Synthesis, structure and biological activity of 3(5)-trifluoromethyl-1H-pyrazoles derived from hemicurcuminoids

Six new 3(5)-trifluoromethyl-5(3)-substituted-styryl-1H-pyrazoles have been synthesized and their tautomerism studied in solution and in the solid state. The determination of their structures has been based on multinuclear NMR spectroscopy together with GIAO/B3LYP/6-311++G(d,p) theoretical calculations of eight structures for each pyrazole (two tautomers and four conformations). Five out of the six compounds present inhibition percentages of the iNOS isoform higher than 50%. With regard to the nNOS inhibitory activity, only two of the studied compounds show an inhibition of about 50%. Finally, concerning the eNOS, there is a compound presenting a low percentage of inhibition (40.2%) attaining in the other cases 50%.