Thiazolyl/oxazolyl formazanyl indoles as potent anti-inflammatory agents

A series of 3-(2'-substituted indolidene aminothiazol-4'-yl)-2-(4-chlorophenyl) indoles (3a-3d), 3-(2'-substituted indolidene amino oxazol-4'-yl)-2-(4-chlorophenyl) indoles (3a'-3d') and 3-[2'-(1'-substituted phenyl-3'-substituted indolyl formazan-4'-yl) thiazol-4'-yl]-2-(4-chlorophenyl) indoles (4a-4h), 3-[2'-(1'-substituted phenyl-3'-substituted indolyl formazan-4'-yl) oxazol-4'-yl]-2-(4-chlorophenyl) indoles (4a'-4h') were synthesized and evaluated for their anti-inflammatory activity against carrageenan induced oedema in albino rats at a dose of 50mg/kg p.o. The structure of all these compounds were established on the basis of elemental and spectral (IR, (1)H NMR and mass spectral data) studies. All the compounds of this series show moderate to good activity. The most active compound of this series 3-(2'-methyl indolidene aminothiazol-4'-yl)-2-(4-chlorophenyl) indole (3b) is found to be the most potent and has shown higher percent of inhibition of oedema, lower ulcerogenic liability and acute toxicity than the reference drug phenyl butazone.