Evaluation of scavenging rate constants of DOPA and tyrosine enantiomers against multiple reactive oxygen species and methyl radical as measured with ESR trapping method

The scavenging rates of DOPA (DL- and L-3-(3,4-dihydroxyphenyl)alanine) and Tyr (tyrosine (DL- and L-3-(4-hydroxyphenyl)alanine)) against five reactive oxygen species (ROS) andmethyl radical were measured with the use of electron spin resonance (ESR) spin-trapping method and the scavenging rate constants of DOPA and Tyr were determined. The scavenging rate constants for multiple active species increased in the order of O-2 center dot< RO center dot < O-1(2) < H3C center dot < HO center dot for Tyr and RO center dot O-2(center dot) < O-1(2) approximate to H3C center dot < HO center dot for DOPA, and the differences in the radical scavenging abilities for L-enantiomers and DL- mixtures of DOPA and Tyr were shown. Further, based on the redox potentials, we have suggested that the primary chemical process of antioxidant reactions with O-2(center dot) and O-1(2) can be characterized with the electron transfer of antioxidants (DOPA and Tyr). (C) 2014 Elsevier Ltd. All rights reserved.