Different barbiturate derivatives linked to aryl hydrazone moieties as urease inhibitors; design, synthesis, urease inhibitory evaluations, and molecular dynamic simulations

New series of barbiturates linked to aryl hydrazone derivatives 4a-n were designed and synthesized. Briefly, aniline derivatives in the presence of HBF4 and NaNO2 convert to aryl diazonium tetrafluoroborate which is further attacked to barbituric acid derivatives in water. Finally, with tautomerization, the desired products were achieved. Next, compounds were evaluated as possible urease inhibitors and all the synthesized compounds (IC50 = 8.43 +/- 0.14-10.91 +/- 0.42 mu M) were more potent than standard inhibitors hydroxyurea (IC50 = 100.00 +/- 0.15 mu M) and thiourea (IC50 = 23 +/- 1.7 mu M) against urease. It was shown that 4-bromo substitution on the phenyl ring of barbiturate improved the inhibitory potency. Furthermore, based on the molecular dynamic studies, compound 4g depicted noticeable interaction with the urease active site and mobile flap residues through the barbituric acid moiety by coordinating toward the metal bi-nickel center and the essential residues at the active site flap-like Cys592, His593, His594, respectively. These interactions cause interfering catalytic activity of the active site and reduce the flexibility of the mobile flap at the entrance of the active site channel, which significantly decreases the ureolytic activity of urease.

Automated summary

A new series of barbiturates linked to aryl hydrazone derivatives 4a-n were designed and synthesized. The compounds showed stronger urease inhibitory activity than standard inhibitors hydroxyurea and thiourea. Molecular dynamic studies revealed that compound 4g exhibited significant interaction with the urease active site and mobile flap residues, leading to interference with catalytic activity and reduced flexibility of the active site flap.