Inhibition of the metalloenzyme urease has important pharmacologic applications in the field of antiulcer and antigastric cancer agents. Urease is involved in many serious infections caused by Helicobacter pylori in the gastric tract as well as by Proteus and related species in the urinary tract. Although numerous studies have described several novel urease inhibitors (UIs) used for the treatment of gastric and urinary infections, all these compounds have exhibited severe side effects, toxicity, and instability. Therefore, to overcome such problems, it is necessary to search for new sources of UIs, such as natural products, that provide reduced side effects, low toxicity, greater stability, and bioavailability. As limited studies have been conducted on plant-derived UIs, this paper aims to highlight and summarize the most promising compounds isolated and identified from plants, such as terpenoids, phenolic compounds, alkaloids, and other substances with inhibitory activities against plant and bacterial ureases; these are in vitro and in vivo studies with an emphasis on structure-activity relationship studies and types of inhibition that show high and promising levels of anti-urease activity. This will aid medicinal chemists in the design and synthesis of novel and pharmacologically potent UIs useful for the development of antiulcer drugs.
- Keywords
- Antiulcer drugs, Bioactive compounds, Gastric and urinary infections, Herbal plants, Urease inhibitors,
- MeSH
- Bacteria enzymology MeSH
- Humans MeSH
- Anti-Ulcer Agents analysis isolation & purification pharmacology MeSH
- Plants enzymology MeSH
- Urease antagonists & inhibitors MeSH
- Structure-Activity Relationship MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
- Names of Substances
- Anti-Ulcer Agents MeSH
- Urease MeSH
Urease activity was detected in the dermatophyte Trichophyton mentagrophytes cells at early exponential phase of growth. Specific activity of urease decreased with culture age. At exogenous urea concentrations above 2 mM formation of urease was inhibited. The pH optimum lay at 7-7.5, the Km being 14 mM. No urease activity could be detected in cell-free culture fluid of T. mentagrophytes. No endo- or exocellular urease activity could be detected in a T. rubrum strain grown with or without urea.
- MeSH
- Ammonia metabolism MeSH
- Hydrogen-Ion Concentration MeSH
- Urea metabolism MeSH
- Trichophyton enzymology metabolism MeSH
- Urease metabolism MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Ammonia MeSH
- Urea MeSH
- Urease MeSH
In experiments on six sheep fed on a low protein diet (6.2 g N/day), it was found that the urease activity of the rumen fluid did not change significantly in the first 6 hours after feeding and that it ranged from 45 to 75 nkat.ml-1. The major portion was bound to the bacterial fraction and formed about 70% of total rumen fluid activity. Urease activity determined in food particles with adherent bacteria removed from the rumen before and 3 and 6 hours after feeding ranged from 20 to 26 nkat.g-1 food (wet weight), and on rumen wall samples with adherent bacteria from 30 to 800 nkat per 2.5 cm2 tissue. Again, no significant changes correlated to the time after feeding were found. The results show that urease activity in the sheep rumen is localized on food particles and on rumen wall epithelium with adherent bacteria, as well as in the rumen fluid.
- MeSH
- Ammonia metabolism MeSH
- Rumen enzymology microbiology MeSH
- Bacteria enzymology MeSH
- Time Factors MeSH
- Sheep MeSH
- Urease metabolism MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Ammonia MeSH
- Urease MeSH
Herein, we present direct experimental evidence of pH oscillatory dynamics in the urea-urease enzymatic reaction conducted in a continuous reactor-membrane-reservoir system. Our results are consistent with earlier model predictions requiring differential transport of H+ and substrate. We report oscillations with periods in hundreds of seconds and the amplitude of ∼0.1 pH units.
It was originally shown [10] that urease retains its enzymatic activity when adsorbed at bare mercury and solid amalgam surfaces. However the opinion later prevailed that, when adsorbed at bare metal electrodes, proteins are irreversibly denatured. Here we confirm that urease is enzymatically active at a bare solid amalgam surface as found by Santhanam et al., and we show that this enzyme is equally active at a thiol-modified amalgam surface. We also show that it is the reduced form of urease, which is enzymatically active at Hg surfaces. Oxidation of the protein, resulting in formation of disulfide bonds, strongly decreases the enzyme activity. Using constant current chronopotentiometric stripping (CPS) we show that the exposure of surface-attached urease to negative potentials results in the protein unfolding. The extent of the unfolding depends upon the amount of time for which the protein is exposed to negative potentials, and at very short times this unfolding can be avoided. At thiol-modified Hg surfaces the protein is less vulnerable to the effects of the electric field. We conclude that the loss of enzymatic activity, resulting from a 10 min exposure of the protein to -0.58 V, is not due to reduction of the disulfide bonds as suggested by Santhanam et al. This loss is probably a result of protein reorientation, due to reduction of the Hg-S bonds (formed by accessible cysteines), followed by prolonged electric field effect on the surface-attached protein.
- Keywords
- Constant-current chronopotentiometric stripping, Mercury containing electrodes, Protein denaturation at negatively charged surfaces, Protein structure at surfaces, Thiol-modified electrodes, Urease enzymatic activity,
- MeSH
- Adsorption MeSH
- Cysteine chemistry MeSH
- Protein Denaturation MeSH
- Disulfides chemistry MeSH
- Dithiothreitol chemistry MeSH
- Electrochemical Techniques MeSH
- Electrodes MeSH
- Catalysis MeSH
- Oxidation-Reduction MeSH
- Surface Properties MeSH
- Mercury chemistry MeSH
- Protein Folding MeSH
- Sulfhydryl Compounds chemistry MeSH
- Temperature MeSH
- Urease chemistry metabolism MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Cysteine MeSH
- Disulfides MeSH
- Dithiothreitol MeSH
- Mercury MeSH
- Sulfhydryl Compounds MeSH
- Urease MeSH
Furan chalcone scaffolds belong to the most privileged and promising oxygen-containing heterocyclic class of compounds, which have a wide spectrum of therapeutic applications in the field of pharmaceutics, pharmacology, and medicinal chemistry. This research described the synthesis of a series of twelve novel and seven reported furan chalcone (conventional synthetic approach) analogues 4a-s through the application of microwave-assisted synthetic methodology and evaluated for therapeutic inhibition potential against bacterial urease enzyme. In the first step, a series of nineteen substituted 5-aryl-2-furan-2-carbaldehyde derivatives 3a-s were achieved in moderate to good yields (40-70%). These substituted 5-aryl-2-furan-2-carbaldehyde derivatives 3a-s were condensed with acetophenone via Claisen-Schmidt condensation to furnish 19 substituted furan chalcone scaffolds 4a-s in excellent yields (85-92%) in microwave-assisted synthetic approach, while in conventional methodology, these furan chalcone 4a-s were furnished in good yield (65-90%). Furan chalcone structural motifs 4a-s were characterized through elemental analysis and spectroscopic techniques. These nineteen (19)-afforded furan chalcones 4a-s were screened for urease inhibitory chemotherapeutic efficacy and most of the furan chalcones displayed promising urease inhibition activity. The most active urease inhibitors were 1-phenyl-3-[5-(2',5'-dichlorophenyl)-2-furyl]-2-propen-1-one 4h with an IC50 value of 16.13 ± 2.45 μM, and 1-phenyl- 3-[5-(2'-chlorophenyl)-2-furyl] -2-propen-1-one 4s with an IC50 value of 18.75 ± 0.85 μM in comparison with reference drug thiourea (IC50 = 21.25 ± 0.15 μM). These furan chalcone derivatives 4h and 4s are more efficient urease inhibitors than reference drug thiourea. Structure-activity relationship (SAR) revealed that the 2,5-dichloro 4h and 2-chloro 4s moiety containing furan chalcone derivatives may be considered as potential lead reagents for urease inhibition. The in silico molecular docking study results are in agreement with the experimental biological findings. The results of this study may be helpful in the future drug discovery and designing of novel efficient urease inhibitory agents from this biologically active class of furan chalcones.
- Keywords
- Claisen–Schmidt condensation, SAR, furan carbaldehyde, furan chalcones, molecular docking, urease inhibition,
- Publication type
- Journal Article MeSH
Urea, as an end product of protein metabolism and an abundant polar compound, significantly complicates the metabolomic analysis of urine by GC-MS. We developed a sample preparation method removing urea from urine samples prior the GC-MS analysis. The method based on urease immobilized on magnetic microparticles was compared with the others that are conventionally used (liquid-liquid extraction, free urease protocol), and samples without any treatment. To study the impact of sample preparation approaches on the quality of analytical data, we employed comprehensive metabolomic analysis (using both GC-MS and LC-MS/MS platforms) of standard material based on human urine. Multivariate statistical analysis has shown that immobilized urease treatment provides similar results to a free urease approach. However, significant alterations in the profiles of metabolites were observed in the samples without any treatment and after the extraction. Compared to other approaches that were tested, the immobilization of urease on microparticles reduces both the number of artifacts and the variability of the metabolites (average CV of extraction 19.7%, no treatment 11.4%, free urease 5.0%, and immobilized urease 2.5%). The method that was developed was applied in a GC-MS metabolomic experiment of glutaric aciduria type I, where both known diagnostically important biomarkers and unknowns, as the most discriminating compounds, were found.
- Keywords
- GC–MS, Immobilized urease, Metabolomics, Urine sample preparation,
- MeSH
- Principal Component Analysis MeSH
- Chromatography, Liquid methods MeSH
- Enzymes, Immobilized urine MeSH
- Glutaryl-CoA Dehydrogenase deficiency metabolism MeSH
- Humans MeSH
- Magnetic Phenomena * MeSH
- Brain Diseases, Metabolic metabolism MeSH
- Metabolome MeSH
- Metabolomics methods MeSH
- Analytic Sample Preparation Methods * MeSH
- Urea metabolism MeSH
- Gas Chromatography-Mass Spectrometry methods MeSH
- Reproducibility of Results MeSH
- Feasibility Studies MeSH
- Tandem Mass Spectrometry MeSH
- Urease urine MeSH
- Amino Acid Metabolism, Inborn Errors metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Enzymes, Immobilized MeSH
- Glutaryl-CoA Dehydrogenase MeSH
- Urea MeSH
- Urease MeSH
Stomach infection with Helicobacter pylori (H. pylori) causes severe gastroduodenal diseases in a large number of patients worldwide. The H. pylori infection breaks up in early childhood, persists lifelong if not treated, and is associated with chronic gastritis and an increased risk of peptic ulcers and gastric cancer. In recent years, the problem of drug-resistant strains has become a global concern that makes the treatment more complicated and the infection persistent at higher levels when the antibiotic treatment is stopped. Such problems have led to the development of new strategies to eradicate an H. pylori infection. Currently, one of the most important strategies for the treatment of H. pylori infection is the use of urease inhibitors. Despite the fact that large numbers of molecules have been shown to exert potent inhibitory activity against H. pylori urease, most of them were prevented from being used in vivo and in clinical trials due to their hydrolytic instability, toxicity, and appearance of undesirable side effects. Therefore, it is crucial to focus attention on the available opportunities for the development of urease inhibitors with suitable pharmacokinetics, high hydrolytic stability, and free toxicological profiles. In this commentary, we aim to afford an outline on the current status of the use of urease inhibitors in the treatment of an H. pylori infection, and to discuss the possibility of their development as effective drugs in clinical trials.
- Keywords
- Helicobacter pylori (H. pylori) infection, children, drug development, pharmacokinetics, urease inhibitors,
- Publication type
- Journal Article MeSH
In experiments on six sheep fed on a low nitrogen diet (3.7 g N/day), urease (EC 3.5.1.5) activity (nkat X mg-1 bacterial dry weight) 3 h after feeding was found to be highest in the bacteria adhering to the rumen wall (13.25 +/- 2.10), lower in the rumen fluid bacteria (8.96 +/- 1.35) and lowest in the bacteria adhering to feed particles in the rumen (5.69 +/- 2.13). The urease activity of bacteria adhering to the rumen wall and of the rumen fluid bacteria of six sheep fed on a high nitrogen diet (21 g N/day) was significantly lower than in sheep with a low N intake and in both cases was roughly the same (3.81 +/- 1.37 and 3.76 +/- 1.02 respectively); it was lowest in bacteria adhering to feed particles in the rumen (1.92 +/- 0.90). It is concluded from the results that the urease activity of rumen fluid bacteria and of bacteria adhering to the rumen wall and to feed particles in the rumen is different and that it falls significantly in the presence of a high nitrogen intake. From the relatively high ureolytic activity of bacteria adhering to the rumen wall in the presence of a low nitrogen intake it is assumed that this is one of the partial mechanisms of the hydrolysis of blood urea entering the rumen across the rumen wall and of its reutilization in the rumen-liver nitrogen cycle in ruminants.
- MeSH
- Rumen enzymology MeSH
- Bacteria enzymology MeSH
- Bacterial Adhesion * MeSH
- Dietary Proteins pharmacology MeSH
- Nitrogen pharmacology MeSH
- Animal Feed MeSH
- Sheep MeSH
- Body Fluids enzymology MeSH
- Urease metabolism MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Dietary Proteins MeSH
- Nitrogen MeSH
- Urease MeSH
Urease activity, expressed as mg N-NH3/g dry weight per 30 min at 25 degrees C, was determined in the various parts of the sheep, chicken and pig digestive apparatus. The results were as follows. Sheep: contents--rumen 1.25"/-0.09, reticulum 0.78+/-0.02, omasum 0.44+/-0.02, abomasum 0.002+/-0.001, duodenum 0.003+/-0.001, jejunum 0.18+/-0.03, ileum 0.42+/-0.03, caecum 1.34+/-0.11, colon 0.76+/-0.08, walls-rumen 0.88+/-0.16, reticulum 0.38+/-0.04, omasum 0.11+/-0.02, abomasum 0.01+/-0.002, ileum 0.092+/-0.01, caecum 0.14+/-0.03, colon 0.16+/-0.02. Chicken: contents--jejunum 0.028+/-0.009, ileum 0.043+/-0.013, caecum 0.17+/-0.03, colon and cloaca 0.04+/-0.013. Pigs: contents--jejunum 0.02+/-0.01, ileum 0.14+/-0.08, caecum 0.62+-0.12, colon 0.43+/-0.06. No urease activity was found in the walls of the digestive apparatus or the contents of the duodenum in chickens, or in the walls of the stomach and intestine and the contents of the duodenum in pigs. The results show that urease activity in the digestive apparatus of pigs and poultry is lower than in sheep. Inadequate urease activity in the digestive apparatus explains why chickens and pigs are significantly less capable than ruminants of utilizing urea nitrogen as a substitute for some of the protein in the diet.
- MeSH
- Cecum enzymology MeSH
- Duodenum enzymology MeSH
- Ileum enzymology MeSH
- Jejunum enzymology MeSH
- Colon enzymology MeSH
- Chickens metabolism MeSH
- Sheep metabolism MeSH
- Swine metabolism MeSH
- Abomasum enzymology MeSH
- Digestive System enzymology MeSH
- Urease metabolism MeSH
- Stomach, Ruminant enzymology MeSH
- Stomach enzymology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Urease MeSH
