Synthesis, characterization, and antibacterial activity studies of two Co(II) complexes with 2-[(E)-(3-acetyl-4-hydroxyphenyl)diazenyl]-4-(2-hydroxyphenyl)thiophene-3-carboxylic acid as a ligand

Two new Cobalt(II) complexes 12 and 13 have been synthesized from 2-[(E)-(3-acetyl-4-hydroxyphenyl)diazenyl]-4-(2-hydroxyphenyl)thiophene-3-carboxylic acid (11) as a novel ligand. These three new compounds were characterized on the basis of their powder X-Ray Diffraction, UV-Vis, IR, NMR, elemental analysis and MS spectral data. DFT/B3LYP mode of calculations were carried out to determine some theorical parameters of the molecular structure of the ligand. The purity of the azoic ligand and the metal complexes were ascertained by TLC and melting points. The analysis of the IR spectra of the polyfunctionalized azo compound 11 and its metal complexes 12 and 13, reveals that the coordination patterns of the ligand are hexadentate and tetradentate respectively. Based on the UV-Vis electronic spectral data and relevant literature reports, the ligand and derived complexes were assigned the E (trans) isomer form. Likewise, octahedral and square-planar geometries were respectively assigned to the cobalt(II) complexes. The broth microdilution method was used for antibacterial assays through the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The ligand 11 displayed moderate antibacterial activity (MIC = 32-128 μg/mL) against Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, Pseudomonas aeruginosa and Klebsiella pneumoniae 22. The octahedral cobalt(II) complex 12 showed moderate activity against Pseudomonas aeruginosa (MIC = 128 μg/mL) and Klebsiella pneumoniae 22 (MIC = 64 μg/mL) and none against Staphylococcus aureus ATCC25923 and Escherichia coli ATCC25922, whereas the square-planar complex 13 displayed moderate activity only on Klebsiella pneumoniae 22 (MIC = 64 μg/mL).

Design and Synthesis of Novel Pyridine-Based Compounds as Potential PIM-1 Kinase Inhibitors, Apoptosis, and Autophagy Inducers Targeting MCF-7 Cell Lines: In Vitro and In Vivo Studies

2-((3-Cyano-4,6-dimethylpyridin-2-yl)oxy)acetohydrazide 1 was used as the precursor for the synthesis of 5-thioxo-1,3,4-oxadiazol-2-yl)methoxy)nicotinonitrile 2. The latter was alkylated with different alkylating agents to produce the S-alkylated products 3-6. Galactosylation of 5-thioxo-1,3,4-oxadiazol-2-yl)methoxy)nicotinonitrile 2 produces a mixture of S- and N-galactosides 8 and 9. The hydrazide 1 is converted to azide 10, coupled with glycine methyl ester hydrochloride and a set of amines to produce the target coupled amides 11-15. New compounds were assigned using NMR and elemental analysis. Compound 12 had potent cytotoxicity with IC50 values of 0.5 and 5.27 μM against MCF-7 and HepG2 cell lines compared with doxorubicin, which displayed the following IC50: 2.14 and 2.48 μM for the mentioned cell lines, respectively. Regarding the molecular target, compound 12 exhibited potent PIM-1 inhibition activity with 97.5% with an IC50 value of 14.3 nM compared to Staurosporine (96.8%, IC50 = 16.7 nM). Moreover, compound 12 significantly activated apoptotic cell death in MCF-7 cells, increasing the cell population by total apoptosis by 33.43% (23.18% for early apoptosis and 10.25% for late apoptosis) compared to the untreated control group (0.64%), and arresting the cell cycle at S-phase by 36.02% compared to control 29.12%. Besides, compound 12 caused tumor inhibition by 42.1% in solid tumors in the SEC-bearing mice. Results disclosed that compound 12 significantly impeded cell migration and cell proliferation by interfering with PIM-1 enzymatic activity via considerable apoptosis-induction, which made it an attractive lead compound for the development of chemotherapeutics to treat breast cancer.

Exploring quantum computational, molecular docking, and molecular dynamics simulation with MMGBSA studies of ethyl-2-amino-4-methyl thiophene-3-carboxylate

2-aminothiophenes derivative, Ethyl-2-amino-4-methyl thiophene-3-carboxylate (EAMC) has been synthesized, characterized, and investigated quantum chemically. It was experimentally investigated by different spectroscopic methods like- NMR (1H-NMR and 13C-NMR), FT-IR, and UV-Visible. B3LYP method and 6-311++G(d,p) basis set were employed for optimization of molecular structure and calculation of wave numbers of normal modes of vibrations and various other important parameters. Calculated bond lengths and angles were compared with the experimental bond lengths and Bond Angle Parameters. Optimized bond parameters and experimental bond parameters were found in good agreement. Complete potential energy distribution assignments were done successfully by VEDA. The HOMO/LUMO energy gap emphasizes adequate charge transfer happening within the molecule. A study of donor-acceptor interconnections was done via NBO analysis. MEP surface analysis was done to demonstrate charge distribution and reactive areas qualitatively in the molecule. The degree of relative localization of electrons was analyzed via ELF Diagram. The Fukui function analysis showed possible sites for attacks by different substituents. By using the TD-DFT method and PCM solvent model, the UV-Vis spectrum (gas, methanol, DMSO) and the maximum absorption wavelength was computed and compared with experimental data. 3D and 2D intermolecular interactions in the crystal were analyzed via Hirshfeld surface analysis and fingerprint plots reveal that the EAMC crystal was stabilized by H--H/H--H/C--H bond formation. The molecular docking was done with 7 different protein receptors on the molecule to find the best ligand-protein interactions. Molecular dynamic simulations and MMGBSA calculations were also carried out to find out the best binding of the ligand with the protein.Communicated by Ramaswamy H. Sarma.

A minireview of 1,2,3-triazole hybrids with O-heterocycles as leads in medicinal chemistry

Over the past few decades, the dynamic progress in the synthesis and screening of heterocyclic compounds against various targets has made a significant contribution in the field of medicinal chemistry. Among the wide array of heterocyclic compounds, triazole moiety has attracted the attention of researchers owing to its vast therapeutic potential and easy preparation via copper and ruthenium-catalyzed azide-alkyne cycloaddition reactions. Triazole skeletons are found as major structural components in a different class of drugs possessing diverse pharmacological profiles including anti-cancer, anti-bacterial, anti-fungal, anti-viral, anti-oxidant, anti-inflammatory, anti-diabetic, anti-tubercular, and anti-depressant among various others. Furthermore, in the past few years, a significantly large number of triazole hybrids were synthesized with various heterocyclic moieties in order to gain the added advantage of the improved pharmacological profile, overcoming the multiple drug resistance and reduced toxicity from molecular hybridization. Among these synthesized triazole hybrids, many compounds are available commercially and used for treating different infections/disorders like tazobactam and cefatrizine as potent anti-bacterial agents while isavuconazole and ravuconazole as anti-fungal activities to name a few. In this review, we will summarize the biological activities of various 1,2,3-triazole hybrids with copious oxygen-containing heterocycles as lead compounds in medicinal chemistry. This review will be very helpful for researchers working in the field of molecular modeling, drug design and development, and medicinal chemistry.

Versatile Synthetic Platform for 1,2,3-Triazole Chemistry

1,2,3-Triazole scaffolds are not obtained in nature, but they are still intensely investigated by synthetic chemists in various fields due to their excellent properties and green synthetic routes. This review will provide a library of all synthetic routes used in the past 21 years to synthesize 1,2,3-triazoles and their derivatives using various metal catalysts (such as Cu, Ni, Ru, Ir, Rh, Pd, Au, Ag, Zn, and Sm), organocatalysts, metal-free as well as solvent- and catalyst-free neat syntheses, along with their mechanistic cycles, recyclability studies, solvent systems, and reaction condition effects on regioselectivity. Constant developments indicate that 1,2,3-triazoles will help lead to future organic synthesis and are useful for creating molecular libraries of various functionalized 1,2,3-triazoles.

New quinoxalin-2(1H)-one-derived VEGFR-2 inhibitors: Design, synthesis, in vitro anticancer evaluations, in silico ADMET, and docking studies

More than 70% of cancer patients who are treated with chemotherapeutics do not show a durable response. As part of the global plan seeking new effective chemotherapeutics, here, we report the synthesis and in vitro and computational studies of new lenvatinib and sorafenib analog quinoxalines as vascular endothelial growth factor receptor II (VEGFR-2) tyrosine kinase inhibitors. The central quinolone and pyridine moieties of the Food and Drug Administration-approved anticancer agents lenvatinib and sorafenib were replaced with the versatile quinoxaline scaffold that has been exploited for developing potent cytotoxic agents. With some minor structural optimizations, all the other pharmacophoric features of lenvatinib and sorafenib were maintained. Accordingly, three new sets of quinoxalines were synthesized to evaluate their activity against liver, colorectal, and breast malignancies. The results obtained in the in vitro cytotoxicity evaluation study revealed the superior activity of three derivatives (20, 25, and 29) compared with that of doxorubicin and sorafenib. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiling and docking of 20, 25, and 29 into the VEGFR-2 receptor were also performed. Results of in silico studies showed the potential of the designed compounds to bind effectively with a number of key residues. The obtained in vitro cytotoxic activity and ADMET profiles of compounds 20, 25, and 29 suggested that they should be subjected to further structural optimizations to develop new candidates in cancer treatment protocols.

Synthesis and anticancer activity of ethyl 5-amino-1-N-substituted-imidazole-4-carboxylate building blocks

A series of 5-amino-1-N-substituted-imidazole-4-carboxylate building blocks was synthesized and assayed for their antiproliferative potential against human cancer cell lines, including HeLa (cervical), HT-29, HCT-15 (colon), A549 (lung), and MDA-MB-231 (breast) cells. The preliminary screening results revealed that several derivatives containing alkyl chains at the N-1 position of the imidazole core demonstrate a certain inhibitory effect on growth and proliferation. A significant effect was observed following ethyl 5-amino-1-dodecyl-1H-imidazole-4-carboxylate (5e) treatment for 72 h. The IC₅₀ value for HeLa cells was 0.737 ± 0.05 μM, whereas that for HT-29 cells was 1.194 ± 0.02 μM. Further investigations revealed that 5e significantly inhibited tumor cell colony formation and migration, and it exhibited antiadhesive effects on HeLa cells as well as antitubulin activity along with the induction of early apoptosis of HeLa and HT-29 cells. In addition, derivative 5e significantly reduced the cell mitochondrial membrane potential in a dose-dependent manner and induced early apoptosis of HeLa and HT-29 cells, indicating that 5e may serve as a lead compound for further drug discovery and development.

Synthesis of new substituted pyridine derivatives as potent anti-liver cancer agents through apoptosis induction: In vitro, in vivo, and in silico integrated approaches

Liver cancer is the most common type of cancer in many countries. New studies and statistics show rising liver cancer worldwide, so it is essential to seek new agents for this type of cancer. PIM1 has an attractive target in the discovery of cancer medications as it is very much expressed in a variety of malignancies and influences such as tumorigenesis, cell cycle progression, cellular proliferation, apoptosis, and cell migration. Accordingly, a series of pyridones and pyridine-amides were synthesized and tested for anti-liver cancer activity. In the synthetic strategy 4,6-diaryl-3-cyano-2-pyridones 3a-n were synthesized using one-pot four component synthetic method. Structural modifications were done on 4,6-diphenyl-3-cayno-2-pyridone 3a to enhance the activity. Alkylation in the presence of K₂CO₃ afforded the O-alkylated products 4-6. The acetoxy hydrazide 7 was synthesized and cyclized into 1,3,4-oxadiazolethione 8 which alkylated on sulfur to give 10. Azide-coupling method was used to couple the 2-(pyridin-2-yloxy)acetohydrazide 7 to different amines and amino acid esters to furnish the products 12a-e and 13a-b. The synthesized derivatives were subjected to cytotoxic screening against HepG2 and THLE-2 cells, Compounds 10, 12e and 13a have a remarkable cytotoxic activity with IC₅₀ values (10.7-13.9 µM). Compound 7 was found to be more cytotoxic by showing the lowest IC₅₀ value of 7.26 compared to 5-FU (IC₅₀ = 6.98 µM). It inhibited cell growth by 76.76%. Additionally, it significantly stimulated apoptotic liver cancer cell death with 49.78-fold (22.90% compared to 0.46% for the control) arresting cell cycle Pre-G1 with 35.16% of a cell population, compared to 1.57% for the control. Moreover, it validated the intrinsic apoptosis through upregulation of P53, and other related genes, with inhibition of anti-apoptotic genes through PIM-1 inhibition.

Synthesis and antiviral activity of a series of novel quinoline derivatives as anti-RSV or anti-IAV agents

We report herein the synthesis of a series of novel quinoline derivatives, based on the lead compound 1a, identified from a rRSV-mGFP high-throughput screening assay. Our results revealed that target compounds 1b, 1g-h, 1af and 1ah (IC₅₀ = 3.10-6.93 μM) had good in vitro activity against RSV, which were better than 1a and ribavirin. In addition, we found that compound 1g displayed the lower cytotoxicity (CC₅₀: 2490.33 μM) and the highest selective index (SI = 673.06), suggesting its promising potential as a candidate for further development. On the other hand, compounds 1a, 1m, 1v, 1ad-1af and 1ah-1ai (IC₅₀s: 1.87-14.28 μM) were more active against IAV than or comparable to ribavirin (IC₅₀: 15.36 ± 0.93 μM). Particularly, the most active compound 1ae (IC₅₀: 1.87 ± 0.58 μM) was found to be 8.2-fold more potent than the reference drug, which could inhibit the virus transcription and replication cycle at an early stage.

Biological Activity of Endophytic Fungi from the Roots of the Medicinal Plant Vernonia anthelmintica

Endophytic fungi were first isolated from the fresh root of the Chinese medicinal plant Vernonia anthelmintica collected from the Hotan Prefecture within the Xinjiang Autonomous region of the People’s Republic of China. This plant has been used in Uyghur traditional medicine to treat vitiligo, a skin condition characterized by patches of the skin losing their pigment. In total, fifteen fungal strains were isolated. Among these, four endophytic fungi were identified by their DNA sequences and registered to GenBank with accession numbers. The isolates were identified as Schizophyllum commune XJA1, Talaromyces sp. XJA4, Aspergillus sp. XJA6, Aspergillus terreus XJA8. Ethyl acetate extracts of all fungal strains were used to quantify melanin content and to identify in vitro biological activity assays including antimicrobial, antioxidant, cytotoxic, antidiabetic and tyrosinase activity on B16 cells. Among the extracts of all four identified strains, the ethyl acetate extract of the Aspergillus sp. XJA6 was chosen for further characterization because it presented the highest biological activity against these tests. In addition, twenty four volatile compounds from the petroleum ether fraction were characterized by GC–MS.

1,2,3-Triazole-containing hybrids as leads in medicinal chemistry: A recent overview

The 1,2,3-triazole ring is a major pharmacophore system among nitrogen-containing heterocycles. These five-membered heterocyclic motifs with three nitrogen heteroatoms can be prepared easily using 'click' chemistry with copper- or ruthenium-catalysed azide-alkyne cycloaddition reactions. Recently, the 'linker' property of 1,2,3-triazoles was demonstrated, and a novel class of 1,2,3-triazole-containing hybrids and conjugates was synthesised and evaluated as lead compounds for diverse biological targets. These lead compounds have been demonstrated as anticancer, antimicrobial, anti-tubercular, antiviral, antidiabetic, antimalarial, anti-leishmanial, and neuroprotective agents. The present review summarises advances in lead compounds of 1,2,3-triazole-containing hybrids, conjugates, and their related heterocycles in medicinal chemistry published in 2018. This review will be useful to scientists in research fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.

Synthesis of novel 2-(1-adamantanylcarboxamido)thiophene derivatives. Selective cannabinoid type 2 (CB2) receptor agonists as potential agents for the treatment of skin inflammatory disease

A set of CB2R ligands, based on the thiophene scaffold, was synthesized and evaluated in in vitro assays. Compounds 8c-i, k, l, bearing the 3-carboxylate and 2-(adamantan-1-yl)carboxamido groups together with apolar alkyl/aryl substituents at 5-position or at 4- and 5-positions of the thiophene ring possess high CB2R affinity at low nanomolar concentration, good receptor selectivity, and agonistic functional activity. The full agonist 8g, showing the best balance between receptor affinity and selectivity, was tested in vitro in an experimental model of allergic contact dermatitis and proved to be able to block the release of MCP-2 in HaCaT cells at 10 μM concentration.

2-Aminothiophene scaffolds: Diverse biological and pharmacological attributes in medicinal chemistry

2-Aminothiophenes are important five-membered heterocyclic building blocks in organic synthesis, and the chemistry of these small molecules is still developing based on the discovery of cyclization by Gewald. Another attractive feature of 2-aminothiophene scaffolds is their ability to act as synthons for the synthesis of biological active thiophene-containing heterocycles, conjugates and hybrids. Currently, the biological actions of 2-aminothiophenes or their 2-N-substituted analogues are still being investigated because of their various mechanisms of action (e.g., pharmacophore and pharmacokinetic properties). Likewise, the 2-aminothiophene family is used as diverse promising selective inhibitors, receptors, and modulators in medicinal chemistry, and these compounds even exhibit effective pharmacological properties in the various clinical phases of appropriate diseases. In this review, major biological and pharmacological reports on 2-aminothiophenes and related compounds have been highlighted; most perspective drug-candidate hits were selected for discussion and described, along with additional synthetic pathways. In addition, we focused on the literature dedicated to 2-aminothiophenes and 2-N-substituted derivatives, which have been published from 2010 to 2017.