Antioxidant and antiradical activities of cinnamic and benzoic acid derivatives, using different methods, were investigated. The total antioxidant effect was evaluated using method with linoleic acid-water emulsion. The ability to scavenge free radicals was checked using 2,2^’-azinobis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS•) or 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•). The reducing power of the studied compounds solutions was also evaluated. It was stated, that the applied measuring method strongly influenced the obtained result, because in the system with ABTS• free radicals, the highest antioxidant activities possessed vanillic, sinapic and protocatechuic acid, whereas the most effective DPPH• radical scavengers were methyl ferulate, methyl syringate, syringaldehyde and vanillic acid. In another method, linoleic acid peroxidation was effectively inhibited by the caffeic, sinapic and syringic acid. The highest reducing powers possessed protocatechuic acid, caffeic, sinapic and ferulic acid, higher than BHT and comparable to Trolox. Methylated derivatives of coumaric acid, caffeic acid, vanillic acid and syringic acid turned out to be weaker antioxidants and reducing agents than the free forms, except methyl ferulate, which possessed only slightly lower antioxidant activity than free ferulic acid, and in some measuring systems was a more effective antioxidant than ferulic acid.

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