Reaction of biological phenolic antioxidants with superoxide generated by cytochrome P-450 model system.

Scavenging of a superoxide and simultaneous formation of free radicals with phenolic antioxidants were investigated with cobalt and iron tetraphenylporphyrin-thiolate complexes as models of P-450 enzymes. The kinetics of decay of the superoxide and development of free radical ESR signal intensities were studied. Based on a molecular orbital calculation of the hyperfine splitting, the radical species generated were confirmed to be those of phenoxyl radicals. The biological implication of superoxide, including active oxygen forms, for the reaction was discussed.