Pyridoxamine scavenges protein carbonyls and inhibits protein aggregation in oxidative stress-induced human HepG2 hepatocytes

Introduction of carbonyl groups into amino acid residues is a hallmark for oxidative damage to proteins by reactive oxygen species (ROS). Protein carbonylation can have deleterious effects on cell function and viability, since it is generally unrepairable by cells and can lead to protein dysfunction and to the production of potentially harmful protein aggregates. Meanwhile, pyridoxamine (PM) is known to scavenge various toxic carbonyl species derived from either glucose or lipid degradation through nucleophilic addition. PM is also demonstrated to catalyze non-enzymatic transamination reactions between amino and α-keto acids. Here, we found that PM scavenges protein carbonyls in oxidized BSA with concomitant generation of pyridoxal and recovers oxidized lysozyme activity. Moreover, we demonstrated that the treatment of H2O2-exposed HepG2 hepatocytes with PM significantly reduced levels of cellular carbonylated proteins and aggregated proteins, and also improved cell survival rate. Our results suggest that PM may have potential efficacy in ameliorating ROS-mediated cellular dysfunction.