Synthesis of [1,2,4]triazolo[1,5-a]pyridines of potential PGE2 inhibitory properties

A variety of 5-amino-6,8-dicyano-1H-[1,2,4]triazolo[1,5-a]pyridin-4-ium-2-thiolate containing compounds 3a-i, 5a-c were prepared via reaction of arylidenemalononitriles 1a-c, 4a and 4b with 2-[(substituted amino)thiocarbonyl]cyanoacetohydrazides 2a-d in refluxing ethanol in the presence of triethylamine. Anti-inflammatory activity screening of the synthesized compounds (at a dose of 50mg/kg body weight) utilizing in vivo acute carrageenan-induced paw oedema standard method in rats exhibited that the prepared heterocycles possess considerable pharmacological properties especially, 3f, 3h, 5b and 5c which reveal remarkable activities relative to indomethacin (which was used as a reference standard at a dose of 10mg/kg body weight). PGE(2) inhibitory properties of the highly promising synthesized anti-inflammatory active agents (3f, 3h, 5b and 5c) were determined by PGE(2) assay kit technique, which reveal remarkable activity coinciding greatly with the observed anti-inflammatory properties. Anti-tumor activity screening of 3b and 3e, as representative examples of the synthesized compounds, at a dose of 10 microM utilizing 59 different human tumor cell lines, representing leukemia, melanoma and cancers of the lung, colon, brain, ovary, breast, prostate and kidney exhibited that the tested compounds reflect mild or no activity at all against most of the used human tumor cell lines. However, compound 3e reveals considerable anti-tumor properties against leukemia CCRF-CEM and HL-60(TB) cell line.