Comparison of radical-scavenging activities for selected phenolic acids

•The capacity of selected phenolic acids (i.e. gallic, salicylic, p-hydroxybenzoic, gentisic, protocatechuic, vanillic, syringic, o-, m-, p-coumaric, caffeic, ferulic, isoferulic, and sinapic acids) to scavenge the “stable” free radical 2,2-diphenyl-1-picrylhydrazyl• (DPPH•) was evaluated using the classical assay. Compounds tested with this method demonstrated radical-scavenging activities to vary to a different extent, but in a concentration-dependent manner. Gallic and gentisic acids showed the strongest antiradical properties (EC50 0.0237 and 0.0292 µmol/assay, respectively) whereas salicylic and p-hydroxybenzoic acids were the least active radical scavengers (EC50 > 800 µmol/assay).