Bactericidal Activities of Radical Species Generated by Catalytic Reaction of Iron(III) Octacarboxyphthalocyanine

Abstract

Strong bactericidal activities against various bacteria were observed in the reaction system of iron(III) octacarboxyphthalocyanine ( Fe III - oapc ) and tert-butyl hydroperoxide (tert-BuOOH). The kinetics of the decomposition of tert-BuOOH catalysed by Fe III -oapc were studied in buffered solutions between pH 5 to 12 using gas chromatography analysis. The rate of catalytic decomposition of tert-BuOOH followed second-order kinetics in tert-BuOOH concentrations. The second-order rate constant (k2) had a maximum value at pH 11. Oxygen evolution was observed at high tert-BuOOH concentration, while oxygen consumption was observed at low tert-BuOOH concentration. The former indicates plural radical chain reactions of the tert-butoxyl radical and the latter suggests decomposition of the tert-butoxyl radical to acetone and methyl radical. By the electron spin resonance spin trapping method using 5,5-dimethyl-1-pyrroline-N-oxide and α-phenyl-N-tert-butylnitrone it was found that the radical species generated in the reaction system is tert-butoxyl radical, which plays crucial roles in bactericidal activities.