Pulse radiolytic investigation of the reaction of hydroxyl radicals with gentamycin

Hydroxyl radicals were generated radiolytically in N₂O-saturated aqueous solutions of the aminoglycoside antibiotic, gentamycin. Using the pulse radiolysis technique, the rate constant of OH radicals with gentamycin determined was 1.2·10⁹ dm³·mol⁻¹·s⁻¹. Upon^.OH attack a transient species with an absorption maximum at 270 nm is observed which decays by second-order kinetics within the solute concentration range of 3.2·10⁻⁵ to 1·10⁻³mol·dm⁻³. Transient species undergoes transformation to a permanent product absorbing between 260 and 340 nm with maximum absorption at 300 nm. Rate constant of the reaction of bimolecular decay of gentamycin radicals, k (Gen^.+Gen^.) was found to be ≈ 1.4·10⁷ dm³·mol⁻¹·s⁻¹.