Synthesis of Pyrazole-Based Inhibitors of the Bacterial Enzyme N -Succinyl-l,l-2,6-Diaminopimelic Acid Desuccinylase (DapE) as Potential Antibiotics.

Based on the inhibitory potencies from earlier reported tetrazole thioether analogs, we now describe the synthesis and inhibition of pyrazole-based inhibitors of N -succinyl-l,l-2,6-diaminopimelic acid desuccinylase (DapE) from Haemophilus influenzae ( Hi DapE). The most potent pyrazole analog 7d bears an aminopyridine amide with an IC ₅₀ of 17.9 ± 8.0 μM, and the single enantiomer of ɑ-methyl analog 7q has an IC ₅₀ of 18.8 µM, with potency residing in the ( R )-enantiomer. Thermal shift revealed strong stabilization upon binding inhibitor (R)-7q with T _m = 50.2 °C and a K _i of 17.3 ± 2.8 μM. Enzyme kinetic experiments confirm competitive inhibition, and docking reveals key active site interactions.