FREE RADICALS IN BIOLOGY AND MEDICINE(FOURTH EDITION)

Barry Halliwell and John M.C. Gutteridge

When the first edition of Free Radicals in Biology and Medicine appeared in 1955, free radicals were mainly studied by radiation chemists and those involved in industrial processes and research relating to rubber, plastics, oils, paint and food. Two major scientific advances changed all this, they discovery of CuZnSOD by McCord and Fridovich in 1968, and the report by Bernie Babior in 1973 that activated neutrophils produce superoxide for microbial purposes. At this time, most of our indirect methodology for measuring the damage caused by free radicals came from the food industry, where the thiobarbituric acid(TBA) assay was widely used to detect and  measure lipid rancidity. In hindsight, this distorted our interpretations by focusing attention on lipid peroxidation as a major causative event in disease processes. It also triggered a corresponding rush to find antioxidants that would protect against it. The explosive growth of interest that followed necessitated the writing of a second edition 4 years later  (1989). The third edition (1999) reflected an enormous expansion in new methodologies to detect and measure oxidative damage to proteins, carbohydrates, DNA and lipids. These changes quickly led to the realization that free radicals and other reactive species are consequential to most (fortunately not all) disease processes, and by implication antioxidants would in general terms be limited and selective in their efficacy. A new free radical, nitric oxide (NO2), gained prominence, some of the discoverers of its biological role being awarded a Nobel Prize. Nitric oxide research reinforced the increasingly recognized concept that free radicals and other reactive species have purposeful and beneficial roles to play in biology, with cell and molecular biology techniques making a significant contribution to this development. Some remain sceptical about the whole concept of free radicals and antioxidants in biological processes. We remain convinced that they permeate the whole of biology and knowledge of them is essential to understand how aerobic life works.