Synthesis, Molecular Docking Screening and Anti-Proliferative Potency Evaluation of Some New Imidazo[2,1-b]Thiazole Linked Thiadiazole Conjugates

Molecular dynamics simulation approach of hybrid chalcone-thiazole complex derivatives for DNA gyrase B inhibition: lead generation

Compounds bearing thiazole and chalcone groups have been reported to be excellent leads for antibacterial, antitubercular and anticancer activities. In view of this, we performed quantitative structure-activity relationship studies using QSARINS for dataset preparation and for developing validated QSAR models that can predict novel series of thiazole-chalcone hybrids and further evaluate them for bioactivities. The molecular descriptors AATS8i, AVP-1, MoRSEE17 and GATSe7 were found to be active in predicting the structure-activity relationship. Molecular docking and dynamics simulation studies of the developed leads have shown insights into structural analysis. Furthermore, computational studies using AutoDock and Desmond predicted the key binding interactions responsible for the activity and the SwissADME tool computed the in silico drug likeliness properties. The lead compound 178 generated through this study creates a route for the optimization and development of novel drugs against tuberculosis infections. RMSD, RMSF, RoG, H-bond and SASA analysis confirmed the stable binding of compound 178 with the 6J90 structure. In addition, MM-PBSA and MM-GBSA also confirm the docking results. We propose the designed compound 178 as the best theoretical lead, which may further be experimentally studied for selective inhibition.

Design, synthesis and molecular docking of novel substituted azepines as inhibitors of PI3K/Akt/TSC2/mTOR signaling pathway in colorectal carcinoma

A series of novel substituted azepines (2-7) was synthesized using both traditional and ultrasonic techniques. The efficiency of the reaction rate and yield was improved by sonication technique. We identified the newly synthesized compounds based on their melting points, elemental analyses, and spectral data. Human cancers are regulated mainly by the phosphatidylinositol 3-kinase/protein kinases B (PI3K/Akt) pathway, and its abnormal activation is linked to carcinogenesis, and angiogenesis. Using in-silico studies, we evaluated the ability of all the novel substituted diazepines and oxazepines to prevent cancer growth and metastasis by targeting the PI3K/Akt signaling pathway. Based on our findings, compounds 4a and 7a were chosen for in-vitro testing as they ranked via molecular docking the highest binding energies of -10.9, -10.3, -10.6, and -10.4 kcal/mol respectively. Compounds 4a and 7a displayed significant cytotoxicity on Caco-2 colorectal cancer cells with IC₅₀ values of 8.445 ± 2.26 and 33.04 ± 2.06 μM, respectively. Additionally, they considerably suppressed the PI3K/Akt proteins and generated reactive oxygen species (ROS), which increased p53 and Bax, decreased Bcl-₂ levels, and arrested the cell cycle at sub-G0/G1 phase. We also observed a remarkable overexpression of the Tuberous Sclerosis Complex 2 (TSC2) gene, an inhibitor of the mammalian target of rapamycin (mTOR). These results showed that compounds 4a and 7a obeyed Lipinski's rule of five and might be potential cancer treatment scaffolds by preventing metastasis and proliferation via blocking the PI3K/Akt/TSC2/m-TOR signaling pathway. This supports our hypothesis that diazepine 4a and oxazepine 7a are promising drug candidates for colorectal cancer.

Novel Thiadiazole-Based Molecules as Promising Inhibitors of Black Fungi and Pathogenic Bacteria: In Vitro Antimicrobial Evaluation and Molecular Docking Studies

Novel 1,3,4-thiadiazole derivatives were synthesized through the reaction of methyl 2-(4-hydroxy-3-methoxybenzylidene) hydrazine-1-carbodithioate and the appropriate hydrazonoyl halides in the presence of a few drops of diisopropylethylamine. The chemical structure of the newly fabricated compounds was inferred from their microanalytical and spectral data. With the increase in microbial diseases, fungi remain a devastating threat to human health because of the resistance of microorganisms to antifungal drugs. COVID-19-associated pulmonary aspergillosis (CAPA) and COVID-19-associated mucormycosis (CAM) have higher mortality rates in many populations. The present study aimed to find new antifungal agents using the disc diffusion method, and minimal inhibitory concentration (MIC) values were estimated by the microdilution assay. An in vitro experiment of six synthesized chemical compounds exhibited antifungal activity against Rhizopus oryzae; compounds with an imidazole moiety, such as the compound 7, were documented to have energetic antibacterial, antifungal properties. As a result of these findings, this research suggests that the synthesized compounds could be an excellent choice for controlling black fungus diseases. Furthermore, a molecular docking study was achieved on the synthesized compounds, of which compounds 2, 6, and 7 showed the best interactions with the selected protein targets.

SAR analysis of heterocyclic compounds with monocyclic and bicyclic structures as antifungal agents

Infections caused by eukaryotic organisms, such as fungi, are generally more difficult to treat than bacterial infections. With the widespread use of antifungal drugs in humans and plants, resistance and toxicity have emerged. Therefore, it is desirable to develop new antifungal drugs with low toxicity that are not susceptible to the development of resistance. This review presents a summary of the past 2017 to 2021 years of research on heterocyclic compounds as antifungal agents for use in humans and plants, focusing on the structure-activity relationships (SAR) of these compounds. This review may provide ideas and data for designing and developing new antifungal drugs with fewer side effects compared with currently available drugs.

Synthesis, Molecular Docking Analysis and in Vitro Biological Evaluation of Some New Heterocyclic Scaffolds-Based Indole Moiety as Possible Antimicrobial Agents

In the present study, a general approach for the synthesis of 1-(1H-indol-3-yl)-3,3-dimercaptoprop-2-en-1-one (1) and 5-(1H-indol-3-yl)-3H-1,2-dithiole-3-thione (2) was performed. They are currently used as efficient precursors for the synthesis of some new compounds bearing five- and/or six-membered heterocyclic moieties, e.g., chromenol (3, 4), 3,4-dihydroquinoline (7, 8) and thiopyran (10, 12)-based indole core. In addition, molecular docking studies were achieved, which showed that all the newly synthesized compounds are interacting with the active site region of the target enzymes, the targets UDP-N-acetylmuramatel-alanine ligase (MurC), and human lanosterol14α-demethylase, through hydrogen bonds and pi-stacked interactions. Among these docked ligand molecules, the compound (9) was found to have the minimum binding energy (−11.5 and −8.5 Kcal/mol) as compared to the standard drug ampicillin (−8.0 and −8.1 Kcal/mol) against the target enzymes UDP-N-acetylmuramatel-alanine ligase (MurC), and Human lanosterol14α-demethylase, respectively. Subsequently, all new synthesized analogues were screened for their antibacterial activities against Gram-positive (Bacillus subtilis), and Gram-negative bacteria (Escherichia coli), as well as for antifungal activities against Candida albicans and Aspergillus flavus. The obtained data suggest that the compounds exhibited good to excellent activity against bacterial and fungi strains. The compound (E)-2-(6-(1H-indole-3-carbonyl)-5-thioxotetrahydrothieno [3,2-b]furan-2(3H)-ylidene)-3-(1H-indol-3-yl)-3-oxopropanedithioic acid (9) showed a high binding affinity as well as an excellent biological activity. Therefore, it could serve as the lead for further optimization and to arrive at potential antimicrobial agent.

Solvent-Free Synthesis, In Vitro and In Silico Studies of Novel Potential 1,3,4-Thiadiazole-Based Molecules against Microbial Pathogens

A new series of 1,3,4-thiadiazoles was synthesized by the reaction of methyl 2-(4-hydroxy-3-methoxybenzylidene) hydrazine-1-carbodithioate (2) with selected derivatives of hydrazonoyl halide by grinding method at room temperature. The chemical structures of the newly synthesized derivatives were resolved from correct spectral and microanalytical data. Moreover, all synthesized compounds were screened for their antimicrobial activities using Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Bacillus subtilis, Staphylococcus aureus, and Candida albicans. However, compounds 3 and 5 showed significant antimicrobial activity against all tested microorganisms. The other prepared compounds exhibited either only antimicrobial activity against Gram-positive bacteria like compounds 4 and 6, or only antifungal activity like compound 7. A molecular docking study of the compounds was performed against two important microbial enzymes: tyrosyl-tRNA synthetase (TyrRS) and N-myristoyl transferase (Nmt). The tested compounds showed variety in binding poses and interactions. However, compound 3 showed the best interactions in terms of number of hydrogen bonds, and the lowest affinity binding energy (−8.4 and −9.1 kcal/mol, respectively). From the in vitro and in silico studies, compound 3 is a good candidate for the next steps of the drug development process as an antimicrobial drug.

Synthesis, characterization, in silico molecular docking, and antibacterial activities of some new nitrogen-heterocyclic analogues based on a p-phenolic unit

Compounds 6a and 6b (with pyrimidine moiety, amide linkage, and phenolic substrate) might be potent bacterial flavohemoglobin (flavoHB) inhibitors and they could set a promising starting point for future design of antibacterial agents.

Synthesis, Identification, Computer-Aided Docking Studies, and ADMET Prediction of Novel Benzimidazo-1,2,3-triazole Based Molecules as Potential Antimicrobial Agents

2-azido-1H-benzo[d]imidazole derivatives 1a,b were reacted with a β-ketoester such as acetylacetone in the presence of sodium ethoxide to obtain the desired molecules 2a,b. The latter acted as a key molecule for the synthesis of new carbazone derivatives 4a,b that were submitted to react with 2-oxo-N-phenyl-2-(phenylamino)acetohydrazonoyl chloride to obtain the target thiadiazole derivatives 6a,b. The structures of the newly synthesized compounds were inferred from correct spectral and microanalytical data. Moreover, the newly prepared compounds were subjected to molecular docking studies with DNA gyrase B and exhibited binding energy that extended from -9.8 to -6.4 kcal/mol, which confirmed their excellent potency. The compounds 6a,b were found to be with the minimum binding energy (-9.7 and -9.8 kcal/mol) as compared to the standard drug ciprofloxacin (-7.4 kcal/mol) against the target enzyme DNA gyrase B. In addition, the newly synthesized compounds were also examined and screened for their in vitro antimicrobial activity against pathogenic microorganisms Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, Aspergillus niger, and Candida albicans. Among the newly synthesized molecules, significant antimicrobial activity against all the tested microorganisms was obtained for the compounds 6a,b. The in silico and in vitro findings showed that compounds 6a,b were the most active against bacterial strains, and could serve as potential antimicrobial agents.

New Amino Acid Schiff Bases as Anticancer Agents via Potential Mitochondrial Complex I-Associated Hexokinase Inhibition and Targeting AMP-Protein Kinases/mTOR Signaling Pathway

Two series of novel amino acid Schiff base ligands containing heterocyclic moieties, such as quinazolinone 3–11 and indole 12–20 were successfully synthesized and confirmed by spectroscopic techniques and elemental analysis. Furthermore, all compounds were investigated in silico for their ability to inhibit mitochondrial NADH: ubiquinone oxidoreductase (complex I) by targeting the AMPK/mTOR signaling pathway and inhibiting hexokinase, a key glycolytic enzyme to prevent the Warburg effect in cancer cells. This inhibitory pathway may be an effective strategy to cause cancer cell death due to an insufficient amount of ATP. Our results revealed that, out of 18 compounds, two (11 and 20) were top-ranked as they exhibited the highest binding energies of −8.8, −13.0, −7.9, and −10.0 kcal/mol in the docking analysis, so they were then selected for in vitro assessment. Compound 11 promoted the best cytotoxic effect on MCF-7 with IC₅₀ = 64.05 ± 0.14 μg/mL (0.135 mM) while compound 20 exhibited the best cytotoxic effect on MDA-231 with IC₅₀ = 46.29 ± 0.09 μg/mL (0.166 mM) Compounds 11 and 20 showed significant activation of AMPK protein and oxidative stress, which led to elevated expression of p53 and Bax, reduced Bcl-2 expression, and caused cell cycle arrest at the sub-G₀/G₁ phase. Moreover, compounds 11 and 20 showed significant inhibition of the mTOR protein, which led to the activation of aerobic glycolysis for survival. This alternative pathway was also blocked as compounds 11 and 20 showed significant inhibitory effects on the hexokinase enzyme. These findings demonstrate that compounds 11 and 20 obeyed Lipinski’s rule of five and could be used as privileged scaffolds for cancer therapy via their potential inhibition of mitochondrial complex I-associated hexokinase.

Effect of the Relative Positions of Di-Laterally Substituted Schiff Base Derivatives: Phase Transition and Computational Investigations

Two new laterally di-substituted derivatives namely, (E)-4-(((2-Chlorophenyl)imino)methyl)-3-methoxyphenyl 4-(alkoxy)benzoate, were designed and investigated for their mesomorphic properties. Elucidation of their molecular structures was carried out by elemental analyses, NMR and FT-IR, spectroscopy. Phase transitions were examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The optimized geometrical architectures of both compounds were deduced theoretically using GAUSSIAN 09 program. In order to establish the most probable conformation for each compound, four probable conformations were predicted for their positional isomers which vary according to the orientations of the two lateral groups. The results were used to correlate the experimental measurements with the predicted conformations. The study revealed that the investigated derivatives are non-mesomorphic and the orientations, as well as positions of the two-lateral groups, have a significant effect on the molecular packing of the molecules, their geometrical and thermal parameters.

Lysozyme and Human Serum Albumin Proteins as Potential Nitric Oxide Cardiovascular Drug Carriers: Theoretical and Experimental Investigation

Nitric oxide-containing drugs present a critical remedy for cardiovascular diseases. Nitroglycerin (NG, O-NO) and S-nitrosoglutathione (SNG, S-NO) are the most common nitric oxide drugs for cardiovascular diseases. Insights regarding the binding affinity of NO drugs with lysozyme and human serum albumin (HSA) proteins and their dissociation mechanism will provide inquisitive information regarding the potential of the proteins as drug carriers. For the first time, the binding interactions and affinities are investigated using molecular docking, conventional molecular dynamics, steered molecular dynamics, and umbrella sampling to explore the ability of both proteins to act as nitric oxide drug carriers. The molecular dynamics simulation results showed higher stability of lysozyme-drug complexes compared to HSA. For lysozyme, cardiovascular drugs were bound in the protein cavity mainly by the electrostatic and hydrogen bond interactions with residues ASP53, GLN58, ILE59, ARG62, TRP64, ASP102, and TRP109. For HSA, key binding residues were ARG410, TYR411, LYS414, ARG485, GLU450, ARG486, and SER489. The free energy profiles produced from umbrella sampling also suggest that lysozyme-drug complexes had better binding affinity than HSA-drug. Binding characteristics of nitric oxide-containing drugs NG and SNG to lysozyme and HSA proteins were studied using fluorescence and UV-vis absorption spectroscopy. The relative change in the fluorescence intensity as a function of drug concentrations was analyzed using Stern-Volmer calculations. This was also confirmed by the change in the UV-vis spectra. Fluorescence quenching results of both proteins with the drugs, based on the binding constant values, demonstrated significantly weak binding affinity to NG and strong binding affinity to SNG. Both computational and experimental studies provided important data for understanding protein-drug interactions and will aid in developing potential drug carrier systems in cardiovascular diseases.

Eco-Friendly Synthesis, Biological Evaluation, and In Silico Molecular Docking Approach of Some New Quinoline Derivatives as Potential Antioxidant and Antibacterial Agents

A new series of quinoline derivatives 5–12 were efficiently synthesized via one-pot multicomponent reaction (MCR) of resorcinol, aromatic aldehydes, β-ketoesters, and aliphatic/aromatic amines under solvent-free conditions. All products were obtained in excellent yields, pure at low-cost processing, and short time. The structures of all compounds were characterized by means of spectral and elemental analyses. In addition, all the synthesized compounds 5–12 were in vitro screened for their antioxidant and antibacterial activity. Moreover, in silico molecular docking studies of the new quinoline derivatives with the target enzymes, human NAD (P)H dehydrogenase (quinone 1) and DNA gyrase, were achieved to endorse their binding affinities and to understand ligand–enzyme possible intermolecular interactions. Compound 9 displayed promising antioxidant and antibacterial activity, as well as it was found to have the highest negative binding energy of -9.1 and -9.3 kcal/mol for human NAD (P)H dehydrogenase (quinone 1) and DNA gyrase, respectively. Further, it complied with the Lipinski’s rule of five, Veber, and Ghose. Therefore, the quinoline analogue 9 could be promising chemical scaffold for the development of future drug candidates as antioxidant and antibacterial agents.

Optical and Thermal Investigations of New Schiff Base/Ester Systems in Pure and Mixed States

New mesomorphic series, 4-hexadecyloxy phenyl-imino-4'-(3-methoxyphenyl)-4″-alkoxybenzoates (An), were prepared and investigated with different thermal and mesomorphic techniques. The synthesized homologous series constitutes four members that differ from each other in the terminal length of flexible chain (n) attached to phenyl ester moiety, which varies between n = 6, 8, 10, and 12 carbons. A lateral CH3O group is attached to the central benzene ring in the meta position with respect to the ester moiety. Molecular structures of all newly prepared homologues were elucidated via FT-IR, 1H and 13C NMR spectroscopy. Mesomorphic and thermal properties were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and the mesophases identified by polarized optical microscopy (POM). DSC and POM examinations revealed that all members of the present series (An) exhibit a purely enantiotropic nematic (N) phase. Comparative evaluations and binary phase diagrams were established between the present homologues and their corresponding shorter one (Bn). The examination revealed that, the length of the flexible alkoxy chain incorporated into the phenylimino moiety is highly effective on the temperature range and stability of the mesophase observed. With respect to the binary mixtures An/Bn, the exhibited N phase showed to cover the whole composition range with eutectic behavior.

Synthesis, Thermal and Optical Characterizations of New Lateral Organic Systems

New laterally OCH3-substituted optical organic Schiff base/ester series, namely 4-(4-(hexyloxyphenyl)iminomethyl)-3-methoxyphenyl 4-alkoxybenzoates, were prepared and characterized with different thermal, mesomorphic, and photoactive techniques. The prepared group constitutes five homologues that differ from each other in the number of carbons in the terminal alkoxy chain (n), which varies between n = 6, 8, 10, 12, and 16 carbons. The laterally protruded methoxy group is attached to the central benzene ring that makes an angle of 120° with the molecular long axis. Molecular structures of all newly prepared homologues were fully elucidated via FT-IR, 1H and 13C NMR spectroscopy. Mesomorphic transitions were determined via differential scanning calorimetry (DSC) and the phases identified by polarized optical microscopy (POM). Independent of the length of the terminal alkoxy chain attached to phenyl ester ring, only a monomorphic nematic (N) phase was observed for all the synthesized compounds. A comparative study was made between the present lateral methoxy-substituted homologues and their corresponding laterally-neat analogues. The results revealed that, depending on the length of the alkoxy chain and the presence or absence of the lateral methoxy group, different mesophases with different thermal stability and temperature ranges were observed. Finally, UV-vis spectra showed that the present nematogenic series possess photoactive properties that are of importance for many applications.

Thiazole-Chalcone Hybrids as Prospective Antitubercular and Antiproliferative Agents: Design, Synthesis, Biological, Molecular Docking Studies and In Silico ADME Evaluation

Compounds bearing thiazole and chalcone pharmacophores have been reported to possess excellent antitubercular and anticancer activities. In view of this, we designed, synthesized and characterized a novel series of thiazole-chalcone hybrids (1-20) and further evaluated them for antitubercular and antiproliferative activities by employing standard protocols. Among the twenty compounds, chalcones 12 and 7, containing 2,4-difluorophenyl and 2,4-dichlorophenyl groups, showed potential antitubercular activity higher than the standard pyrazinamide (MIC = 25.34 µM) with MICs of 2.43 and 4.41 µM, respectively. Chalcone 20 containing heteroaryl 2-thiazolyl moiety exhibited promising antiproliferative activity against the prostate cancer cell line (DU-145), higher than the standard methotrexate (IC50 = 11 ± 1 µM) with an IC50 value of 6.86 ± 1 µM. Furthermore, cytotoxicity studies of these compounds against normal human liver cell lines (L02) revealed that the target molecules were comparatively less selective against L02. Additional computational studies using AutoDock predicted the key binding interactions responsible for the activity and the SwissADME tool computed the in silico drug likeliness properties. The lead compounds generated through this study, create a way for the optimization and development of novel drugs against tuberculosis infections and prostate cancer.

Novel sulphonic acid liquid crystal derivatives: experimental, computational and optoelectrical characterizations

A novel liquid crystal homologous series based on the benzene sulphonic acid moiety, namely (E)-4-((4-((4-(alkoxy)benzoyl)oxy)benzylidene)amino)benzenesulfonic acid (Sn), was synthesized and examined via different experimental and theoretical measurements. The four synthesized members have terminally connected alkoxy chain groups, which vary between 6 and 12 carbons. FT-IR and NMR spectroscopy, as well as elemental analyses, were used to confirm their molecular structures. Mesomorphic and optical investigations of the prepared homologues were also conducted using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The DSC and POM characterization revealed that all of the synthesized sulphonic acid members are monomorphic, exhibiting a pure smectic A (SmA) mesophase with enantiotropic properties. Moreover, all compounds in the group have high thermal transition temperatures. The terminal electron-withdrawing group –SO₃H plays a considerable role in the stabilization of the molecule, which in return resulted in high thermal SmA stability. Furthermore, the experimental data relating to the mesophase behavior were substantiated via computational studies using the DFT approach. In addition, the terminal –SO₃H moiety has an essential impact on the thermal and physical parameters of possible geometries. All members of the synthesized Sn series exhibit ohmic behavior with electrical resistance in the GΩ range, as revealed by electrical measurements. The S10 electrode had the highest electrical conductivity: 35.16 pS. It also showed two direct optical band gaps of 3.58 and 3.23 eV with Urbach energies of 1261.1 and 502.4 meV. Upon decreasing the number of carbon atoms to n = 6, the main bandgap for S6 reduced to 3.3 eV. The highest conductivity, good absorption, and two large bandgaps recorded for the chain derivative S10 make it suitable for investigations relating to energy-based applications.

A novel liquid crystal homologous series based on the benzene sulphonic acid moiety, namely (E)-4-((4-((4-(alkoxy)benzoyl)oxy)benzylidene)amino)benzenesulfonic acid (Sn), was synthesized and examined via different experimental and theoretical measurements.