Studies on new urease inhibitors by using biochemical, STD-NMR spectroscopy, and molecular docking methods

Abstract

Discovery of new urease inhibitors is an important approach towards the treatment of diseases caused by ureolytic bacteria. Urease has an important role in several pathologies, such as urolithiasis, peptic and duodenal ulcers, etc. In this regard, urease inhibitory activity of heterocyclic synthetic compounds 1–14, belonging to different chemical classes was evaluated by employing in vitro biochemical assay, and saturation transfer difference-NMR technique. Compounds 1, 3–5, 7, 10, and 12 have shown urease inhibitory potential in vitro. Among them, compound 1 was found to be more potent (IC₅₀ of 12.90 ± 0.63 µM) than a clinical drug, acetohydroxamic acid (IC₅₀ = 41.5 ± 1.50 µM) (Standard). Compounds 3 (IC₅₀ = 15.0 ± 1.10 µM), 4 (IC₅₀ = 24.67 ± 2.87 µM), and 5 (IC₅₀ = 25.50 ± 0.63 µM) were also identified as potent inhibitors of urease enzyme. These compounds showed strong interactions with the urease enzyme (receptor) in saturation transfer difference-NMR spectra. Specifically, aromatic protons of active compounds received maximum Rf saturation from the receptor protein, thus were inferred to be as in close proximity to the protein. New inhibitors identified through biochemical assay and saturation transfer difference-nuclear magnetic resonance techniques were then subjected to kinetic and molecular docking studies to investigate their mode of inhibition, and production of their interactions with the protein at atomic level, respectively. Active compounds were found to be non-cytotoxic against mouse fibroblast (3T3) cell line MTT assay. Present study thereby identifies new inhibitors of urease enzyme in vitro as leads for further investigation towards the development of novel mechanism-based urease inhibitors.