Development of 1,3,4-oxadiazole thione based novel anticancer agents: Design, synthesis and in-vitro studies

Discovery of Potential Inhibitors of CDK1 by Integrating Pharmacophore-Based Virtual Screening, Molecular Docking, Molecular Dynamics Simulation Studies, and Evaluation of Their Inhibitory Activity

The ability of CDK1 to compensate for the absence of other cell cycle CDKs poses a great challenge to treat cancers that overexpress these proteins. Despite several studies focusing on the area, there are no FDA-approved drugs selectively targeting CDK1. Here, the study aimed to develop potential CDK1 selective inhibitors through drug repurposing and leveraging the structural insights provided by the hit molecules generated. Approximately 280,000 compounds from DrugBank, Selleckchem, Otava and an in-house library were screened initially based on fit values using 3D QSAR pharmacophores built for CDK1 and subsequently through Lipinski, ADMET, and TOPKAT filters. 10,310 hits were investigated for docking into the binding site of CDK1 determined using the crystal structure of human CDK1 in complex with NU6102. The best 55 hits with better docking scores were further analyzed, and 12 hits were selected for 100 ns MD simulations followed by binding energy calculations using the MM-PBSA method. Finally, 10 hit molecules were tested in an in vitro CDK1 Kinase inhibition assay. Out of these, 3 hits showed significant CDK1 inhibitory potential with IC50 < 5 μM. These results indicate these compounds can be used to develop subtype-selective CDK1 inhibitors with better efficacy and reduced toxicities in the future.

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

A series of new RS-, RS-CH2- and R2N-CH2-functionalized сatechols with heterocyclic fragments such as 1,3,4-oxadiazole, 1,2,4-triazole, thiazole, or pyridine were synthesized by the reaction of 3,5-di-tert-butyl-o-benzoquinone or 3,5-di-tert-butyl-6-methoxymethylcatechol with different heterocyclic thiols. The S-functionalized catechols were prepared by the Michael reaction from 3,5-di-tert-butyl-o-benzoquinone and the corresponding thiols. The starting reagents such as substituted 1,3,4-oxadiazole-2-thiols and 4H-triazole-3-thiols are characterized by thiol-thione tautomerism, therefore their reactions with 3,5-di-tert-butyl-6-methoxymethylcatechol can proceed at the sulfur or nitrogen atom. In the case of mercapto-derivatives of thiazole or pyridine, this process leads to the formation of the corresponding thioethers with a methylene linker. At the same time, thiolated 1,3,4-oxadiazole or 1,2,4-triazole undergo alkylation at the nitrogen atom in the reaction with 3,5-di-tert-butyl-6-methoxymethylcatechol to form the corresponding thiones. The yield of reaction products ranges from 42 to 80%. The crystal structures of catechols with 3-nitropyridine or 1,3,4-oxadiazole-2(3H)-thione moieties were established by single-crystal X-ray analysis. The possibility of forming intra- and intermolecular hydrogen bonds has been established for these compounds. The electrochemical behavior of the studied compounds is influenced by several factors: the nature of the heterocycle and its substituents, the presence of a sulfur atom in the catechol ring, or a thione group in the heterocyclic core. The radical scavenging activity and antioxidant properties were determined using the reaction with synthetic radicals, the cupric reducing antioxidant capacity assay, the inhibition process of superoxide radical anion formation by xanthine oxidase, and the process of lipid peroxidation of rat liver (Wistar) homogenates in vitro.

Unveiling the chemistry of 1,3,4-oxadiazoles and thiadiazols: A comprehensive review

Oxadiazoles and thiadiazoles are malleable heterocycles that have recently generated major interest in the field of medicinal chemistry. Compounds based on these moieties have versatile biological applications such as anticonvulsant, anticancer, antidiabetic, and antioxidant agents. Due to the versatile nature and stability of the oxadiazole and thiadiazole nucleus, medicinal chemists have changed the structural elements of the ring in numerous ways. These compounds have shown significant anticonvulsant effects, demonstrating their potential in the management of epileptic disorders. In this review, we have covered numerous biological pathways and in silico targeted proteins of oxadiazole and thiadiazole derivatives for treating various biological disorders. The data compiled in this article will be helpful for researchers, research scientists, and research chemists who work in the field of drug discovery and drug development.

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.

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.

Synthesis of cytotoxic urs-12-ene- and 28-norurs-12-ene- type conjugates with amino- and mercapto-1,3,4-oxadiazoles and mercapto-1,2,4-triazoles

A small library of 2-mercapto-1,3,4-oxadiazoles, 2-amino-1,3,4-oxadiazoles, and 3-mercapto-1,2,4-triazoles attached to the urs-12-ene- and 28-nor-urs-12-ene skeleton has been obtained. Ursolic acid derived hydrazides have been identified as useful starting materials for the developed synthesis. Ursolic acid hydrazide provided access to oxadiazoles attached directly to C-17 of the ursane core, but synthesis of structurally related 3-mercapto-1,2,4-triazoles was not possible in this way due to steric hindrance of the triterpenoid. Ester- and amide-linked hydrazides arising from ethoxycarbonylmethyl ursolate and ursolic acid amide with methyl β-alaninate served as key starting materials for the remotely connected mercapto-and amino-azoles. Antioxidant activities (DPPH method) of the newly obtained compounds are mediocre. However, excellent cytotoxicity and selectivity against MCF7 cell line were found for 28-nor-urs-12-ene 2-amino-1,3,4-oxadiazole conjugate. Also some other library members exceeded the cytotoxicity values of natural ursolic acid. The novel hybrid heterocycles with amino and mercapto substituents possess a great potential for further derivatization and are prospective scaffolds for the synthesis of triterpenoid analogs with chemopreventive and cytotoxic properties.

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.

PARP inhibitor re‑sensitizes Adriamycin resistant leukemia cells through DNA damage and apoptosis

Resistance to Adriamycin (ADR) is an increasing problem in the treatment of leukemia and the development of novel therapeutic strategies is becoming increasingly important. Olaparib is a poly (adenosine diphosphate-ribose) polymerase (PARP) 1 inhibitor, which has promising antitumor activity in patients with metastatic breast cancer and germline BRCA mutations. Previously published studies have indicated that Olaparib is able to overcome drug resistance in cancer; however, its underlying mechanism of action is yet to be elucidated. The aim of the present study was to explore the mechanism underlying re-sensitization. Annexin V-propidium iodide staining indicated that the percentage of apoptotic ADR resistant cells was markedly increased and the cell cycle was blocked at the G2/M-phase following treatment with ADR combined with Olaparib, when compared with the control group. The alkaline comet assay demonstrated that ADR combined with Olaparib significantly upregulated the induction of the DNA damage response in ADR-resistant cells. Western blot analysis revealed that the protein expression of γ-H2A histone family member X, cleaved PARP, caspase 3 and cleaved caspase 3 was markedly enhanced, while the cell cycle-associated protein cyclin B1 was downregulated in K562/ADR cells following treatment with a combination of ADR and Olaparib. Similar synergistic cytotoxicity was observed in blood mononuclear cells, which were isolated from patients with chemotherapy-resistant leukemia. As Olaparib is available for clinical use, the results of the present study provide a rationale for the development of Olaparib combinational therapies for cases of ADR resistant leukemia.

Synthesis and biological evaluation of 3-(1,3,4-oxadiazol-2-yl)-1,8-naphthyridin-4(1H)-ones as cisplatin sensitizers

A series of novel 3-(1,3,4-oxadiazol-2-yl)-1,8-naphthyridin-4(1H)-one derivatives were synthesized and their anti-cancer as well as cisplatin sensitization activities were evaluated. Among them, compounds 6e and 6h exhibited significant cisplatin sensitization activity against HCT116. Hoechst staining and annexin V-FITC/PI dual-labeling studies demonstrated that the combination of 6e/6h and cisplatin can induce tumour cell apoptosis. Western blot showed that the expression of ATR downstream protein, CHK1, decreased in 6e + cisplatin and 6h + cisplatin groups compared with that in the test compound and cisplatin group. Furthermore, docking of 6e/6h into the ATR structure active site revealed that the N1 and N8 atoms in the naphthyridine ring and the hybrid atom in the oxadiazole ring are involved in hydrogen bonding with Val170, Glu168 and Tyr155. Additionally, the naphthyridine ring is also involved in π-π stacking with Trp169. Accordingly, compounds 6e and 6h can be expected to be potential cisplatin sensitizers that can participate in HCT116 cancer therapy.

Anti-Cancer Activity of Lobaric Acid and Lobarstin Extracted from the Antarctic Lichen Stereocaulon alpnum

Lobaric acid and lobarstin, secondary metabolites derived from the antarctic lichen Stereocaulon alpnum, exert various biological activities, including antitumor, anti-proliferation, anti-inflammation, and antioxidant activities. However, the underlying mechanisms of these effects have not yet been elucidated in human cervix adenocarcinoma and human colon carcinoma. In the present study, we evaluated the anticancer effects of lobaric acid and lobarstin on human cervix adenocarcinoma HeLa cells and colon carcinoma HCT116 cells. We show that the proliferation of Hela and HCT116 cells treated with lobaric acid and lobarstin significantly decreased in a dose- and time-dependent manner. Using flow cytometry analysis, we observed that the treatment with these compounds resulted in significant apoptosis in both cell lines, following cell cycle perturbation and arrest in G2/M phase. Furthermore, using immunoblot analysis, we investigated the expression of cell cycle and apoptosis-related marker genes and found a significant downregulation of the apoptosis regulator B-cell lymphoma 2 (Bcl-2) and upregulation of the cleaved form of the poly (ADP-ribose) polymerase (PARP), a DNA repair and apoptosis regulator. These results suggest that lobaric acid and lobarstin could significantly inhibit cell proliferation through cell cycle arrest and induction of apoptosis via the mitochondrial apoptotic pathway in cervix adenocarcinoma and colon carcinoma cells. Taken together, our data suggests that lobaric acid and lobarstin might be novel agents for clinical treatment of cervix adenocarcinoma and colon carcinoma.