3,4-Dimethoxybenzohydrazide derivatives as antiulcer: Molecular modeling and density functional studies

3,4-Dimethoxybenzohydrazide derivatives (1–25) have been synthesized and evaluated for their urease inhibitory potential. Among the series, compounds 2, 3, 4 and 5 with IC₅₀ values 12.61 ± 0.07, 18.24 ± 0.14, 19.22 ± 0.21, and 8.40 ± 0.05 µM, respectively, showed excellent urease inhibitory potentials when compared with standard thiourea (IC₅₀ value 21.40 ± 0.21 µM). Compounds 1, 6, 8, 18, 19 and 20 also showed good to moderate inhibition, while the remaining compounds were found to be completely inactive. The structures of compounds 6 and 25 were confirmed through X-ray crystallography while the structures of remaining compounds were confirmed through ESI-MS and ¹H NMR. Molecular docking studies were performed understand the binding interactions with enzyme active site. The synthesized compounds were evaluated for cytotoxicity and found to be nontoxic.     

Natural urease inhibitors from Aloe vera resin and Lycium shawii and their structural-activity relationship and molecular docking study

Bio-assay guided fractionation of the methanolic extract of Aloe vera resin and Lycium shawii stem successively afforded twenty three compounds; fourteen (1–14) from A. vera and nine (15–23) from L. shawii. All these compounds were characterized by 1D and 2D NMR spectroscopic techniques viz., ¹H, ¹³C, DEPT, HSQC, HMBC, and COSY, and NEOSY, ESI-MS and compared with the reported literature. These compounds were assessed for their potential as urease inhibitors targeted in peptic ulcer. Among crude extracts and fractions of A. vera resin, n-butanol fraction (23.5 ± 1.7 μg·mL⁻¹) showed the most potent urease inhibition followed by methanol (30.9 ± 0.3 μg/mL) and ethyl acetate (31.7 ± 0.5 μg·mL⁻¹). In case of L. shawii, ethyl acetate fraction exhibited the highest urease activity (41.0 ± 1.4 μg/mL) trailed by dichloromethane (55.2 ± 1.5 μg/mL) fraction. Among the isolates, compounds 7, 11 and 23 were found to be excellent urease inhibitors with IC₅₀ values of 14.5 ± 0.90 µM, (16.7 ± 0.16 µM) and 14.0 ± 0.8 µM, respectively. To the best of our knowledge, this is the first report on the urease enzyme inhibitory activity of the said compounds excluding compound 18. In addition, the urease activity of different fractions of L. shawii stem was also reported for the first time. The molecular docking studies showed that all the active compounds well accommodate in the active site of the urease enzyme by interacting with key amino acids.     

Synthesis and molecular docking study of some novel 2,3-disubstituted quinazolin-4(3H)-one derivatives as potent inhibitors of urease

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

Synthesis,in vitro urease inhibition and molecular docking studies of some novel quinazolin-4(3H)-one derivatives containing triazole,thiadiazole and thiosemicarbazide functionalities

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

Synthesis, in vitro and in silico studies of novel potent urease inhibitors: N-[4-({5-[(3-Un/substituted-anilino-3-oxopropyl)sulfanyl]-1,3,4-oxadiazol-2-yl}methyl)-1,3-thiazol-2-yl]benzamides

The present article describes the synthesis, in vitro urease inhibition and in silico molecular docking studies of a novel series of bi-heterocyclic bi-amides. The synthesis of title compounds was initiated by benzoylation, with benzoyl chloride (1), of the key starter ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate (2) in weak basic aqueous medium followed by hydrazide formation, 4, and cyclization with CS₂ to reach the parent bi-heterocyclic nucleophile, N-{4-[(5-sulfanyl-1,3,4-oxadiazol-2-yl)methyl]-1,3-thiazol-2-yl}benzamide (5). Various electrophiles, 8a–l, were synthesized by a two-step process and these were finally coupled with 5 to yield the targeted bi-heterocyclic bi-amide molecules, 9a–l. The structures of the newly synthesized products were corroborated by IR, ¹H NMR, ¹³C NMR, EI-MS and elemental analysis. The in vitro screening of these molecules against urease explored that most of the compounds exhibit potent inhibitory potential against this enzyme. The compound 9j, with IC₅₀ value of 2.58?±?0.02?µM, exhibited most promising inhibitory activity among the series, relative to standard thiourea having IC₅₀ value of 21.11?±?0.12?µM. In silico studies fully augmented the experimental enzyme inhibition results. Chemo-informatics analysis showed that synthesized compounds (9a–l) mostly obeyed the Lipinski's rule. Molecular docking study suggested that ligand 9j exhibited good binding energy value (?7.10?kcal/mol) and binds within the active region of target protein. So, on the basis of present investigation, it was inferred that 9j may serve as a novel scaffold for designing more potent urease inhibitors.     

Synthesis and molecular docking study of piperazine derivatives as potent urease inhibitors

Urease is known to be one of the major causes of diseases induced by Helicobacter pylori, thus allow them to survive at low pH inside the stomach and thereby, play an important role in the pathogenesis of gastric and peptic ulcer, apart from cancer as well. Keeping in view the great importance of urease inhibitors, here in this study we have synthesized piperazine derivatives (1–15) and evaluated for their urease inhibitory activity. All analogs showed excellent inhibitory potential with IC₅₀ values ranging between 1.1 ± 0.01 and 33.40 ± 1.50 µM when compared with the standard inhibitor thiourea (IC₅₀ = 21.30 ± 1.10 µM). Structure activity relationship has been established for all compounds which are mainly based upon the substitution on phenyl ring. Molecular docking study was performed in order to understand the binding interaction of the compounds in the active site of enzyme.     

Synthesis,Biological Activity Evaluation,Docking and Molecular Dynamics Studies of New Triazole-Tetrahydropyrimidinone(thione) Hybrid Scaffolds as Urease Inhibitors

New series of triazole-tetrahydropyrimidinone(thione) hybrids ( 9a – g ) were synthesized. FT-IR, ¹H-NMR, ¹³C-NMR, elemental analysis and mass spectroscopic studies characterized the structures of the synthesized compounds. Then, the synthesized compounds were screened to determine the urease inhibitory activity. Methyl 4-(4-((1-(2-chlorobenzyl)-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate ( 9c ) exhibited the highest urease inhibitory activity (IC₅₀=25.02 μM) among the compounds which was almost similar to thiourea as standard (IC₅₀=22.32 μM). The docking study of the screened compounds demonstrated that these compounds fit well in the urease active site. Based on the docking study, compound 9c with the highest urease inhibitory activity showed chelates with both Ni²⁺ ions of the urease active site. Moreover, the molecular dynamic study of the most potent compounds showed that they created important interactions with the active site flap residues, His322, Cys321, and Met317.     

Design,synthesis, and biological evaluation of novel 4-oxobenzo[d]1,2,3-triazin-benzylpyridinum derivatives as potent anti-Alzheimer agents

Novel 4-oxobenzo[d]1,2,3-triazin derivatives bearing pyridinium moiety 6a–q were synthesized and screened against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Most of the synthesized compounds showed good inhibitory activity against AChE. Among the synthesized compounds, the compound 6j exhibited the highest AChE inhibitory activity. It should be noted that these compounds displayed low anti-BuChE activity with the exception of the compound 6i, as it exhibited BuChE inhibitory activity more than donepezil. The kinetic study of the compound 6j revealed that this compound inhibited AChE in a mixed-type inhibition mode. This finding was also confirmed by the docking study. The latter study demonstrated that the compound 6j interacted with both the catalytic site and peripheral anionic site of the AChE active site. The compound 6j was also observed to have significant neuroprotective activity against H₂O₂-induced PC12 oxidative stress, but low activity against β-secretase.     

Developing new hybrid scaffold for urease inhibition based on carbazole-chalcone conjugates: Synthesis,assessment of therapeutic potential and computational docking analysis

Although a diverse range of chemical entities offering striking therapeutic potential against urease enzyme has been reported, the key challenges (toxicity and safety) associated with these inhibitors create a large unmet medical need to unveil new, potent and safe inhibitors of urease enzyme. In this pursuit, the present study demonstrates the successful synthesis of carbazole-chalcone hybrids (4a-n) in good yields. The evaluation of the preliminary in vitro biological results showed that selected members of the investigated library of hybrid compounds possess excellent urease inhibitory efficacy. In particular, compounds 4c and 4k were the most potent inhibitors with lowest IC₅₀ values of 8.93 ± 0.21 and 6.88 ± 0.42 μM, respectively. Molecular docking analysis of the most potent inhibitor 4k suggests that the compound is fitted neatly at the active site interface and mediates interaction with both nickel atoms present in the active site. Several other obvious interactions including metal-carbonyl contact, hydrogen bonding and hydrophobic interactions were also observed, playing a crucial part in the stabilization of 4k in the active site of urease.     

Synthetic nicotinic/isonicotinic thiosemicarbazides: In vitro urease inhibitory activities and molecular docking studies

Nicotinic and isonicotinic thiosemicarbazide or hydrazine carbothioamides 3–27 were synthesized and the structures of synthetic compounds were elucidated by various spectroscopic techniques such as EI-MS, ¹H-, and ¹³C NMR. Synthetic derivatives were evaluated for their urease inhibitory activity which revealed that except few all derivatives demonstrated excellent inhibition in the range of IC₅₀ values of 1.21–51.42 μM as compared to the standard thiourea (IC₅₀ = 21.25 ± 0.13 μM). Among the twenty-five synthetic derivatives nineteen 1–5, 7, 8, 10, 12, 14–18, 20–22, 24–27 were found to be more active showing IC₅₀ values between 1.13 and 19.74 μM showing superior activity than the standard. Limited structure-activity relationship demonstrated that the positions of substituent as well as position of nitrogen in pyridine ring are very important for inhibitory activity of this class of compound. To verify these interpretations, in silico study was also performed. A good correlation was obtained between the biological evaluation of active compounds and docking study.     

Design,synthesis, in vitro evaluation,molecular docking and ADME properties studies of hybrid bis-coumarin with thiadiazole as a new inhibitor of Urease

Hybrid bis-coumarin derivatives 1–18 were synthesized and evaluated for their in vitro urease inhibitory potential. All compounds showed outstanding urease inhibitory potential with IC₅₀ value (The half maximal inhibitory concentration) ranging in between 0.12 SD 0.01 and 38.04 SD 0.63 µM (SD standard deviation). When compared with the standard thiourea (IC₅₀ = 21.40 ± 0.21 µM). Among these derivatives, compounds 7 (IC₅₀ = 0.29 ± 0.01), 9 (IC₅₀ = 2.4 ± 0.05), 10 (IC₅₀ = 2.25 ± 0.05) and 16 (IC₅₀ = 0.12 ± 0.01) are better inhibitors of the urease compared with thiourea (IC₅₀ = 21.40 ± 0.21 µM). To find structure–activity relationship molecular docking as well as absorption, distribution, metabolism, and excretion (ADME) studies were also performed. Various spectroscopic techniques like ¹H NMR, ¹³C NMR, and EI-MS were used for characterization of all synthesized analogs. All compounds were tested for cytotoxicity and found non-toxic.     

Hybrid benzothiazole analogs as antiurease agent: Synthesis and molecular docking studies

Benzothiazole analogs (1–20) have been synthesized, characterized by EI-MS and ¹H NMR, and evaluated for urease inhibition activity. All compounds showed excellent urease inhibitory potential varying from 1.4 ± 0.10 to 34.43 ± 2.10 μM when compared with standard thiourea (IC₅₀ 19.46 ± 1.20 μM). Among the series seventeen (17) analogs 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, and 18 showed outstanding urease inhibitory potential. Analogs 15 and 19 also showed good urease inhibition activity. When we compare the activity of N-phenylthiourea 20 with all substituted phenyl derivatives (1–18) we found that compound 15 showed less activity than compound 20 having 3-methoxy substituent. The binding interactions of these active analogs were confirmed through molecular docking.     

Synthesis,antimicrobial, antioxidant,cytotoxic, antiurease and molecular docking studies of N-(3-trifluoromethyl)benzoyl-N′-aryl thiourea derivatives

An irrefutable advancement has been noted for the infectious diseases caused due to ureolytic bacteria through the development of various drugs. Keeping in mind the extremely valuable synthetic utility and medicinal significance of thiourea derivatives, synthesis of new 3-trifluoromethyl benzoic acid thiourea derivatives (3a–j) were carried out. The biological potential of all compounds in terms of antimicrobial, antioxidant, cytotoxic and antiurease activities were studied. The compounds 3a, 3c and 3i with dichloro and methoxy groups substitution on the aryl group showed significant activity against all strain of bacteria while moderate to no activity was observed in remaining compounds. Whereas the antifungal evaluation showed that all compounds were active againts C. Albican and no activity was observed against C. Prapsilosis. The cytotoxic findings revealed the non-toxic nature of these compounds as IC₅₀ values of majority of the compounds are above 100 μm except for compounds 3f and 3g. In addition, these compounds exhibited better antioxidant potential as 100 μm concentration inhibited >50% reactive oxygen species (ROS) production except compounds 3e, 3f and 3j. The compound 3a proved to be the most potent urease inhibitor showing the highest enzyme % inhibition (93.1%) with IC₅₀ value of 8.17 ± 0.24 µM and found more active as compare to standard followed by compound 3e (92.6%), 3h (91.6%), 3d (90.8%), 3b (90.6%) and 3f (90.0%) with their respective IC₅₀ values. All the synthesized compounds were docked into the binding cavity of Urease (PDB ID: 4ubp). The most active compound 3a was also ranked as top on the docking score as it was found to show valuable interactions with the target protein along with good docking scores. Hence our results revealed that the synthesized compounds have potential to be used as potent urease inhibitors after further detailed mechanistic studies.     

Synthesis, molecular docking and biological evaluation of metronidazole derivatives as potent Helicobacter pylori urease inhibitors

Fourteen metronidazole derivatives (compounds 3a–f and 4b–h) have been synthesized by coupling of metronidazole and salicylic acid derivatives. All of them are reported for the first time. Their chemical structures are characterized by ¹H NMR, MS, and elemental analysis. The inhibitory activities against Helicobacter pylori urease have been investigated in vitro and many compounds have showed promising potential inhibitory activities of H. pylori urease. The effect of compounds 4b (IC₅₀ = 26 μM) and 4g (IC₅₀ = 12 μM) was comparable with that of acetohydroxamic acid, a well known H. pylori urease inhibitor used as a positive control. The experimental values of IC₅₀ showed that inhibitor was potent urease inhibitor. A docking analysis using the autodock 4.0 program could explain the inhibitory activities of compound 4g against H. pylori urease.     

Syntheses,in vitro urease inhibitory activities of urea and thiourea derivatives of tryptamine,their molecular docking and cytotoxic studies

Urease is an enzyme of amidohydrolase family and is responsible for the different pathological conditions in the human body including peptic ulcers, catheter encrustation, kidney stone formation, hepatic coma, encephalopathy, and many others. Therefore, the search for potent urease inhibitors has attracted major scientific attention in recent years. Urea and thiourea derivatives of tryptamine (1–25) were synthesized via reaction of tryptamine with different substituted phenyl isocyanates/isothiocyanates. The synthetic compounds were evaluated for their urease enzyme inhibitory activity and they exhibited good inhibitory potential against urease enzyme in the range of (IC₅₀ = 11.4 ± 0.4–24.2 ± 1.5 μM) as compared to the standard thiourea (IC₅₀ = 21.2 ± 1.3 μM). Out of twenty-five compounds, fourteen were found to be more active than the standard. Limited structure-activity relationship suggested that the compounds with CH₃, and OCH₃ substituents at aryl part were the most potent derivatives. Compound 14 (IC₅₀ = 11.4 ± 0.4 μM) with a methyl substituent at ortho position was found to be the most active member of the series. Whereas, among halogen substituted derivatives, para substituted chloro compound 16 (IC₅₀ = 13.7 ± 0.9 μM) showed good urease inhibitory activity. These synthetic derivatives were found to be non-cytotoxic in cellular assay. Kinetic studies revealed that the compounds 11, 12, 14, 17, 21, 22, and 24 showed a non-competitive type of inhibition. In silico study identified the possible bindings interactions of potential inhibitors with the active site of enzyme. These newly identified inhibitors of urease enzyme can serve as leads for further research and development.     

Synthesis,in vitro urease inhibitory activity,and molecular docking studies of thiourea and urea derivatives

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

Solution-phase microwave assisted parallel synthesis,biological evaluation and in silico docking studies of N,N′-disubstituted thioureas derived from 3-chlorobenzoic acid

A facile and robust microwave-assisted solution phase parallel synthesis protocol was exercised for the development of a 38-member library of N,N′-disubstituted thiourea analogues (1–38) by using an identical set of conditions. The reaction time for synthesis of N,N′-disubstituted thiourea analogues was drastically reduced from a reported duration of 8–12 h for conventional methods to only 1.5–2.0 min. All the derivatives (1–38) were characterized by physico-analytical techniques such as elemental analysis in combination with FT-IR, ¹H, ¹³C NMR and by single crystal XRD analysis have also been performed. These compounds were screened for their in vitro urease inhibition activities. Majority of compounds exhibited potent urease inhibition activities, however, the most significant activity was found for 16, with an IC₅₀ value of 1.23 ± 0.1 μM. Furthermore, the synthesized compounds were screened for their cytotoxic potential against lungs cancer cell lines. Cell culture studies demonstrated significant toxicity of the compounds on the cell lines, and the levels of toxicity were altered in the presence of various side groups. The molecular docking studies of the most potent inhibitors were performed to identify the probable binding modes in the active site of the urease enzymes. These compounds have a great potential and significance for further investigations.     

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.     

Dihydropyrimidine based hydrazine dihydrochloride derivatives as potent urease inhibitors

Four series of heterocyclic compounds 4-dihydropyrimidine-2-thiones 7–12 (series A), N,S-dimethyl-dihydropyrimidines 13–18 (series B), hydrazine derivatives of dihydropyrimidine 19–24 (series C), and tetrazolo dihydropyrimidine derivatives 25–30 (series D), were synthesized and evaluated for in vitro urease inhibitory activity. The series B–D were first time examined for urease inhibition. Series A and C were found to be significantly active with IC₅₀ values between 34.7–42.9 and 15.0–26.0 μM, respectively. The structure–activity relationship showed that the free S atom and hydrazine moiety are the key pharmacophores against urease enzyme. The kinetic studies of the active series A (7–12) and C (19–24) were carried out to determine their modes of inhibition and dissociation constants K_i. Compounds of series A (7–12) and series C (19–24) showed a mixed-type of inhibition with K_i values ranging between 15.76–25.66 and 14.63–29.42 μM, respectively. The molecular docking results showed that all the active compounds of both series have significant binding interactions with the active sites specially Ni-ion of the urease enzyme. Cytotoxicity of all series A–D was also evaluated against mammalian mouse fibroblast 3T3 cell lines, and no toxicity was observed in cellular model.     

Synthesis and in vitro urease inhibitory activity of benzohydrazide derivatives,in silico and kinetic studies

Benzohydrazide derivatives 1–43 were synthesized via “one-pot” reaction and structural characterization of these synthetic derivatives was carried out by different spectroscopic techniques such as ¹H NMR and EI-MS. The synthetic molecules were evaluated for their in vitro urease inhibitory activity. All synthetic derivatives showed good inhibitory activities in the range of (IC₅₀ = 0.87 ± 0.31–19.0 ± 0.25 µM) as compared to the standard thiourea (IC₅₀ = 21.25 ± 0.15 µM), except seven compounds 17, 18, 23, 24, 29, 30, and 41 which were found to be inactive. The most active compound of the series was compound 36 (IC₅₀ = 0.87 ± 0.31 μM) having two chloro groups at meta positions of ring A and methoxy group at para position of ring B. The structure–activity relationship (SAR) of the active compounds was established on the basis of different substituents and their positions in the molecules. Kinetic studies of the active compounds revealed that compounds can inhibit enzyme via competitive and noncompetitive modes. In silico study was also performed to understand the binding interactions of the molecules (ligand) with the active site of enzyme.