Synthesis of oxadiazole-coupled-thiadiazole derivatives as a potent β-glucuronidase inhibitors and their molecular docking study

Anion-Driven C-F Bond Activation of Trifluoromethyl N-Aryl Hydrazones: Application to the Synthesis of 1,3,4-Oxadiazoles

The CF3 group attached to N-aryl hydrazone could be activated upon treatment with a suitable base, thus serving as an excellent C1 unit for the assembly of a series of 1,3,4-oxadiazoles by reaction with hydrazides. The transformation is proposed to proceed via the intermediate formation of a gem-difluorinated azoalkene. Furthermore, this reaction features simple conditions and a broad substrate scope with respect to both trifluoromethyl N-aryl hydrazones and hydrazides.

Design and synthesis of thiadiazole-oxadiazole-acetamide derivatives: Elastase inhibition, cytotoxicity, kinetic mechanism, and computational studies

Considering the biological significance of 1,3,4-thiadiazole/oxadiazole heterocyclic scaffolds, a novel series of 1,3,4-thiadiazole-1,3,4-oxadiazole-acetamide derivatives (7a-j) was designed and synthesized using molecular hybridization. The inhibitory effects of the target compounds on elastase were evaluated, and all of these molecules were found to be potent inhibitors compared to the standard reference oleanolic acid. Compound 7f exhibited the excellent inhibitory activity (IC₅₀ = 0.06 ± 0.02 μM), which is 214-fold more active than oleanolic acid (IC₅₀ = 12.84 ± 0.45 μM). Kinetic analysis was also performed on the most potent compound (7f) to determine the mode of binding with the target enzyme, and it was discovered that 7f inhibits the enzyme in a competitive manner. Furthermore, the MTT assay method was used to assess their toxicity on the viability of B16F10 melanoma cell lines, and all compounds did not display any toxic effect on the cells even at high concentrations. The molecular docking studies of all compounds also justified with their good docking score and among them, compound 7f had a good conformational state with hydrogen bond interactions within the receptor binding pocket, which is consistent with the experimental inhibition studies.

Synthesis, Characterization, Cytotoxicity Analysis and Evaluation of Novel Heterocyclic Derivatives of Benzamidine against Periodontal Disease Triggering Bacteria

Periodontal disease (PD) is multifactorial oral disease that damages tooth-supporting tissue. PD treatment includes proper oral hygiene, deep cleaning, antibiotics therapy, and surgery. Despite the availability of basic treatments, some of these are rendered undesirable in PD treatment due to side effects and expense. Therefore, the aim of the present study is to develop novel molecules to combat the PD triggering pathogens. The study involved the synthesis of 4-((5-(substituted-phenyl)-1,3,4-oxadiazol-2-yl)methoxy)benzamidine (5a-e), by condensation of 2-(4-carbamimidoylphenoxy)acetohydrazide (3) with different aromatic acids; and synthesis of 4-((4-(substituted benzylideneamino)-4H-1,2,4-triazol-3-yl)methoxy)benzamidine (6a-b) by treatment of compound 3 with CS₂ followed by hydrazination and a Schiff reaction with different aromatic aldehydes. Synthesized compounds were characterized based on the NMR, FTIR, and mass spectrometric data. To assess the effectiveness of the newly synthesized compound in PD, new compounds were subjected to antimicrobial evaluation against P. gingivalis and E. coli using the micro-broth dilution method. Synthesized compounds were also subjected to cytotoxicity evaluation against HEK-293 cells using an MTT assay. The present study revealed the successful synthesis of heterocyclic derivatives of benzamidine with significant inhibitory potential against P. gingivalis and E. coli. Synthesized compounds exhibited minimal to the absence of cytotoxicity. Significant antimicrobial potential and least/no cytotoxicity of new heterocyclic analogs of benzamidine against PD-triggering bacteria supports their potential application in PD treatment.

Discovery of a series of 5-phenyl-2-furan derivatives containing 1,3-thiazole moiety as potent Escherichia coli β-glucuronidase inhibitors

Gut microbial β-glucuronidases have drawn much attention due to their role as a potential therapeutic target to alleviate some drugs or their metabolites-induced gastrointestinal toxicity. In this study, fifteen 5-phenyl-2-furan derivatives containing 1,3-thiazole moiety (1-15) were synthesized and evaluated for their inhibitory effects against Escherichia coli β-glucuronidase (EcGUS). Twelve of them showed satisfactory inhibition against EcGUS with IC₅₀ values ranging from 0.25 μM to 2.13 μM with compound 12 exhibited the best inhibition. Inhibition kinetics studies indicated that compound 12 (K_i = 0.14 ± 0.01 μM) was an uncompetitive inhibitor for EcGUS and molecular docking simulation further predicted the binding model and capability of compound 12 with EcGUS. A preliminary structure-inhibitory activity relationship study revealed that the heterocyclic backbone and bromine substitution of benzene may be essential for inhibition against EcGUS. The compounds have the potential to be applied in drug-induced gastrointestinal toxicity and the findings would help researchers to design and develop more effective 5-phenyl-2-furan type EcGUS inhibitors.

Thiazolidin-2-cyanamides derivatives as novel potent Escherichia coli β-glucuronidase inhibitors and their structure-inhibitory activity relationships

Gut microbial β-glucuronidases have the ability to deconjugate glucuronides of some drugs, thus have been considered as an important drug target to alleviate the drug metabolites-induced gastrointestinal toxicity. In this study, thiazolidin-2-cyanamide derivatives containing 5-phenyl-2-furan moiety (1–13) were evaluated for inhibitory activity against Escherichia coli β-glucuronidase (EcGUS). All of them showed more potent inhibition than a commonly used positive control, d-saccharic acid 1,4-lactone, with the IC₅₀ values ranging from 1.2 µM to 23.1 µM. Inhibition kinetics studies indicated that compound 1–3 were competitive type inhibitors for EcGUS. Molecular docking studies were performed and predicted the potential molecular determinants for their potent inhibitory effects towards EcGUS. Structure–inhibitory activity relationship study revealed that chloro substitution on the phenyl moiety was essential for EcGUS inhibition, which would help researchers to design and develop more effective thiazolidin-2-cyanamide type inhibitors against EcGUS.

Inhibition Properties of Arylsulfatase and β-Glucuronidase by Hydrogen Peroxide, Hypochlorite, and Peracetic Acid

Arylsulfatase and β-glucuronidase are two important enzymes in humans, which play an important role in the dynamic equilibrium of steroidal estrogens. This work probably for the first time reported that hydrogen peroxide (H₂O₂), hypochlorite, and peracetic acid (PAA) could effectively inhibit the activities of arylsulfatase and/or β-glucuronidase. The 50% of inhibitions (IC₅₀) of H₂O₂, hypochlorite, and PAA on arylsulfatase were found to be 142.90 ± 9.00, 91.83 ± 10.01, and 43.46 ± 2.92 μM, respectively. The corresponding IC₅₀ values of hypochlorite and PAA on β-glucuronidase were 704.90 ± 41.40 and 23.26 ± 0.82 μM, whereas H₂O₂ showed no inhibition on β-glucuronidase. The inhibitions of arylsulfatase and/or β-glucuronidase by these three chemicals were pH-dependent. It was further revealed that the inhibitions of hypochlorite on both arylsulfatase and β-glucuronidase were irreversible. On the contrary, the inhibitions by H₂O₂ and PAA were reversible. In addition, the inhibition by H₂O₂ was competitive and that by PAA was noncompetitive. In general, H₂O₂ and hypochlorite can be endogenously produced in humans, which suggested that the two compounds are potential endocrine disruption compounds (EDCs) as they can cause endocrine disruption via the inhibition of arylsulfatase and β-glucuronidase. This work further indicated that any agent that can induce the production of H₂O₂ or hypochlorite in humans is a potential EDC, which explains why some EDCs with very weak or no estrogenic potency can cause endocrine disruption, which is confirmed in epidemiological studies.

2,5-Disubstituted furan derivatives containing 1,3,4-thiadiazole moiety as potent α-glucosidase and E. coli β-glucuronidase inhibitors

In this paper, the 2,5-disubstituted furan derivatives containing 1,3,4-thiadiazole were synthesized and screened for their inhibitory activity against α-glucosidase and β-glucuronidases to obtain potent α-glucosidase inhibitor 9 (IC₅₀ = 0.186 μM) and E. coli β-glucuronidase inhibitor 26 (IC₅₀ = 0.082 μM), respectively. The mechanisms of the compounds were studied. The kinetic study revealed that compound 9 is a competitive inhibitor against α-glucosidase (Ki = 0.05 ± 0.003 μM) and molecular docking simulation showed several key interactions between 9 and the target including hydrogen bond and p-π stacking interaction. Derivative 26 (Ki = 0.06 ± 0.005 μM) displayed uncompetitive inhibition behavior against EcGUS. Furthermore, the result of docking revealed the furan ring of 26 may be a key moiety in obstructing the active domain of EcGUS. In addition, compound 15 exhibited significant inhibitory activity against these two enzymes, with potential therapeutic effects against diabetes and against CPT-11-induced diarrhea. At the same time, their low toxicity against normal liver tissue LO2 cells lays the foundation for in vivo studies and the development of bifunctional drug.

Synthetic approaches to unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles and their MAO-B inhibitory activity. A review

Selective monoamine oxidase type B (MAO-B) inhibitors are currently used as coadjuvants for treating early motor symptoms of Parkinson's disease. Aiming at the elucidation of MAO-B inhibitors with 1,3,4-oxadiazole scaffolds, we make a comprehensive update on the new and old chemical methods employed for the synthesis of the unsymmetrical oxadiazole derivatives that lead to high yield compounds. We summarize a state of the selective MAO-B inhibitors with oxadiazole scaffold, describing the results, structures, structure-activity relationships (SARs) and medicinal chemistry strategies over the years. The analysis of the recent papers would facilitate tracking the increasing number of oxadiazole derivatives as new chemical spaces with MAO-B inhibitory potential designed to ensure the safe use of the compounds and elimination of the unwanted drug-drug interactions.

One-pot synthesis of thioxo-tetrahydropyrimidine derivatives as potent β-glucuronidase inhibitor, biological evaluation, molecular docking and molecular dynamics studies

A series of N,N-diethyl phenyl thioxo-tetrahydropyrimidine carboxamide have been synthesized and investigated for their β-glucuronidase inhibitory activities. All molecules exhibited excellent inhibition with IC₅₀ values ranging from 0.35 to 42.05 µM and found to be even more potent than the standard d-saccharic acid. Structure-activity relationship analysis indicated that the meta-aryl-substituted derivatives significantly influenced β-glucuronidase inhibitory activities while the para-substitution counterpart outperforming moderate potency. The most potent compound in this series was 4g bearing thiophene motif with IC₅₀ of 0.35 ± 0.09 µM. To verify the SAR, molecular docking and molecular dynamics studies were also performed.

Therapeutic significance of β-glucuronidase activity and its inhibitors: A review

The emergence of disease and dearth of effective pharmacological agents on most therapeutic fronts, constitutes a major threat to global public health and man's existence. Consequently, this has created an exigency in the search for new drugs with improved clinical utility or means of potentiating available ones. To this end, accumulating empirical evidence supports molecular target therapy as a plausible egress and, β-glucuronidase (βGLU) - a lysosomal acid hydrolase responsible for the catalytic deconjugation of β-d-glucuronides has emerged as a viable molecular target for several therapeutic applications. The enzyme's activity level in body fluids is also deemed a potential biomarker for the diagnosis of some pathological conditions. Moreover, due to its role in colon carcinogenesis and certain drug-induced dose-limiting toxicities, the development of potent inhibitors of βGLU in human intestinal microbiota has aroused increased attention over the years. Nevertheless, although our literature survey revealed both natural products and synthetic scaffolds as potential inhibitors of the enzyme, only few of these have found clinical utility, albeit with moderate to poor pharmacokinetic profile. Hence, in this review we present a compendium of exploits in the present millennium directed towards the inhibition of βGLU. The aim is to proffer a platform on which new scaffolds can be modelled for improved βGLU inhibitory potency and the development of new therapeutic agents in consequential.