Synthesis and pharmacological investigation of 5-substituted-3-methylsulfanyl-1H-pyrazole-4-carboxylic acid ethyl esters as new analgesic and anti-inflammatory agents.

PURPOSE To synthesize a new series of 5-substituted-3-methylsulfanyl-1H-pyrazole-4-carboxylic acid ethyl esters for their analgesic and anti-inflammatory activity. METHODS The title compound synthesized by reacting the amino group of 5-amino-3-methylsulfanyl-1H-pyrazole-4-carboxylic acid ethyl ester with acid anhydrides, acid chlorides and phenyl dithiocarbamates. The synthesized compounds were characterized by IR, 1H-NMR and mass spectral data; the purity of the compounds was determined by elemental analysis. The title compounds were investigated for analgesic, anti-inflammatory and ulcerogenic behaviour. RESULTS The compound 5-benzoylamino-3-methylsulfanyl-1-phenyl-1H-pyrazole-4-carboxylic acid ethyl ester (4c) emerged as the most active compound and exhibiting imperative analgesic and anti-inflammatory activities. Interestingly the test compounds showed only mild ulcerogenic potential when compared to indomethacin. CONCLUSION The compound (4c) could serve as a lead molecule for further modification to obtain a clinically useful novel class of analgesic and anti-inflammatory agents.