Synthesis and antimicrobial evaluation of some novel bis-α,β-unsaturated ketones, nicotinonitrile, 1,2-dihydropyridine-3-carbonitrile, fused thieno[2,3-b]pyridine and pyrazolo[3,4-b]pyridine derivatives

In silico and in vitro evaluation of newly synthesized pyrazolo-pyridine fused tetrazolo-pyrimidines derivatives as potential anticancer and antimicrobial agents

Diversely functionalized pyrazolo-pyridine fused tetrazolo-pyrimidines 10aa-am and 10ba-bn were successfully synthesized via a catalyst-free synthetic protocol with moderate to very good yields. The compounds were evaluated for cytotoxicity against MCF-7 and HEK-293 cells using MTT assay. Among the tested compounds, 10ab (IC50- 23.83 µM) and 10ah (IC50- 23.30 µM) demonstrated the highest potency against MCF-7 cells, while 10bc (IC50- 14.46 µM) and 10bh (IC50- 2.53 µM) exhibited excellent cytotoxicity against HEK-293 cells. Additionally, antibacterial screening was performed against three Gram-negative bacteria (E. coli, P. aeruginosa, and S. enterica) and three Gram-positive bacteria (S. aureus, B. megaterium, and B. subtilis) using broth dilution method, while antifungal activity was assessed against three fungal strains (A. niger, Penicillium, and S. cerevisiae) using agar well diffusion method. In antimicrobial screening, the majority of the compounds demonstrated significant antibacterial efficacy compared to antifungal activity. We also conducted comprehensive computational studies, including DFT calculations, molecular docking and dynamics, and drug-likeness assessments. In the DFT study, compounds 10ac and 10bc displayed stable conformations, indicating their potential for higher therapeutic activity. Molecular docking analyses revealed compelling interactions, with compound 10ah demonstrating docking score -7.42 kcal/mol against catalytical domain PARP1 (PDB ID: 7KK4) and 10bh exhibiting a best docking score -10.77 kcal/mol against human corticotropin-releasing factor receptor 1 (PDB ID: 4Z9G). A 100 ns molecular dynamics (MD) simulation study of compounds 10ah and 10bh revealed the stable conformation and binding energy in a stimulating environment. In drug-likeness assessments, both the compounds 10ah and 10bh adhere all the established guidelines.Communicated by Ramaswamy H. Sarma.

Discovery of new symmetrical and asymmetrical nitrile-containing 1,4-dihydropyridine derivatives as dual kinases and P-glycoprotein inhibitors: synthesis, in vitro assays, and in silico studies

Two new series of symmetric (1a-h) and asymmetric (2a-l) 1,4-DHP derivatives were designed, synthesised, and evaluated as anticancer agents. In vitro anticancer screening of target compounds via National cancer institute “NCI” revealed that analogues 1g, 2e, and 2l demonstrated antiproliferative action with mean growth inhibition percentage “GI%” = 41, 28, and 64, respectively. The reversal doxorubicin (DOX) effects of compounds 1g, 2e, and 2l were examined and illustrated better cytotoxic activity with IC₅₀ =1.12, 3.64, and 3.57 µM, respectively. The most active anticancer analogues, 1g, 2e, and 2l, were inspected for their putative mechanism of action by estimating their epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER-2), and Bruton’s tyrosine kinase (BTK) inhibitory activities. Furthermore, the antimicrobial activity of target compounds was assessed against six different pathogens, followed by determining the minimum inhibitory concentration “MIC” values for the most active analogues. Molecular docking study was achieved to understand mode of interactions between selected inhibitors and different biological targets.

Pyridine Compounds with Antimicrobial and Antiviral Activities

In the context of the new life-threatening COVID-19 pandemic caused by the SARS-CoV-2 virus, finding new antiviral and antimicrobial compounds is a priority in current research. Pyridine is a privileged nucleus among heterocycles; its compounds have been noted for their therapeutic properties, such as antimicrobial, antiviral, antitumor, analgesic, anticonvulsant, anti-inflammatory, antioxidant, anti-Alzheimer’s, anti-ulcer or antidiabetic. It is known that a pyridine compound, which also contains a heterocycle, has improved therapeutic properties. The singular presence of the pyridine nucleus, or its one together with one or more heterocycles, as well as a simple hydrocarbon linker, or grafted with organic groups, gives the key molecule a certain geometry, which determines an interaction with a specific protein, and defines the antimicrobial and antiviral selectivity for the target molecule. Moreover, an important role of pyridine in medicinal chemistry is to improve water solubility due to its poor basicity. In this article, we aim to review the methods of synthesis of pyridine compounds, their antimicrobial and antiviral activities, the correlation of pharmaceutical properties with various groups present in molecules as well as the binding mode from Molecular Docking Studies.

Discovery of New Pyrazolopyridine, Furopyridine, and Pyridine Derivatives as CDK2 Inhibitors: Design, Synthesis, Docking Studies, and Anti-Proliferative Activity

New pyridine, pyrazoloyridine, and furopyridine derivatives substituted with naphthyl and thienyl moieties were designed and synthesized starting from 6-(naphthalen-2-yl)-2-oxo-4-(thiophen-2-yl)-1,2-dihydropyridine-3-carbonitrile (1). The chloro, methoxy, cholroacetoxy, imidazolyl, azide, and arylamino derivatives were prepared to obtain the pyridine-⁻C² functionalized derivatives. The derived pyrazolpyridine-N-glycosides were synthesized via heterocyclization of the C²-thioxopyridine derivative followed by glycosylation using glucose and galactose. The furopyridine derivative 14 and the tricyclic pyrido[3′,2′:4,5]furo[3,2-d]pyrimidine 15 were prepared via heterocyclization of the ester derivative followed by a reaction with formamide. The newly synthesized compounds were evaluated for their ability to in vitro inhibit the CDK2 enzyme. In addition, the cytotoxicity of the compounds was tested against four different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549). The CDK2/cyclin A2 enzyme inhibitory results revealed that pyridone 1, 2-chloro-6-(naphthalen-2-yl)-4-(thiophen-2-yl)nicotinonitrile (4), 6-(naphthalen-2-yl)-4-(thiophen-2-yl)-1H-pyrazolo[3,4-b]pyridin-3-amine (8), S-(3-cyano-6-(naphthaen-2-yl)-4-(thiophen-2-yl)pyridin-2-yl) 2-chloroethanethioate (11), and ethyl 3-amino-6-(naphthalen-2-yl)-4-(thiophen-2-yl)furo[2,3-b]pyridine-2-carboxylate (14) are among the most active inhibitors with IC₅₀ values of 0.57, 0.24, 0.65, 0.50, and 0.93 µM, respectively, compared to roscovitine (IC₅₀ 0.394 μM). Most compounds showed significant inhibition on different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549) with IC₅₀ ranges of 31.3–49.0, 19.3–55.5, 22.7–44.8, and 36.8–70.7 μM, respectively compared to doxorubicin (IC₅₀ 40.0, 64.8, 24.7 and 58.1 µM, respectively). Furthermore, a molecular docking study suggests that most of the target compounds have a similar binding mode as a reference compound in the active site of the CDK2 enzyme. The structural requirements controlling the CDK2 inhibitory activity were determined through the generation of a statistically significant 2D-QSAR model.

Discovery of Novel 3-Cyanopyridines as Survivin Modulators and Apoptosis Inducers

The overexpression of survivin is usually accompanied by an increased resistance of cancer cells to chemotherapeutic agents in addition to cancer aggressiveness. Consequently, survivin is considered as an attractive target to develop new promising anticancer candidates. A series of novel 3-cyanopyridine derivatives was synthesized and assessed for their cytotoxic activity against three human cancer cell lines: prostate carcinoma (PC-3), breast cancer (MDA-MB-231) and hepatocellular carcinoma (HepG2). In addition, their activities were evaluated in comparison with a standard anticancer drug 5-FU. Compounds 5c and 5e both exhibited promising cytotoxicity against all the tested cell lines; especially, 5e showed better cytotoxic effect than the reference drug 5-FU. In order to evaluate the safety of these compounds, they were tested on the normal cell line WI-38, revealing their toxic selectivity toward cancer cells over normal ones. Further studies were performed in order to understand their mechanism of action; we examined the ability of our promising compounds 5c and 5e to induce cell cycle arrest. Both resulted in a notable induction of cell cycle arrest at the G2/M phase, along with an increase in the DNA content in the pre-G1 phase, giving us an indication of the incidence of apoptosis. 5c and 5e were further subjected to additional study using Annexin V-FITC assay in order to evaluate their ability to induce apoptosis. The results showed a marked increase in the early and late apoptotic cells, as well as an increase in the percentage of necrosis. Furthermore, Western blotting assay was accomplished using different concentrations of 5c and 5e. The results revealed a striking reduction in survivin expression through proteasome-dependent survivin degradation in addition to a decrease in the expression of some other inhibitor of apoptosis proteins (IAP) family proteins: Livin, XIAP, and C-IAP1 in a concentration-dependent manner. A docking study of 5c and 5e compounds in the dimerization site of survivin was also performed, showing agreement with the in vitro anti-survivin activity.

Discovery of novel 2-aminonicotinonitrile derivatives with new potential autophagy activity

Background: To clarify the molecular mechanism of novel 2-aminonicotinonitrile autophagy enhancers, two series of novel 2-aminonicotinonitrile derivatives are synthesized and their structure-activity relationship and biological activity were analyzed. Results & methodology: Structure-activity relationship analysis revealed that substituents at C-4 and C-6 position of 7a contribute to enhance their autophagy-inducing activity, while C-5 position substituents have the opposite effect. The most promising compound 7g showed the strongest autophagy-inducing activity and better antiproliferative activity by inducing cell apoptosis and blocking cell cycle G1 arrest in SGC-7901 cells. Conclusion: The novel 2-aminonicotinonitrile autophagy enhancers were for the first time discovered and 7g might be a promising new autophagy enhancer with potential anticancer activity.

Crystal structure, vibrational and optic properties of 2-N-methylamino-3-methylpyridine N-oxide - Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations

The crystal and molecular structure and physicochemical properties of 2-N-methylamino-3-methylpyridine N-oxide (MA3MPO) have been studied. MA3MPO was synthesized from 2-amino-3-methylpyridine by several steps to form colorless crystals suitable for crystallographic analysis. The data reveal that MA3MPO crystallizes in the monoclinic space group P21/n. The studied compound contains a nearly flat triply substituted pyridine skeleton whose structure is stabilized by an intramolecular N-H⋅⋅⋅O hydrogen bond. The N-oxide molecules are connected together by weak C-H⋯O hydrogen bonds, an acceptor of which is the oxygen atom from the N-oxide group. This leads to creation of two-dimensional network of hydrogen bonds. Its IR, Raman, UV-Vis and luminescence spectra have been measured and analyzed on the basis of DFT and NBO quantum chemical calculations in which the B3LYP/6-311++G(d,p) approach was applied. The distribution of the electron levels in the studied compound has been analyzed in terms of the possibility of its participation in the ligand-to-lanthanide ion energy transfer.

Synthesis, Docking Studies, and In Vitro Evaluation of Some Novel Thienopyridines and Fused Thienopyridine-Quinolines as Antibacterial Agents and DNA Gyrase Inhibitors

A series of novel thienopyridines and pyridothienoquinolines (3a,b–14) was synthesized, starting with 2-thioxo-1,2-dihydropyridine-3-carbonitriles 1a and 1b. All compounds were evaluated for their in vitro antimicrobial activity against six bacterial strains. Compounds 3a,b, 4a, 5b, 6a,b, 7a, 9b, 12b, and 14 showed significant growth inhibition activity against both Gram-positive and Gram-negative bacteria compared with the reference drug. The most active compounds (4a, 7a, 9b, and 12b) against Staphylococcus aureus were also tested for their in vitro inhibitory action on methicillin-resistant Staphylococcus aureus (MRSA). The tested compounds showed promising inhibition activity, with the performance of 12b being equal to gentamicin and that of 7a exceeding it. Moreover, the most promising compounds were also screened for their Escherichia coli DNA gyrase inhibitory activity, compared with novobiocin as a reference DNA gyrase inhibitor. The results revealed that compounds (3a, 3b, 4a, 9b, and 12b) had the highest inhibitory capacity, with IC₅₀ values of 2.26–5.87 µM (that of novobiocin is equal to 4.17 µM). Docking studies were performed to identify the mode of binding of the tested compounds to the active site of E. coli DNA gyrase B.

Synthesis, characterization, and antimicrobial evaluation of novel 5-benzoyl-N-substituted amino- and 5-benzoyl-N-sulfonylamino-4-alkylsulfanyl-2-pyridones

The present research describes the synthesis of novel 5-benzoyl-N-substituted-amino- and 5-benzoyl-N-sulfonylamino-4-alkylsulfanyl-2-pyridones 5a–c and 6a–c via the reaction of 2-benzoyl-3,3-bis(alkylthio)acrylonitriles 2a–c with N-cyanoacetohydrazide 3 and cyanoaceto-N-phenylsulfonylhydrazide 4, respectively. Also, the reactivity of the compounds 5a–c toward hydrazine hydrate to give product 1H-pyrazolo[4,3-c]pyridine derivative 7 was studied. In addition, the reactivity of the 2a–c toward 1-cyanoacetyl-4 arylidenesemicarbazides 8a–c afforded 3,5-dihydro[1,2,4]triazolo[1,5-a]pyridine-6-carbonitrile derivatives (12–14)a–c, which reacted with hydrazine hydrate to give 3H-pyrazolo[4,3-c][1,2,4]triazolo[1,5-a]pyridine-6-carbonitrile derivatives 15a–c. The structures of the new products were characterized based on ¹H nuclear magnetic resonance, ¹³C nuclear magnetic resonance, infrared, mass-spectroscopy, and elemental analyses. The products were screened in vitro for their antibacterial and antifungal activity properties.

The mononuclear nickel(II) complex bis(azido-κN)bis[2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ2 N2 ,N3 ]nickel(II) protects tomato from Verticillium dahliae by inhibiting fungal growth and activating plant defences

BACKGROUND

The antifungal properties of the nickel(II) complex bis(azido-κN)bis[2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ² N² ,N³ ]nickel(II) [NiL₂ (N₃ )₂ ] and its parental ligand 2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole were examined to evaluate their ability to protect tomato plants against Verticillium dahliae. Our main objectives were to determine their effects on the in vitro growth of the pathogen, and their aptitude for controlling verticillium wilt and activating plant defence responses in the greenhouse.

RESULTS

NiL₂ (N₃ )₂ exhibited in vitro an elevated inhibition of radial growth of three strains of the pathogen. According to the strain, the EC₅₀ values ranged from 10 to 29 µg mL^-1 for NiL₂ (N₃ )₂ . In the greenhouse, it induced an elevated protection against V. dahliae when it was applied twice as foliar sprays at 50 µg mL^-1 . It reduced the leaf alteration index by 85% and vessel browning by 96%. In addition, its protective ability was associated with the accumulation of H₂ O₂ and the activation of total phenolic content, as well as potentiation of the activity of peroxidase and polyphenol oxidase.

CONCLUSION

These results demonstrated that the coordination of the ligand with Ni associated with the azide as a coligand resulted in an improvement in its biological activity by both inhibiting the growth of V. dahliae and activating plant defence responses. © 2016 Society of Chemical Industry.

Synthesis and Characterization of Some New Bis-Pyrazolyl-Thiazoles Incorporating the Thiophene Moiety as Potent Anti-Tumor Agents

A new series of 1,4-bis(1-(5-(aryldiazenyl)thiazol-2-yl)-5-(thiophen-2-yl)-4,5-dihydro-1H-pyrazol-3-yl)benzenes 3a–i were synthesized via reaction of 5,5′-(1,4-phenylene)bis(3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide) (1) with hydrazonoyl halides 2a–i. In addition, reaction of 1 with ethyl chloroacetate afforded bis-thiazolone derivative 8 as the end product. Reaction of compound 8 with methyl glyoxalate gave bis-thiazolone derivative 10. The structures of the newly synthesized compounds were established on the basis of spectroscopic evidences and their alternative syntheses. All the synthesized compounds were evaluated for their anti-tumor activities against hepatocellular carcinoma (HepG2) cell lines, and the results revealed promising activities of compounds 3g, 5e, 3e, 10, 5f, 3i, and 3f with IC₅₀ equal 1.37 ± 0.15, 1.41 ± 0.17, 1.62 ± 0.20, 1.86 ± 0.20, 1.93 ± 0.08, 2.03 ± 0.25, and 2.09 ± 0.19 μM, respectively.

Microwave assistant synthesis, antifungal activity and DFT theoretical study of some novel 1,2,4-triazole derivatives containing pyridine moiety

In order to investigate the biological activity of novel 1,2,4-triazole compounds, seventeen novel 1,2,4-triazole derivatives containing pyridine moiety were synthesized under microwave assistant condition by multi-step reactions. The structures were characterized by ¹H NMR, MS and elemental analyses. The target compounds were evaluated for their fungicidal activities against Stemphylium lycopersici (Enjoji) Yamamoto, Fusarium oxysporum. sp. cucumebrium, and Botrytis cinerea in vivo, and the results indicated that some of the title compounds displayed excellent fungicidal activities. Theoretical calculation of the title compound was carried out with B3LYP/6-31G (d,p). The full geometry optimization was carried out using 6-31G (d,p) basis set, and the frontier orbital energy, atomic net charges were discussed, and the structure-activity relationship was also studied.