scavenge'' the R.. Because many R. are re active forms of oxygen, an effective scavenger is often referred to as an antioxidant. To be an effective antioxidant physiologically, a sub stance must have certain chemical and biological properties: it must b e present in adequate amounts in the body; it must react with a variet y of R.; it must be suitable for compartmentation; it must be readily available; it might be suitable for regeneration; it must be conserved by the kidneys; and it must have tolerable toxicity. Several water-so luble candidates are mentioned, with most having no more than one or t wo of the attributes listed. Ascorbic acid is discussed in detail, and an analysis is made of whether it has the properties mentioned.