Free radicals in the 1900's: from in vitro to in vivo

Remarkable progress has been achieved in the past 100 years in the field of free radical chemistry, biology and medicine since the discovery of free radicals in 1900. Free radical-mediated processes play a major role in the present industrial chemistry, but they also cause deleterious effects on rubber, plastics, oil products and foods. The importance of free radicals in vivo has been recognized increasingly from both positive and negative sides. Free radicals play an important role in phagocytosis, the production of some biologically essential compounds and possibly cell signaling. At the same time, they may cause oxidative modification of biological molecules, which leads to oxidative damage and eventually to various diseases, cancer and aging. The role and beneficial effects of antioxidants against such oxidative stress support this view. Furthermore, novel issues have been continuously found in this fascinating and yet controversial field of free radicals in biology. In this short article, the past work, present problems and future perspectives of free radicals in life science will be briefly discussed.