Design, synthesis, in vitro, and in silico investigations of new barbituric acid-hydrazone-chalcone derivatives as promising urease inhibitors

Abstract

The present study focuses on the synthesis of a library of arylated hydrazones of barbituric acid, aiming to develop exceptionally potent urease inhibitors. A two-step synthesis was adopted; first, chalcone derivatives were synthesized by reacting 4-aminoacetophenone with variously substituted aldehydes under basic conditions, these derivatives were then treated with barbituric acid to afford barbituric acid hybrids 5a-n. The FTIR, CHNS, ¹H NMR, and ¹³C NMR were structurally characterized. All compounds were examined for their potential against the urease enzyme and displayed remarkable results with IC₅₀ values ranging from 4.84 ± 0.62 to 13.36 ± 0.23 µM. The structure-activity relationship was also established, revealing that compound 5n (IC₅₀ = 4.84 ± 0.62 µM) with -Cl and -NO₂ substitutions para to each other plays a major role in urease inhibition and is identified as the most potent analog of the library. Moreover, molecular docking investigations indicated the barbituric acid rings in all compounds align consistently, with the carbonyl group at C2 positioned toward the bi-nickel center atoms, resembling the orientation in AHA and thiourea. Chalcone and hydrazone subunits occupy a similar conformation near the active site's entrance. Compound 5n is stabilized at the active site's bi-nickel center by the barbiturate moiety, which forms metal coordination bonds and hydrogen bonds with key residues like Asp633, His492, and Cys592. Additional interactions with His593, Arg439, and His594 contribute to its stability and influence the flexibility of the active site's mobile flap, ultimately inhibiting urease activity.