Synthesis, molecular modeling and biological evaluation of 2-aminomethyl-5-(quinolin-2-yl)-1,3,4-oxadiazole-2(3H)-thione quinolone derivatives as novel anticancer agent

Design, synthesis, computational molecular docking studies of novel heterocyclics bearing 1,2,4-triazole, 1,3,4-oxadiazole conjugates as potent antibacterial and antitubercular agents

Herein, we report the synthesis, and characterization of a new series of 1,3,4-oxadiazole and 1,2,4-triazole derivatives based on azaindole acetamides and assigned as potential antibacterial and antitubercular substances. The structures of these compounds were established by 1H NMR, 13C NMR, and HRMS spectral analysis. In preliminary antibacterial studies, analogues 6b, 6d, and 6e were found to be most effective against S. aureus with MIC of 12.5, 6.25, and 12.5 μg/mL, whereas 8d displayed excellent activity against S. aureus, B. subtilis, E. coli bacterial strains with zones of inhibition 12.5, 25, and 12.5 μg/mL respectively. Particularly, the prepared scaffolds 8c, 8d, and 8e showed remarkable antifungal activity with MIC value 12.5, 12.5, and 6.25 μg/mL against A. flavus and 6d, 6c producing an increase in the activity against C. Albicans with zones of inhibition 12.5 and 12.5 μg/mL respectively. Also, through the antitubercular studies, we found that compounds 6e and 8b have a strong activity with M. tuberculosis H37Rv with MICs 3.26, and 6.48 μg/mL, respectively. The protein stability, fluctuations of APO-Protein, and protein-ligand complexes were investigated through Molecular Dynamics (MD) simulations studies using Desmond Maestro 11.3, and potential lead molecules were identified. Our findings were further confirmed using molecular docking, revealing that azaindole based ligand 6e, 6f, and 8a has strong hydrophobic Tyr179, Trp183, Ile177, Ile445, and H-bondings interactions Arg151 and Arg454 through molecular dynamics simulation studies, making it potential biological compound. These compounds were further evaluated for their ADMET and physicochemical properties by using SwissADME.Communicated by Ramaswamy H. Sarma.

A combined crystallographic and theoretical investigation of noncovalent interactions in 1,3,4-oxadiazole-2-thione-N-Mannich derivatives: in vitro bioactivity and molecular docking

Two 1,3,4-oxadiazole-2-thione-N-Mannich derivatives, specifically 5-(4-chlorophenyl)-3-[(2-trifluoromethylphenylamino)methyl]-1,3,4-oxadiazole-2(3H)-thione (1) and 5-(4-chlorophenyl)-3-[(2,5-difluorophenylamino)methyl]-1,3,4-oxadiazole-2(3H)-thione (2), were synthesized and then characterized by elemental analysis and NMR (1H and 13C) spectroscopy and the single crystal X-ray diffraction method. The formed weak intermolecular interactions in the solid-state structures of these derivatives were thoroughly investigated utilizing a variety of theoretical tools such as Hirshfeld surface analysis and quantum theory of atoms in molecules (QTAIM). Furthermore, the CLP-PIXEL and density functional theory calculations were used to study the energetics of molecular dimers. Numerous weak intermolecular interactions such as C-H⋯S/Cl/F/π interactions, a directional C-Cl⋯Cl halogen bond, π-stacking, type C-F⋯F-C contact and a short F⋯O interaction, help to stabilize the crystal structure of 1. Crystal structure 2 also stabilizes with several weak intermolecular contacts, including N-H⋯S, C-H⋯N//Cl/F interactions, a highly directional C1-Cl1⋯C(π) halogen bond and C(π)⋯C(π) interaction. In vitro antimicrobial potency of compounds 1 and 2 was assessed against various Gram-positive and Gram-negative bacterial strains and the pathogenic yeast-like Candida albicans. Both compounds showed marked activity against all tested Gram-positive bacteria and weak activity against Escherichia coli and lacked inhibitory activity against Pseudomonas aeruginosa. In addition, compounds 1 and 2 displayed good in vitro anti-proliferative activity against hepatocellular carcinoma (HepG-2) and mammary gland breast cancer (MCF-7) cancer cell lines. Molecular docking studies revealed the binding modes of title compounds at the active sites of prospective therapeutic targets.

Pyrazole-promoted synthesis of pyrrolo[3,4-c] quinoline-1,3-diones in a novel diketene-based reaction

We describe the first classic example of green synthesis of pyrrolo[3,4-c]quinolones scaffolds by catalyst-free unusual reaction of diketene, isatin, and primary amines in ethanol in the presence of pyrazole as a promoter for 4 h. The whole structure of the new product was confirmed by X-ray analysis. The overall transformation involves the cleavage and generation of multiple carbon-nitrogen and carbon-carbon bonds. This report represents a simple and straightforward approach for the synthesis of pyrrolo[3,4-c]quinoline-1,3-diones, which has significant advantages like readily available precursors, non-use of toxic solvent, operational simplicity, mild conditions, good atom economy, and excellent yields; therefore it provides a green and sustainable strategy for access to a range of interesting N-containing heterocyclic compounds in medicinal and organic chemistry.

Application of Quinoline Ring in Structural Modification of Natural Products

Natural compounds are rich in pharmacological properties that are a hot topic in pharmaceutical research. The quinoline ring plays important roles in many biological processes in heterocycles. Many pharmacological compounds, including saquinavir and chloroquine, have been marketed as quinoline molecules with good anti-viral and anti-parasitic properties. Therefore, in this review, we summarize the medicinal chemistry of quinoline-modified natural product quinoline derivatives that were developed by several research teams in the past 10 years and find that these compounds have inhibitory effects on bacteria, viruses, parasites, inflammation, cancer, Alzheimer's disease, and others.

RNAseq Analysis of Novel 1,3,4-Oxadiazole Chalcogen Analogues Reveals Anti-Tubulin Properties on Cancer Cell Lines

1,3,4-Oxadiazole derivatives are among the most studied anticancer drugs. Previous studies have analyzed the action of different 1,3,4-oxadiazole derivatives and their effects on cancer cells. This study investigated the characterization of two new compounds named 6 and 14 on HeLa and PC-3 cancer cell lines. Based on the previously obtained IC₅₀, cell cycle effects were monitored by flow cytometry. RNA sequencing (RNAseq) was performed to identify differentially expressed genes, followed by functional annotation using gene ontology (GO), KEGG signaling pathway enrichment, and protein-protein interaction (PPI) network analyses. The tubulin polymerization assay was used to analyze the interaction of both compounds with tubulin. The results showed that 6 and 14 strongly inhibited the proliferation of cancer cells by arresting them in the G2/M phase of the cell cycle. Transcriptome analysis showed that exposure of HeLa and PC-3 cells to the compounds caused a marked reprograming of gene expression. Functional enrichment analysis indicated that differentially expressed genes were significantly enriched throughout the cell cycle and cancer-related biological processes. Furthermore, PPI network, hub gene, and CMap analyses revealed that compounds 14 and 6 shared target genes with established microtubule inhibitors, indicating points of similarity between the two molecules and microtubule inhibitors in terms of the mechanism of action. They were also able to influence the polymerization process of tubulin, suggesting the potential of these new compounds to be used as efficient chemotherapeutic agents.

Telomerase: A prominent oncological target for development of chemotherapeutic agents

Telomerase is a ribonucleoprotein (RNP) responsible for the maintenance of chromosomal integrity by stabilizing telomere length. Telomerase is a widely expressed hallmark responsible for replicative immortality in 80-90% of malignant tumors. Cancer cells produce telomerase which prevents telomere shortening by adding telomeres sequences beyond Hayflick's limit; which enables them to divide uncontrollably. The activity of telomerase is relatively low in somatic cells and absent in normal cells, but the re-activation of this RNP in normal cells suppresses p53 activity which leads to the avoidance of senescence causing malignancy. Here, we have focused explicitly on various anti-telomerase therapies and telomerase-inhibiting molecules for the treatment of cancer. We have covered molecules that are reported in developmental, preclinical, and clinical trial stages as potent telomerase inhibitors. Apart from chemotherapy, we have also included details of immunotherapy, gene therapy, G-quadruplex stabilizers, and HSP-90 inhibitors. The purpose of this work is to discuss the challenges behind the development of novel telomerase inhibitors and to identify various perspectives for designing anti-telomerase compounds.

An Understanding of Mechanism-Based Approaches for 1,3,4-Oxadiazole Scaffolds as Cytotoxic Agents and Enzyme Inhibitors

The world's health system is plagued by cancer and a worldwide effort is underway to find new drugs to treat cancer. There has been a significant improvement in understanding the pathogenesis of cancer, but it remains one of the leading causes of death. The imperative 1,3,4-oxadiazole scaffold possesses a wide variety of biological activities, particularly for cancer treatment. In the development of novel 1,3,4-oxadiazole-based drugs, structural modifications are important to ensure high cytotoxicity towards malignant cells. These structural modification strategies have shown promising results when combined with outstanding oxadiazole scaffolds, which selectively interact with nucleic acids, enzymes, and globular proteins. A variety of mechanisms, such as the inhibition of growth factors, enzymes, and kinases, contribute to their antiproliferative effects. The activity of different 1,3,4-oxadiazole conjugates were tested on the different cell lines of different types of cancer. It is demonstrated that 1,3,4-oxadiazole hybridization with other anticancer pharmacophores have different mechanisms of action by targeting various enzymes (thymidylate synthase, HDAC, topoisomerase II, telomerase, thymidine phosphorylase) and many of the proteins that contribute to cancer cell proliferation. The focus of this review is to highlight the anticancer potential, molecular docking, and SAR studies of 1,3,4-oxadiazole derivatives by inhibiting specific cancer biological targets, such as inhibiting telomerase activity, HDAC, thymidylate synthase, and the thymidine phosphorylase enzyme. The purpose of this review is to summarize recent developments and discoveries in the field of anticancer drugs using 1,3,4-oxadiazoles.

Synthesis, Anticancer Activity and Molecular Docking Studies of Novel N-Mannich Bases of 1,3,4-Oxadiazole Based on 4,6-Dimethylpyridine Scaffold

Cancer is one of the greatest challenges in modern medicine today. Difficult and long-term treatment, the many side effects of the drugs used and the growing resistance to treatment of neoplastic cells necessitate new approaches to therapy. A very promising targeted therapy is based on direct impact only on cancer cells. As a continuation of our research on new biologically active molecules, we report herein the design, synthesis and anticancer evaluation of a new series of N-Mannich-base-type hybrid compounds containing morfoline or different substituted piperazines moieties, a 1,3,4-oxadiazole ring and a 4,6-dimethylpyridine core. All compounds were tested for their potential cytotoxicity against five human cancer cell lines, A375, C32, SNB-19, MCF-7/WT and MCF-7/DX. Two of the active N-Mannich bases (compounds 5 and 6) were further evaluated for growth inhibition effects in melanoma (A375 and C32), and normal (HaCaT) cell lines using clonogenic assay and a population doubling time test. The apoptosis was determined with the neutral version of comet assay. The confocal microscopy method enabled the visualization of F-actin reorganization. The obtained results demonstrated that compounds 5 and 6 have cytotoxic and proapoptotic effects on melanoma cells and are capable of inducing F-actin depolarization in a dose-dependent manner. Moreover, computational chemistry approaches, molecular docking and electrostatic potential were employed to study non-covalent interactions of the investigated compounds with four receptors. It was found that all the examined molecules exhibit a similar binding affinity with respect to the chosen reference drugs.

In Silico Design, Synthesis, and Biological Evaluation of Anticancer Arylsulfonamide Endowed with Anti-Telomerase Activity

Telomerase, a reverse transcriptase enzyme involved in DNA synthesis, has a tangible role in tumor progression. Several studies have evidenced telomerase as a promising target for developing cancer therapeutics. The main reason is due to the overexpression of telomerase in cancer cells (85–90%) compared with normal cells where it is almost unexpressed. In this paper, we used a structure-based approach to design potential inhibitors of the telomerase active site. The MYSHAPE (Molecular dYnamics SHared PharmacophorE) approach and docking were used to screen an in-house library of 126 arylsulfonamide derivatives. Promising compounds were synthesized using classical and green methods. Compound 2C revealed an interesting IC₅₀ (33 ± 4 µM) against the K-562 cell line compared with the known telomerase inhibitor BIBR1532 IC₅₀ (208 ± 11 µM) with an SI ~10 compared to the BALB/3-T3 cell line. A 100 ns MD simulation of 2C in the telomerase active site evidenced Phe494 as the key residue as well as in BIBR1532. Each moiety of compound 2C was involved in key interactions with some residues of the active site: Arg557, Ile550, and Gly553. Compound 2C, as an arylsulfonamide derivative, is an interesting hit compound that deserves further investigation in terms of optimization of its structure to obtain more active telomerase inhibitors

Synthesis and cytotoxic activity evaluation of some new 1, 3, 4-oxadiazole, 1, 3, 4-thiadiazole and 1, 2, 4- triazole derivatives attached to phthalimide

Background and purpose

In the last few decades, nitrogen-rich heterocyclic compounds such as 1, 3, 4-thiadiazoles, 1, 2, 4-triazoles and 1, 3, 4-oxadiazoles have received considerable attention because of their notable biological properties, especially cytotoxic effects. The small molecules of mentioned azole derivatives revealed very intensive antitumor activity. In addition, phthalimide-thiadiazole and naphthalimide-triazole hybrid derivatives have shown remarkable cytotoxic effects. According to these observations, some of the hybrid derivatives containing the phthalimide-five-membered azoles were prepared in three steps in this research.

Experimental approach

The thiol group of azoles was treated with ethyl chloroacetate which was followed by a reaction with hydrazine hydrate to provide acid hydrazide derivatives. Subsequently, the corresponding acid hydrazides were utilized to prepare the final derivatives through the reaction with phthalic anhydride. Cytotoxic activity of final compounds was evaluated against MCF-7 and HeLa cell lines using MTT assay.

Findings/Results

Compound 3d containing two phthalimide moieties in its structure showed a significant improvement in cytotoxic activity with an IC₅₀ value of 29 μM against HeLa cell line. Compounds 3a-3c showed less cytotoxic effects against both cell lines.

Conclusion and implications

The combination of the thiadiazole nucleus with two phthalimide structures increased the cytotoxic activity against the HeLa cell line. This increase in cytotoxic activity is probably due to its being more lipophilic characteristic and interaction of this derivative with the biological targets of two directions.

A One-pot Synthesis of Novel Derivatives of Oxadiazine-4-thione, and its Antibacterial Activity, and Molecular Modeling Studies

BACKGROUND

The synthesis of a novel series of oxadiazine-4-thione biological molecules was executed through the incorporation of the ortho-, meta-, and para-benzoyl isocyanates to the tetrabromophthalimide nucleus.

OBJECTIVES

A one-pot multicomponent methodology in a solvent-free microwave irradiation environment was employed to afford this series of oxadiazine-4-thione, deriving a comparison with the conventional method. Subsequently, the yielded derivatives were subjected to further biological assessment.

MATERIALS AND METHODS

The acquired results denoted that the one-pot procedure, which delivered products in a 2-4 min. interval, was more efficient in evaluation against the classical method, which consumed a 1-2:30 hr. interval.

RESULTS

The application of the antibacterial analyses was subjected to all the compounds, resulting in molecules 6a and 6c demonstrating the highest activity regarding Aspergillus Favus; molecules 5b and 5c exhibiting an equivalent level of activity towards E-coli and Fusarium Moniliform; and molecules 4b, 4c, 5b, and 5c presenting an identical level of activity to the aforementioned derivatives involving Staphylococcus. Concluison: Molecular modeling studies by the MOE, the preceding antibacterial behavior was conducted to advocate the newly prepared compounds. Moreover, the spectroscopic approaches were exploited to verify and establish the structures and mechanisms of the synthesized derivatives' reactions.

1,3,4-Oxadiazole N-Mannich Bases: Synthesis, Antimicrobial, and Anti-Proliferative Activities

The reaction of 5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thione 3 with formaldehyde solution and primary aromatic amines or 1-substituted piperazines, in ethanol at room temperature yielded the corresponding N-Mannich bases 3-arylaminomethyl-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 4a–l or 3-[(4-substituted piperazin-1-yl)methyl]-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 5a–d, respectively. The in vitro inhibitory activity of compounds 4a–l and 5a–d was assessed against pathogenic Gram-positive, Gram-negative bacteria, and the yeast-like pathogenic fungus Candida albicans. The piperazinomethyl derivatives 5c and 5d displayed broad-spectrum antibacterial activities the minimal inhibitory concentration (MIC) 0.5–8 μg/mL) and compounds 4j, 4l, 5a, and 5b showed potent activity against the tested Gram-positive bacteria. In addition, the anti-proliferative activity of the compounds was evaluated against prostate cancer (PC3), human colorectal cancer (HCT-116), human hepatocellular carcinoma (HePG-2), human epithelioid carcinoma (HeLa), and human breast cancer (MCF7) cell lines. The optimum anti-proliferative activity was attained by compounds 4l, 5a, 5c, and 5d.

Synthesis, cytotoxic evaluation, and molecular docking studies of some new 1, 3, 4-oxadiazole-based compounds

Background and purpose

Oxadiazole-derived compounds have been shown to have a wide range of pharmacological activities. 2, 5-Disubstituted 1, 3, 4-oxadiazole derivatives have occupied a specific place in the design of anti-proliferative agents. In the present work a series of 2, 5-disubstituted 1, 3, 4-oxadiazoles derivatives containing amide group has been synthesized via a two-step reaction.

Experimental approach

A mixture of substituted carboxylic acid derivatives, semicarbazide, and phosphorus oxychloride in reflux condition yielded 2-amino-5-aryl-1, 3, 4-oxadiazole derivatives. Acylation of the amino group of the resultant oxadiazole with 6-chloronicotinoyl chloride in dry tetrahydrofuran/pyridine afforded the final products. The synthesized molecules were docked in the active sites of the epidermal growth factor receptor tyrosine kinase domain (PDB: 1M17) crystal structure to study the possible interactions with the active site. Cytotoxic activities of final products against HeLa and MCF-7 cells were also assessed by MTT assay.

Findings/Results

Compounds IIb, IIc, and IIe had a considerable cytotoxic activity with IC50 values of 19.9, 35, and 25.1 μM, respectively against HeLa cells. The highest docking score was -7.89 kcal/mol for compound IIe.

Conclusion and implications

Compound IIe exhibited remarkable cytotoxic activity against the two tested cell lines particularly HeLa cells which was in accordance with the in silico ΔG _bind result but further evaluations are necessary to prove these findings.

1,3,4-Oxadiazole Containing Compounds As Therapeutic Targets For Cancer Therapy

BACKGROUND

Cancer is the first or second leading cause of premature death in 134 of 183 countries in the world. 1,3,4-Oxadiazoles are five memebered heterocyclic rings containing two nitrogen (two atoms) and oxygen (one atom). They show better thermal stability, metabolic stability, aqueous solubility and lower lipophilicity than the other isomeric oxadiazoles. They are important class of heterocycles present in many drug structures like Raltegravir, Furamizole Tidazosin, Nesapidil, Setileuton (MK-0633) and Zibotentan. Presence of this nucleus in the therapeutics has made them an indispensable anchor for drug design and development. Several 1,3,4-oxadiazoles are prepared and reported as anticancer agents by numerous scientists worldwide.

OBJECTIVES

The present review discusses the anticancer potentials together with the molecular targets of 1,3,4-oxadiazoles reported since 2010. The structure activity relationship (SAR) and molecular docking simulation on different targets have also been discussed herein. Some of the important cancer targets have also been explored.

METHODS

The most potent 1,3,4-oxadiazoles reported in literature was highlighted in the manuscript. The anticancer activity was reported in terms of growth percent (GP), percent growth inhibition (%GI), GI50, IC50, and LC50 and TGI.

RESULTS

1,3,4-Oxadiazoles are an important heterocyclic scaffolds with broad spectrum biological activities. They may be either mono substituted or disubstituted and act as an indispensable anchor for drug design and discovery due to their thermal stability together with low lipophilicity. They exhibited anticancer potentials and showed the inhibitions of various cancer targets.

CONCLUSION

The discussion outlined herein will proved to be a helpful and vital tool for medicinal chemists investigating and working with 1,3,4-oxadiazoles and anticancer research programs.

Molecular modelling of quinoline derivatives as telomerase inhibitors through 3D-QSAR, molecular dynamics simulation, and molecular docking techniques

Rising mortality due to cancer has led to the development and identification of newer targets and molecules to cure the disease. Telomerase is one of the attractive targets for design of many chemotherapeutic drugs. This research highlights the designing of novel telomerase inhibitors using ligand-based (3D-QSAR) and structure-based (molecular docking and molecular dynamics simulation) approaches. For the development of the 3D-QSAR model, 37 synthetic molecules reported earlier as telomerase inhibitors were selected from diversified literature. Three different alignment methods were explored; among them, distill alignment was found to be the best method with good statistical results and was used for the generation of QSAR model. Statistically significant CoMSIA model with a correlation coefficient (r²_ncv) value of 0.974, leave one out (q²) value of 0.662 and predicted correlation coefficient (r²_pred) value of 0.560 was used for the analysis of QSAR. For the MDS study, A-chain of telomerase was stabilised for 50 ns with respect to 1-atm pressure, with an average temperature of 299.98 k and with potential energy of 1,145,336 kJ/m converged in 997 steps. Furthermore, the behaviour study of variants towards the target revealed that active variable gave better affinity without affecting amino acid sequences and dimensions of protein which was accomplished through RMSD, RMSF and Rg analysis. Results of molecular docking study supported the outcomes of QSAR contour maps as ligand showed similar interactions with surrounded amino acids which were identified in contour map analysis. The results of the comprehensive study might be proved valuable for the development of potent telomerase inhibitors.

A comprehensive review on the biological interest of quinoline and its derivatives

Amongst heterocyclic compounds, quinoline is an advantaged scaffold that appears as a significant assembly motif for the development of new drug entities. Quinoline and its derivatives tested with diverse biological activity constitute an important class of compounds for new drug development. Therefore, many scientific communities have developed these compounds as intent structure and evaluated their biological activities. The present, review provides brief natural sources of quinoline and including a new extent of quinoline-based marketed drugs. This review also confers information about the biological activities of quinoline derivatives such as antibacterial, antifungal, antimycobacterial, antiviral, anti-protozoal, antimalarial, anticancer, cardiovascular, CNS effects, antioxidant, anticonvulsant, analgesic, anti-inflammatory, anthelmintic and miscellaneous activities.

Synthesis, telomerase inhibitory and anticancer activity of new 2-phenyl-4H-chromone derivatives containing 1,3,4-oxadiazole moiety

Based on previous studies, 66 2-phenyl-4H-chromone derivatives containing amide and 1,3,4-oxadiazole moieties were prepared as potential telomerase inhibitors. The results showed most of the title compounds exhibited significantly inhibitory activity on telomerase. Among them, some compounds demonstrated the most potent telomerase inhibitory activity (IC₅₀ < 1 µM), which was significantly superior to the staurosporine (IC₅₀ = 6.41 µM). In addition, clear structure–activity relationships were summarised, indicating that the substitution of the methoxy group and the position, type and number of the substituents on the phenyl ring had significant effects on telomerase activity. Among them, compound A33 showed considerable inhibition against telomerase. Flow cytometric analysis showed that compound A33 could arrest MGC-803 cell cycle at G2/M phase and induce apoptosis in a concentration-dependent way. Meanwhile, Western blotting revealed that this compound could reduce the expression of dyskerin, which is a fragment of telomerase.

Groundbreaking Anticancer Activity of Highly Diversified Oxadiazole Scaffolds

Nowadays, an increasing number of heterocyclic-based drugs found application in medicinal chemistry and, in particular, as anticancer agents. In this context, oxadiazoles—five-membered aromatic rings—emerged for their interesting biological properties. Modification of oxadiazole scaffolds represents a valid strategy to increase their anticancer activity, especially on 1,2,4 and 1,3,4 regioisomers. In the last years, an increasing number of oxadiazole derivatives, with remarkable cytotoxicity for several tumor lines, were identified. Structural modifications, that ensure higher cytotoxicity towards malignant cells, represent a solid starting point in the development of novel oxadiazole-based drugs. To increase the specificity of this strategy, outstanding oxadiazole scaffolds have been designed to selectively interact with biological targets, including enzymes, globular proteins, and nucleic acids, showing more promising antitumor effects. In the present work, we aim to provide a comprehensive overview of the anticancer activity of these heterocycles, describing their effect on different targets and highlighting how their structural versatility has been exploited to modulate their biological properties.

Anti-tuberculosis activity and its structure-activity relationship (SAR) studies of oxadiazole derivatives: A key review

With the increasing number of cases of inactive and drug-resistance tuberculosis, there is an urgent need to develop new potent molecules set for fighting this brutal disease. Medicinal chemistry concerns the discovery, the development, the identification, and the interpretation of the mode of action of biologically active compounds at the molecular level. Molecules bearing oxadiazoles are one such class that could be considered to satisfy this need. Oxadiazole regioisomers have been investigated in drug discovery programs for their capacity to go about as powerful linkers and as pharmacophoric highlights. Oxadiazoles can go about as bioisosteric substitutions for the hydrazide moiety which can be found in first-line anti-TB drugs, and some have been likewise answered to cooperate with more current anti-TB targets. This present review summarizes the current innovations of oxadiazole-based derivatives with potential antituberculosis activity and bacteria discussing various aspects of structure-activity relationship (SAR).

Design and Synthesis of 4(1H)-quinolone Derivatives as Autophagy Inducing Agents by Targeting ATG5 Protein

Background:

Quinolines have been characterized as a class of potential antitumor agents, and a large number of natural and synthetic quinolines acting as antitumor agents were reported.

Methods:

A series of 7-chloro-4(1H)-quinolone derivatives were synthesized. The antiproliferative effect of these compounds was evaluated by MTT assay against five human tumor cell lines. The mechanism of action of the selected compound 7h was also investigated.

Results and Discussion:

Most of the compounds had more potent antiproliferative activities than the lead compound 7-chloro-4(1H)-quinolone 6b. Compound 7h was found to be the most potent antiproliferative agent against human tumor cell lines. Further investigation demonstrated that compound 7h triggered ATG5-dependent autophagy of colorectal cancer cells by promoting the functions of LC3 proteins.

Conclusion:

These results were useful for designing and discovering more potent novel antitumor agents endowed with better pharmacological profiles.

Targeting telomerase for its advent in cancer therapeutics

Telomerase has emerged as an important primary target in anticancer therapy. It is a distinctive reverse transcriptase enzyme, which extends the length of telomere at the 3' chromosomal end, and uses telomerase reverse transcriptase (TERT) and telomerase RNA template-containing domains. Telomerase has a vital role and is a contributing factor in human health, mainly affecting cell aging and cell proliferation. Due to its unique feature, it ensures unrestricted cell proliferation in malignancy and plays a major role in cancer disease. The development of telomerase inhibitors with increased specificity and better pharmacokinetics is being considered to design and develop newer potent anticancer agents. Use of natural and synthetic compounds for the inhibition of telomerase activity can lead to an opening of new vistas in cancer treatment. This review details about the telomerase biochemistry, use of natural and synthetic compounds; vaccines and oncolytic virus in therapy that suppress the telomerase activity. We have discussed structure-activity relationships of various natural and synthetic telomerase inhibitors to help medicinal chemists and chemical biology researchers with a ready reference and updated status of their clinical trials. Suppression of human TERT (hTERT) activity through inhibition of hTERT promoter is an important approach for telomerase inhibition.

In silico design of telomerase inhibitors

Telomerase is a reverse transcriptase enzyme involved in DNA synthesis at the end of linear chromosomes. Unlike in most other cells, telomerase is reactivated most cancerous cells and, therefore, has become a promising new anticancer target. Despite extensive research, direct telomerase inhibitors have yet not been introduced to the clinics because of the complexity of this enzyme. Structures of this protein from simple organisms and human homology models are currently available and have been used in structure-based drug design efforts to find potential inhibitors. Different is silico strategies have been applied and different chemical groups have been explored. Here, we provide an overview of recent discoveries.

Therapeutic strategies for targeting telomerase in cancer

Telomere and telomerase play important roles in abnormal cell proliferation, metastasis, stem cell maintenance, and immortalization in various cancers. Therefore, designing of drugs targeting telomerase and telomere is of great significance. Over the past two decades, considerable knowledge regarding telomere and telomerase has been accumulated, which provides theoretical support for the design of therapeutic strategies such as telomere elongation. Therefore, the development of telomere-based therapies such as nucleoside analogs, non-nucleoside small molecules, antisense technology, ribozymes, and dominant negative human telomerase reverse transcriptase are being prioritized for eradicating a majority of tumors. While the benefits of telomere-based therapies are obvious, there is a need to address the limitations of various therapeutic strategies to improve the possibility of clinical applications. In this study, current knowledge of telomere and telomerase is discussed, and therapeutic strategies based on recent research are reviewed.

Oxadiazole-An Important Bioactive Scaffold for Drug Discovery and Development Process Against HIV and Cancer- A Review

Background:

Acquired immunodeficiency syndrome (AIDS) and cancer treatment have been a major task for research scientists and pharmaceutical industry for the last many years. Seeking to the development, many promising chemical entities especially five-membered heterocyclic rings like oxadiazole have revealed good anticancer and anti HIV activities. The current review enlists some recently developed anti-HIV and anti-cancer oxadiazole moieties.

Methods:

on the basis of structural modification for the syntheses of new oxadiazole analogs, the new anti-HIV and anti-cancer agents have been summarized, which can improve treatment of AIDs and cancer.

Results:

The oxadiazole ring is more potent in comparison to some other heterocyclic rings (five and six membered) towards anti-HIV and anti-cancer activities. The important mechanisms involved for anti HIV and anticancer activity are mainly inhibition of enzymes like protease, HIV-integrase, telomerase, histone deacetylase, methionine amino peptidase, thymidylate synthase and focal adhesion kinase and inhibition of some growth factors.

Conclusion:

By reviving the past literature about 50 most potent oxadiazole derivatives, depending upon activity and structural modifications, have been selected as potent anti-HIV, and anti-cancer agents. Thus, oxadiazole seems to be a ‘privileged structure’ for further screening and syntheses of the new drug analogs against life threatening HIV and cancer like diseases.

A Review Exploring Therapeutic Worth of 1,3,4-Oxadiazole Tailored Compounds

1,3,4-Oxadiazole, a five-membered aromatic ring can be seen in a number of synthetic molecules. The peculiar structural feature of 1,3,4-oxadiazole ring with pyridine type of nitrogen atom is beneficial for 1,3,4-oxadiazole derivatives to have effective binding with different enzymes and receptors in biological systems through numerous weak interactions, thereby eliciting an array of bioactivities. Research in the area of development of 1,3,4-oxadiazole-based derivatives has become an interesting topic for the scientists. A number of 1,3,4-oxadiazole based compounds with high therapeutic potency are being extensively used for the treatment of different ailments, contributing to enormous development value. This work provides a systematic and comprehensive review highlighting current developments of 1,3,4-oxadiazole based compounds in the entire range of medicinal chemistry such as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents. It is believed that this review will be of great help for new thoughts in the pursuit for rational designs for the development of more active and less toxic 1,3,4-oxadiazole based medicinal agents.

Synthesis, Molecular Docking and β-Glucuronidase Inhibitory Potential of Indole Base Oxadiazole Derivatives

β-glucuronidase is a lysosomal glycosidase enzyme which catalyzes the extracellular matrix of cancer and normal cells and the glycosaminoglycans of the cell membrane, which is important for cancer cell proliferation, invasion, and metastasis. Liver cancer, colon carcinoma, and neoplasm bladder are triggered by the increase of the level of β-glucuronidase activity. The most valuable structures are indole and oxadiazole which has gain immense attention because of its pharmacological behavior and display many biological properties. Twenty-two (1⁻22) analogs of indole based oxadiazole were synthesized and screened for their inhibitory potential against β-glucuronidase. Majority of the compounds showed potent inhibitory potential with IC₅₀ values ranging between 0.9 ± 0.01 to 46.4 ± 0.9 µM, under positive control of standard drug d-saccharic acid 1,4 lactone (IC₅₀ = 48.1 ± 1.2 µM). Structural activity relationship (SAR) has been established for all synthesized compounds. To shed light on molecular interactions between the synthesized compounds and β-glucuronidase, 1, 4, and 6 compounds were docked into the active binding site of β-glucuronidase. The obtained results showed that this binding is thermodynamically favorable and β-glucuronidase inhibition of the selected compounds increases with the number of hydrogen bonding established in selected compound-β-glucuronidase complexes.

Synthesis and anticancer evaluation of new lipophilic 1,2,4 and 1,3,4-oxadiazoles

A series of1,2,4- and 1,3,4-oxadiazole derivatives were synthesized and evaluated for their anticancer activity. Halogenated 1,2,4-oxadiazoles were obtained from benzonitrile and coupled either lipophilic amines or with aminoalcohols. Lipophilic 1,3,4-oxadiazole derivatives were obtained through the Mannich reactions between 5-(aryl)-1,3,4-oxadiazole-2-thiol and alkylated or acylated amines. The in vitro cytotoxic effects were evaluated against 4T1- mammary carcinoma and CT26 - colon cancer cells. The best results were obtained for the 1,3,4-oxadiazole coupled to alkylated piperazine with 10-14 carbon chain moiety, with IC₅₀ values ranging from 1.6 to 3.55μΜ for the 4T1 cell line, and from 1.6 to 3.9 μM for the CT26.WT cell line, and selectivity index up to 19. The most potent compounds were investigated with AnnexinV and PI staining as indicative of apoptosis induction.

Anti-Cancer Activity of Derivatives of 1,3,4-Oxadiazole

Compounds containing 1,3,4-oxadiazole ring in their structure are characterised by multidirectional biological activity. Their anti-proliferative effects associated with various mechanisms, such as inhibition of growth factors, enzymes, kinases and others, deserve attention. The activity of these compounds was tested on cell lines of various cancers. In most publications, the most active derivatives of 1,3,4-oxadiazole exceeded the effect of reference drugs, so they may become the main new anti-cancer drugs in the future.

Synthesis of 5-(5-methyl-benzofuran-3-ylmethyl)-3H- [1, 3, 4] oxadiazole-2-thione and investigation of its spectroscopic, reactivity, optoelectronic and drug likeness properties by combined computational and experimental approach

This paper reports the synthesis of 5-(5-methyl-benzofuran-3-ylmethyl)-3H- [1, 3, 4] oxadiazole-2-thione (5MBOT) and characterization by FT-IR, FT-Raman, ¹H NMR, ¹³C NMR and UV spectral studies. The density functional theory (DFT) calculations have been executed for the 5MBOT using B3LYP/6-31++G (d, p) basis set. The fundamental modes of the vibrations were designated by the potential energy distribution (PED), and the computed and experimental values support each other. The ¹H NMR and ¹³C NMR chemical shifts of 5MBOT were estimated by gauge-including atomic orbitals (GIAO) method and compared with the experimental chemical shifts. The UV-Vis method used to study the visible absorption maxima (λ_max) by using Time-Dependent DFT. Further, the Mulliken population analysis (MPA), natural population analysis (NPA) charges, thermodynamic properties at different temperatures were presented. The calculated HOMO and LUMO energies show that charge transfer within the molecule. The natural bonds orbital (NBO) also computed. Optoelectronic properties have been carried out by combination of DFT calculations and molecular dynamics (MD) simulations, in order to assess the potential of this structure for applications in organic electronics. Further, the study encompassed calculations of reorganization energies for holes and electrons and charge transfer rates. DFT calculations have been also used in order to identify locations possibly sensitive towards the autoxidation mechanism, which correlates between bond dissociation energy for hydrogen abstraction and the mechanism. The MD simulations have been used to understand interaction of 5MBOT with water molecules. Molecular docking studies reveals the antifungal activity of 5MBOT may be due to hydrogen bonding and hydrophobic interactions with different antifungal proteins.

Synthesis of pyrrolo[3,4-c]quinoline-1,3-diones: a sequential oxidative annulation followed by dehydrogenation and N-demethylation strategy

A synthetic strategy for pyrrolo[3,4-c]quinoline-1,3-diones via oxidative annulation followed by DDQ mediated dehydrogenation and N-demethylation.