Free radicals in biological systems—a review orientated to inflammatory processes

Abstract

Free radicals are chemical species with one or more unpaired electrons in their outer orbital. Their production is essential to normal metabolism but they are theoretically destructive unless tightly controlled. We review the chemistry of free radical production and the intra/extracellular defence systems that limit their toxicity. Particular reference is made to biochemical processes which we believe are relevant to maintaining an inflammatory reaction. As a clinical illustration we describe mechanisms pertinent to the perpetuation of the chronic inflammation of rheumatoid synovitis.