N-pyridinyl-indole-3-(alkyl)carboxamides and derivatives as potential systemic and topical inflammation inhibitors

N-substituted-(indol-3-yl)carboxamides 10-15 and alkanamides 16-18 were prepared starting from the corresponding acids and submitted to screening for evaluation of their anti-inflammatory activity. None of the considered carboxamides exhibited significant inhibitory effect in the carrageenin-induced rat paw oedema after oral administration of 0.1 mM x kg(-1); nevertheless introduction of an alkyl chain, leading to alkanamides 16-18, induced moderate to high activity: 46-95% inhibition. The efficacy of these compounds in the inhibition of topical inflammation was confirmed by measuring reduction of ear thickness in the acute tetradecanoyl phorbol acetate (TPA)-induced mouse ear swelling assay. Preliminary pharmacomodulation brought to the fore that toxic effects induced, at 0.4 mM x kg(-1), by N-(pyridin-4-yl)(indol-3-yl)propanamide (17) could be attenuated or suppressed by 5-fluorination or introduction of a methoxycarbonylborane moiety, leading to 18 and 21.