Application of ESR spectroscopy in toxicology

Spin trapping in vivo was first achieved in the author's laboratory and is shown to be a feasible method for demonstrating that highly reactive free radical intermediates are generated in the tissues of intact animals as a result of the exposure to certain toxic compounds and to ionizing radiation. The method is based on the property of spin trapping agents (nitrones) to react readily with reactive free radicals to produce stable radical adducts at the site of their origin in target organs. The radical adducts can then be detected by electron spin resonance spectroscopy to determine the intensity of radical production (i.e., number of radicals which were trapped), and, in most cases, identify the nature of the radical that was produced. The type of spin trapping agent employed determines the type of radicals which can be trapped and, at this stage of development of the technique, the number of useful in vivo trapping agents is rather limited.