The free radical scavenging effect of the hydrochloride of (±)-trans-2-(1-pyrrolidinyl-) cyclohexylester of 3-(n)-pentyloxy carbanilic acid, pentacaine (trapencaine I.N.N), and its derivatives and other substances, lidocaine, stobadine, mannitol, and ascorbic acid was tested in the presence of diphenyl-p-picrylhydrazyl (decrease in absorbance). In this method, more pronounced antiradical activity was observed with trapencaine, more effective than stobadine, ascorbate, and mannitol. Trapen- caine derivatives and lidocaine were less effective in comparison with trapencaine. After introducing a methylene group into the hydrophilic moiety of the trapencaine molecule (stereoisomers P-18, P-20), there was a loss of antiradical activity, but the cis-isomer is more effective than the transisomer. The results demonstrate the existence of relationships between the chemical structure, antiradical and gastric-cytoprotective activity.

        Key words: trapencaine - lidocaine - stobadine - antiradical activity - gastrocytoprotective activity