2-((Benzimidazol-2-yl)thio)-1-arylethan-1-ones: Synthesis, crystal study and cancer stem cells CD133 targeting potential

Screening and identification of potential MERS-CoV papain-like protease (PLpro) inhibitors; Steady-state kinetic and Molecular dynamic studies

MERS-CoV belongs to the coronavirus group. Recent years have seen a rash of coronavirus epidemics. In June 2012, MERS-CoV was discovered in the Kingdom of Saudi Arabia, with 2,591 MERSA cases confirmed by lab tests by the end of August 2022 and 894 deaths at a case-fatality ratio (CFR) of 34.5% documented worldwide. Saudi Arabia reported the majority of these cases, with 2,184 cases and 813 deaths (CFR: 37.2%), necessitating a thorough understanding of the molecular machinery of MERS-CoV. To develop antiviral medicines, illustrative investigation of the protein in coronavirus subunits are required to increase our understanding of the subject. In this study, recombinant expression and purification of MERS-CoV (PLpro), a primary goal for the development of 22 new inhibitors, were completed using a high throughput screening methodology that employed fragment-based libraries in conjunction with structure-based virtual screening. Compounds 2, 7, and 20, showed significant biological activity. Moreover, a docking analysis revealed that the three compounds had favorable binding mood and binding free energy. Molecular dynamic simulation demonstrated the stability of compound 2 (2-((Benzimidazol-2-yl) thio)-1-arylethan-1-ones) the strongest inhibitory activity against the PLpro enzyme. In addition, disubstitutions at the meta and para locations are the only substitutions that may boost the inhibitory action against PLpro. Compound 2 was chosen as a MERS-CoV PLpro inhibitor after passing absorption, distribution, metabolism, and excretion studies; however, further investigations are required.

Molecular design, synthesis and biological evaluation of novel 1,2,5-trisubstituted benzimidazole derivatives as cytotoxic agents endowed with ABCB1 inhibitory action to overcome multidrug resistance in cancer cells

Multidrug resistance (MDR) is a leading cause for treatment failure in cancer patients. One of the reasons of MDR is drug efflux by ATP-binding cassette (ABC) transporters in eukaryotic cells especially ABCB1 (P-glycoprotein). In this study, certain novel 1,2,5-trisubstituted benzimidazole derivatives were designed utilising ligand based pharmacophore approach. The designed benzimidazoles were synthesised and evaluated for their cytotoxic activity towards doxorubicin-sensitive cell lines (CCRF/CEM and MCF7), as well as against doxorubicin-resistant cancer cells (CEM/ADR 5000 and Caco-2). In particular, compound VIII showed a substantial cytotoxic effect in all previously mentioned cell lines especially in doxorubicin-resistant CEM/ADR5000 cells (IC₅₀ = 8.13 µM). Furthermore, the most promising derivatives VII, VIII and XI were tested for their ABCB1 inhibitory action in the doxorubicin-resistant CEM/ADR 5000 subline which is known for overexpression of ABCB1 transporters. The results showed that compound VII exhibited the best ABCB1 inhibitory activity at three tested concentrations (22.02 µM (IC₅₀), 50 µM and 100 µM) in comparison to verapamil as a reference ABCB1 inhibitor. Such inhibition resulted in a synergistic effect and a massive decrease in the IC₅₀ of doxorubicin (34.5 µM) when compound VII was used in a non-toxic dose in combination with doxorubicin in doxorubicin-resistant cells CEM/ADR 5000 (IC_50(Dox+VII) = 3.81 µM). Molecular modelling studies were also carried out to explain the key interactions of the target benzimidazoles at the ABCB1 binding site. Overall the obtained results from this study suggest that 1,2,5-trisubstituted benzimidazoles possibly are promising candidates for further optimisation and development of potential anticancer agents with ABCB1 inhibitory activity and therefore overcome MDR in cancer cells.

Thioethers: An Overview

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Spreading rapidly in recent years, cancer has become one of the causes of the highest mor-tality rates after cardiovascular diseases. The reason for cancer development is still not clearly under-stood despite enormous research activities in this area. Scientists are now working on the biology of cancer, especially on the root cause of cancer development. The aim is to treat the cancer disease and thus cure the patients. The continuing efforts for the development of novel molecules as potential anti-cancer agents are essential for this purpose. The main aim of this review was to present a survey on the medicinal chemistry of thioethers and provide practical data on their cytotoxicities against various cancer cell lines. The research articles published between 2001-2020 were consulted to pre-pare this review article; however, patent literature has not been included. The thioether-containing heterocyclic compounds may emerge as a new class of potent and effective anti-cancer agents in the future.

Synthesis and in vitro anticancer activity of certain novel 1-(2-methyl-6-arylpyridin-3-yl)-3-phenylureas as apoptosis-inducing agents

In connection with our research program on the development of novel anticancer candidates, herein we report the design and synthesis of novel series of 1-(2-methyl-6-arylpyridin-3-yl)-3-phenylureas 5a-l. The target pyridins were evaluated for their in vitro anticancer activity against two cancer cell lines: non-small cell lung cancer A549 cell line and colon cancer HCT-116 cell line. Compound 5l emerged as the most active congener towards both A549 and HCT-116 cell lines with IC50 values equal to 3.22 ± 0.2 and 2.71 ± 0.16 µM, respectively, which are comparable to those of Doxorubicin; 2.93 ± 0.28 and 3.10 ± 0.22, respectively. Furthermore, compound 5l stood out as the most potent pyridine derivative (mean % GI = 40), at US-NCI Developmental Therapeutic Program anticancer assay, with broad-spectrum antitumor activity against the most tested cancer cell lines from all subpanels. Compound 5l was able to provoke apoptosis in HCT-116 cells as evidenced by the decreased expression of the anti-apoptotic Bcl-2 protein, and the enhanced expression of the pro-apoptotic proteins levels; Bax, cytochrome C, p53, caspase-3 and caspase-9. Moreover, 5l disrupted the HCT-116 cell cycle via alteration of the Sub-G1 phase and arresting the G2-M stage. Also, 5l showed a significant increase in the percent of annexinV-FITC positive apoptotic cells from 1.99 to 15.76%.

Synthesis and anti-HSV activity of tricyclic penciclovir and hydroxybutylguanine derivatives

A series of tricyclic penciclovir (PCV) and hydroxybutylguanine (HBG) derivatives have been prepared with enhanced lipophilicity following an efficient synthetic route. All the novel tricyclic derivatives were evaluated for inhibitory activity against herpes simplex virus 1 and 2 (HSV-1, HSV-2) and thymidine kinase deficient (ACV resistant) HSV-1. The tricyclic HBG derivatives were devoid of inhibitory activity however several of the tricyclic PCV derivatives showed promising antiviral activity, in particular 9g (R = 4-MeO-C₆H₄) displayed good inhibitory activity (HSV-1 EC₅₀ 1.5 μM, HSV-2 EC₅₀ 0.8 μM) and retained inhibitory activity in HSV-1 TK⁻ cells (EC₅₀ 0.8 μM). Computational docking experiments supported the biological data observed and this preliminary study provides useful data for further development of tricyclic acyclic nucleoside derivatives with improved lipophilicity and retention of activity in HSV-1 TK deficient strains. Also, the new tricyclic derivatives were evaluated against a broad range of other DNA and RNA viruses, but were found to be inactive at subtoxic concentrations. In addition, weak to moderate cytostatic effect was observed for the new compounds.

SLC-0111 enaminone analogs, 3/4-(3-aryl-3-oxopropenyl) aminobenzenesulfonamides, as novel selective subnanomolar inhibitors of the tumor-associated carbonic anhydrase isoform IX

SLC-0111, an ureido substituted benzenesulfonamide, is a selective carbonic anhydrase (CA, EC 4.2.1.1) IX inhibitor that is currently in Phase I/II clinical trials for the treatment of advanced hypoxic tumors complicated with metastases. Herein we report the synthesis of two series of 3/4-(3-aryl-3-oxopropenyl) aminobenzenesulfonamides 5a-i and 6a-j as SLC-0111 enaminone congeners. The prepared enaminones were in vitro investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA I, II, IV and IX, using a stopped-flow CO₂ hydrase assay. All these isoforms were inhibited by the enaminones reported here in variable degrees. The target tumor-associated isoform hCA IX was undeniably the most affected one (K_Is: 0.21-7.1 nM), with 6- to 21-fold enhanced activity than SLC-0111 (K_I = 45 nM). All the prepared enaminones displayed interesting selectivity towards hCA IX over hCA I (SI: 32 - >35714), hCA II (SI: 2 - 1689) and hCA IV (SI: 11 - >45454). Of particular interest, bioisosteric replacement of phenyl tail with the bulkier 2-naphthyl tail, sulfonamide 6h, achieved the higher II/IX selectivity herein reported with SI of 1689.

Pyridine-Ureas as Potential Anticancer Agents: Synthesis and In Vitro Biological Evaluation

In our endeavor towards the development of effective anticancer agents, a novel series of pyridine-ureas 8a⁻n were synthesized. All the newly prepared derivatives were evaluated in vitro for their growth inhibitory activity towards the proliferation of breast cancer MCF-7 cell line. Compounds 8e and 8n were found to be the most active congeners against MCF-7 cells (IC₅₀ = 0.22 and 1.88 µM after 48 h treatment; 0.11 and 0.80 µM after 72 h treatment, respectively) with increased activity compared to the reference drug doxorubicin (IC₅₀ = 1.93 µM). Moreover, eight selected pyridines 8b, 8d, 8e, 8i, 8j and 8l⁻n were evaluated for their in vitro anticancer activity according to the US-NCI protocol. Pyridines 8b and 8e proved to be the most effective anticancer agents in the NCI assay with mean inhibition = 43 and 49%, respectively. Both 8b and 8e exhibited anti-proliferative activity against all tested cancer cell lines from all subpanels growth inhibition (GI for 8b; 12⁻78%, GI for 8e; 15⁻91%). Pyridines 8b and 8e were screened in vitro for their inhibitory activity against VEGFR-2. Both compounds inhibited VEGFR-2 at micromolar IC₅₀ values 5.0 ± 1.91 and 3.93 ± 0.73 µM, respectively. The most active pyridines were filtered according to the Lipinski and Veber rules and all of them passed these filters. Finally, several ADME descriptors were predicted for the active pyridines through a theoretical kinetic study.

Solvent-Free Ring Cleavage Hydrazinolysis of Certain Biginelli Pyrimidines

Certain Biginelli pyrimidines with ester substitution in C5 were subjected to unexpected ring opening upon solvent-free reaction with hydrazine hydrate to give three products: pyrazole, arylidenehydrazines, and urea/thiourea, respectively. The nonisolable carbohydrazide intermediates are formed firstly followed by the intermolecular nucleophilic attack of terminal amino group of hydrazide function on sp2 C6 rather than the sp3 C4 to give the ring adduct which was produced as a final product.

Cancer stem cells CD133 inhibition and cytotoxicity of certain 3-phenylthiazolo[3,2-a]benzimidazoles: design, direct synthesis, crystal study and in vitro biological evaluation

Cancer stem cells (CSCs) have been objects of intensive study since their identification in 1994. Adopting a structural rigidification approach, a novel series of 3-phenylthiazolo[3,2-a]benzimidazoles 4a-d was designed and synthesised, in an attempt to develop potent anticancer agent that can target the bulk of tumour cells and CSCs. The anti-proliferative activity of the synthesised compounds was evaluated against two cell lines, namely; colon cancer HT-29 and triple negative breast cancer MDA-MB-468 cell lines. Also, their inhibitory activity against the cell surface expression of CD133 was examined. In particular, compound 4b emerged as a promising hit molecule as it manifested good antineoplastic potency against both tested cell lines (IC50 = 9 and 12 μM, respectively), beside its ability to inhibit the cell surface expression of CD133 by 50% suggesting a promising potential of effectively controlling the tumour by eradicating the tumour bulk and inhibiting the proliferation of the CSCs. Moreover, compounds 4a and 4c showed moderate activity against HT-29 (IC50 = 21 and 29 μM, respectively) and MDA-MB-468 (IC50 = 23 and 24 μM, respectively) cell lines, while they inhibited the CD133 expression by 14% and 48%, respectively. Finally, a single crystal X-ray diffraction was recorded for compound 4d.

Benzimidazole Scaffold as Anticancer Agent: Synthetic Approaches and Structure-Activity Relationship

Cancer, also known as malignant neoplasm, is a dreadful disease which involves abnormal cell growth having the potential to invade or spread to other parts of the body. Benzimidazole is an organic compound that is heterocyclic and aromatic in nature. It is a bicyclic compound formed by the fusion of the benzene and imidazole ring systems. It is an important pharmacophore and a privileged structure in medicinal chemistry. According to the World Health Organisation (2015 survey), one in six deaths is due to cancer around the globe, accounting for 8.8 million deaths of which 70% of the cases were from low- and middle-income countries. In the efforts to develop suitable anticancer drugs, medicinal chemists have focussed on benzimidazole derivatives. This review article covers the current development of benzimidazole-based anticancer agents along with the synthetic approaches and structure-activity relationships (SAR).

Synthesis, Crystal Study, and Anti-Proliferative Activity of Some 2-Benzimidazolylthioacetophenones towards Triple-Negative Breast Cancer MDA-MB-468 Cells as Apoptosis-Inducing Agents

On account of its poor prognosis and deficiency of therapeutic stratifications, triple negative breast cancer continues to form the causative platform of an incommensurate number of breast cancer deaths. Aiming at the development of potent anticancer agents as a continuum of our previous efforts, a novel series of 2-((benzimidazol-2-yl)thio)-1-arylethan-1-ones 5a–w was synthesized and evaluated for its anti-proliferative activity towards triple negative breast cancer (TNBC) MDA-MB-468 cells. Compound 5k was the most active analog against MDA-MB-468 (IC₅₀ = 19.90 ± 1.37 µM), with 2.1-fold increased activity compared to 5-fluorouracil (IC₅₀ = 41.26 ± 3.77 µM). Compound 5k was able to induce apoptosis in MDA-MB-468, as evidenced by the marked boosting in the percentage of florecsein isothiocyanate annexin V (Annexin V–FITC)-positive apoptotic cells (upper right (UR) + lower right (LR)) by 2.8-fold in comparison to control accompanied by significant increase in the proportion of cells at pre-G1 (the first gap phase) by 8.13-fold in the cell-cycle analysis. Moreover, a quantitative structure activity relationship (QSAR) model was established to investigate the structural requirements orchestrating the anti-proliferative activity. Finally, we established a theoretical kinetic study.

Bis[4-(5-anilino-1,3,4-thiadiazol-2-yl)pyridinium] sulfate

The asymmetric unit of the title salt, 2C13H11N4S+·SO4−, comprises two 4-(5-anilino-1,3,4-thiadiazol-2-yl)pyridinium cations and one sulfate anion. In one cation, the phenyl ring is inclined to the pyridinium ring at a dihedral angle of 34.82 (6)°, while in other cation the rings are almost coplanar with a corresponding dihedral angle 5.33 (10)°. Strong N—H...O hydrogen bonds link the cations to the sulfate anion in the asymmetric unit. Additional N—H...O, C—H...N, C—H...O and C—H...S hydrogen bonds further stabilize the crystal structure. Weak C—H...π and π–π interactions are also observed in the crystal structure.