Effects of Imidazole and Its Derivatives on Radiation-Induced Dephosphorylation of Glycero-1-Phosphate in Deaerated Aqueous Solutions

The effect of imidazole, histamine, histidine, and their nitro derivatives on the radiation-induced transformations of glycero-1-phosphate and ethanol in deaerated aqueous solutions at pH 7 has been studied It has been found that the test substances in equimolar concentrations to glycero-1-phosphate inhibit the radiation-induced dephosphorylation by scavenging the radical products of water radiolysis. At an additive-to-substrate ratio of 1 : 100, the nitro derivatives of histidine and metronidazole efficiently inhibit the radiation-induced dephosphorylation of glycero-1-phosphate due to the interaction with its carbon-centered radicals with constants of (3.1–5.1) × 109 L mol–1 s–1. Using the radiolysis of a 1 M aqueous solution of ethanol, it was demonstrated that 5-nitroimidazoles quantitatively oxidize α-hydroxyethyl radicals; this manifested itself in the absence of 2,3-butanediol among the radiolysis products and a ~20-fold increase in the yield of acetaldehyde, as compared to that in a control experiment. Thus, metronidazole and the nitro derivatives of histidine are capable of suppressing the radiation-induced dephosphorylation of glycero-1-phosphate and, probably, glycerophospholipids due to the oxidation of their α-hydroxylcontaining carbon-centered radicals.