Free radical-induced redox chemistry of Nedaplatin and Satraplatin under physiological conditions.

Abstract Temperature-dependent kinetics for the reactions of hydroxyl radicals and hydrated electrons with the anti-cancer drug nedaplatin have been determined using a combination of electron pulse radiolysis and absorption spectroscopy. Under physiological pH and chloride concentrations, the kinetics was well described by the equations and corresponding to Arrhenius activation energies of 15.88 ± 1.16 and 14.14 ± 1.41 kJ mol−1 for hydroxyl radical oxidation and hydrated electron reduction, respectively. Through a comparison of spectral and kinetic literature it is believed that the oxidation reaction gives predominantly an intermediate Pt(III) species, whereas reduction gives a Pt(I) moiety. Analogous hydrated electron measurements for the Pt(IV) drug satraplatin showed multiple-component decays at higher temperatures (>20°C), indicating that significant thermal degradation of this chemical occurs. From double-exponential curve fitting, the satraplatin reduction kinetics was found to be well described by...