Michael H. N Golden

Free radicals and malnutrition

A free radical is simply an atom or molecule with an unpaired electron. This confers very considerable reactivity on the molecule. As the unpaired electron seeks to be paired, it may either abstract an electron from a donor molecule, leaving a new radical in its place, or attach itself to a second molecule, forming an adduct: the position of the unpaired electron may then change to form a new radical. Only when two molecules react, both of which have unpaired electrons, will the radical reaction terminate without a radical product. The single electron step may be an intermediate in an essential biological process that incorporates a safe mechanism to provide the pairing electron. It is important to emphasize that these reactions are common to many of the normal transformations and energy producing metabolic steps of the body: free radicals are common and normal intermediates in metabolism. All the monooxygenases, several dehydrogenases, cytochrome-P450 and b6, prostaglandin synthetase, leucotriene synthetase, vitamin K-dependent enzymes, the mitochondrial respiratory chain, and many other enzymes normally generate radicals. Photochemical production of radicals occurs on exposure to sunlight, and the production of radicals in the retina leads to changes in molecular configuration that are perceived as light. There is nothing esoteric or unusual about radical reactions: they are commonplace.