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

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.

An overview of the privileged synthetic heterocycles as urease enzyme inhibitors: Structure-activity relationship

Urease is a metalloenzyme including two Ni2+ ions, found in some plants, bacteria, fungi, microorganisms, invertebrate animals, and animal tissues. Urease acts as a significant virulence factor, mainly in catheter blockage and infective urolithiasis as well as in the pathogenesis of gastric infection. Therefore, studies on urease lead to novel synthetic inhibitors. In this review, the synthesis and antiurease activities of a collection of privileged synthetic heterocycles such as (thio)barbiturate, (thio)urea, dihydropyrimidine, and triazol derivatives were described and discussed according to structure-activity relationship findings in search of the best moieties and substituents that are answerable for encouraging the desired activity even more potent than the standard. It was found that linking substituted phenyl and benzyl rings to the heterocycles led to potent urease inhibitors.

Novel benzimidazole-linked (thio)barbiturates as non-hydroxamate HDAC6 inhibitors targeting leukemia: Design, synthesis, and structure-activity relationship

Based on the well-established pharmacophoric features required for histone deacetylase (HDAC) inhibition, novel easy-to-prepare benzimidazole-linked (thio)barbiturate derivatives were designed and synthesized as HDAC6 inhibitors. The proposed structures of the title compounds were confirmed based on their spectral data and elemental analyses. The newly synthesized compounds were screened in vitro against HDAC6. All tested compounds showed potent HDAC6 inhibition at the nanomolar level. Several compounds displayed a remarkable HDAC6 inhibitory activity (IC₅₀  = 48.85-75.62 nM), superior to that of the reference drug suberoylanilide hydroxamic acid (SAHA; IC₅₀  = 91.73 nM). The most potent derivatives were further assessed for their in vitro anticancer activity against two human leukemia cell lines. Thiobarbiturate 3e was two times more potent than SAHA against the tested cells. The detailed structure-activity relationship was also described. Furthermore, molecular docking simulation revealed the ability of the title compounds to chelate the catalytic Zn⁺² ion located within the binding pocket of HDAC6. In silico evaluation of physicochemical properties indicated that the target compounds are promising candidates in terms of pharmacokinetic aspects.

Computational, in vitro and radiation-based in vivo studies on acetamide quinazolinone derivatives as new proposed purine nucleoside phosphorylase inhibitors for breast cancer

The present work describes a quinazolinone-based lead optimization for the development of novel purine nucleoside phosphorylase (PNP) inhibitors with quinazolinone scaffold. Nineteen compounds were proposed and docked against PNP, the best 14 compounds with highest docking and affinity scores and low RMSD values were synthesized. Synthesis of new quinazolinone derivatives with variable acetamide substituents on two positions on quinazoline ring was performed. The structures assigned to the products were concordant with the microanalytical and spectral data. In vitro cytotoxicity on human breast cancer cell line (MCF7) was performed and identified compound 6g as the most potent with IC₅₀ (0.99 ± 0.11 μM) which was further tested against five different breast cancer cell lines in addition to normal breast cell to determine the selectivity. Compound 6g was subjected to molecular dynamic simulation study, radiolabelling and biodistribution study to investigate its stability and selectivity toward breast cancers. The in vitro PNP inhibition results were aligned with the in silico, cytotoxicity, and biodistribution results where 6g showed the most potent PNP inhibitory activity with IC₅₀ (0.159 ± 0.007 μM) when compared to Peldesine (BCX-34) IC₅₀ (0.041 ± 0.002 μM).

1,3,4-Thiadiazole and 1,2,4-triazole-5-thione derivatives bearing 2-pentyl-5-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-one ring: Synthesis, molecular docking, urease inhibition, and crystal structure

Two series of 1,3,4-thiadiazole (40a-o) and 1,2,4-triazole-5-thione (41a-l) derivatives bearing a 2-pentyl-5-phenyl-1,2,4-triazole-3-one ring were synthesized and then studied for their urease inhibitory activities using thiourea as a standard drug. Among the two groups, the first group (40a-o) did not show good activity while the second group (41a-l) showed excellent activity. Compound 41j (1091.24 ± 14.02 µM) of the second series of compounds showed lower activity than thiourea, while the remaining 11 compounds (41a-i, k, and l) showed better activity than thiourea (183.92 ± 13.14 µM). Among the 11 compounds, 41b (15.96 ± 2.28 µM) having the 3-F group on the phenyl ring showed the highest inhibitory activity. Urease kinetic studies of 41b, which is the most active compound, determined it to have an un-competitive inhibition potential. Moreover, in silico analysis against urease from jack bean with 27 new heterocyclic compounds and the reference molecule was carried out to see the necessary interactions responsible for urease activity. The docking calculations of all compounds supported stronger binding to the receptor than the reference molecule, with high inhibition constants. In addition, compound 40m was characterized by single-crystal X-ray diffraction analysis. X-ray analysis reveals that the structures of the compound 40m crystallize in the monoclinic P21/c space group with the cell parameters: a = 10.2155(9) Å, b = 22.1709(18) Å, c = 21.4858(17) Å, β = 99.677(8)°, V = 4797.0(7) ų . X-ray diffraction analyses were also performed to gain insights into the role of weak intermolecular interactions and C-H…X (halogen) interactions in compound 40m that influence the crystal packing.

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.

Design and synthesis of new N-thioacylated ciprofloxacin derivatives as urease inhibitors with potential antibacterial activity

A new series of N-thioacylated ciprofloxacin 3a-n were designed and synthesized based on Willgerodt-Kindler reaction. The results of in vitro urease inhibitory assay indicated that almost all the synthesized compounds 3a-n (IC₅₀ = 2.05 ± 0.03-32.49 ± 0.32 μM) were more potent than standard inhibitors, hydroxyurea (IC₅₀ = 100 ± 2.5 μM) and thiourea (IC₅₀ = 23 ± 0.84 μM). The study of antibacterial activity against Gram-positive species (S. aureus and S. epidermidis) revealed that the majority of compounds were more active than ciprofloxacin as the standard drug, and 3h derivative bearing 3-fluoro group had the same effect as ciprofloxacin against Gram-negative bacteria (P. aeruginosa and E. coli). Based on molecular dynamic simulations, compound 3n exhibited pronounced interactions with the critical residues of the urease active site and mobile flap pocket so that the quinolone ring coordinated toward the metal bi-nickel center and the essential residues at the flap site like His593, His594, and Arg609. These interactions caused blocking the active site and stabilized the movement of the mobile flap at the entrance of the active site channel, which significantly reduced the catalytic activity of urease. Noteworthy, 3n also exhibited IC₅₀ values of 5.59 ± 2.38 and 5.72 ± 1.312 µg/ml to inhibit urease enzyme against C. neoformans and P. vulgaris in the ureolytic assay.

Synthesis, 99mTc-labeling, in-vivo study and in-silico investigation of 6-amino-5-[(bis-(2-hydroxy-ethyl)-amino]methyl]2-methyl pyrimidin-4-ol as a potential probe for tumor targeting

This study aimed to synthesize a new pyrimidine derivative with a good synthesis yield of 87% to act as a new cancer marker after radiolabeling with Tc-99m in a high radiochemical yield of 92.3%. In-vivo study in tumor-bearing Swiss albino mice model revealed promising data with high uptake in cancer. Docking study showed good binding interactions of the radiosynthesized complex at the binding site. In conclusion, this novel complex could be a potential probe for cancer targeting.

Optimization, purification, and structure elucidation of Anthraquinone pigment derivative from Talaromyces purpureogenus as a novel promising antioxidant, anticancer, and kidney radio-imaging agentAnthraquinone pigment as a promising antioxidant, anticancer, and radio-imaging agent

This study aims to investigate the bioproduction and prospective biological applications of a natural red pigment from Talaromyces purpureogenus AUMC2603. Maximum pigment yield was achieved by a numerical optimization at pH 6, temperature 25°C, and an 18-day incubation period on Yeast Malt Broth (YMB) media. The crude pigment was separated and purified into two pigment fractions via solid-phase extraction and then characterized as anthraquinone (dominant) and herquinone by LC/MS and ¹HNMR analysis. The crude pigment extract and the two separated fractions displayed a potential antioxidant activity. Additionally, they showed a powerful anticancer activity towards cancer cell lines, MCF-7, HepG-2, and HCT116 with less cytotoxicity on normal cell lines, MCF12F and BJ-1T. The radioiodination efficiency of the radiosynthesized ^99mTc-anthraquinone pigment complex was also investigated and optimized, obtaining a radiochemical yield of 92.70% ± 0.89%. An in vivo biodistribution study of the ^99mTc-anthraquinone pigment complex demonstrated a high kidney uptake of 34% injected dose per gram of organ tissue 60min after intravenous injection, and the complex retention remained high up to 120min. The current study is the first bioassay report on the efficacy of a purified anthraquinone from T. purpureogenus as a potent agent for kidney radio-imaging that could be applied in kidney cancer diagnosis.

Novel benzimidazole derivatives; synthesis, bioactivity and molecular docking study as potent urease inhibitors

BACKGROUND

Benzimidazole derivatives are widely used to design and synthesize novel bioactive compounds. There are several approved benzimidazole-based drugs on the market.

OBJECTIVES

In this study, we aimed to design and synthesize a series of novel benzimidazole derivatives 8a-n that are urease inhibitors.

METHODS

All 8a-n were synthesized in a multistep. To determine the urease inhibitory effect of 8a-n, the urease inhibition kit was used. The cytotoxicity assay of 8a-n was determined using MTT method. Molecular modelling was determined using autodock software.

RESULTS

All 8a-n were synthesized in high yield, and their structures were determined using 1H-NMR, 13C-NMR, MS, and elemental analyses. In compared to thiourea and hydroxyurea as standards (IC50: 22 and 100 µM, respectively), all 8a-n had stronger urease inhibition activity (IC50: 3.36-10.81 µM). With an IC50 value of 3.36 µM, 8e had the best enzyme inhibitory activity. On two evaluated cell lines, the MTT cytotoxicity experiment revealed that all 8a-n have IC50 values greater than 50 µM. Finally, a docking investigation revealed a plausible way of interaction between the 8e and 8d and the enzyme's active site's key residues.

CONCLUSION

The synthesized benzimidazole derivatives exhibit high activity, suggesting that further research on this family of compounds would be beneficial to finding a potent urease inhibitor.

Histopathology, pharmacokinetics and estimation of interleukin-6 levels of Moringa oleifera leaves extract-functionalized selenium nanoparticles against rats induced hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most dangerous cancers in all the world. This study focused on prevention and therapy of hepatocellular carcinoma (HCC) using Moringa oleifera extract combined with vitamin C and selenium in a nanoplatform (MO/asc.-Se-NPs).

Results

Full characterization of MO/asc.-Se-NPs was performed by using different analytical techniques (TEM, DLS, zeta-sizer), and its antioxidant capacity was measured by DPPH assay. Biodistribution study was performed with the aid of radiolabeling technique using technetium-99m in normal albino mice. HCC was induced in Wister albino rats to evaluate the efficiency of MO/asc.-Se-NPs in the treatment of HCC. The biomarker analysis (ALT, AST and ALB) shows improvement in its values in prevention and treated groups by using MO/asc.-Se NP. The levels of inflammatory marker interleukin 6 (IL6 tissue homogenate) was improved by decreasing its values in these two groups also. Histology section of tissue liver showed alleviation in treated and prevention groups.

Conclusions

In conclusion, MO/asc.-Se-NPs can be used as a potential agent for prevention and treatment of HCC after further preclinical studies.

Conventional and microwave-assisted synthesis, anticancer evaluation, 99mTc-coupling and In-vivo study of some novel pyrazolone derivatives

New pyrazolone derivatives were successfully synthesized by both microwave-assisted and conventional techniques. Compound 3 (3-(3-Methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)-3-oxopropanehydrazide) displayed remarkable anti-cancer activity (IC₅₀ obtained at 8.71 and 10.63 µM for HCT-116 and MCF-7, respectively. Moreover, biodistribution study using radiolabeling approach revealed a remarked uptake of [^99mTc]Tc-compound 3 complex into tumour induced in mice. The biodistribution showed high accumulation in tumour tissues with T/NT of 6.92 after 60 min post injection. As a result of these promising data, the newly synthesized compounds especially compound 3 affords a potential radio-carrier that could be used as a tumour marker and can be used for cancer therapy after further preclinical studies.

Design and synthesis of novel nitrothiazolacetamide conjugated to different thioquinazolinone derivatives as anti-urease agents

The present article describes the design, synthesis, in vitro urease inhibition, and in silico molecular docking studies of a novel series of nitrothiazolacetamide conjugated to different thioquinazolinones. Fourteen nitrothiazolacetamide bearing thioquinazolinones derivatives (8a-n) were synthesized through the reaction of isatoic anhydride with different amine, followed by reaction with carbon disulfide and KOH in ethanol. The intermediates were then converted into final products by treating them with 2-chloro-N-(5-nitrothiazol-2-yl)acetamide in DMF. All derivatives were then characterized through different spectroscopic techniques (1H, 13C-NMR, MS, and FTIR). In vitro screening of these molecules against urease demonstrated the potent urease inhibitory potential of derivatives with IC50 values ranging between 2.22 ± 0.09 and 8.43 ± 0.61 μM when compared with the standard thiourea (IC50 = 22.50 ± 0.44 μM). Compound 8h as the most potent derivative exhibited an uncompetitive inhibition pattern against urease in the kinetic study. The high anti-ureolytic activity of 8h was confirmed against two urease-positive microorganisms. According to molecular docking study, 8h exhibited several hydrophobic interactions with Lys10, Leu11, Met44, Ala47, Ala85, Phe87, and Pro88 residues plus two hydrogen bound interactions with Thr86. According to the in silico assessment, the ADME-Toxicity and drug-likeness profile of synthesized compounds were in the acceptable range.

Hepatoprotective, antioxidant and anti-inflammatory potentials of Vit-E/C@SeNPs in rats: Synthesis, characterization, biochemical, radio-biodistribution, molecular and histopathological studies

This study aimed to synthesize a nano-structure between selenium, Vit. C, and Vit. E (Vit-E/C@SeNPs) as a promising protective and therapeutic agent for hepatocellular carcinoma. Vit-E/C@SeNPs were characterized using TEM and DLS and its zetapotential was measured to evaluate its stability. DPPH assay and SRB test were performed to estimate its antioxidant capacity and cytotoxicity, respectively. A radiosynthesis of ^99mTc-Vit-E/C@SeNPs was done for further in-vivo pharmacokinetic studies on normal and solid tumor induced mice. Further, in-vivo studies were conducted to investigate Vit-E/C@SeNPs efficacy against hepatocellular damage in Wistar albino rats induced by diethylnitrosamine (DEN) / Carbon Tetra chloride (CCl₄). The synthesis results showed spherical Vit-E/C@SeNPs with core size of 50 nm, radical scavenging activity (%RSC) of 75.9%, and IC₅₀ of 27.9 µg/ml. The biochemical analysis results showed that the lower liver function biomarker values (ALT, AST, ALP, total bilirubin and GGT) has gone for the Vit-E/C@SeNPs prevention and treated group, which also showed significant depletion of liver tissue l-MDA, and obvious increase in GSH concentration and CAT activity and marked improvement in the histological feature of liver tissue. Additionally, a significant up-regulation of mRNA gene expression levels of inflammatory gene (TGFβ1, NFκB, iNOS, PPAR-γ and TNFα) and Apoptotic gene (P53) were determined by using Quantitative real-time PCR (qPCR). The values down regulate and tend to normal in prevention and control group. All of these introduce Vit-E/C@SeNPs as a promising agent as protective and therapeutic agent against DEN/ CCl₄-induced hepatocellular damage (Hepatocellular carcinoma).

Isolation and Characterization of Antibacterial Carotane Sesquiterpenes from Artemisia argyi Associated Endophytic Trichoderma virens QA-8

Carotane sesquiterpenes are commonly found in plants but are infrequently reported in the fungal kingdom. Chemical investigation of Trichoderma virens QA-8, an endophytic fungus associated with the inner root tissue of the grown medicinal herb Artemisia argyi H. Lév. and Vaniot, resulted in the isolation and characterization of five new carotane sesquiterpenes trichocarotins I-M (1-5), which have diverse substitution patterns, and seven known related analogues (6-12). The structures of these compounds were established on the basis of a detailed interpretation of their NMR and mass spectroscopic data, and the structures including the relative and absolute configurations of compounds 1-3, 5, 9, and 10 were confirmed by X-ray crystallographic analysis. In the antibacterial assays, all isolates exhibited potent activity against Escherichia coli EMBLC-1, with MIC values ranging from 0.5 to 32 µg/mL, while 7β-hydroxy CAF-603 (7) strongly inhibited Micrococcus luteus QDIO-3 (MIC = 0.5 µg/mL). Structure-activity relationships of these compounds were discussed. The results from this study demonstrate that the endophytic fungus T. virens QA-8 from the planted medicinal herb A. argyi is a rich source of antibacterial carotane sesquiterpenes, and some of them might be interesting for further study to be developed as novel antibacterial agents.

New quinoxaline compounds as DPP-4 inhibitors and hypoglycemics: design, synthesis, computational and bio-distribution studies

The current work represents the design and synthetic approaches of a new set of compounds 6–10 bearing the 1,4-dimethyl-2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonamide scaffold. The biological evaluation revealed that most of the new compounds were promising selective dipeptidyl peptidase-IV (DPP-4) inhibitors and in vivo hypoglycemic agents utilizing linagliptin as a standard drug. The acute toxicity examination confirmed the safety profile of all compounds. Molecular docking studies related the significant DPP-4 suppression activity of compounds 9a, 10a, 10f, 10g to their nice fitting in the active pocket of DPP-4. In addition, the molecular dynamic study exhibited the stability of both 10a and 10g within the active site of DPP-4. The QSAR study showed that the difference between the predicted activities is very close to the experimental suppression effect. Moreover, both compounds 10a and 10g obeyed Lipinski's rule, indicating their efficient oral bioavailability. Compound 10a was radiolabeled, forming the ¹³¹I-SQ compound 10a to study the pharmacokinetic profile of this set of compounds. The biodistribution pattern hit the target protein since the tracer accumulated mainly in the visceral organs where DPP-4 is secreted in a high-level, thus with consequent stimulation of insulin secretion, leading to the target hypoglycemic effect.

The current work represents the design and synthetic approaches of a new set of compounds 6–10 bearing the 1,4-dimethyl-2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonamide scaffold.