Reaction of a hydrated electron with gentamycin and collagen—A pulse radiolysis study

Abstract The reactions of a hydrated electron (eaq−) with aminoglycoside anbiotic gentamycin and collagen in aqueous medium at different pH have been investigated employing a pulse radiolysis technique. The pseudo-first order equation of reaction kinetics was used to give an accurate description of the decay of eaq− in gentamycin solutions. The rate constant of the eaq− decay in collagen solution was high and reached 3.2 × 1010 M−1 s−1. The rate constants for the reaction of the eaq− with gentamycin were found to be influenced by pH, decreasing with the deprotonation of the −NH3 groups, while for pH > pKa which for gentamycin is equal to 7.8, the rate constant was unchanged. These observations suggest that when the amino groups are protonated, reductive deamination occurs, but for unprotonated non-reactive amino groups, a radical anion is formed on the glycoside moiety.