ANTIOXIDANT ACTIVITIES OF DIHYDROXYLATED SALICYLIC-ACID DERIVATIVES

The ability of hydroxylated metabolites of salicylic acid to scavenge reactive oxygen species and to inhibit arachidonic acid metabolism was investigated. The tested trihydroxybenzoic acids (THBAs) were potent scavengers of hydroxyl and superoxide anion radicals produced by Fento n reaction and xanthine/xanthine oxidase system or activated macrophag es respectively, In the same tests, salicylic acid possessed moderate O-2(-) and low OH. scavenging activities. Our results demonstrate that adding two hydroxyl groups to salicylic acid strongly increases the r eactive oxygen species (ROS) scavenging activities. Adding two hydroxy l groups at position 4 and 5 (2,4,5-THBA) affords the most active ROS scavenging activity probably due to the ortho unsubstituted catechol m oiety. In fact, we can consider that the ROS scavenging properties of salicylic acid are essentially due to its metabolic products such as 2 ,3- and 2,5-DHBAs, catechol and also to THBAs.