FREE-RADICAL INDUCED REDOX REACTIONS OF DRUGS - A PULSE-RADIOLYSIS STUDY

The kinetics and mechanism of free-radical induced redox reactions contributing to the metabolism of drugs was investigated by pulse radiolysis. The ortho-methoxy-phenolic structure of the molecule of silybin, a liver-protecting flavonoid, was assigned as the major target for attack by oxidizing free radicals at biological pH. The dihydroquinoline type antioxidants, CH 402 and MTDQ-DA, were shown to efficiently reduce superoxide radical anion (O2-). The reductive deiodination of amiodarone, an antiarrhytmic/antianginal drug, proceeds via ketyl radical intermediates and generates reactive aryl radicals, likely to be responsible for the toxicity of the drug on prolonged administration.