A new series of quinazolinone derivatives containing triazole, thiadiazole, thiosemicarbazide functionalities was synthesized and then screened for their in vitro urease inhibition properties. Most of the compounds showed excellent activity with IC50 values ranging between 1.88 ± 0.17 and 6.42 ± 0.23 µg/mL, compared to that of thiourea (IC50 = 15.06 ± 0.68) and acetohydroxamic acid (IC50 = 21.03 ± 0.94), as reference inhibitors. Among the synthesized molecules, compounds 5c, 5e and 5a showed the best inhibitory effect against urease enzyme with IC50 values of 1.88 ± 0.17 µg/mL, 1.90 ± 0.10 and 1.96 ± 0.07 µg/mL, respectively. Moreover in order to give better understanding of the inhibitory activity of synthesized compounds, molecular docking studies were applied at the target sites of jack bean urease enzyme (JBU). Their binding poses and energy calculations were analyzed using induced fit docking (IFD) and prime-MMGBSA tool. Binding poses of studied compounds were determined using induced fit docking (IFD) algorithms.

A new series of quinazolinone hybrid molecules containing coumarin, furan, 1,2,4-triazole and 1,2,4-thiadiazole rings was designed, synthesized, and screened for their urease inhibition activities. All newly synthesized compounds showed outstanding urease inhibitory potentials with IC50 values ranging between 1.26 ± 0.07 and 7.35 ± 0.31 μg/mL. Among the series, coumarin derivatives (10a-d) exhibited the best inhibitory effect against urease in the range of IC50  = 1.26 ± 0.07 to 1.82 ± 0.10 μg/mL, when compared to standard urease inhibitors such as acetohydroxamic acid and thiourea (IC50  = 21.05 ± 0.96 and 15.08 ± 0.71 μg/mL, respectively). Molecular docking studies were also performed to analyze the binding mode of compound 10b, and supported the experimental results.

Current study is based on the biology-oriented drug synthesis (BIODS) of S-naproxen (NSAID) derivatives and the evaluation of their urease inhibitory potential. In this regard, a variety of S-naproxen derivatives 2-39 including hydrazide 1, Schiff bases 2-21, aroyl substituted hydrazides 22-24, sulfohydrazides 25-34, 2-mercapto oxadiazole 35, phenacyl substituted 2-mercapto oxadiazoles 36-39 were synthesized under the umbrella of BIODS by simple chemical transformation of its pharmacophoric carboxylic group. Compounds 1-39 were evaluated for in vitro urease inhibitory activity and most of them showed good to moderate inhibitory potential in the range of IC50 = 14.01 ± 0.23-76.43 ± 0.8 µM as compared to standard acetohydroxamic acid (IC50 = 27.0 ± 0.5 µM). Limited structure-activity relationship (SAR) was established in order to rationalize the participation of varying groups (R) in the inhibitory potential of compounds. Molecular docking study on all active compounds was also carried out to decipher the interactions detail of the ligand with the receptors of active site of enzyme.

Current study deals with the evaluation of indane-1,3-dione based compounds as new class of urease inhibitors. For that purpose, benzylidine indane-1,3-diones (1-30) were synthesized and fully characterized by different spectroscopic techniques including EI-MS, HREI-MS, 1H, and 13C NMR. All synthetic molecules 1-30 were evaluated for urease inhibitory activity and showed good to moderate inhibitory potential within the range of (IC50 = 11.60 ± 0.3-257.05 ± 0.7 µM) as compared to the standard acetohydroxamic acid (IC50 = 27.0 ± 0.5 µM). Compound 1 (IC50 = 11.60 ± 0.3 µM) was found to be most potent inhibitor amongst all derivatives. The key binding interactions of most active compounds within the enzyme pocket were evaluated through in silico studies.

The objective of this experiment was to evaluate the effects of urea hydrolysis rate on ruminal bacterial diversity level and cellulolytic bacteria abundance in vitro. To control urea hydrolysis rate, urea and urease inhibitor (acetohydroxamic acid, AHA) were supplemented to a 2 × 2 factorial design, with urea supplemented at 0 or 20 g/kg dry matter (DM) of substrate, and AHA equivalent to 0 or 450 mg/kg DM of substrate. Ruminal fluid was collected from three Chinese Holstein dairy cows, fed a TMR, and incubated at 39 °C for 12 h after the addition of urea and AHA. Rumen fermentation parameters, which indicated the rate of ammonia formation (including ammonia-nitrogen (NH3-N) and urea-nitrogen concentrations, urease activity, and microbial crude protein) were measured by chemical analysis. Bacterial diversity was analyzed by denaturing gradient gel electrophoresis (DGGE). Total bacteria and cellulolytic bacteria abundance was detected by quantitative PCR. Results showed that AHA addition significantly decreased the rate of ammonia formation when urea was supplemented. Urea and AHA supplementation significantly increased the bacterial community diversity level according to the Shannon-Weiner index of 16S DGGE images. Furthermore, ruminal bacterial profiles were separated by ammonia release rate when urea was supplemented, according to the DGGE and hierarchical cluster analysis. Urea supplementation reduced the abundance of cellulolytic bacteria, such as Ruminococcus albus, R. flavefaciens, Fibrobacter succinogenes, and Butyrivibrio fibrosolvens, but inhibition of urea hydrolysis by AHA addition alleviated the reductions during the early period of incubation. In conclusion, slow release of ammonia induced by urease inhibitor influenced the ruminal bacterial diversity level and lessened the inhibition of total bacteria growth at the incubation of 12 h and F. succinogenes during the early period of incubation.

The current study deals with the synthesis of urea and thiourea derivatives 1-37 which were characterized by various spectroscopic techniques including FAB-MS, 1H-, and 13C NMR. The synthetic compounds were subjected to urease inhibitory activity and compounds exhibited good to moderate urease inhibitory activity having IC50 values in range of 10.11-69.80 µM. Compound 1 (IC50 = 10.11 ± 0.11 µM) was found to be most active and even better as compared to the standard acetohydroxamic acid (IC50 = 27.0 ± 0.5 µM). A limited structure-activity relationship (SAR) was established and the compounds were also subjected to docking studies to confirm the binding interactions of ligands (compounds) with the active site of enzyme.

A new series of 2,3-disubstituted quinazolin-4(3H)-one compounds including oxadiazole and furan rings was synthesized. Their inhibitory activities on urease were assessed in vitro. All newly synthesized compounds exhibited potent urease inhibitory activity in the range of IC50 = 1.55 ± 0.07-2.65 ± 0.08 µg/mL, when compared with the standard urease inhibitors such as thiourea (IC50 = 15.08 ± 0.71 µg/mL) and acetohydroxamic acid (IC50 = 21.05 ± 0.96 µg/mL). 2,3-Disubstituted quinazolin-4(3H)-one derivatives containing furan ring (3a-e) were found to be the most active inhibitors when compared with the compounds 2a-e bearing oxadiazole ring. Compound 3a, bearing 4-chloro group on phenyl ring, was found as the most effective inhibitor of urease with the IC50 value of 1.55 ± 0.11 µg/mL. The molecular docking studies of the newly synthesized compounds were performed to identify the probable binding modes in the active site of the Jack bean urease (JBU) enzymes.

The continuing emergence of drug-resistant Helicobacter pylori (HP) drives the ongoing need for the development of new and effective anti-HP drugs. Urease inhibitor has now gained strong interest as an alternative approach for HP infections. 3-Chlorophenyl-3-hydroxypropionylhydroxamic acid (CPH), a novel urease inhibitor identified in our group, shows impressive potency, which was optically separated for a further exploration. Here, we report in vitro/in vivo pharmacological evaluation of (±)-CPHs and the enantiomers. The raceme and the individual enantiomers significantly suppress gastritis at 32 mg/kg b.i.d dose with lower toxicity to mammalian cells (with CC50s ≥ 3.16 mM) and mice (LD50s ≥ 2338 mg/kg) than the clinically used agent acetohydroxamic acid. Furthermore, a significant increase of eradication of HP is observed for the combination of (±)-CPHs or the enantiomers with an antimicrobial. These studies revealed that CPH is a promising candidate for an alternative treatment of HP-dependent conditions by targeting virulence factor urease, and CPH may be used as a raceme.

Hydroxamic acids have emerged as the most promising candidates from among the different classes of inhibitors of urease. In order to understand the mechanism of their action, we have studied in detail using quantum mechanics the active site of Helicobacter pylori urease complexed with acetohydroxamic acid. A diverse library of ligands having the hydroxamate moiety has been prepared and docked into the active site of urease using the QM/MM methodology. It is found that hydroxamic acids with hydrophobic groups attached to them are more potent inhibitors of urease because they can easily penetrate the hydrophobic environment surrounding the active site. The -CONHO- moiety of the hydroxamic acid is also found to be absolutely necessary for chelation and inhibition of urease. In order to determine the roles of residues His 221 and Ala 365, which are not part of the active site, but are nevertheless involved in hydrogen bonding with the ligand, we have performed Molecular Dynamics simulations, both on the wild urease and also on its mutated counterpart, with the two residues substituted, respectively, by alanine and glycine.

Natural organic matter is known to influence the mobility of plutonium (Pu) in the environment via complexation and reduction mechanisms. Hydroxamate siderophores have been specifically implicated due to their strong association with Pu. Hydroxamate siderophores can also break down into di and monohydroxamates and may influence the Pu oxidation state, and thereby its mobility. In this study we explored the reactions of Pu(VI) and Pu(V) with a monohydroxamate compound (acetohydroxamic acid, AHA) and a trihydroxamate siderophore desferrioxamine B (DFOB) at an environmentally relevant pH (5.5-8.2). Pu(VI) was instantaneously reduced to Pu(V) upon reaction with AHA. The presence of hydroxylamine was not observed at these pHs; however, AHA was consumed during the reaction. This suggests that the reduction of Pu(VI) to Pu(V) by AHA is facilitated by a direct one electron transfer. Importantly, further reduction to Pu(IV) or Pu(III) was not observed, even with excess AHA. We believe that further reduction of Pu(V) did not occur because Pu(V) does not form a strong complex with hydroxamate compounds at a circum-neutral pH. Experiments performed using desferrioxamine B (DFOB) yielded similar results. Broadly, this suggests that Pu(V) reduction to Pu(IV) in the presence of natural organic matter is not facilitated by hydroxamate functional groups and that other natural organic matter moieties likely play a more prominent role.