Quinones in Biology: Functions in electron transfer and oxygen activation

Abstract

Abstract The widespread occurrence and function of quinones in diverse biological systems with particular reference to their role in oxygen activation has been reviewed and discussed. The importance of quinones in such basic metabolic processes as respiration and photosynthesis has been well established. Less clear are the conditions which lead to loss of the normal metabolic functions of quinones, often resulting in the generation of active oxygen species. Exogenous quinones have been used extensively as tools to investigate physiological processes. In addition, they are increasingly applied to influence such reactions artificially. In particular, the loss of normal quinone function invariably has toxicological consequences, in which the activation of oxyqen hy quinone redox reactions plays a central role. The present review discusses hiological and toxicological aspects of quinone metabolism. Physical and chemical data are considered in order to attempt to explain the physiological effects.