Synthesis, antitumor and antimicrobial activities of 4-(4-chlorophenyl)-3-cyano-2-(β-O-glycosyloxy)-6-(thien-2-yl)-nicotinonitrile

Recent Advances in the Synthesis of Acyclic Nucleosides and Their Therapeutic Applications

DNA is commonly known as the "molecule of life" because it holds the genetic instructions for all living organisms on Earth. The utilization of modified nucleosides holds the potential to transform the management of a wide range of human illnesses. Modified nucleosides and their role directly led to the 2023 Nobel prize. Acyclic nucleosides, due to their distinctive physiochemical and biological characteristics, rank among the most adaptable modified nucleosides in the field of medicinal chemistry. Acyclic nucleosides are more resistant to chemical and biological deterioration, and their adaptable acyclic structure makes it possible for them to interact with various enzymes. A phosphonate group, which is linked via an aliphatic functionality to a purine or a pyrimidine base, distinguishes acyclic nucleoside phosphonates (ANPs) from other nucleotide analogs. Acyclic nucleosides and their derivatives have demonstrated various biological activities such as anti-viral, anti-bacterial, anti-cancer, anti-microbial, etc. Ganciclovir, Famciclovir, and Penciclovir are the acyclic nucleoside-based drugs approved by FDA for the treatment of various diseases. Thus, acyclic nucleosides are extremely useful for generating a variety of unique bioactive chemicals. Their biological activities as well as selectivity is significantly influenced by the stereochemistry of the acyclic nucleosides because chiral acyclic nucleosides have drawn a lot of interest due to their intriguing biological functions and potential as medicines. For example, tenofovir's (R) enantiomer is roughly 50 times more potent against HIV than its (S) counterpart. We can confidently state, "The most promising developments are yet to come in the realm of acyclic nucleosides!" Herein, we have covered the most current developments in the field of chemical synthesis and therapeutic applications of acyclic nucleosides based upon our continued interest and activity in this field since mid-1990's.

Pyridine Derivatives as Insecticides─Part 4: Synthesis, Crystal Structure, and Insecticidal Activity of Some New Thienylpyridines, Thienylthieno[2,3-b]pyridines, and Related Heterocyclic Derivatives

The reaction of ethyl 5-cyano-2-methyl-4-(thiophen-2-yl)-6-thioxo-1,6-dihydropyridine-3-carboxylate (1) with 2-chloroacetamide or its N-aryl derivatives gave ethyl 6-((2-amino-2-oxoethyl)thio)-5-cyano-2-methyl-4-(thiophen-2-yl) nicotinate (2a) or its N-aryl derivatives 2b-f, respectively. Cyclization of 2a-f into their isomers 3a-f was carried out by heating in absolute ethanol in the presence of a catalytic amount of sodium ethoxide. The o-aminoamide 3a was reacted with some aryl aldehydes in refluxing ethanol containing a few drops of conc. HCl to afford the corresponding tetrahydropyrimidinones 4a-d. The cyclocondensation reaction of 3a with some cycloalkanones such as cyclopentanone and cyclohexanone gave the corresponding spiro compounds 5a,b. The crystal structures of compounds 2a and 2d were determined by single-crystal X-ray diffraction techniques. All new compounds were evaluated for their insecticidal activity toward nymphs and adults of Aphis gossypi.

Synthesis of Some Mono- and Disaccharide-Grafting Phthalazine Derivatives and Some New Se-Nucleoside Analogues: Antibacterial Properties, Quantum Chemical Calculations, and Cytotoxicity

A highly efficient and versatile synthetic approach for the synthesis of 4-(pyren-1-ylmethyl)-1-(d-glycosyloxy) phthalazine nucleosides 11a,b, 13, β-S-nucleosides 16, 18, 20, and acyclo C-nucleosides 23a,b, 24, 25 and 27a-f was described and fully characterized. Furthermore, a series of desired new nucleoside analogues containing Se of 4-(pyren-1-ylmethyl) phthalazine-1(2H)-selenone 28-33 were synthesized. The structures of all reported compounds were confirmed by IR, ¹H-NMR, ¹³C-NMR, MS and elemental analysis. All compounds have been screened for their antibacterial and antifungal activities. Maximum activity was shown by 20 and 33a comparable to the standard drugs with lower toxicity. The cytotoxicity of the selected compound was measured and evaluated. The energy gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital was calculated using theoretical computations to reflect the chemical reactivity and kinetic stability of the synthesized compounds. Using density functional theory (DFT), electronic parameters such as the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) and the molecular electrostatic potential (MEPS) were calculated. On the basis of different studied structures, these properties were computed in order to elucidate the chemical reactivity and the kinetic stability. Obviously, the band gap energy (Eg) of structures studied reveals that the lowest band gap obtained for the structure 16-a indicates that it has the highest chemical reactivity and lowest kinetic stability.

A Small-Molecule Inhibitor to the Cytokine Interleukin-4

Interleukin-4 (IL-4) is a multifunctional cytokine and an important regulator of inflammation. When deregulated, IL-4 activity is associated with asthma, allergic inflammation, and multiple types of cancer. While antibody-based inhibitors targeting the soluble cytokine have been evaluated clinically, they failed to achieve their end points in trials. Small-molecule inhibitors are an attractive alternative, but identifying effective chemotypes that inhibit the protein-protein interactions between cytokines and their receptors remains an active area of research. As a result, no small-molecule inhibitors to the soluble IL-4 cytokine have yet been reported. Here, we describe the first IL-4 small-molecule inhibitor identified and characterized through a combination of binding-based approaches and cell-based activity assays. The compound features a nicotinonitrile scaffold with micromolar affinity and potency for the cytokine and disrupts type II IL-4 signaling in cells. Small-molecule inhibitors of these important cell-signaling proteins have implications for numerous immune-related disorders and inform future drug discovery and design efforts for these challenging protein targets.

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.

Facile synthesis and antiproliferative activity of new 3-cyanopyridines

Background

Pyridines have been reported to possess various pharmacological activities.

Results

Sodium 3-oxo-3-(2-oxo-2H-chromen-3-yl)prop-1-en-1-olate (2) and sodium 3-oxo-3-(3-oxo-3H-benzo[f]chromen-2-yl)prop-1-en-1-olate (7) were prepared and reacted with 2-cyano-N'-(1-aryl(heteryl)ethylidene)acetohydrazides 3a-d to produce 2-oxo-1,2-dihydropyridine-3-carbonitrile derivatives 5a-d and 9a-d, respectively, in good yields. Also, 3a-d reacted with sodium (2-oxocyclopentylidene)methanolate (11a) or sodium (2-oxocyclohexylidene) methanolate (11b) to yield 2-oxo-tetrahydro-1H-cyclopenta[b]pyridine-3-carbonitriles 13a-d and 2-oxo-hexahydroquinoline-3-carbonitriles 13e-h, respectively. The mechanisms that account for the formation of the products are discussed. Additionally, the structures of all the newly synthesized products are confirmed, based on elemental analysis and spectral data. Several of the newly synthesized compounds are evaluated for their antitumor activity against HEPG2 and their structure activity relationship (SAR) was studied.

Conclusions

The results revealed that the pyridine derivatives 5c and 5d (IC₅₀ = 1.46, 7.08 µM, respectively) have promising antitumor activity against liver carcinoma cell line (HEPG2), compared to the reference drug, doxorubicin.

Cytotoxic Effects of Newly Synthesized Heterocyclic Candidates Containing Nicotinonitrile and Pyrazole Moieties on Hepatocellular and Cervical Carcinomas

In this study, a series of newly synthesized substituted pyridine 9, 11-18, naphthpyridine derivative 10 and substituted pyrazolopyridines 19-23 by using cycnopyridone 8 as a starting material. Some of the synthesized candidates are evaluated as anticancer agents against different cancer cell lines. In vitro cytotoxic activities against hepatocellular and cervical carcinoma cell lines were evaluated using standard MTT assay. Different synthesized compounds exhibited potential in vitro cytotoxic activities against both HepG2 and HeLa cell lines. Furthermore, compared to standard positive control drugs, compounds 13 and 19 showed the most potent cytotoxic effect with IC₅₀ values of 8.78 ± 0.7, 5.16 ± 0.4 μg/mL, and 15.32 ± 1.2 and 4.26 ± 0.3 μg/mL for HepG2 and HeLa cells, respectively.

Synthesis, Molecular Docking and in Vitro Screening of Some Newly Synthesized Triazolopyridine, Pyridotriazine and Pyridine⁻Pyrazole Hybrid Derivatives

A series of novel pyridine and fused pyridine derivatives have been prepared starting from 6-(3,4-dimethylphenyl)-2-hydrazinyl-4-(thiophen-2-yl)-pyridine-3-carbonitrile 1 which on treatment with appropriate formic acid, acetic acid/acetic anhydride, benzoyl chloride and/or carbon disulfide afforded the corresponding triazolopyridine derivatives 2–5. Also, treatment of hydrazide 1 with diethyloxalate, chloroacetyl chloride, chloroacetic acid and/or 1,2-dichloroethane yielded the corresponding pyridotriazine derivatives 7–10. Further transformation of compound 1 with a different active methylene group, namely acetyl acetone, diethylmalonate, ethyl cyanoacetate, ethyl benzoylacetate and/or ethyl acetoacetate, produced the pyridine–pyrazole hybrid derivatives 11–15. These newly synthesized compounds (1–15) were subjected to in silico molecular docking screenings towards GlcN-6-P synthase as the target protein. The results revealed moderate to good binding energies of the ligands on the target protein. All the newly prepared products exhibited antimicrobial and antioxidant activity.

2-Methylpyridinium 2-carboxy-6-nitrobenzoate

In the title molecular salt, C6H8N+·C8H4NO6−, the pyridine ring is protonated at the N atom and the anion is deprotonated at one of the hydroxy O atoms. The dihedral angle between the planes of the benzene and pyridine rings is 8.45 (9)°. In the anion, the deprotonated carboxylate group is twisted at an angle of 73.78 (11)° from the attached benzene ring, whereas the carboxy group is slightly oriented at an angle of 14.98 (10)°. N—H...O and O—H...O hydrogen bonds link the anions and cations into an infinite chain along thecaxis and these chains are further consolidated by C—H...O hydrogen bonds to form a three-dimensional network. The crystals structure is also influenced by weak π–π interactions [centroid–centroid distance = 3.9055 (9) Å].

New 3-Cyano-2-Substituted Pyridines Induce Apoptosis in MCF 7 Breast Cancer Cells

The synthesis of new 3-cyano-2-substituted pyridines bearing various pharmacophores and functionalities at position 2 is described. The synthesized compounds were evaluated for their in vitro anti-cancer activities on five cancer cell lines using 5-FU as reference compound. The results revealed that the benzohydrazide derivative 9a induced growth inhibition in human breast cancer cell line MCF-7 with an IC₅₀ value of 2 μM and it showed lower cytotoxicity on MCF-12a normal breast epithelial cells. Additionally, 9a induced apoptotic morphological changes and induced apoptosis in MCF-7 in a dose and time-dependent manner according to an enzyme linked immunosorbent apoptosis assay which is further confirmed by a TUNEL assay. Flow cytometric analysis indicated that 9a arrested MCF-7 cells in the G1 phase, which was further confirmed by increased expression of p21 and p27 and reduced expression of CDK2 and CDK4. Western blot data revealed significant upregulation of the expression of p53, Bax, caspase-3 and down-regulation of Bcl-2, Mdm-2 and Akt. Additionally, 9a increased the release of cytochrome c from mitochondria to cytoplasm which provokes the mitochondrial apoptotic pathway while it showed no significant change on the expression of the death receptor proteins procaspase-8, caspase-8 and FAS. Furthermore, 9a reduced the expression of phospho AKT and β-catenin in dose dependent manner while inhibiting the expression of migration-related genes such as matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGF). Our findings suggest that compound 9a could be considered as a lead structure for further development of more potent apoptosis inducing agents with anti-metastatic activities.

Synthesis and Biological Evaluation of 2-Oxo/Thioxoquinoxaline and 2-Oxo/Thioxoquinoxaline-Based Nucleoside Analogues

Several O- and S-quinoxaline glycosides have been prepared by glycosidation of 3-methyl-2-oxo(thioxo)-1,2-dihydroquinoxalines 1a,b with α-D-glucopyranosyl, α-D-galactopyranosyl, and α-D-lactosyl bromide in the presence of K2CO3 followed by deacetylation with Et3N/H2O. Furthermore, alkylation of 1a,b with 4-bromobutyl acetate, 2-acetoxyethoxymethyl bromide, and 3-chloropropanol afforded the corresponding O- and S-acycloquinoxaline nucleosides. Reaction of 1b with chloroacetic acid followed by condensation with sulfacetamide and sulfadiazine in the presence of Et3N/THF and ethyl chloroformate gave the corresponding sulfonamide derivatives 14 and 15, respectively. The structures of new compounds were confirmed by using IR, (1)H, (13)C NMR spectra and microanalysis. Some of these compounds were screened in vitro for antitumor and antifungal activities.

Synthesis and antimicrobial activity of some 2-pyridone nucleosides containing a sulfonamide moiety

Glycosylation of 2-pyridonesulfonamide 1a,b with glycosyl/galactosyl bromide gave the corresponding glycosides 2a,b, 3a,b, 6a,b, and 7a,b, respectively. Deacetylation of the resulting glycosides gave the corresponding glycosides 4a,b, 5a,b, 8a,b, and 9a,b, respectively, in good yields. Furthermore, reaction of 2-pyridonesulfonamide 1b with lactosyl bromide gave a mixture the corresponding N, O-lactosides 10 and 11, which were deacetylated to give the corresponding glycosides 12 and 13, respectively. The structures of the new synthesized compounds were characterized by using IR, 1H, 13C NMR spectra, and microanalysis. Selected members of these compounds were screened for antimicrobial activity.

Crystal structure of 2-benzyl-amino-4-(4-bromo-phen-yl)-6,7-di-hydro-5H-cyclo-penta-[b]pyridine-3-carbo-nitrile

In the title compound C22H18BrN3, the cyclo-pentane ring adopts an envelope conformation with the central methyl-ene C atom as the flap. The dihedral angles between the central pyridine ring and the pendant benzyl and and bromo-benzene rings are 82.65 (1) and 47.23 (1)°, respectively. In the crystal, inversion dimers linked by pairs of N-H⋯Nn (n = nitrile) hydrogen bonds generate R 2 (2)(12) loops. These dimers are linked by weak π-π inter-actions [centroid-centroid distance = 3.7713 (14) Å] into a layered structure.

Crystal structure of 2-(2-bromo-phen-yl)-4-(1H-indol-3-yl)-6-(thio-phen-2-yl)pyridine-3-carbo-nitrile

In the title compound, C24H14BrN3S, the dihedral angles between the planes of the pyridine ring and the pendant thio-phene ring, the indole ring system (r.m.s. deviation = 0.022 Å) and the bromo-benzene ring are 9.37 (17), 21.90 (12) and 69.01 (15)°, respectively. The approximate coplanarity of the central ring and the indole ring system is supported by two intra-molecular C-H⋯N inter-actions. In the crystal, inversion dimers linked by pairs of N-H⋯N hydrogen bonds generate R 2 (2)(16) loops and the dimers are linked by C-H⋯π and aromatic π-π stacking [shortest centroid-centroid separation = 3.729 (3) Å] into a three-dimensional network.

Synthesis and biological evaluation of 2-oxonicotinonitriles and 2-oxonicotinonitrile based nucleoside analogues

Drug resistance and emergence of new pathogens highlight the need for developing new therapeutic agents. We focused on 2-oxonicotinonitrile (2-ONN) as derivative of the natural product 2-pyridinone.1 Herein, we describe the synthesis of 2-ONNs bearing two aryl groups, which we coupled with organohalides, including three glycosyl bromides, to prepare the nucleoside analogues. Coupling occurred mostly at the 2-ONN ring nitrogen to give the aimed targets, and in a few cases, it happened at the 2-oxo position giving O-alkylation products. Free 2-ONNs and their acetylated nucleosides were tested against a number of viruses. The nucleoside analogue 2a_Ac showed good anti SARS-CoV and anti influenza A (H₅N₁) activities. Additionally, 7b had good activity against Gram positive bacterium, Bacillis subtilis.

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2-Oxonicotinonitriles with two aryl groups were coupled with several organohalides.

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The coupling occurred mostly at the ring nitrogen.

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In a few cases, the coupling occurred at the 2-oxo position.

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Antimicrobial and antiviral activities were tested for acetylated and free compounds.

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One nucleoside analogue showed good anti SARS and anti influenza activity.

Synthesis of alkynyl/alkenyl-substituted pyridine derivatives via heterocyclization and Pd-mediated Sonogashira/Heck coupling process in one-pot: a new MCR strategy

The present MCR strategy opens new avenues in the development of i) a diversity-oriented new cyanopyridine based compound library and ii) new chemical entities other than the present reported molecules.

6-(4-Aminophenyl)-2-methoxy-4-phenylnicotinonitrile

In the structure of the title nicotino­nitrile derivative, C₁₉H₁₅N₃O, the pyridine ring makes dihedral angles of 11.50 (7) and 43.36 (8)° with the 4-amino­phenyl and phenyl rings, respectively, and the dihedral angle between the phenyl rings is 36.28°. In the crystal, mol­ecules are linked by N—H⋯N hydrogen bonds into wave-like sheets parallel to (10-2). These sheets are stacked by π–π inter­actions between the 4-amino­phenyl rings of adjacent sheets, with centroid–centroid distances of 3.7499 (9) Å. C—H⋯π inter­actions are also present.

6-Methoxy-4-(2,4,5-trimethoxyphenyl)-2,2′-bipyridine-5-carbonitrile

In the title 3-cyano­pyridine derivative, C₂₁H₁₉N₃O₄, the 3-cyano-substituted pyridine ring forms dihedral angles of 2.35 (5) and 41.60 (5)° with the unsubstituted pyridine and 2,4,5-trimeth­oxy-substituted benzene rings, respectively. The dihedral angle between the unsubstituted pyridine and benzene rings is 39.84 (5)°. The meth­oxy groups form C_meth­yl—O—C—(C,N) torsion angles in the range 0.80 (15)–11.45 (15)°. In the crystal, mol­ecules related by 2₁ screw axes are linked by weak C—H⋯N hydrogen bonds along [010]. In addition, weak C—H⋯π inter­actions and π–π stacking inter­actions between pyridine rings, with a centroid–centroid distance of 3.6448 (6) Å, are observed.