Redox properties of Mn(III)porphyrins in hyaluronan oxidative degradation: Single electron transfer mechanism.

Abstract

Cationic Mn(III)-meso-tetraarylporphyrin derivatives, substituted in para position with different size alkyl chains, were investigated to function as antioxidants in free-radical degradation of high-molar-mass hyaluronan by the methods of rotational viscometry and oximetry. The results of rotational viscometry showed that MnTM-4-PyP5+, MnTE-4-PyP5+, MnTPr-4-PyP5+, MnTPen-4-PyP5+ and MnTHep-4-PyP5+ showed high efficiency in decomposing H2O2, and reducing of peroxidized hyaluronan. When using oxygen electrode, MnTE-4-PyP5+, MnTPr-4-PyP5+, MnTPen-4-PyP5+, and MnTHep-4-PyP5+ applied to function as protective antioxidants in hyaluronan degradation, the uptake of dissolved oxygen from the reaction milieu was rapid, followed by continual increase in oxygen concentration up to the end of the measurement. However, when especially MnTE-4-PyP5+, MnTPr-4-PyP5+, and MnTPen-4-PyP5+ were examined as hyaluronan chain-breaking antioxidants, after short-term dissolved oxygen uptake, almost no increase in oxygen concentration was shown.