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.