Biological Action of X-Rays, Nitrogen Mustards, Diepoxides and Peroxides

Abstract

ORGANIC peroxides have recently been shown to be mutagenic¹ and to induce chromosome abnormalities in Vicia faba². The broad similarity of the effects produced by the nitrogen mustards and the diepoxides³, which almost certainly react by a carbonium ion mechanism, and those produced by X-rays and peroxides, which react by a free radical mechanism, prompts one to look for similarities in their mode of action. At least two points of similarity may be observed: (a) Free radicals, like carbonium ions, are electrophilic reactants⁴; (b) the reaction of a carbonium ion derived from a mustard molecule with a nucleophilic centre in a biological system gives a product which is still electrophilic owing to the reactivity of the second halogen atom. Likewise, the reaction of a free radical with such a centre can also lead to the production of an electrophilic centre (see below). Schematically: (A) + (B) → (C) → (D). A is the reacting centre in the system, B the reactant, C the intermediate product, and D the electrophilic centre derived from C.