Analytical Aspects of Antioxidants and Free Radical Activity in Clinical Biochemistry

This review discusses electron spin resonance (ESR) and then the numerous methods which have been used to determine lipid peroxidation and much of the review concentrates on the latter area because it has been applied widely in biomedical free radical research.

Abstract

The nature of free radicals (atoms or molecules with one or more unpaired electrons), particularly those with a very short life span and high reactivity, has made direct measurement in human subjects especially difficult. This difficulty has led to the development of many different methods for the measurement of free radical activity indirectly by their effects on biological systems, e.g. by measuring products of free radical attack on macromolecules, or by their effect on the antioxidant defence system. An in-depth examination of all methods is beyond the scope of this review. We have attempted to highlight the key references for each method group with a brief explanation and to provide such information on limitations, interferences and reference ranges as is available. More detailed enquiry into a method is possible from the key references. Why then should the reader of the Annals of Clinical Biochemistry be interested in free radicals and antioxidants? It is likely that the clinical biochemist of the future will be undertaking measurements of free radical activity and antioxidants because of greater knowledge of their involvement in cardiovascular, neurodegenerative and chronic inflammatory disease and cancer, as recently reviewed in a series of articles in the Lancet, and in the Annals of Clinical Biochemistryl It is likely also, that therapies based on our knowledge of free radical processes will emerge and be used in clinical practice. (For an analysis of vitamins with antioxidant functions see Bates.') This review discusses electron spin resonance (ESR) and then the numerous methods which have been used to determine lipid peroxidation. Much of the review concentrates on the latter area because it has been applied widely in biomedical free radical research. Methods