Pro-oxidative and antioxidant effects of salicylates

Abstract

The antioxidant or pro-oxidant properties of dihydroxybenzoic acid (DHBA) derivatives, salicylates, as well as the standard antioxidant compound trolox, were evaluated for inhibition or promotion of the selected reactive oxygen and nitrogen species (O2·−, ·OH, NO, ONO2−) under physiological conditions (pH value 7.4) and at five concentrations (5 to 100 μg ml−1). Tests were also carried out on their ability to influence the antioxidant system on isolated liver mitochondria. According to the findings, selected salicylic acid dihydroxy derivatives do not exhibit significant scavenging activity towards O2·; nor do they differ greatly in activity against ·OH (~ − 6–34%). By comparing their scavenging capabilities with the activity of selected enzyme antioxidants and the concentration of reduced glutathione, 2,5- and 3,4-DHBA in particular are considered able to modulate H2O2 concentrations and thus mediate signalling pathways. The effects on NO were much more pronounced (~ 14–78%) with 2,6-DHBA and 3,5-DHBA causing a decrease in NO inhibitory activity together with ONO2− overproduction. This leads to the prediction that they may act as selective effectors of NO levels. In summary, we can say that selected salicylic acid dihydroxy derivatives predominantly interfere with redox homeostasis by reactions with ·OH and NO.