We have previously described a series of 4,5-dihydro-1H-pyrazole as moderately potent nNOS inhibitors. As a follow up of these studies, we report here the preparation and the preliminary evaluation of a series of 1-alkyl-3-benzoyl-4,5-dihydro-1H-pyrazole and 1-alkyl-3-benzoyl-1H-pyrazole as potential inhibitors of both neuronal and inducible nitric oxide synthases (nNOS and iNOS). None of the reported compounds exhibited significant iNOS or nNOS inhibition, although the 1-benzyl-3-(2-amino-5-chlorobenzoyl)-1H-pyrazole-5-carboxylic acid ethyl ester derivative (10l), which shows an inhibition of 50% versus iNOS at a 1mM final concentration and no activity against nNOS, is potentially amenable of further optimization. The reasons for the inactivity of the reported series are discussed on the basis of docking studies.
