Synthesis and pharmacological evaluation of indole derivatives as deaza analogues of potent human neutrophil elastase inhibitors

A number of N-benzoylindoles were designed and synthesized as deaza analogs of pre- viously reported potent and selective HNE inhibitors with an indazole scaffold. The new compounds containing substituents and functions that were most active in the previous series were active in the micromolar range (the most potent had IC50 = 3.8 microM) or inactive. These results demonstrated the importance of N-2 in the indazole nucleus. Docking studies performed on several compounds contain- ing the same substituents but with an indole or an indazole scaffold, respectively, highlight interesting aspects concerning the molecule orientation and H-bonding interactions, which could help to explain the lower activity of this new series.