Synthesis, structures and Helicobacter pylori urease inhibitory activity of copper(II) complexes with tridentate aroylhydrazone ligands

Synthesis of 2-aminothiazole sulfonamides as potent biological agents: Synthesis, structural investigations and docking studies

A simplified synthetic approach involving sulfonylation followed by amino group alkylation produced new 2-aminothiazole derivatives. UV/Vis, infrared, and NMR spectroscopies confirmed their structures. Compounds 36, 22, 34, and 35 showed strong inhibition against Jack bean and Bacillus Pasteurii urease, with IC50 values from 14.06 to 20.21 μM/mL. Compounds 20, 26, 21, 29, 30, 31, and 32 exhibited potent inhibitory effects against α-glucosidase and α-amylase, with IC50 values between 20.34 and 37.20 μM/mL. Compounds 33, 26, and 27 demonstrated potent DPPH scavenging, with IC50 values around 34.4-39.2 μM/mL. FMO analysis showed compounds 21, 22, 24, and 25 having parallel aromatic ring systems due to π cloud interactions, while compounds 32 and 38 had distinct electronic density distributions. Compound 22 had HOMO and LUMO energy gaps of 5.805 eV, with bromo and fluoro substitutions in compounds 21 and 24 slightly increasing the gaps to 6.089 eV and 6.078 eV, respectively. Nitro groups in compounds 25 and 32 reduced the gaps to 0.384 eV and 1.187 eV. All compounds demonstrated high gastrointestinal absorption, non-permeability to the blood-brain barrier, and optimal skin permeation (Log Kp between -5.83 and -6.54 cm/s). Compounds 22, 24, and 38 had promising QED scores of 0.719, 0.707, and 0.860, respectively, with synthetic accessibility scores from 2.057 to 2.517. ADMET predictions indicated minimal toxicity, cardiovascular safety, and significant inhibitory potential for CYP enzymes. Strong in silico binding affinities (binding energies -5.75 to -7.63 kcal/mol) and metabolic stability suggest these derivatives are promising candidates for further drug development.

Clodronic Acid has Strong Inhibitory Interactions with the Urease Enzyme of Helicobacter pylori: Computer-aided Design and in vitro Confirmation

BACKGROUND

Helicobacter pylori (HP) infection could lead to various gastrointestinal diseases. Urease is the most important virulence factor of HP. It protects the bacterium against gastric acid.

OBJECTIVE

Therefore, we aimed to design urease inhibitors as drugs against HP infection.

METHODS

The DrugBank-approved library was assigned with 3D conformations and the structure of the urease was prepared. Using a re-docking strategy, the proper settings were determined for docking by PyRx and GOLD software. Virtual screening was performed to select the best inhibitory drugs based on binding affinity, FitnessScore, and binding orientation to critical amino acids of the active site. The best inhibitory drug was then evaluated by IC50 and the diameter of the zone of inhibition for bacterial growth.

RESULTS

The structures of prepared drugs were screened against urease structure using the determined settings. Clodronic acid was determined to be the best-identified drug, due to higher PyRx binding energy, better GOLD FitnessScore, and interaction with critical amino acids of urease. In vitro results were also in line with the computational data. IC50 values of Clodronic acid and Acetohydroxamic Acid (AHA) were 29.78 ± 1.13 and 47.29 ± 2.06 μg/ml, respectively. Diameters of the zones of inhibition were 18 and 15 mm for Clodronic acid and AHA, respectively.

CONCLUSION

Clodronic acid has better HP urease inhibition potential than AHA. Given its approved status, the development of a repurposed drug based on Clodronic acid would require less time and cost. Further, in vivo studies would unveil the efficacy of Clodronic acid as a urease inhibitor.

Investigation of a set of flavonoid compounds as Helicobacter pylori urease inhibitors: insights from in silico studies

Helicobacter pylori (H. pylori) is a spiral, microaerophilic gram-negative bacterium, which is associated with the destruction of the lining of the stomach, leads to chronic inflammation of the stomach, which can cause stomach and duodenal ulcers. The problems caused by the treatment with antibiotics have caused researchers to use new approaches to treat infections caused by H. pylori, among them specific treatments with flavonoids. Urease enzyme, as one of the most important pathogenic and antigenic factors of this bacterium, is a suitable target for this purpose. In this study, the inhibitory effect of flavonoid compounds compared to acetohydroxamic acid on H. pylori urease enzyme was evaluated using molecular modeling methods. First, the interaction of flavonoids with urease enzyme compared with acetohydroxamic acid was investigated by molecular docking method to produce efficient docking poses. Then the physicochemical properties and toxicity of the best flavonoid compounds were analyzed using the swissadme server. Also, molecular dynamics calculations were performed to precisely understand the interactions between ligands and protein. The results of this study show that all the investigated flavonoid compounds are capable of inhibiting H. pylori urease. Among these compounds, six compounds chrysin, galangin, kaempferol, luteolin, morin and quercetin showed a greater tendency to bind to urease, compared to the acetohydroxamic acid inhibitor. These compounds are desirable in terms of physicochemical properties. This study also revealed that the flavonoids with their hydroxyl groups (-OH) play an important role during bond formation with amino acids Ala278, Ala169, His314, Asp362 and Asn168. Therefore, flavonoid compounds, due to their suitable location in the active site of the urease, create a more effective inhibition than the chemical drug acetohydroxamic acid and can be suitable candidates for the treatment of Helicobacter pylori under in vitro and in vivo investigations.Communicated by Ramaswamy H. Sarma.

Synthesis and Evaluation of 1,3,5-Triaryl-2-Pyrazoline Derivatives as Potent Dual Inhibitors of Urease and α-Glucosidase Together with Their Cytotoxic, Molecular Modeling and Drug-Likeness Studies

In the present work, a concise library of 1,3,5-triaryl-2-pyrazolines (2a-2q) was designed and synthesized by employing a multistep strategy, and the newly synthesized compounds were screened for their urease and α-glucosidase inhibitory activities. The compounds (2a-2q) were characterized using a combination of several spectroscopic techniques including FT-IR, 1H NMR, 13C NMR, and EI-MS. All the synthesized compounds, except compound 2i, were potent against urease as compared to the standard inhibitor thiourea (IC50 = 21.37 ± 0.26 μM). These analogs disclosed varying degrees of urease inhibitory activities ranging from 9.13 ± 0.25 to 18.42 ± 0.42 μM. Compounds 2b, 2g, 2m, and 2q having IC50 values of 9.36 ± 0.27, 9.13 ± 0.25, 9.18 ± 0.35, and 9.35 ± 0.35 μM, respectively, showed excellent inhibitory activity as compared to standard thiourea (IC50 = 21.37 ± 0.26 μM). A kinetic study of compound 2g revealed that compound 2g inhibited urease in a competitive mode. Among the synthesized pyrazolines, the compounds 2c, 2k, 2m, and 2o exhibited excellent α-glucosidase inhibitory activity with the lowest IC50 values of 212.52 ± 1.31, 237.26 ± 1.28, 138.35 ± 1.32, and 114.57 ± 1.35 μM, respectively, as compared to the standard acarbose (IC50 = 375.82 ± 1.76 μM). The compounds (2a-2q) showed α-glucosidase IC50 values in the range of 114.57 ± 1.35 to 462.94 ± 1.23 μM. Structure-activity relationship revealed that the size and electron-donating or -withdrawing effects of substituents influenced the activities, which led to the urease and α-glucosidase inhibiting properties. Compound 2m was a dual potent inhibitor against urease and α-glucosidase due to the presence of 2-CF3 electron-withdrawing functionality on the phenyl ring. To the best of our knowledge, these synthetic compounds were found to be the most potent dual inhibitors of urease and α-glucosidase with minimum IC50 values. The cytotoxicity of the compounds (2a-2q) was also investigated against human cell lines MCF-7 and HeLa. Compound 2l showed moderate cytotoxic activity against MCF-7 and HeLa cell lines. Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease and α-glucosidase enzymes. Some compounds exhibited drug-like characteristics due to their lower cytotoxic and good ADME profiles.

Discovery of Novel Dihydropyrimidine and hydroxamic acid hybrids as potent Helicobacter pylori Urease inhibitors

Two novel series of Dihydropyrimidine-hydroxamic acid hybrids (4a-4l and 5a-5l) were designed, synthesized and evaluated for in vitro Helicobacter pylori urease inhibition. In vitro enzyme inhibition screening led to the discovery of three potent urease inhibitors 2-[[4-(4-hydroxy phenyl)-6-oxo-1,6-dihydropyrimidine-2-yl]-amino]-N-hydroxy acetamide (4g), 2-[[4-(4-chloro phenyl)-6-oxo-1,6-dihydropyrimidine-2-yl]-amino]-N-hydroxy acetamide (4b) and 3-[[4-(3-methoxy phenyl)-6-oxo-1,6-dihydropyrimidine-2-yl]-amino]-N-hydroxy propanamide (5l). Compound 4g showed excellent urease inhibition with IC₅₀ value of 14 ± 1 nM, indicated by its strong interactions with both metallic Ni⁺⁺ ions, Gly279, His221, Ala365, Asp362, Asn168, Arg338 and His322 residues of the active site of urease. Further, compounds 4b and 5l displayed very good activity with IC₅₀ value of 0.082 ± 0.004 µM and 0.14 ± 0.013 µM respectively compared to standard Acetohydroxamic acid (IC₅₀ - 27.4 ± 1.2 µM). Kinetic studies revealed that a mixed inhibition with both competitive and non-competitive aspects is involved in the urease inhibition mechanism. The in vitro urease inhibition results were supported by molecular docking studies. Collectively, this study indicates that 4g could be considered as promising lead molecule that can be further developed as a potent drug molecule for the treatment of Helicobacter pylori caused gastritis for further studies.

Insights into the Design of Inhibitors of the Urease Enzyme - A Major Target for the Treatment of Helicobacter pylori Infections

Expressed by a variety of plants, fungi and bacteria, the urease enzyme is directly associated with the virulence factor of many bacteria, including Helicobacter pylori, a gram-negative bacterium related to several gastrointestinal diseases and responsible for one of the most frequent bacterial infections throughout the world. The Helicobacter pylori Urease (HPU) is a nickel-dependent metalloenzyme expressed in response to the environmental stress caused by the acidic pH of the stomach. The enzyme promotes the increase of gastric pH through acid neutralization by the products of urea hydrolysis, then critically contributing to the colonization and pathogenesis of the microorganism. At the same time, standard treatments for Helicobacter pylori infections have limitations such as the increasing bacterial resistance to the antibiotics used in the clinical practice. As a strategy for the development of novel treatments, urease inhibitors have proved to be promising, with a wide range of chemical compounds, including natural, synthetic and semisynthetic products to be researched and potentially developed as new drugs. In this context, this review highlights the advances in the field of HPU inhibition, presenting and discussing the basis for the research of new molecules aiming at the identification of more efficient therapeutic entities.

Lead Molecules for Targeted Urease Inhibition: An Updated Review from 2010 -2018

The field of enzyme inhibition is a tremendous and quickly growing territory of research. Urease a nickel containing metalloenzyme found in bacteria, algae, fungi, and plants brings hydrolysis of urea and plays important role in environmental nitrogen cycle. Apart from this it was found to be responsible for many pathological conditions due to its presence in many microorganisms such as H. Pylori, a ureolytic bacteria having urease which elevates pH of gastric medium by hydrolyzing urea present in alimentary canal and help the bacteria to colonize and spread infection. Due to the infections caused by the various bacterial ureases such as Bacillus pasteurii, Brucella abortus, H. pylori, H. mustelae, Klebsiella aerogenes, Klebsiella tuberculosis, Mycobacterium tuberculosis, Pseudomonas putida, Sporosarcina pasteurii and Yersinia enterocolitica, it has been the current topic of today's research. About a wide range of compounds from the exhaustive literature survey has been discussed in this review which is enveloped into two expansive classes, as Inhibitors from synthetic origin and Inhibitors from natural origin. Moreover active site details of enzyme, mechanism of catalysis of substrate by enzyme, uses of plant urease and its pathogenic behavior has been included in the current review. So, overall, this review article diagrams the current landscape of the developments in the improvements in the thriving field of urease inhibitory movement in medicinal chemistry from year 2010 to 2018, with an emphasis on mechanism of action of inhibitors that may be used for more development of recent and strong urease inhibitors and open up new doors for assist examinations in a standout amongst the most lively and promising regions of research.

Copper(ii) complexes with NNO ligands: synthesis, crystal structures, DNA cleavage, and anticancer activities

Three novel copper(ii) complexes, Cu(L1)₂ (1), Cu(L2)₂·2DMF (2), and Cu(L3)₂·2DMF (3), were synthesized using three aroylhydrazone ligands, (E)-2-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL1), (E)-3-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL2) and (E)-4-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL3). The complexes were characterized by elemental analysis, infrared (IR), and Ultraviolet-visible light (UV-vis) spectroscopy. The X-ray crystal structures of the complexes all possess a distorted octahedral coordination geometry. Both an absorption spectral titration and a competitive binding assay (ethidium bromide, 4',6-diamidino-2-phenylindole (DAPI), and methyl green) revealed that complexes 2 and 3 bind readily to calf thymus DNA (ctDNA) through intercalative and minor groove binding modes. Complexes 2 and 3 also exhibited oxidative cleavage of supercoiled plasmid DNA (pUC19) in the presence of ascorbic acid as an activator. Cytotoxicity studies showed that complexes 2 and 3 possessed high cytotoxicities toward the HeLa human cervical cancer cell line, but weak toxicities toward the L929 normal mouse fibroblast cell line. We therefore have reason to believe that complexes 2 and 3 both show potential as promising anticancer candidate drugs.

Inhibition assays of free and immobilized urease for detecting hexavalent chromium in water samples

The present work describes the inhibition studies of free as well as immobilized urease by different heavy metals. Porous silicon (PS) films prepared by electrochemical etching were used for urease immobilization by physical adsorption. The enzyme was subjected to varying concentrations of Cr⁶⁺, Cr³⁺, Cu²⁺, Fe²⁺, Cd²⁺ and Ni²⁺ and analyzed for the variation in the activity. To study the effect of other heavy metals on the interaction of urease and Cr⁶⁺, free as well as immobilized urease was subjected to the combination of each metal ion with Cr⁶⁺. Results proved the sensitivity of free as well as immobilized urease towards heavy metals by observed reduction in activity. Immobilized urease showed less degree of inhibition compared to free urease when tested for inhibition by individual metal ions and in combination with Cr⁶⁺. IC₅₀ values were found higher for inhibition by the combination of metal ions with Cr⁶⁺. Interaction of heavy metal ions with functional groups in active site of urease and limitations of mass transfer are the two factors responsible for the variation in activity of urease. Relation between the variation of urease activity and amount of heavy metals can be applied in biosensor development for determining the concentration of Cr⁶⁺ present in the water samples.

Schiff bases and their metal complexes as urease inhibitors - A brief review

Schiff bases, an aldehyde- or ketone-like compounds in which the carbonyl group is replaced by an imine or azomethine, are some of the most widely used organic compounds. Indeed, they are widely used for industrial purposes and also exhibit a broad range of biological activities, including anti-urease activity. Ureases, enzymes that catalyze urea hydrolysis, have received considerable attention for their impact on living organisms’ health, since the persistence of urease activity in human and animal cells can be the cause of some diseases and pathogen infections. This short review compiles examples of the most antiurease Schiff bases (0.23 μM < IC₅₀ < 37.00 μM) and their metal complexes (0.03 μM < IC₅₀ < 100 μM). Emphasis is given to ureases of Helicobacter pylori and Canavalia ensiformis, although the active site of this class of hydrolases is conserved among living organisms.

Modulating the DNA cleavage ability of copper(ii) Schiff bases through ternary complex formation

Copper(ii) Schiff-bases were electrochemically synthesized and characterized. The presence of co-ligands such as 2,2′-bpy or phen in the metal coordination environment increases the DNA cleavage efficiency.

Metal complexes of a novel heterocyclic benzimidazole ligand formed by rearrangement-cyclization of the corresponding Schiff base. Electrosynthesis, structural characterization and antimicrobial activity

One-pot electrochemical synthesis of metal complexes containing a novel heterocyclic benzimidazole ligand is reported and characterized.