Structurally Diversified Heterocycles and Related Privileged Scaffolds as Potential Urease Inhibitors: A Brief Overview

Enhanced urease inhibitory activity of quercetin via conjugation with silver nanoparticles: synthesis, characterization, and DFT study

Urease plays a crucial role in the survival and colonization of Helicobacter pylori (H. pylori). Consequently, urease inhibitors are important in managing various diseases associated with H. pylori infection. Given the widespread use of silver nanoparticles (AgNPs) as antibacterial agents and quercetin's known urease inhibitory properties, we sought to develop a potent urease inhibitor by conjugating quercetin onto AgNPs. In fact, this study aimed to enhance the urease inhibitory activity of quercetin through its conjugation with AgNPs. Quercetin-loaded silver nanoparticles (Ag@QNPs) were successfully synthesized using the Frens method and characterized using various techniques, including UV-Vis spectroscopy, FT-IR spectroscopy, XRD analysis, DLS, and TEM. The urease inhibitory activity of Ag@QNPs was significantly higher (approximately 250 times) than that of pure quercetin, demonstrating a synergistic effect. In contrast, AgNPs alone exhibited minimal inhibitory activity against urease. Density functional theory (DFT) calculations revealed a favorable interaction energy between quercetin and the silver surface. These findings suggest the potential of Ag@QNPs as promising nanomaterials for applications in urease-related diseases.

Discovery of bis-chalcones and bis-pyrimidines as potential urease inhibitors: from synthesis to computational insights

AIMS

This study focuses on the design and evaluation of bis-chalcones and bis-pyrimidines as potential urease inhibitors.

MATERIALS AND METHODS

A series of bis-chalcone and bis-pyrimidine derivatives were synthesized and assessed for their in vitro urease inhibitory activity. Kinetic studies were conducted using Lineweaver-Burk plots to determine the inhibition mechanism of the most potent compound. Molecular docking was employed to investigate the binding interactions with the urease active site, followed by MD simulations to validate complex stability. Computational ADMET analysis was performed to assess the drug-like properties of the most active inhibitor.

RESULTS

Several synthesized compounds exhibited potent urease inhibitory activity, significantly surpassing the standard inhibitor thiourea. The most active compound, 8P, displayed noncompetitive inhibition, as confirmed by kinetic studies. SAR analysis revealed that electron-withdrawing substituents enhanced inhibitory potency. Molecular docking studies demonstrated favorable interactions between inhibitors and key urease residues, while MD simulations confirmed complex stability. ADMET analysis supported the drug-like potential of 8P.

CONCLUSIONS

This study provides valuable insights into the development of target compounds as promising urease inhibitors. These findings suggest their potential therapeutic applications for urease-related disorders.

Urease inhibitory potential of pyridine-containing triazolothiadiazole and triazolothiadiazine scaffolds for the treatment of ulceration and kidney stone: in vitro screening, kinetics mechanism, and in silico computational analysis

The hyperactivity of urease enzyme leads to various complications including gastritis and peptic ulcer. A diverse variety of natural and synthetic inhibitors have shown a tremendous potential to inhibit the urease enzyme, thus decreasing the hyperactivity and reducing the risk for the development of urinary calculi and other similar problems. Therefore, we herein report a family of fused heterocycles such as triazolothiadiazoles (4a-h, 5a-f) and triazolothiadiazines (6a-h) as potential antiurease agents with IC50 values in the range 10.41-41.20 µM. Several compounds were identified as potential lead candidates. Among them, compounds 4e and 4f from triazolothiadiazole series showed the highest inhibitory potential with IC50 values of 11.62 ± 0.34 and 10.35 ± 0.14 µM), respectively, whereas 6e from triazolothiadiazine series emerged as the most potent inhibitor with an IC50 value of 10.41 ± 0.13 µM. These compounds exhibited two-fold strong inhibitory efficacy against urease as compared to standard inhibitor, thiourea (IC50 = 22.48 ± 0.67 µM). The mechanistic insights from kinetics experiments for compounds 4e, 4f, and 6e revealed the competitive mode of inhibition with Ki values of 8.65 ± 0.004, 7.04 ± 0.012, and 8.31 ± 0.007 µM, respectively. The in vitro results were further explored through in silico computational docking analysis which reflects that binding of ligands with Ni ions and His492 play a crucial role in urease inhibition. In silico predicted physicochemical properties and ADME profile reflect drug-like nature of these molecules.Communicated by Ramaswamy H. Sarma.

New Antioxidant Caffeate Esters of Fatty Alcohols Identified in Robinia pseudoacacia

The stem bark of black locust (Robinia pseudoacacia L.) was extracted, and nine antioxidant compounds (R1-R9) were detected by high-performance thin-layer chromatography combined with the radical scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH•) assay, multi-detection, and heated electrospray high-resolution mass spectrometry. For structure elucidation, the methanolic crude extract was fractionated by solid-phase extraction, and the compounds were isolated by reversed-phase high-performance liquid chromatography with diode array detection. The structures of isolated compounds were elucidated by nuclear magnetic resonance and attenuated total reflectance Fourier-transform infrared spectroscopy as well as gas chromatography-mass spectrometry to determine the double bond position. 3-O-Caffeoyl oleanolic acid (R1), oleyl (R2), octadecyl (R3), gadoleyl (R4), eicosanyl (R5), (Z)-9-docosenyl (R6), docosyl (R7), tetracosyl (R8), and hexacosanyl (R9) caffeates were identified. While R1 has been reported in R. pseudoacacia stem bark, the known R3, R5, R7, R8, and R9 are described for the first time in this species, and the R2, R4, and R6 are new natural compounds. All nine caffeates demonstrated antioxidant activity. The antioxidant effects of the isolated compounds R1-R8 were quantified by a microplate DPPH• assay, with values ranging from 0.29 to 1.20 mol of caffeic acid equivalents per mole of isolate.

Design and discovery of urease and Helicobacter pylori inhibitors based on benzofuran/benzothiophene-sulfonate and sulfamate scaffolds for the treatment of ureolytic bacterial infections

A series of sulfonate and sulfamate derivatives bearing benzofuran or benzothiophene scaffold exhibited potent inhibitory effect on urease enzyme. Most of the derivatives exhibited significantly higher potency than thiourea, the standard inhibitor. Compound 1s was identified as the most potent urease inhibitor with an IC50 value of 0.42 ± 0.08 μM, which is 53-fold more potent than thiourea, positive control (IC50 = 22.3 ± 0.031 μM). The docking results further revealed the binding interactions towards the urease active site. Phenotypic screening revealed that compounds 1c, 1d, 1e, 1f, 1j, 1n, and 1t exhibit high potency against H. pylori with MIC values ranging from 0.00625 to 0.05 mM and IC50 values ranging from 0.0031 to 0.0095 mM, much more potent than the positive control, acetohydroxamic acid (MIC and IC50 values were 12.5 and 7.38 mM, respectively). Additional studies were performed to investigate the toxicity of these compounds against the gastric epithelial cell line (AGS) and their selectivity profile against E. coli, and five Lactobacillus species representative of the gut microflora. Permeability characteristics of the most promising derivatives were investigated in Caco-2 cell line. The results indicate that the compounds could be targeted in the GIT only without systemic side effects.

Exploration of morpholine-thiophene hybrid thiosemicarbazones for the treatment of ureolytic bacterial infections via targeting urease enzyme: Synthesis, biochemical screening and computational analysis

An important component of the pathogenicity of potentially pathogenic bacteria in humans is the urease enzyme. In order to avoid the detrimental impact of ureolytic bacterial infections, the inhibition of urease enzyme appears to be an appealing approach. Therefore, in the current study, morpholine-thiophene hybrid thiosemicarbazone derivatives (5a-i) were designed, synthesized and characterized through FTIR, 1H NMR, 13C NMR spectroscopy and mass spectrometry. A range of substituents including electron-rich, electron-deficient and inductively electron-withdrawing groups on the thiophene ring was successfully tolerated. The synthesized derivatives were evaluated in vitro for their potential to inhibit urease enzyme using the indophenol method. The majority of compounds were noticeably more potent than the conventional inhibitor, thiourea. The lead inhibitor, 2-(1-(5-chlorothiophen-2-yl)ethylidene)-N-(2-morpholinoethyl)hydrazinecarbothioamide (5g) inhibited the urease in an uncompetitive manner with an IC50 value of 3.80 ± 1.9 µM. The findings of the docking studies demonstrated that compound 5g has a strong affinity for the urease active site. Significant docking scores and efficient binding free energies were displayed by the lead inhibitor. Finally, the ADME properties of lead inhibitor (5g) suggested the druglikeness behavior with zero violation.

Anti-Helicobacter pylori Activity of Six Major Compounds Isolated from Rumex acetosa

Gastric problems are often caused by the well-known Helicobacter pylori (H. pylori) bacterium. One of the biggest obstacles to the treatment of H. pylori infections is increasing the antibiotic resistance. During our search for naturally derived anti-H. pylori compounds, six major compounds were isolated from the methylene chloride (CH2Cl2) and ethyl acetate (EtOAc) fractions of Rumex acetosa that showed anti-H. pylori activity. Three anthraquinones and three anthraquinone glucosides were identified as the major chemical constituents of the CH2Cl2 and EtOAc fractions, respectively. The chemical structures were identified to be emodin (1), chrysophanol (2), physcion (3), emodin-8-O-β-d-glucoside (4), chrysophanol-8-O-β-d-glucoside (5), and physcion-8-O-β-d-glucoside (6) by UV, 1H NMR, 13C NMR, and mass spectrometry. Anti-H. pylori activity, including the minimum inhibitory concentration (MIC) value of each compound, was evaluated against two H. pylori strains. All isolates exhibited anti-H. pylori activity with different potencies, with an MIC value ranging between 3.13 and 25 μM. However, some variations were found between the two strains. While compound 5 displayed the most potent antibacterial activity with an MIC50 value of 8.60 μM and an MIC90 value of 15.7 μM against H. pylori strain 51, compound 1 exhibited the most potent inhibitory activity against H. pylori strain 43504. The two compounds also showed moderate urease inhibitory activity, with compound 1 demonstrating activity higher than that of compound 5. Furthermore, a molecular docking study revealed the high binding ability of compounds 1 and 5 to the active site of H. pylori urease. The present study suggests that the six anthraquinones isolated from R. acetosa with the whole parts of this plant may be natural candidates for the treatment of H. pylori infection. Further studies are required to determine the exact mechanism of action and to evaluate safety issues in the human body.

Benzimidazolone-piperazine/triazole/thiadiazole/furan/thiophene conjugates: Synthesis, in vitro urease inhibition, and in silico molecular docking studies

This study describes the synthesis, in vitro urease inhibition, and molecular docking studies of benzimidazolone derivatives incorporating the piperazine, triazole, thiadiazole, furan, thiophene, and thiosemicarbazide moieties. All newly synthesized compounds demonstrated varying degrees of urease inhibitory activity, with IC50 values ranging between 0.64 ± 0.099 and 0.11 ± 0.017 µM, when compared with the standard drug thiourea (IC50 value of 0.51 ± 0.028 µM). To confirm the experimental urease inhibition results and elucidate the mode of interaction of the synthesized compounds with the binding site of the urease enzyme, molecular docking studies were performed using the Schrödinger Suite package. Molecular docking studies showed that compounds with high in vitro urease inhibition interacted with key residues of the urease active site such as His221, Glu222, Asp223, His322, Arg338, and Ni2+ cations via hydrogen bonding, metal coordination, salt bridge, π-π stacking, and π-cation interactions.

Triazolothiadiazoles and Triazolothiadiazines as New and Potent Urease Inhibitors: Insights from In Vitro Assay, Kinetics Data, and In Silico Assessment

Hyperactivity of the urease enzyme induces the pathogenesis of peptic ulcers and gastritis. The identification of new urease inhibitors can reduce the activity of urease. Therefore, in the current study, we have evaluated 28 analogues of triazolothiadiazole and triazolothiadiazine heteroaromatics for their in vitro urease inhibitory efficacy. All the tested compounds displayed a remarkable inhibitory potential ranging from 3.33 to 46.83 μM. Among them, compounds 5k and 5e emerged as lead inhibitors with IC50 values of 3.33 ± 0.11 and 3.51 ± 0.49 μM, respectively. The potent inhibitory potential of these compounds was ∼6.5-fold higher than that of the marketed drug thiourea (IC50 = 22.45 ± 0.30 μM). The mechanistic insights from kinetics experiments of the highest potent inhibitors (4g, 5e, and 5k) revealed a competitive type of inhibition with ki values 2.25 ± 0.0028, 3.11 ± 0.0031, and 3.62 ± 0.0034 μM, respectively. In silico modeling was performed to investigate the binding interactions of potent inhibitors with the enzyme active site residues, which strongly supported our experimental results. Furthermore, ADME analysis also showed good druglikeness properties demonstrating the potential of these compounds to be developed as lead antiurease agents.

Exploring the Synthetic Chemistry of Phenyl-3-(5-aryl-2-furyl)- 2-propen-1-ones as Urease Inhibitors: Mechanistic Approach through Urease Inhibition, Molecular Docking and Structure-Activity Relationship

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.

Design and synthesis of novel anti-urease imidazothiazole derivatives with promising antibacterial activity against Helicobacter pylori

Urease enzyme is a known therapeutic drug target for treatment of Helicobacter pylori infection due to its role in settlement and growth in gastric mucosa. In this study, we designed a new series of sulfonates and sulfamates bearing imidazo[2,1-b]thiazole scaffold that exhibit a potent inhibitory activity of urease enzyme. The most potent compound 2c inhibited urease with an IC50 value of 2.94 ± 0.05 μM, which is 8-fold more potent than the thiourea positive control (IC50 = 22.3 ± 0.031 μM). Enzyme kinetics study showed that compound 2c is a competitive inhibitor of urease. Molecular modeling studies of the most potent inhibitors in the urease active site suggested multiple binding interactions with different amino acid residues. Phenotypic screening of the developed compounds against H. pylori delivered molecules of that possess high potency (1a, 1d, 1h, 2d, and 2f) in comparison to the positive control, acetohydroxamic acid. Additional studies to investigate the selectivity of these compounds against AGS gastric cell line and E. coli were performed. Permeability of the most promising derivatives (1a, 1d, 1h, 2d, and 2f) in Caco-2 cell line, was investigated. As a result, compound 1d presented itself as a lead drug candidate since it exhibited a promising inhibition against urease with an IC50 of 3.09 ± 0.07 μM, MIC value against H. pylori of 0.031 ± 0.011 mM, and SI against AGS of 6.05. Interestingly, compound 1d did not show activity against urease-negative E. coli and exhibited a low permeability in Caco-2 cells which supports the potential use of this compound for GIT infection without systemic effect.

New thioxothiazolidinyl-acetamides derivatives as potent urease inhibitors: design, synthesis, in vitro inhibition, and molecular dynamic simulation

To identify potent urease inhibitors, in the current study, a series of thioxothiazolidinyl-acetamides were designed and synthesized. The prepared compounds were characterized by spectroscopic techniques, including FTIR, ¹HNMR, ¹³CNMR, and elemental analysis. In the enzymatic assessments, it was demonstrated that all derivatives had significant urease inhibition with IC₅₀ values in the range of 1.473-9.274 µM in comparison with the positive control hydroxyurea (IC₅₀ = 100.21 ± 2.5 µM) and thiourea (IC₅₀ = 23.62 ± 0.84 µM). Compound 6i (N-benzyl-3-butyl-4-oxo-2-thioxothiazolidine-5-carboxamide) was the most active agent with an IC₅₀ value of 1.473 µM. Additionally, kinetic investigation and in silico assessments of 6i was carried out to understand the type of inhibition and behavior of the most potent derivative within the binding site of the enzyme. Noteworthy, the anti-urease assay against P. vulgaris revealed 6e and 6i as the most active agents with IC₅₀ values of 15.27 ± 2.40 and 17.78 ± 3.75 µg/mL, respectively. Antimicrobial evaluations of all compounds reveal that compounds 6n and 6o were the most potent antimicrobial agents against the standard and resistant S. aureus. 6n and 6o also showed 37 and 27% inhibition in the development of biofilm by S. aureus at 512 µg/ml. Furthermore, the MTT test showed no toxicity up to 100 µM. Taken together, the study suggests that the synthesized thioxothiazolidinyl-acetamides bases derivatives may serve as potential hits as urease inhibitors.

Synthesis, Characterization, Optical Properties, Molecular Modeling and Urease Inhibition Analysis of Organic Ligands and Their Metal Complexes

Recently, screening of efficient urease inhibitors by employing organic small molecules metalloderivatives interests the scientific community due to their efficacy for treatment of urease triggered health complications. This study comprises the synthesis, urease inhibition activity, optical analysis and molecular modeling of hydrazinecarbothioamide and hydrazinecarboxamide metalloderivatives. Characterization of synthesized materials was done by UV-visible, fluorescence, NMR and FTIR spectroscopic analysis. Metalloderivatization of ligands induce increment in urease inhibition potential and effect was prominent for copper complexes with 10-fold enhancement, cobalt complex with 3.5 fold's enhancement and palladium with 2-fold increment in the inhibition efficacy toward urease when it was compared with reference urease inhibitor. Zinc and iron complexes cause declined urease inhibition activity of the bare ligand. The overall activity of hydrazinecarbothioamide slightly exceeds than that of hydrazinecarboxamide, possibly due to larger complexation ability of sulfur-based ligand in comparison to oxygenated derivatives i.e., hydrazinecarboxamide. The enzyme inhibition kinetics for the most active complexes represent the mixed type urease inhibition for 3a and competitive urease inhibition for 5a, as determined by Lineweaver-Burk plots. The docked scoring values for both the ligands were calculated to be 61.34, 64.72, 56.68, 62.94, 64.98 and 58.98. Three active hydrogen bonds were observed in docking complex upon computational analysis of most potent metallodrug 3a inside active region of targeted protein.

Metabolic Profiling by GC-MS, In Vitro Biological Potential, and In Silico Molecular Docking Studies of Verbena officinalis

Verbena officinalis L. is a traditionally important medicinal herb that has a rich source of bioactive phytoconstituents with biological benefits. The objective of this study was to assess the metabolic profile and in vitro biological potential of V. officinalis. The bioactive phytoconstituents were evaluated by preliminary phytochemical studies, estimation of polyphenolic contents, and gas chromatography-mass spectrometry (GC-MS) analysis of all fractions (crude methanolic, n-hexane, ethyl acetate, and n-butanol) of V. officinalis. The biological investigation was performed by different assays including antioxidant assays (DPPH, ABTS, CUPRAC, and FRAP), enzyme inhibition assays (urease and α-glucosidase), and hemolytic activity. The ethyl acetate extract had the maximum concentration of total phenolic and total flavonoid contents (394.30 ± 1.09 mg GAE·g^-1 DE and 137.35 ± 0.94 mg QE·g^-1 DE, respectively). Significant antioxidant potential was observed in all fractions by all four antioxidant methods. Maximum urease inhibitory activity in terms of IC₅₀ value was shown by ethyl acetate fraction (10 ± 1.60 µg mL^-1) in comparison to standard hydroxy urea (9.8 ± 1.20 µg·mL^-1). The n-hexane extract showed good α-glucosidase inhibitory efficacy (420 ± 20 µg·mL^-1) as compared to other extract/fractions. Minimum hemolytic activity was found in crude methanolic fraction (6.5 ± 0.94%) in comparison to positive standard Triton X-100 (93.5 ± 0.48%). The GC-MS analysis of all extract/fractions of V. officinalis including crude methanolic, n-hexane, ethyl acetate, and n-butanol fractions, resulted in the identification of 24, 56, 25, and 9 bioactive compounds, respectively, with 80% quality index. Furthermore, the bioactive compounds identified by GC-MS were analyzed using in silico molecular docking studies to determine the binding affinity between ligands and enzymes (urease and α-glucosidase). In conclusion, V. officinalis possesses multiple therapeutical potentials, and further research is needed to explore its use in the treatment of chronic diseases.

Enzymes Inhibition and Antioxidant Potential of Medicinal Plants Growing in Oman

The recent study was designed to explore Dodonaea viscosa, Juniperus excelsa, Helianthemum lippii, and Euryops pinifolius using methanolic (MeOH) extract. Their subfractions were examined against urease, carbonic anhydrase II (CA-II), α-glucosidase enzymes, and free radicals scavenging significance based on local practices via standard methods. Significance potential against the urease enzyme was presented by ethyl acetate fraction (EtOAc) of D. viscosa with (IC₅₀ = 125 ± 1.75 μg/mL), whereas the H. lippii (IC₅₀ = 146 ± 1.39 μg/mL) in the EtOAc was found efficient to scavenge the free radicals. Besides, that appreciable capacity was observed by the J. excelsa, D. viscosa, J. excelsa, and E. pinifolius as compared to the standard acarbose (IC₅₀ = 377.24 ± 1.14 μg/mL). Maximum significance was noticed in methanolic (MeOH) extract of J. excelsa and presented carbonic anhydrase CA-II (IC₅₀ = 5.1 ± 0.20 μg/mL) inhibition as compared to the standard (acetazolamide). We are reporting, for the first time, the CA-II inhibition of all the selected medicinal plants and α-glucosidase, urease, and antioxidant activities of the E. pinifolius. Thus, further screening is needed to isolate the promising bioactive ingredients which act as an alternative remedy to scavenge the free radicals, antiulcer, and act as a potential source to develop new antidiabetic drugs for controlling postprandial blood sugar as well as carbonic anhydrase inhibitors.

Efficacy of Phytochemicals Derived from Roots of Rondeletia odorata as Antioxidant, Antiulcer, Diuretic, Skin Brightening and Hemolytic Agents—A Comprehensive Biochemical and In Silico Study

Roots of Rondeletia odorata are a rich source of phytochemicals with high antioxidant potential and thus may possess health benefits. This study used the LC-MS technique to identify phytoconstituents in R. odorata roots extract/fractions. Results revealed that n-butanol fraction and ethanolic extract contained total phenolic and flavonoid contents with values of 155.64 ± 0.66 mgGAE/g DE and 194.94 ± 0.98 mgQE/g DE, respectively. Significant potential of antioxidants was observed by DPPH, CUPRAC and FRAP methods while the ABTS method showed moderate antioxidant potential. Maximum % inhibition for urease, tyrosinase and carbonic anhydrase was shown by ethanolic extract (73.39 ± 1.11%), n-butanol soluble fraction (80.26 ± 1.59%) and ethyl acetate soluble fraction (76.50 ± 0.67%) which were comparable with thiourea (standard) (98.07 ± 0.74%), kojic acid (standard) (98.59 ± 0.92%) and acetazolamide (standard) (95.51 ± 1.29%), respectively, while all other extract/fractions showed moderate inhibition activity against these three enzymes. Hemolytic activity was also observed to range from 18.80 ± 0.42 to 3.48 ± 0.69% using the standard (triton X-100) method. In total, 28 and 20 compounds were identified tentatively by LC-MS analysis of ethanolic extract and n-butanol soluble fraction, respectively. Furthermore, molecular docking was undertaken for major compounds identified by LC-MS for determining binding affinity between enzymes (urease, tyrosinase and carbonic anhydrase) and ligands. It was concluded that active phytochemicals were present in roots of R. odorata with potential for multiple pharmacological applications and as a latent source of pharmaceutically important compounds. This should be further explored to isolate important constituents that could be used in treating different diseases.

New acetylphenol-based acyl thioureas broaden the scope of drug candidates for urease inhibition: synthesis, in vitro screening and in silico analysis

Helicobacter pylori urease remains a validated drug target for the eradication of pervasive chronic stomach infection that leads to severe human health diseases such as gastritis and stomach cancer. The increased failure of current treatment protocols because of resistance to broadband antibiotics, severe side effects and low compliance underscore the need for a targeted eradication therapy. Therefore, in the present research, we have developed a new series of acetylphenol-based acyl thioureas that can potentially provide a new template for drug candidates to inhibit urease enzyme. Newly synthesized compounds 7a-j were evaluated for urease inhibitory strength using thiourea as a positive control. In vitro inhibitory results revealed that all the tested compounds were significantly potent than the standard drug. The most active lead 7f competitively inhibited the enzyme and displayed an IC50 value of 0.054 ± 0.002 μM, a ~413-fold strong inhibitory potential than thiourea (IC50 = 22.3 ± 0.031 μM). Various insightful structure-activity relationships were developed showing the key structural requirements for potent inhibitory effects. Molecular docking analysis of 7f inside the active pocket of urease suggested several important interactions with amino acid residues such as ILE411, MET637, ARG439, GLN635, ALA636 and ALA440. Finally, pharmacokinetic properties suggested that the tested derivatives are safe to develop as low-molecular-weight drugs to treat ureolytic bacterial infections.

Centroid⋯centroid and hydrogen bond interactions as robust supramolecular units for crystal engineering: X-ray crystallographic, computational and urease inhibitory investigations of 1,2,4-triazolo[3,4-a]phthalazines

The antiparallel π-stacked dimer of compound 6 (left) presenting a large dimerization energy (ΔE5 = −11.2 kcal mol−1) and confirming its relevance in the solid state of compound 6. 3D binding mode of 6 (right) docked in the catalytic domain of urease.

Selenourea and thiourea derivatives of chiral and achiral enetetramines: Synthesis, characterization and enzyme inhibitory properties

A series of chiral and achiral cyclic seleno- and thiourea compounds bearing benzyl groups on N-atoms were prepared from enetetramines and appropriate Group VI elements in good yields. All the synthesized compounds were characterized by elemental analysis, FT-IR, ¹H NMR and ¹³C NMR spectroscopy, and the molecular and crystal structures of (R,R)-4b and (R,R)-5b were confirmed by the single-crystal X-ray diffraction method. These assayed for their activities against metabolic enzymes acetylcholinesterase, butyrylcholinesterase, and α-glycosidase. These selenourea and thiourea derivatives of chiral and achiral enetetramines effectively inhibit AChE and BChE with IC₅₀ values in the range of 3.32-11.36 and 1.47-9.73 µM, respectively. Also, these compounds inhibited α-glycosidase enzyme with IC₅₀ values varying between 1.37 and 8.53 µM. The results indicated that all the synthesized compounds exhibited excellent inhibitory activities against mentioned enzymes as compared with standard inhibitors. Representatively, the most potent compound against α-glycosidase enzyme, (S,S)-5b, was 12-times more potent than standard inhibitor acarbose; 7b and 8a as most potent compounds against cholinesterase enzymes, were around 5 and 13-times more potent than standard inhibitor tacrine against achethylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively.

Discovery of urease inhibitory effect of sulfamate derivatives: Biological and computational studies

The discovery of life-changing medicines continues to be the driving force for the rapid exploration and expansion of chemical space, enabling access to innovative small molecules of medicinal importance. These small molecules remain the backbone for modern drug discovery. In this context, the treatment of ureolytic bacterial infections inspires the identification of potent and effective inhibitors of urease, a promising and highly needed target for H. pylori eradication. The present study explores the evaluation of sulfamate derivatives for the inhibition of urease enzyme. The tested compounds showed remarkable inhibitory effect and high level of potency. Compound 1q emerged as the lead inhibitor with an IC₅₀ value of 0.062 ± 0.001 µM, ∼360-fold more potent than thiourea (IC₅₀ = 22.31 ± 0.031 µM). The assessment of various contributing factors towards the inhibition profile allowed for the establishment of diverse structure-activity relationships. Kinetics studies revealed the competitive mode of inhibition of compound 1q while molecular modeling analysis identified various crucial binding interactions with ARG609, ARG439, HIS519, HIS492, HIS593, ALA440, and ALA636 in the active pocket of the enzyme. Finally, the calculated pharmacokinetic properties suggest a promising profile of our potent sulfamate-based urease inhibitors.

Alkynoates as Versatile and Powerful Chemical Tools for the Rapid Assembly of Diverse Heterocycles under Transition-Metal Catalysis: Recent Developments and Challenges

Heterocycles, heteroaromatics and spirocyclic entities are ubiquitous components of a wide plethora of synthetic drugs, biologically active natural products, marketed pharmaceuticals and agrochemical targets. Recognizing their high proportion in drugs and rich pharmacological potential, these invaluable structural motifs have garnered significant interest, thus enabling the development of efficient catalytic methodologies providing access to architecturally complex and diverse molecules with high atom-economy and low cost. These chemical processes not only allow the formation of diverse heterocycles but also utilize a range of flexible and easily accessible building units in a single operation to discover diversity-oriented synthetic approaches. Alkynoates are significantly important, diverse and powerful building blocks in organic chemistry due to their unique and inherent properties such as the electronic bias on carbon-carbon triple bonds posed by electron-withdrawing groups or the metallic coordination site provided by carbonyl groups. The present review highlights the comprehensive picture of the utility of alkynoates (2007-2019) for the synthesis of various heterocycles (> 50 types) using transition-metal catalysts (Ru, Rh, Pd, Ir, Ag, Au, Pt, Cu, Mn, Fe) in various forms. The valuable function of versatile alkynoates (bearing multifunctional groups) as simple and useful starting materials is explored, thus cyclizing with an array of coupling partners to deliver a broad range of oxygen-, nitrogen-, sulfur-containing heterocycles alongside fused-, and spiro-heterocyclic compounds. In addition, these examples will also focus the scope and reaction limitations, as well as mechanistic investigations into the synthesis of these heterocycles. The biological significance will also be discussed, citing relevant examples of drug molecules highlighting each class of heterocycles. This review summarizes the recent developments in the synthetic methods for the synthesis of various heterocycles using alkynoates as readily available starting materials under transition-metal catalysis.

Synthetic and medicinal chemistry of phthalazines: Recent developments, opportunities and challenges

Fused diaza-heterocycles constitute the core structure of numerous bioactive natural products and effective therapeutic drugs. Among them, phthalazines have been recognized as remarkable structural leads in medicinal chemistry due to their wide application in pharmaceutical and agrochemical industries. Accessing such challenging pharmaceutical agents/drug candidates with high chemical complexity through synthetically efficient approaches remains an attractive goal in the contemporary medicinal chemistry and drug discovery arena. In this review, we focus on the recent developments in the synthetic routes towards the generation of phthalazine-based active pharmaceutical ingredients and their biological potential against various targets. The general reaction scope of these innovative and easily accessible strategies was emphasized focusing on the functional group tolerance, substrate and coupling partner compatibility/limitation, the choice of catalyst, and product diversification. These processes were also accompanied by the mechanistic insights where deemed appropriate to demonstrate meaningful information. Moreover, the rapid examination of the structure-activity relationship analyses around the phthalazine core enabled by the pharmacophore replacement/integration revealed the generation of robust, efficient, and more selective compounds with pronounced biological effects. A large variety of in silico methods and ADME profiling tools were also employed to provide a global appraisal of the pharmacokinetics profile of diaza-heterocycles. Thus, the discovery of new structural leads offers the promise of improving treatments for various tropical diseases such as tuberculosis, leishmaniasis, malaria, Chagas disease, among many others including various cancers, atherosclerosis, HIV, inflammatory, and cardiovascular diseases. We hope this review would serve as an informative collection of structurally diverse molecules enabling the generation of mature, high-quality, and innovative routes to support the drug discovery endeavors.

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.

New frontiers in the transition-metal-free synthesis of heterocycles from alkynoates: an overview and current status

This review highlights the successful utilization of transition-metal-free approaches for the modular assembly of various heterocycles from alkynoates.

Robust therapeutic potential of carbazole-triazine hybrids as a new class of urease inhibitors: A distinctive combination of nitrogen-containing heterocycles

The inhibition of urease enzyme is very important as it plays a key role in the treatment of several urinary and gastrointestinal tract infections. This enzyme provides a suitable environment for Helicobacter pylori at the low pH of the stomach, a causative agent of gastric and peptic ulcer that may lead to cancer. In agriculture, the high urease content causes environmental and economic problems. In this pursuit, given the well-established importance of integrated pharmacophores in medicinal chemistry and to explore new inhibitors of urease featuring two distinct heterocyclic functionalities, we herein report a facile synthesis of carbazole-triazine hybrids (3a-j). These new propeller-shaped chemical scaffolds were evaluated for their urease inhibitory potential in order to identify suitable leads. The initial structure-activity survey work guided through in vitro bioactivity results recognized 3e and 3f as new starting point hits incorporating bulky iodo (3e) and strong electron-withdrawing nitro (3f) groups at the para-position of aryl amine component. The potent compounds (3e &3f) exhibited the highest activity with IC₅₀ values of 5.6 and 6.7 µM, respectively. In the molecular docking analysis, these compounds depicted excellent binding interactions with the active site residues. The key interactions observed include hydrogen bonding, π-π interactions, π-cation and nickel atom coordination to the triazine nitrogen of both inhibitors.

Utility of anthranilic acid and diethylacetylenedicarboxylate for the synthesis of nitrogenous organo/organometallic compounds as urease inhibitors

Fumarate diester 3 was synthesized upon reacting anthranilic acid with diethylacetylenedicarboxylate. Compound 3 was reacted with different nucleophiles in mild reaction conditions. Selected reaction routes that afforded products 6, 9, 10, 11, and 12 were explained. The estimated mechanism for the reaction of 3 with ethylenediamine to afford 9 was proved by X-ray single-crystal and retro-synthetic reaction. Acetyl anthranilic acid was utilized with zinc and copper to afford the organometallic compounds 14a and 14b, respectively. Three single crystals were afforded for 3, 9 and the organocopper complex 14b. Target compounds were screened for their inhibitory potential against urease enzyme. Most compounds were more potent than thiourea as standard inhibitor, considering that oxopiperazine 9 exhibited double the activity: IC₅₀ = 8.16 ± 0.65 µM (thiourea IC₅₀ = 20.04 ± 0.33 µM). Docking studies were in agreement with the in vitro enzyme assay.

Synthesis of terpenoid oxo derivatives with antiureolytic activity

Urease is an important virulence factor for a variety of pathogenic bacteria strains such as Helicobacter pylori, which colonizes human gastric mucosa, and Proteus sp., responsible for urinary tract infections. Specific inhibition of urease activity could be a promising adjuvant strategy for eradication of these pathogens. Due to the interesting antiureolytic activity of carvone and the scant information regarding the inhibitory properties of corresponding monoterpenes, we decided to study selected monoterpenic ketones and their oxygen derivatives. Several monoterpenes and their terpenoid oxygen derivatives were evaluated in vitro against Sporosarcina pasteurii urease. The most effective inhibitors-derivatives of β-cyclocitral (ester 10 and bromolactone 14)-were described with [Formula: see text] of 46.7 µM and 45.8 µM, respectively. Active inhibitors of native urease were tested against H. pylori and Proteus mirabilis whole cells. Here, the most active inhibitor, 14, was characterized with IC₅₀ values of 0.32 mM and 0.61 mM for P. mirabilis and H. pylori, respectively. The antibacterial activity of a few tested inhibitors was also observed. Compound 14 limited the growth of E. coli ([Formula: see text]= 250 μg/mL). Interestingly, 10 was the only compound that was effective against both Gram-negative and Gram-positive bacteria. It had a [Formula: see text] of 150 μg/mL against E. coli and S. aureus. In the presented study a group of novel antiureolytic compounds was characterised. Besides carvone stereoisomers, these are the only terpenoid urease inhibitors described so far.

Synthesis and Studies of Fluorescein Based Derivatives for their Optical Properties, Urease Inhibition and Molecular Docking

Herein, we design and synthesized new fluorescein based derivatives by insitu formation of fluorescein ester and further treated with corresponding hydrazide and amine to yield respective compounds i.e. FB1, FB2, FB3 and FB4. The spectral purity and characterization was done by using IR, NMR and Mass spectroscopies. The synthesized derivatives were examined for their photophysical properties by using variety of organic solvents and results were discussed in details. The structural diversity of synthesized compounds motivate us to evaluate these compounds for urease inhibition. The compound FB3 (IC₅₀ = 0.0456 μM) shows 100 fold more active against Jack bean urease than standard drug thiourea (IC₅₀ = 4.7455 μM). Other synthesized compounds showed potent activity. Free radical percentage scavenging assay further supported the capacity of compounds to urease inhibition. While, molecular docking simulations helps to examine the molecular interactions of active compounds FB1, FB2, FB3 and FB4 within the binding site of urease enzyme.

Palladium(0) catalyzed Suzuki cross-coupling reaction of 2,5-dibromo-3-methylthiophene: selectivity, characterization, DFT studies and their biological evaluations

Thiophene derivatives have shown versatile pharmacological activities. The Suzuki reaction proved a convenient method for C-C bond formations in organic molecules. In the present research work novel derivatives of 2,5-dibromo-3-methylthiophene (3a-k and 3l-p) has been synthesized, via Suzuki coupling reaction in low to moderate yields. A wide range of functional groups were well tolerated in reaction. Density functional theory investigations on all synthesized derivatives (3a-3p) were performed in order to explore the structural properties. The pharmaceutical potential of synthesized compounds was investigated through various bioassays (antioxidant, antibacterial, antiurease activities). The compounds 3l, 3g, 3j, showed excellent antioxidant activity (86.0, 82.0, 81.3%), respectively by scavenging DPPH. Synthesized compounds showed promising antibacterial activity against tested strains. 3b, 3k, 3a, 3d and 3j showed potential antiurease activity with 67.7, 64.2, 58.8, 54.7 and 52.1% inhibition at 50 µg/ml. Results indicated that synthesized molecules could be a potential source of pharmaceutical agents.

Monotherapy with a novel intervenolin derivative, AS-1934, is an effective treatment for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H. pylori) infection causes various gastrointestinal diseases including gastric cancer. Hence, eradication of this infection could prevent these diseases. The most popular first-line treatment protocol to eradicate H. pylori is termed "triple therapy" and consists of a proton pump inhibitor (PPI), clarithromycin, and amoxicillin or metronidazole. However, the antibiotics used to treat H. pylori infection are hindered by the antibiotics-resistant bacteria and by their antimicrobial activity against intestinal bacteria, leading to side effects. Therefore, an alternative treatment with fewer adverse side effects is urgently required to improve the overall eradication rate of H. pylori.

OBJECTIVE

The aim of this study was to assess the effectiveness and mechanism of action of an antitumor agent, intervenolin, and its derivatives as an agent for the treatment of H. pylori infection.

RESULTS

We demonstrate that intervenolin, and its derivatives showed selective anti-H. pylori activity, including antibiotic-resistant strains, without any effect on intestinal bacteria. We showed that dihydroorotate dehydrogenase, a key enzyme for de novo pyrimidine biosynthesis, is a target and treatment with intervenolin or its derivatives decreased the protein and mRNA levels of H. pylori urease, which protects H. pylori against acidic conditions in the stomach. Using a mouse model of H. pylori infection, oral monotherapy with the intervenolin derivative AS-1934 had a stronger anti-H. pylori effect than the triple therapy commonly used worldwide to eradicate H. pylori.

CONCLUSION

AS-1934 has potential advantages over current treatment options for H. pylori infection.

Biological Evaluation and Molecular Docking of Protocatechuic Acid from Hibiscus sabdariffa L. as a Potent Urease Inhibitor by an ESI-MS Based Method

Studies on enzyme inhibition remain a crucial area in drug discovery since these studies have led to the discoveries of new lead compounds useful in the treatment of several diseases. In this study, protocatechuic acid (PCA), an active compound from Hibiscus sabdariffa L. has been evaluated for its inhibitory properties against jack bean urease (JBU) as well as its possible toxic effect on human gastric epithelial cells (GES-1). Anti-urease activity was evaluated by an Electrospray Ionization-Mass Spectrometry (ESI-MS) based method, while cytotoxicity was assayed by the MTT method. PCA exerted notable anti-JBU activity compared with that of acetohydroxamic acid (AHA), with IC50 values of 1.7 and 3.2 µM, respectively. PCA did not show any significant cytotoxic effect on (GES-1) cells at concentrations ranging from 1.12 to 3.12 µM. Molecular docking study revealed high spontaneous binding ability of PCA to the active site of urease. Additionally, the anti-urease activity was found to be related to the presence of hydroxyl moieties of PCA. This study presents PCA as a natural urease inhibitor, which could be used safely in the treatment of diseases caused by urease-producing bacteria.