Synthesis, biological assay in vitro and molecular docking studies of new Schiff base derivatives as potential urease inhibitors

In silico DFT and molecular modeling of novel pyrazine-bearing thiazolidinone hybrids derivatives: elucidating in vitro anti-cancer and urease inhibitors

In the present work, one of the leading health issues i.e. cancer was targeted by synthesizing and biologically investigating the potential of pyrazine-based thiazolidinone derivatives (1-13). The basic structure of the synthesized compounds was determined using a variety of spectroscopic techniques, including 1H NMR, 13C NMR, and HREI-MS. These scaffolds were studied for their biological profiles as anti-cancer as well as anti-urease agents. The biological effectiveness of these compounds was compared using the reference tetrandrine (IC50 = 4.50 ± 0.20 µM) and thiourea (IC50 = 5.10 ± 0.10 µM), respectively. Among novel compounds, scaffold 3, 6, 7 and 10 demonstrated an excellent potency with highest inhibitory potential (IC50 = 1.70 ± 0.10 and 1.30 ± 0.20 µM), (IC50 = 4.20 ± 0.10 and 5.10 ± 0.30 µM), (IC50 = 2.10 ± 0.10 and 3.20 ± 0.20 µM) and (IC50 = 2.70 ± 0.20 and 4.20 ± 0.20 µM), respectively, out of which scaffold 3 emerged as the leading compound due to the presence of highly reactive -CF3 moiety which interacts via hydrogen bonding. Molecular docking investigations of the potent compounds was also carried out which revealed the binding interactions of ligands with the active sites of enzyme. Moreover, the electronic properties, nucleophilic and electrophilic sited of the lead compounds were also studied under density functional theory (DFT).

Design and synthesis of terephthalic dihydrazide analogues as dual inhibitors of glycation and urease

The overexpression of urease is the root cause of peptic ulcers and gastritis. Therefore, introducing new inhibitors against urease is a possible therapeutic approach to overcoming the pathogenesis; for instance, limiting the risk of development of urinary calculi. Moreover, glycation is the leading cause of several complications. Thus, in this study, we synthesized novel terephthalic dihydrazide analogues and evaluated their biological importance. These terephthalic dihydrazide analogues were characterized using advanced spectroscopic techniques, such as 1H NMR, 13C NMR, 19F NMR and HRMS (ESI+), and FT-IR. Fortunately, 6 of the 11 synthesized compounds exhibited urease inhibitory capability, and 8 compounds exhibited anti-glycation capability. Compounds 13-14, 20 and 23 showed significant urease inhibition with IC50 values of 63.12 ± 0.28, 65.71 ± 0.40, 49.2 ± 0.49 and 51.45 ± 0.39 μM, respectively. Meanwhile, they exhibited potent anti-glycation activity with IC50 values of 67.53 ± 0.46, 68.06 ± 0.43, 48.32 ± 0.42 and 54.36 ± 0.40 μM, respectively. Molecular docking of active urease inhibitors showed their good binding at the entrance of the active site and good correlation with our in vitro results.

Design and synthesis aldehydes-thiourea and thiazolyl hydrazine derivatives as promising antifungal agents against Monilinia fructicola

BACKGROUND

Fungal diseases present a significant threat to global agriculture, necessitating the development of new, safe, and effective fungicides. Existing fungicides face resistance and health risks, prompting the synthesis of novel compounds. Researchers have synthesized aldehyde-based thiourea and thiazolyl hydrazine derivatives, evaluating their antifungal activities to identify impactful pesticide molecules.

RESULTS

The results showed that most of the compounds had broad-spectrum antifungal activity against six plant pathogenic fungi and four post-harvest fungi. Notably, compound LN18 showed the best antifungal activity against Monilinia fructicola with a half-maximal effective concentration (EC50) of 0.17 μg mL-1, which was better than the commercial fungicide natamycin. A structure-activity relationship (SAR) study showed that the presence of unsaturated double bonds in the structure and the length of the carbon chain were the main factors affecting antifungal activity. The presence of unsaturated double bonds and an increase in the length of the carbon chain greatly improved inhibitory activity against the tested pathogens. The preliminary mechanism study showed that LN18 could damage the integrity of the mycelial plasma membrane, leading to leakage of intracellular nucleic acid and protein. LN18 also induced an increase in the intracellular reactive oxygen species level to exert its antifungal effects. In addition, compound LN18 had a stronger antifungal effect in vivo, and better phytotoxicity than natamycin, indicating broad application prospects in agriculture.

CONCLUSION

Aldehydes-thiourea and thiazolyl hydrazine derivatives demonstrate remarkable antifungal efficacy against plant pathogenic and post-harvest fungi, offering a promising avenue for commercialization as highly efficacious, cost-effective and safe antifungal agents. © 2024 Society of Chemical Industry.

Exploring Acyl Thiotriazinoindole Based Pharmacophores: Design, Synthesis, and SAR Studies with Molecular Docking and Biological Activity Profiling against Urease, α-amylase, α-glucosidase, Antimicrobial, and Antioxidant Targets

A diminutive chemical library of acyl thiotriazinoindole (ATTI) based bioactive scaffolds was synthesized, instigated by taking the economical starting material Isatin, through a series of five steps. Isatin was first nitrated followed by the attachment of pentyl moiety via nucleophilic substitution reaction. The obtained compound was reacted with thiosemicarbazide to obtain thiosemicarbazone derivative, which was eventually cyclized using basic conditions in water as solvent. Finally, the reported series was obtained through reaction of nitrated thiotriazinoindole moiety with differently substituted phenacyl bromides. The synthesized compounds were characterized using NMR spectroscopy and elemental analysis. Finally, the synthesized motifs were scrutinized for their potential to impede urease, α-glucosidase, DPPH, and α-amylase. Compound 5 h with para cyano group manifested the most pivotal biological activity among all, displaying IC50 values of 29.7 ± 0.8, 20.5 ± 0.5 and 36.8 ± 3.9 µM against urease, α-glucosidase, and DPPH assay, respectively. Simultaneously, for α-amylase compound 5 g possessing a p-CH3 at phenyl ring unfolded as most active, with calculated IC50 values 90.3 ± 1.1 µM. The scaffolds were additionally gauged for their antifungal and antibacterial activity. Among the tested strains, 5d having bromo as substituent exhibited the most potent antibacterial activity, while it also demonstrated the highest potency against Aspergillus fumigatus. Other derivatives 5b, 5e, 5i, and 5j also exhibited dual inhibition against both antibacterial and antifungal strains. The interaction pattern of derivatives clearly displayed their SAR, and their docking scores were correlated with their IC50 values. In molecular docking studies, the importance of interactions like hydrogen bonding was further asserted. The electronic factors of various substituents engendered variety of interactions between the ligands and targets implying their importance in the structures of the synthesized heterocyclic scaffolds. To conclude, the synthesized compounds had satisfactory biological activity against various important targets. Further studies are therefore encouraged by attachment of different substitutions in the structure at various positions to enhance the activity of these compounds.

Recent development and strategies towards target interactions: Synthesis, characterization and in silico analysis of benzimidazole based thiadiazole as potential anti-Alzheimer agents

In the current research study, we aim to design and synthesize highly potent hybrid analogs of benzimidazole derived thiadiazole based Schiff base derivatives which can combat the cholinesterase enzymes (acetylcholinesterase and butyrylcholinesterase) accountable for developing Alzheimer's disease. In this context, we have synthesized 15 analogs of benzimidazole based thiadiazole derivatives, which were subsequently confirmed through spectroscopic techniques including 1H NMR, 13C NMR and HREI-MS. Biological investigation of all the analogs revealed their varied acetylcholinesterase inhibitory potency covering a range between 3.20 ± 0.10 μM to 20.50 ± 0.20 μM as well as butyrylcholinesterase inhibitory potential with a range of 4.30 ± 0.50 μM to 20.70 ± 0.50 μM when compared with the standard drug Donepezil having IC50 = 6.70 ± 0.20 μM for AChE and 7.90 ± 0.10 μM for BuChE. The promising inhibition by the analogs was evaluated in SAR analysis, where analog-1 (IC50 = 3.20 ± 0.10 μM for AChE and 4.30 ± 0.50 μM for BuChE), analog-4 (IC50 = 4.30 ± 0.30 μM for AChE and 5.50 ± 0.20 μM for BuChE) and analog-5 (IC50 = 4.10 ± 0.30 μM for AChE and 4.60 ± 0.40 μM for BuChE) were found as the lead candidates. Moreover, molecular docking and ADME analysis were conducted to explore the better binding interactions and drugs likeness respectively.

Designing and Synthesis of Novel Fexofenadine-Derived Hydrazone-Schiff Bases as Potential Urease Inhibitors: In-Vitro, Molecular Docking and DFT Investigations

Thirteen novel hydrazone-Schiff bases (3-15) of fexofenadine were succesfully synthesized, structurally deduced and finally assessed their capability to inhibit urease enzyme (in vitro). In the series, six compounds 12 (IC50=10.19±0.16 μM), 11 (IC50=15.05±1.11 μM), 10 (IC50=17.01±1.23 μM), 9 (IC50=17.22±0.81 μM), 13 (IC50=19.31±0.18 μM), and 14 (IC50=19.62±0.21 μM) displayed strong inhibitory action better than the standard thiourea (IC50=21.14±0.24 μM), while the remaining compounds displayed significant to less inhibition. LUMO and HOMO showed the transferring of charges from molecules to biological transfer and MEP map showed the chemically reactive zone appropriate for drug action are calculated using DFT. AIM charges, non-bonding orbitals, and ELF are also computed. The urease protein binding analysis benefited from the docking studies.

Discovering phenoxy acetohydrazide derivatives as urease inhibitors and molecular docking studies

Helicobacter pylori causes severe stomach disorders and the use of enzyme inhibitors for treatment is one of the possible therapies. The great biological potential of imine analogs as urease inhibitors has been the focus of researchers in past years. In this regard, we have synthesized twenty-one derivatives of dichlorophenyl hydrazide. These compounds were characterized by different spectroscopic techniques i.e. NMR and HREI-MS. Compounds 2 and 10 were found to be the most active in the series. Structure-activity relationship has been established for all compounds based on different substituents attached to the phenyl ring that play a vital role in enzyme inhibition. From the structure-activity relationship, it has been observed that these analogs showed excellent potential for urease and can be an alternate therapy in the future. The molecular docking study was performed to further explore the binding interactions of synthesized analogs with enzyme active sites.Communicated by Ramaswamy H. Sarma.

Utilizing the drug repurposing strategy on current drugs: new leads for peptic ulcers via biochemical and biomolecular dynamics studies

The hyperactivity of urease enzymes plays a crucial role in the development of hepatic coma, hepatic encephalopathy, urolithiasis, gastric and peptic ulcers. Additionally, these enzymes adversely impact the soil's nitrogen efficiency for crop production. In the current study 100 known drugs were tested against Jack Bean urease and Proteus mirabilis urease and identified three inhibitors i.e. terbutaline (compound 1), Ketoprofen (compound 2) and norepinephrine bitartrate (compound 3). As a result, these compounds showed excellent inhibition against Jack Bean urease i.e. (IC50 = 2.1-11.3 µM), and Proteus mirabilis urease (4.8-11.9 µM). Moreover, in silico studies demonstrate maximum interactions of compounds in the enzyme's active site. Furthermore, intermolecular interactions between compounds and enzyme atoms were examined using STD-NMR spectrophotometry. In parallel, molecular dynamics simulation was carried out to study compounds dynamic behavior within the urease binding region. Urease remained stable during most of the simulation time and ligands were bound in the protein active pocket as observed from the Root mean square deviation (RMSD) and ligand RMSD analyses. Furthermore, these compounds display interactions with the crucial residues, including His492 and Asp633, in 100 ns simulations. In the binding energy analysis, norepinephrine bitartrate exhibited the highest binding energy (-76.32 kcal/mol) followed by Ketoprofen (-65.56 kcal/mol) and terbutaline (-62.15 kcal/mol), as compared to acetohydroxamic acid (-52.86 kcal/mol). The current findings highlight the potential of drug repurposing as an effective approach for identifying novel anti-urease compounds.Communicated by Ramaswamy H. Sarma.

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.

Exploration of Thiourea-Based Scaffolds for the Construction of Bacterial Ureases Inhibitors

A series of 32 thiourea-based urease inhibitors were synthesized and evaluated against native bacterial enzyme and whole cells of Sporosarcina pasteurii and Proteus mirabilis strains. The proposed inhibitors represented structurally diverse thiosemicarbazones and thiocarbohydrazones, benzyl-substituted thiazolyl thioureas, 1H-pyrazole-1-carbothioamides, and dihydropirimidine-2(1H)-thiones. Kinetic characteristics with purified S. pasteurii enzyme determined low micromolar inhibitors within each structural group. (E)-2-(1-Phenylethylidene)hydrazine-1-carbothioamide 19 (Ki = 0.39 ± 0.01 μM), (E)-2-(4-methylbenzylidene)hydrazine-1-carbothioamide 16 (Ki = 0.99 ± 0.04 μM), and N'-((1E,2E)-1,3-diphenylallylidene)hydrazinecarbothiohydrazide 29 (Ki = 2.23 ± 0.19 μM) were used in modeling studies that revealed sulfur ion coordination of the active site nickel ion and hydrogen bonds between the amide group and the side chain of Asp363 and Ala366 carbonyl moiety. Whole-cell studies proved the activity of compounds in Gram-positive and Gram-negative microorganisms. Ureolysis control observed in P. mirabilis PCM 543 (e.g., IC50 = 304 ± 14 μM for 1-benzyl-3-(4-(4-hydroxyphenyl)thiazol-2-yl)thiourea 52) is a valuable achievement, as urease is recognized as a major virulence factor of this urinary tract pathogen.

Synthesis of novel mono- and bis-pyrazolylthiazole derivatives as anti-liver cancer agents through EGFR/HER2 target inhibition

3-Bromoacetyl-4-(2-naphthoyl)-1-phenyl-1H-pyrazole (6) was synthesized from 2-acetylnaphthalene and was used as a new key building block for constructing the title targets. Thus, the reaction of 6 with the thiosemicarbazones 7a-d and 9-11 afforded the corresponding simple naphthoyl-(3-pyrazolyl)thiazole hybrids 8a-d and 12 ~ 14. The symmetric bis-(2-naphthoyl-pyrazol-3-yl)thiazol-2-yl)hydrazono)methyl)phenoxy)alkanes 18a-c and 21a-c were similarly synthesized from reaction of 6 with the appropriate bis-thiosemicarbazones 17a-c and 19a-c, respectively. The synthesized two series of simple and symmetrical bis-molecular hybrid merging naphthalene, thiazole, and pyrazole were evaluated for their cytotoxicity. Compounds 18b,c and 21a showed the most potent cytotoxicity (IC₅₀ = 0.97-3.57 µM) compared to Lapatinib (IC₅₀ = 7.45 µM). Additionally, they were safe (non-cytotoxic) against the THLE2 cells with higher IC₅₀ values. Compounds 18c exhibited promising EGFR and HER-2 inhibitory activities with IC₅₀ = 4.98 and 9.85 nM, respectively, compared to Lapatinib (IC₅₀ = 6.1 and 17.2 nM). Apoptosis investigation revealed that 18c significantly activated apoptotic cell death in HepG2 cells, increasing the death rate by 63.6-fold and arresting cell proliferation at the S-phase. Compound 18c upregulated P53 by 8.6-fold, Bax by 8.9-fold, caspase-3,8,9 by 9, 2.3, and 7.6-fold, while it inhibited the Bcl-2 expression by 0.34-fold. Thereby, compound 18c exhibited promising cytotoxicity against EGFR/HER2 inhibition against liver cancer.

I2/DMSO-Promoted Synthesis of Diaryl Sulfide- and Selenide-Embedded Arylhydrazones

Functionalization and derivatization of arylhydrazones are important in pharmaceutical, medicinal, material, and coordination chemistry. In this regard, a facile I₂/DMSO-promoted cross-dehydrogenative coupling (CDC) for direct sulfenylation and selenylation of arylhydrazones has been accomplished utilizing arylthiols/arylselenols at 80 °C. This method provides a metal-free benign route for the synthesis of a variety of arylhydrazones embedded with diverse diaryl sulfide and selenide moieties in good to excellent yield. In this reaction, molecular I₂ acts as a catalyst, and DMSO is utilized as a mild oxidant as well as solvent to produce several sulfenyl and selenyl arylhydrazones through a CDC-mediated catalytic cycle.

N-Arylacetamide derivatives of methyl 1,2-benzothiazine-3-carboxylate as potential drug candidates for urease inhibition

Urease enzyme is an infectious factor that provokes the growth and colonization of virulence pathogenic bacteria in humans. To overcome the deleterious effects of bacterial infections, inhibition of urease enzyme is one of the promising approaches. The current study is designed to synthesize new 1,2-benzothiazine-N-arylacetamide derivatives 5(a-n) that can effectively provide a new drug candidate to avoid bacterial infections by urease inhibition. After structural elucidation by FT-IR, proton and carbon-13 NMR and mass spectroscopy, the synthesized compounds 5(a-n) were investigated to evaluate their inhibitory potential against urease enzyme. In vitro analysis against positive control of thiourea indicated that all the synthesized compounds have strong inhibitory strengths as compared to the reference drug. Compound 5k, being the most potent inhibitor, strongly inhibited the urease enzymes and revealed an IC50 value of 9.8 ± 0.023 µM when compared with the IC50 of thiourea (22.3 ± 0.031 µM)-a far more robust inhibitory potential. Docking studies of 5k within the urease active site revealed various significant interactions such as H-bond, π-alkyl with amino acid residues like Val744, Lys716, Ala16, Glu7452, Ala37 and Asp730.

Para-Substituted Thiosemicarbazones as Cholinesterase Inhibitors: Synthesis, In Vitro Biological Evaluation, and In Silico Study

The current research reports the synthesis of 14 para-substituted thiosemicarbazone derivatives in good to excellent yields using standard procedures. Initially, 4-ethoxybenzaldehyde (1) and 4-nitrobenzaldehyde (2) were refluxed with thiosemicarbazide in the presence of acetic acid in ethanol for 4-5 h. Then, various substituted phenacyl bromides were treated with the desired thiosemicarbazones (3 and 4) in the presence of triethylamine in ethanol with constant stirring for 5-6 h. The resulting derivatives were confirmed through electron impact mass spectrometry and ¹H NMR spectroscopy and evaluated for anticholinesterase inhibitory activity. Among the series, four compounds, 19, 17, 7, and 6, showed potent inhibitory activity against the acetylcholinesterase (AChE) enzyme, having IC₅₀ values of 110.19 ± 2.32, 114.57 ± 0.15, 140.52 ± 0.11, and 160.04 ± 0.02 μM, respectively, compared with standard galantamine (IC₅₀ = 104.5 ± 1.20 μM). Similarly, compounds 19 (IC₅₀ = 145.11 ± 1.03 μM), 9 (IC₅₀ = 147.20 ± 0.09 μM), 17 (IC₅₀ = 150.36 ± 0.18 μM), and 6 (IC₅₀ = 190.21 ± 0.13 μM) were the most excellent inhibitors of butyrylcholinesterase (BChE) when compared with the standard drug galantamine (IC₅₀ = 156.8 ± 1.50 μM). In silico studies were accomplished on the produced derivatives in order to explain the binding interface of compounds with the active sites of AChE and BChE enzymes.

Piperazine-based Semicarbazone Derivatives as Potent Urease Inhibitors: Design, Synthesis, and Bioactivity Screening

Background:

An enzyme called urease assists highly pathogenic bacteria in colonizing and maintaining themselves. Accordingly, inhibiting urease enzymes has been shown to be a promising strategy for preventing ureolytic bacterial infections.

Objective:

This study aimed to synthesize and evaluate the bioactivity of a series of semicarbazone derivatives.

Methods:

A series of piperazine-based semicarbazone derivatives 5a-o were synthesized and isolated, and their structures were elucidated by 1H-NMR and 13C-NMR spectroscopic techniques besides MS and elemental analysis. The urease inhibition activity of these compounds was evaluated using the standard urease enzyme inhibition kit. An MTT assay was performed on two different cell lines (NIH-3T3 and MCF-7) to investigate the cytotoxicity profile.

Results:

All semicarbazone 5a-o exhibited higher urease inhibition activity (3.95–6.62 μM) than the reference standards thiourea and hydroxyurea (IC50: 22 and 100 μM, respectively). Derivatives 5m and 5o exhibited the best activity with the IC50 values of 3.95 and 4.05 μM, respectively. Investigating the cytotoxicity profile of the target compound showed that all compounds 5a-o have IC50 values higher than 50 μM for both tested cell lines.

Conclusion:

The results showed that semicarbazone derivatives could be highly effective as urease inhibitors.

New Triazinoindole Bearing Benzimidazole/Benzoxazole Hybrids Analogs as Potent Inhibitors of Urease: Synthesis, In Vitro Analysis and Molecular Docking Studies

Twenty-four analogs based on triazinoindole bearing benzimidazole/benzoxazole moieties (1-25) were synthesized. Utilizing a variety of spectroscopic methods, including 1H-, 13C-NMR, and HREI-MS, the newly afforded compounds (1-25) were analyzed. The synthesized analogs were tested against urease enzyme (in vitro) as compared to the standard thiourea drug. All triazinoindole-based benzimidazole/benzoxazole analogs (1-25) exhibited moderate to excellent inhibition profiles, having IC50 values of 0.20 ± 0.01 to 36.20 ± 0.70 μM when evaluated under the positive control of thiourea as a standard drug. To better understand the structure-activity relationship, the synthesized compounds were split into two groups, "A" and "B." Among category "A" analogs, analogs 8 (bearing tri-hydroxy substitutions at the 2,4,6-position of aryl ring C) and 5 (bearing di-hydroxy substitutions at the 3,4-position of aryl ring C) emerged as the most potent inhibitors of urease enzyme and displayed many times more potency than a standard thiourea drug. Besides that, analog 22 (which holds di-hydroxy substitutions at the 2,3-position of the aryl ring) and analog 23 (bearing ortho-fluoro substitution) showed ten-fold-enhanced inhibitory potential compared to standard thiourea among category "B" analogs. Molecular docking studies on the active analogs of each category were performed; the results obtained revealed that the presence of hydroxy and fluoro-substitutions on different positions of aryl ring C play a pivotal role in binding interactions with the active site of the targeted urease enzyme.

Development of urease inhibitors by fragment-based dynamic combinatorial chemistry

In this study, fragment-based dynamic combinatorial chemistry (DCC) was explored for the development of novel urease inhibitors. Based on a rationally designed fragment, two iteratively evolved dynamic combinatorial libraries (DCLs) were generated and screened in the presence of urease template. The best ligand identified revealed not only strong urease inhibition but also low cytotoxicity. Additionally, possible inhibitory mechanism was elucidated in the binding kinetic study and docking simulation.

Thiosemicarbazone derivatives: Evaluation as cruzipain inhibitors and molecular modeling study of complexes with cruzain

The development of cruzipain inhibitors represents one of the most attractive challenges in the search for drugs for the treatment of Chagas disease. A recombinant form of this enzyme, cruzain, has been crystallized with numerous inhibitors, excluding thiosemicarbazones. These compounds have been established as potent inhibitors of cruzain, although there is very little data in the literature of thiosemicarbazones tested on cruzipain. In this work, we present the results of the evaluation of eleven thiosemicarbazones on cruzipain, isolated from T. cruzi epimastigotes, six of them previously evaluated on cruzain. For these latter, we studied through computational methods, the mode of interaction with the active site of cruzain and the contribution of geometric parameters to the possible mechanism of action involved in the observed inhibition. Finally, from some geometric parameters analyzed on modeled TSC-cruzain complexes, a semi-quantitative relationship was established that could explain the inhibitory activity of thiosemicarbazones on cruzipain, the enzyme actually present in the parasite.

Bio-oriented synthesis of new sulphadiazine derivatives for urease inhibition and their pharmacokinetic analysis

Current research is based on biology-oriented synthesis of sulphadiazine derivatives and determination of their urease inhibitory activity. In this regard, a series of (E)-4-(benzylideneamino)-N-(pyrimidin-2-yl)benzenesulfonamide was synthesized from sulphadiazine and substituted aromatic aldehydes. The structures of synthesized compounds were ascertained by spectroscopic techniques, such as, FTIR, NMR and HRMS analysis, and in-vitro and in-silico investigation were carried out for the inhibition of urease. Ureases are harmful for humans by producing by-products of urea (ammonia and carbon dioxide). The most active compound (3l) against urease exhibited IC50 value of 2.21 ± 0.45 µM which is 10 times more potent than the standard thiourea (20.03 ± 2.06 µM). It is noteworthy that most of our synthesized compounds showed significant to excellent activities against urease enzyme and most of them substituted by halogen or hydroxy groups at ortho and para positions in their structures. Inhibition of enzyme by the synthesized analogues was in descending order as 3l > 3a > 3b > 3q > 3e > 3o > 3s > 3t > 3g > 3k > 3r > 3f > 3m > 3p > 3n > 3j > 3i > 3h. Moreover, molecular docking studies were performed to rationalize the binding interactions of the synthesized motifs with the active pocket of the urease enzyme. The synthesized sulphadiazine derivatives (3a-u) were found to be non-toxic, and presented passive gastrointestinal absorption.

New isolate from Salvinia molesta with antioxidant and urease inhibitory activity

Urease plays a significant role in the pathogenesis of urolithiasis pyelonephritis, urinary catheter encrustation, hepatic coma, hepatic encephalopathy, and peptic acid duodenal ulcers. Salvinia molesta was explored to identify new bioactive compounds with particular emphasis on urease inhibitors. The aqueous methanol extract was fractionated using solvents of increasing polarity. A series of column chromatography and later HPLC were performed on butanol extract. The structures of the resulting pure compounds were resolved using NMR (1D and 2D), infrared, and mass spectroscopy. The novel isolate was evaluated for antioxidant activity (using DPPH, superoxide anion radical scavenging, oxidative burst, and Fe⁺² chelation assays), anti-glycation behavior, anticancer activity, carbonic anhydrase inhibition, phosphodiesterase inhibition, and urease inhibition. One new glucopyranose derivative 6'-O-(3,4-dihydroxybenzoyl)-4'-O-(4-hydroxybenzoyl)-α/β-D-glucopyranoside (1) and four known glycosides were identified. Glycoside 1 demonstrated promising antioxidant potential with IC₅₀ values of 48.2 ± 0.3, 60.3 ± 0.6, and 42.1 ± 1.8 μM against DPPH, superoxide radical, and oxidative burst, respectively. Its IC₅₀ in the Jack bean urease inhibition assay was 99.1 ± 0.8 μM. The mechanism-based kinetic studies presented that compound 1 is a mixed-type inhibitor of urease with a K_i value of 91.8 ± 0.1 μM. Finally, molecular dynamic simulations exploring the binding mode of compound 1 with urease provided quantitative agreement between estimated binding free energies and the experimental results. The studies corroborate the use of compound 1 as a lead for QSAR studies as an antioxidant and urease inhibitor. Moreover, it needs to be further evaluated through the animal model, that is, in vivo or tissue culture-based ex-vivo studies, to establish their therapeutic potential against oxidative stress phosphodiesterase-II and urease-induced pathologies.

Synthesis of new urease enzyme inhibitors as antiulcer drug and computational study

In search of potent urease inhibitor indole analogues (1-22) were synthesized and evaluated for their urease inhibitory potential. All analogues (1-22) showed a variable degree of inhibitory interaction potential having IC₅₀ value ranging between 0.60 ± 0.05 to 30.90 ± 0.90 µM when compared with standard thiourea having IC₅₀ value 21.86 ± 0.90 µM. Among the synthesized analogues, the compounds 1, 2, 3, 5, 6, 8, 12, 14, 18, 20 and 22 having IC₅₀ value 3.10 ± 0.10, 1.20 ± 0.10, 4.60 ± 0.10, 0.60 ± 0.05, 5.30 ± 0.20, 2.50 ± 0.10, 7.50 ± 0.20, 3.90 ± 0.10, 3.90 ± 0.10, 2.30 ± 0.05 and 0.90 ± 0.05 µM respectively were found many fold better than the standard thiourea. All other analogues showed better urease interaction inhibition. Structure activity relationship (SAR) has been established for all analogues containing different substituents on the phenyl ring. To understand the binding interaction of most active analogues with enzyme active site docking study were performed.Communicated by Ramaswamy H. Sarma.

Therapeutic potential of N4-substituted thiosemicarbazones as new urease inhibitors: Biochemical and in silico approach

Urease enzyme plays a key role in pathogenesis of gastritis and peptic ulcers. Its inhibition averts our bodies from many disorders including formation of urinary calculi. In agriculture, the high urease content causes severe environmental and hence economic problems. Due to deficiency of effective and safer drugs to tackle the aforementioned disorders, the quest for new scaffolds becomes mandatory in the field of medicinal chemistry. In this regard, we herein report a new series of N⁴-substituted thiosemicarbazones 3a-v as potential candidates for urease inhibition. These new N⁴-substituted thiosemicarbazones 3a-v of distant chemical scaffolds were characterized by advanced spectroscopic techniques, such as FTIR, ¹HNMR, ¹³CNMR, ESI-MS and in the case of compound 3g by single crystal X-ray analysis. The compounds were evaluated for their urease inhibitory potential. All newly synthesized compounds showed significant urease inhibitions with IC₅₀ values in range of 2.7 ± 0.320-109.2 ± 3.217 μM. Molecular docking studies were used for interactions pattern and structure-activity relationship for all compounds, which demonstrated excellent binding interactions with the active site residues, such as hydrogen bonding, π-π interactions, π-H and nickel atom coordination.

Synthesis, biological evaluation of antioxidant-antibacterial activities and computational studies of novel anthracene- and pyrene-based Schiff base derivatives

Schiff base derivatives with anthracene- and pyrene-based units, A1-A6 and P1-P6 were synthesized (89%–99% yields). Schiff base derivatives were designed to possess an heterocyclic moiety on one side to enhance the coordination ability towards metals. To investigate the biological assay of the newly synthesized compounds, their DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, metal chelating, reducing power, antibacterial and DNA binding activities were tested. A6 (63.1%) showed the maximum free radical scavenging activity among all. However, compound P3 at concentration of 200 μg/mL possessed the highest metal chelating (45.8%) activity and power of reduction. In addition, P3 and A6 showed antibacterial activity against all bacteria tested and both compounds were very well bound to CT-DNA. Density functional theory method with B3LYP/6-311++G(d,p) basis set was performed to get information about the structural and electronic properties of the present compounds. In addition, the metal coordination properties of the dimers of the parent Schiff bases were investigated through interactions with Zn²⁺.

Design, synthesis, molecular docking, in silico ADMET profile and anticancer evaluations of sulfonamide endowed with hydrazone-coupled derivatives as VEGFR-2 inhibitors

A new series of sulfonamide endowed with hydrazone coupled to dimethyl and/or diethyl malonates were prepared. Various sulfa drugs were diazotized and followed by coupling with active methylene of dimethyl and/or diethyl malonate to afford the new intermediates hydrazones 3_a-c and 4_a-c. The reactivity of hydrazone derivatives towards hydrazines was investigated. Thus, a novel series of 3,5-dioxopyrazolidine7_a-cwere obtained by treatment with hydrazine hydrate. When hydrazones were allowed to react with phenyl hydrazine, the alkyl 2-((4-(N-(substituted)sulfamoyl)phenyl)diazenyl)-3-oxo-3-(2-phenylhydrazinyl)propanoateswere obtained 8_a-c and/or 10_a-c. Their anticancer activities were evaluated against HepG2, HCT-116 and MCF-7. HepG2 was the most sensitive one. In particular, compounds 7_c, 7_b and 10_c were found to be the most potent derivatives with IC₅₀ = 6.43 ± 0.5, 9.66 ± 0.8, 10.57 ± 0.9 µM, 8.65 ± 0.7, 7.49 ± 0.6, 14.29 ± 1.3 µM and 8.97 ± 0.7, 10.13 ± 0.9, 13.82 ± 1.1 µM respectively. Sorafenib and doxorubicin were used as reference drugs. The most potent derivatives 7_a, 7_b, 7_c, 8_c and 10_c were tested for their cytotoxicity against normal VERO cell lines. Compounds 7_a, 7_b, 7_c, 8_c and 10_c are respectively, 2.41, 4.85, 4.08, 3.23 and 5.89 fold times more toxic in HCT116 than in VERO normal cells. Moreover, the most active anti-proliferative derivatives 7_a, 7_b, 7_c, 8_c and 10_c were subjected to further biological study to evaluate their inhibitory potentials against VEGFR-2. The tested compounds displayed high to good inhibitory activity with IC₅₀ values ranging from 0.14 ± 0.02 to 0.23 ± 0.03 µM. Among them, compounds 7_c, 7_b and 10_c were found to be the most potent derivative that inhibited VEGFR-2 at IC₅₀ values of 0.14 ± 0.02, 0.15 ± 0.02 and 0.15 ± 0.02 µM respectively. sorafenib was used as reference drug. Furthermore, ADMET profile was evaluated for the four most active compounds in comparison to doxorubicin as a reference drug. The data obtained from docking studies were highly correlated with that obtained from the biological screening.

Synthesis of novel xanthene based analogues: Their optical properties, jack bean urease inhibition and molecular modelling studies

In this work, a series of the rhodamine 6G based derivatives 5a-5g, were synthesized. The structural framework of the synthesized compounds was established by using ¹H NMR, ¹³C NMR, FT-IR, and LC-MS analytical methods. The spectroscopic properties of the target compounds were determined by using absorption and fluorescence study in four different solvents. Furthermore, the synthesized derivatives were assessed for in-vitro screening against jack bean urease inhibition and in-silico molecular docking study. The result reveals that all the compounds exhibit good urease inhibitory activity against this enzyme but among the series, the compound 5a &5c with an IC₅₀ values of 0.1108 ± 0.0038 μM and 0.1136 ± 0.0295 μM shows to be most auspicious inhibitory activity compared to a standard drug (Thiourea) having IC₅₀ value 4.7201 ± 0.0546 μM. Subsequently, the molecular docking experiment was analysed to distinguish the enzyme-inhibitor binding interaction.

Immobilized Metal Affinity Chromatography as a Drug Discovery Platform for Metalloenzyme Inhibitors

Immobilized metal-ion affinity chromatography (IMAC) used to purify recombinant proteins features a resin-bound 1:1 Ni(II)-iminodiacetic acid (IDA) complex. This hemi-saturated Ni(II)-IDA system containing exchangeable sites at the metal ion is re-cast as a surrogate of a coordinatively-unsaturated metalloenzyme active site, with utility for selecting compounds with metal-binding groups from mixtures as potential metalloenzyme inhibitors. Exchanging Ni(II) for other metal ions could broaden the scope of metalloenzyme target. This work examined the performance of Cu(II)-, Fe(III)-, Ga(III)-, Ni(II)-, or Zn(II)-IMAC resins to reversibly bind experimental or clinical metalloenzyme inhibitors of Zn(II)-ACE1, Zn(II)-HDAC, Fe(II)/(III)-5-LO or Cu(II)-tyrosinase from a curated mixture (1-17). Each IMAC system gave a distinct selection profile. The Zn(II)-IMAC system selectively bound the thiol-containing Zn(II)-ACE1 inhibitors captopril and omapatrilat, and the Fe(III)-IMAC system selectively bound the Fe(II)/(III)-5-LO inhibitor licofelone, demonstrating a remarkable IMAC-metalloenzyme metal ion match. IMAC provides a simple, water-compatible platform, which could accelerate metalloenzyme inhibitor discovery.

Novel thiobarbiturates as potent urease inhibitors with potential antibacterial activity: Design, synthesis, radiolabeling and biodistribution study

Urease enzyme is a virulence factor that helps in colonization and maintenance of highly pathogenic bacteria in human. Hence, the inhibition of urease enzymes is well-established to be a promising approach for preventing deleterious effects of ureolytic bacterial infections. In this work, novel thiobarbiturate derivatives were synthesized and evaluated for their urease inhibitory activity. All tested compounds effectively inhibited the activity of urease enzyme. Compounds 1, 2a, 2b, 4 and 9 displayed remarkable anti-urease activity (IC₅₀ = 8.21-16.95 μM) superior to that of thiourea reference standard (IC₅₀ = 20.04 μM). Moreover, compounds 3a, 3g, 5 and 8 were equipotent to thiourea. Among the tested compounds, morpholine derivative 4 (IC₅₀ = 8.21 µM) was the most potent one, showing 2.5 folds the activity of thiourea. In addition, the antibacterial activity of the synthesized compounds was estimated against both standard strains and clinical isolates of urease producing bacteria. Compound 4 explored the highest potency exceeding that of cephalexin reference drug. Moreover, biodistribution study using radiolabeling approach revealed a remarked uptake of ^99mTc-compound 4 into infection induced in mice. Furthermore, a molecular docking analysis revealed proper orientation of title compounds into the urease active site rationalizing their potent anti-urease activity.

N-monosubstituted thiosemicarbazide as novel Ure inhibitors: synthesis, biological evaluation and molecular docking

Background: Identification of novel Ure inhibitors with high potency has received considerable attention. Methodology & results: Ure inhibition was determined using the indophenol method, the affinities to Ure were estimated via surface plasmon resonance. Seventeen new plus ten known N-monosubstituted thiosemicarbazides were synthesized and identified as novel Ure inhibitors. Out of these compounds, compound b5 shows excellent activity against both crude Ure from Helicobacter pylori (IC₅₀ = 0.04 μM) and Ure in living cell (IC₅₀ = 0.27 μM), with the potency being over 600-fold higher than clinical used drug acetohyroxamic acid, respectively. Surface plasmon resonance demonstrated the high affinity (K_d.#x00A0;= 6.32 nM) of b5 to Ure. Conclusion: This work provides a class of novel and promising Ure inhibitors.

Design, synthesis, biological evaluation, QSAR analysis and molecular modelling of new thiazol-benzimidazoles as EGFR inhibitors

Heterocyclic rings such as thiazole and benzimidazole are considered as privileged structures, since they constitute several FDA-approved drugs for cancer treatment. In this work, a new set of 2-(2-(substituted) hydrazinyl)-4-(1-methyl-1H-benzo[d]imidazol-2-yl) thiazoles 4a-q were designed as epidermal growth factor receptor (EGFR) inhibitors and synthesized using concise synthetic methods. The new target compounds have been evaluated in vitro for their suppression activity against EGFR TK. Compounds 4n, 4h, 4i, 4a and 4d exhibited significant potency in comparison with erlotinib which served as a reference drug (IC50, 71.67-152.59 nM; IC50 erlotinib, 152.59 nM). Furthermore, MTT assay revealed that compounds 4j, 4a, 4f, 4h, 4n produced the most promising cytotoxic potency against the human breast cancer cell line (MCF-7) (IC50; 5.96-11.91 µM; IC50 erlotinib; 4.15 µM). Compound 4a showed promising activity as EGFR TK inhibitor as well as anti-breast cancer agent. In addition, 4a induced apoptotic effect and cell cycle arrest at G2/M phase preventing the mitotic cycle in MCF-7 cells. Moreover, 4a upregulated the oncogenic parameters; caspase-3, p53, Bax/Bcl-2 as well as it inhibited the level of PARP-1 enzyme. QSAR study was carried out for the new derivatives and it revealed the goodness of the models. Furthermore, molecular docking studies represented the binding modes of the promising compounds in the active pocket of EGFR.