New N-pyridinyl(methyl)-indole-2- and 3-(alkyl)carboxamides and derivatives acting as systemic and topical inflammation inhibitors

A series of novel N-substituted-(indol-2-yl)carboxamides (12 -18) and (indol-3-alkyl)carboxamides (25-31) were synthesized and evaluated as inhibitors of the inflammation process. Pharmacomodulation at the level of the amidic nitrogen by incorporation of the previously described pharmacophoric moieties 6-aminolutidine, beta-picolylamine, 4-aminopyridine and piperazine was investigated; only two compounds (12) and (31) exhibited significant (similar to40%) inhibitory effect in the carrageenan-induced rat paw edema after oral administration of a dose of 0.1 mM kg(-1) . Replacement of the indole core by indazole failed to increase activity. Incorporation of an alkyl chain spacer led to more efficient compounds (46-52) especially in the indolepropanamide sub-series. Determination of the efficiency of the most active compounds on topical inflammation, by measuring reduction of ear thickness in the acute tetradecanoyl phorbol acetate (TPA)-induced mouse ear swelling assay, confirmed the high potency of propanamides ( 49) and (51) after oral administration: ID50 =0.041+/-0.013 and 0.042+/-0.016 mM kg(-1) respectively. The less toxic propanamide (51) exerted a high level of inhibitory activity after topical application of 2 x 100 mug/ear: 78+/-2%.