Computational investigation of bioactive 2,3-diaryl quinolines using DFT method: FT- IR, NMR spectra, NBO, NLO, HOMO-LUMO transitions, and quantum-chemical properties

The role of biochemical and biophysical properties, molecular docking and dynamics studies on azelastine

The structure of the 4-(4-chlorobenzyl)-2-(1-methylazepan-4-yl) phthalazin-1(2H)-one (IA) was optimized through computational study. The optimized structure revealed that the bond length between atoms C3 and C5 was the longest at 1.54 Å, while the bond between atoms C10 and H31 had the lowest length at about 1.01 Å, respectively. The natural bond orbital (NBO) analysis indicates that the bonding π(C3-C20) to anti-bonding π∗(N2-C3) interaction exhibits the most significant stabilization energy of about 253.59 kcal/mol. Due to the solvent's influence, the gas phase MEP value and HOMO-LUMO band gap value are lower, when compared to solvents. A localized bond pair that undergoes movement between two atoms, and a bond pair that undergoes movement between two different pairs of atoms are identified by electron localized function (ELF), localized orbital locator (LOL), and average localized ionization energy (ALIE) studies, respectively. The electron density and thermodynamic properties were determined using Gaussian software. This study examined various parameters such as non-linear optical (NLO), molecular electrostatic potential (MEP), UV-vis, and HOMO-LUMO in different solvents. Further, the biological activity of the IA compound was studied using molecular docking and dynamics on the target Mycobacterium tuberculosis ArgF (7NOR) protein, which showed favorable protein-ligand interaction energy.

Multimodal evaluation of lipoxygenase-targeting NSAIDs using integrated in vitro, SAR, in silico, cytotoxicity towards MCF-7 cell line, DNA docking and MD simulation approaches

Lipoxygenase (LOX) and cyclooxygenase (COX) pathways generate biologically active mediators implicated in inflammatory disorders and several classes of cancer. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the COX pathway by inhibiting the COX-1 and COX-2 enzymes. We reported earlier that several NSAIDs, including naproxen, aspirin and acetaminophen, inhibited lipoxygenase (LOX) enzyme at sub-micromolar concentrations. In continuation, the present work demonstrates the anti-LOX activity of nine more NSAIDs supported by in vitro, in silico, MD simulation and breast cancer cell line studies. All tested drugs displayed potent to excellent inhibitory profiles with IC50 values <24.93 ± 0.64 μM. Aceclofenac (IC50 0.85 ± 0.06 μM) was the most active drug, followed by indomethacin (IC50 1.13 ± 0.07 μM), meloxicam (IC50 1.94 ± 0.07 μM) and ketorolac (IC50 9.26 ± 0.82 μM). Celecoxib (IC50 15.81 ± 0.71 μM), lornoxicam (IC50 16.54 ± 0.28 μM) and nimesulide (IC50 19.87 ± 0.85 μM) showed excellent inhibitory profiles. Flurbiprofen (IC50 21.73 ± 0.93 μM) and etoricoxib (IC50 24.93 ± 0.64 μM) moderately inhibited the target enzyme. SAR studies revealed that active molecules decorated with the carboxylate group afforded strong binding interactions as observed by in vitro assays and structural features. Other drugs, including enol derivatives and celecoxib, also showcased enhanced binding interactions. However, the cytotoxic effects of NSAIDs against the MCF-7 breast cancer cell line did not disclose significant anticancer activity. Molecular docking studies against human 5-LOX offered the best binding affinities for aceclofenac (-13.54 kcal/mol), accompanied by conventional hydrogen bonding and hydrophobic interactions as supported by the in vitro results. Docking studies with DNA dodecamer established minor groove binding with their possible role in DNA replication and gene expression. Density functional theory (DFT) and ESP studies, MD simulations and MMPBSA free energy calculations further reiterated the stability of ligand-receptor complexes. Overall, these findings highlight the potential of targeted NSAIDs as dual COX/LOX inhibitors with broader therapeutic relevance in inflammatory disorders.

Nanomolar activity of coumarin-3-thiosemicarbazones targeting Trypanosoma cruzi cruzain and the T. brucei cathepsin L-like protease

Trypanosoma cruzi (T. cruzi) and Trypanosoma brucei (T. brucei) urgently demand innovative drug development due to their impact on public health worldwide. Their cysteine proteases, Cruzain (CRZ) and the T. brucei Cathepsin L-like protease (TbrCATL) are established drug targets for these parasites. In this study, our coumarin-3-thiosemicarbazones demonstrated nanomolar IC50 values (22-698 nM) toward these proteases. Against T. cruzi amastigotes and T. brucei trypomastigotes, LASF-01 displayed a promising result. Herein, MCG-02, the most potent TbrCATL inhibitor, underwent comprehensive analyses, including cytotoxicity assessments and in vitro tests. Molecular dynamics (MD) simulations and a multiscale Quantum Mechanics/Quantum Mechanics (QM/QM) approach were used to generate insights into their binding modes. These suggested that MCG-02 could be a reversible, competitive covalent inhibitor. Further, confirmatory assays were experimentally performed changing different parameters to prove its efficacy. Additionally, the predicted pharmacokinetic profile showed that there is no violation of the Lipinski rule of five. Notably, coumarin-3-thiosemicarbazone hybrids emerged as promising candidates for designing highly active inhibitors against CRZ and TbrCATL. Overall, the integration of in silico and experimental approaches enhanced our understanding regarding the binding modes of MCG-02, which were experimentally corroborated, providing valuable insights for future drug development.

Exploring the relationship between metal ion valency and electron transfer in copigmentation processes of cyanidin-3-O-glucoside in simulated fruit wine solutions

In this experiment, five metal ions (K+, Mg2+, Al3+, Ga3+, and Sn4+) were utilized as copigments to investigate their copigmentation processes with cyanidin-3-O-glucoside (C3OG) in simulated fruit wine solutions. The color characteristics were analyzed using Glories and CIELAB methods, and the copigmentation effects were determined spectrophotometrically. Thermodynamic parameters, including the equilibrium constant (K) and standard Gibbs free energy (ΔG°), were calculated to comprehend the binding affinity between metal ions and C3OG. Ultra-fast femtosecond spectroscopy was employed to monitor the photoinduced electron transfer process between C3OG and cations. Theoretical calculations were also conducted to support experimental findings. The results revealed that the presence of metal ions significantly enhanced the color intensity of C3OG in simulated fruit wine solutions. Higher valency cations, particularly Sn4+, Ga3+, and Al3+, exhibited superior copigmentation effects, resulting in significant bathochromic and hyperchromic changes. Thermodynamic analysis confirmed that the interaction between C3OG and metal ions was spontaneous and exothermic. Ultra-fast femtosecond spectroscopy demonstrated that electron transfer from C3OG to metal ions occurred, with the efficiency of transfer being dependent on valency. Theoretical calculations corroborated the experimental results by highlighting the role of metal ions in stabilizing C3OG/metal complexes through electron transfer. The findings presented in this study contribute to a more comprehensive understanding of pigment/metal complexes and the underlying chemistry behind fruit wine color. Furthermore, it advances the theoretical foundation of copigmentation and broadens its applications in the beverage industry.

Design, Synthesis and Biological Evaluation of C3‐Indolyl/(3‐chloro‐indolyl)‐C4‐aryl/heteroaryl‐azetidin‐2‐ones

Herein, trans‐ and cis‐azetidin‐2‐ones 3–6 were strategically synthesized, capitalizing on the bioactivity of azetidin‐2‐ones and indole pharmacophore, followed by a comprehensive characterization using a diverse array of spectroscopic techniques. The sixteen azetidin‐2‐ones were examined for antimicrobial activities against both Gram‐negative (P. aeruginosa, E. coli, A. baumannii) and Gram‐positive bacteria (S. aureus, E. faecium, B. cereus), as well as against C. albicans and C. tropicalis fungal strains. The highly potent compounds (5 a, 6 b, 6 d) demonstrated maximum inhibition against all multidrug‐resistant strains, with minimum inhibitory concentrations ranging from 0.97–3.9 μg/mL, surpassing the potency of standard ampicillin (MIC: 3.12–50 μg/mL). Moreover, 6 b and 6 d exhibited significant inhibitory effects on C. albicans (MIC: 0.97 μg/mL), comparable to fluconazole. The presence of C3‐(3‐chloro‐indolyl) scaffold, combined with diverse electronic effects at N1/C4‐centers, particularly the inclusion of thiophen‐2‐yl motif, greatly influenced the activity of target compounds. Assessment of 4 d, 4 i–k and 6 d on THLE‐2 cell lines revealed their preferential safety. Molecular docking studies revealed seven compounds with active dual targeting of DNA GyrB and PBP2a proteins, demonstrating a potent broad‐spectrum antibacterial effect. In silico ADME analysis affirms positive drug‐likeness and favorable pharmacokinetic characteristics of indole‐derived hybrids, indicating a promising potential for addressing challenges in evolving multidrug resistance.

Spectroscopic characterization, DFT, antimicrobial activity and molecular docking studies on 4,5-bis[(E)-2-phenylethenyl]-1H,1'H-2,2'-biimidazole

The newly synthesized imidazole derivative namely, 4,5-bis[(E)-2-phenylethenyl]-1H,1'H-2,2'-biimidazole (KA1), was studied for its molecular geometry, docking studies, spectral analysis and density functional theory (DFT) studies. Experimental vibrational frequencies were compared with scaled ones. The reactivity sites were determined using average localized ionization analysis (ALIE), electron localized function (ELF), localized orbital locator (LOL), reduced density gradient (RDG), Fukui functions and frontier molecular orbital (FMO). Due to the solvent effect, a lower gas phase energy gap was observed. Through utilization of the noncovalent interaction (NCI) method, the hydrogen bond interaction, steric effect and Vander Walls interaction were investigated. Molecular docking simulations were employed to determine the specific atom inside the molecules that exhibits a preference for binding with protein. The parameters for the molecular electrostatic potential (MESP) and global reactivity descriptors were also determined. The thermodynamic characteristics were determined through calculations employing the B3LYP/cc-pVDZ basis set. Antimicrobial activity was carried out using the five different microorganisms like Escherichia coli, Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae and Candida albicans.

Unveiling the Influence of Glutathione in Suppressing the Conversion of Aspirin to Salicylic Acid: A Fluorescence and DFT Study

Aspirin is a commonly used nonsteroidal anti-inflammatory drug, associated with many adverse effects. The adverse effects of aspirin such as tinnitus, Reye's syndrome and gastrointestinal bleeding are caused due to conversion of aspirin into its active metabolite salicylic acid after oral intake. Glutathione is a naturally occurring antioxidant produced by the liver and nerve cells in the central nervous system. It helps to metabolize toxins, break down free radicles, and support immune function. This study aims to investigate and explore the possibility of inhibiting aspirin to salicylic acid conversion in presence of glutathione at a molecular level using spectroscopic techniques such as UV-Visible absorption, time-Resolved and time-dependent fluorescence and theoretical DFT/ TD-DFT calculations. The results of steady state fluorescence spectroscopy and time-dependent fluorescence indicated that the aspirin to salicylic acid conversion is considerably inhibited in presence of glutathione. Further, the results presented here might have significant clinical implications for individuals with variations in glutathione level.

Synthesis, solvent role, absorption and emission studies of cytosine derivative

The (E)-4-((4-hydroxy-3-methoxy-5-nitrobenzylidene) amino) pyrimidin-2(1H)-one (C5NV) was synthesized from cytosine and 5-nitrovanilline by simple straightforward condensation reaction. The structural characteristics of the compound was determined and optimized by WB97XD/cc-pVDZ basis set. The vibrational frequencies were computed and subsequently compared to the experimental frequencies. We investiated the electronic properties of the synthesized compound in gas and solvent phases using the time-dependent density functional theory (TD-DFT) approach, and compared them to experimental values. The fluorescence study showed three different wavelengths indicating the nature of the optical material properties. Frontier molecular orbital (FMO) and molecular electrostatic potential (MEP) analyses were conducted for the title compound, and electron localized functions (ELF) and localized orbital locators (LOL) were used to identify the orbital positions of localized and delocalized atoms. Non-covalent interactions (H-bond interactions) were investigated using reduced density gradients (RDGs). The objective of the study was to determine the physical, chemical, and biological properties of the C5NV. The molecular docking study was conducted between C5NV and 2XNF protein, its lowest binding energy score is -7.92 kcal/mol.

Interactions between DNA and the acridine intercalator: A computational study

Cancer is a global public health problem characterized by deviations in the mechanisms that control cell proliferation, resulting in mutations and variations in the structure of DNA. The mechanisms of action of chemotherapeutic drugs are related to their interactions and binding with DNA; consequently, the development of antineoplastic agents that target DNA has extensively focused on use of acridine, a heterocyclic molecule that binds to deoxyribonucleic acid via intercalation, a process that modifies DNA and makes replication impossible. In this context, this study aimed to computationally investigate how acridine intercalators interact with DNA by evaluating the mechanism of interactions, binding, and interaction energies using quantum mechanics calculations. Molecular electrostatic potential (MEP) analysis revealed that acridine has well- distributed negative charges in the center of the molecule, indicative of a dominant electron-rich region. Acridine exhibits well-defined π orbitals (HOMO and LUMO) on the aromatic rings, suggesting that charge transfer occurs within the molecule and may be responsible for the pharmacological activity of the compound. Structural analysis revealed that acridine interacts with DNA mainly through hydrogen bonds between HAcridine… ODNA with bond lengths ranging from 2.370 Å to 3.472 Å. The Binding energy (ΔEBind) showed that acridine interacts with DNA effectively for all complexes and the electronic energy results (E+ZPE) for complexes revealed that the complexes are more stable when the DNA-centered acridine molecule. The Laplacian-analysis topological QTAIM parameter (∇2ρ(r)) and total energy (H(r)) categorized the interactions as being non-covalent in nature. The RGD peak distribution in the NCI analysis reveals the presence of van der Waals interactions, predominantly between the intercalator and DNA. Accordingly, we confirm that acridine/DNA interactions are relevant for understanding how the intercalator acts within nucleic acids.

Preparation and Antioxidant Activity of New Carboxymethyl Chitosan Derivatives Bearing Quinoline Groups

A total of 16 novel carboxymethyl chitosan derivatives bearing quinoline groups in four classes were prepared by different synthetic methods. Their chemical structures were confirmed by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and elemental analysis. The antioxidant experiment results in vitro (including DPPH radical scavenging ability, superoxide anion radical scavenging ability, hydroxyl radical scavenging ability, and ferric reducing antioxidant power) demonstrated that adding quinoline groups to chitosan (CS) and carboxymethyl chitosan (CMCS) enhanced the radical scavenging ability of CS and CMCS. Among them, both N, O-CMCS derivatives and N-TM-O-CMCS derivatives showed DPPH radical scavenging over 70%. In addition, their scavenging of superoxide anion radicals reached more than 90% at the maximum tested concentration of 1.6 mg/mL. Moreover, the cytotoxicity assay was carried out on L929 cells by the MTT method, and the results indicated that all derivatives showed no cytotoxicity (cell viability > 75%) except O-CMCS derivative 1a, which showed low cytotoxicity at 1000 μg/mL (cell viability 50.77 ± 4.67%). In conclusion, the carboxymethyl chitosan derivatives bearing quinoline groups showed remarkable antioxidant ability and weak cytotoxicity, highlighting their potential use in food and medical applications.

Exploring the binding mechanism and adverse toxic effects of degradation metabolites of pyrethroid insecticides to human serum albumin: Multi-spectroscopy, calorimetric and molecular docking approaches

Pyrethroid insecticides (PIs), a class of structurally similar non-persistent organic pollutants, can be degraded and metabolized to more toxic, and longer half-life products. In this study, the binding interaction mechanisms between human serum albumin (HSA) and the main degradation metabolites of PIs, 3-phenoxybenzoic acid (3-PBA) and 4-fluoro-3-phenoxybenzoic acid (4-F-3-PBA), were studied by theoretical simulation and experimental verification. Steady state fluorescence spectra showed that the fluorescence quenching mechanism was static. According to the binding constant, 4-F-3-PBA (1.53 × 105 L mol-1) was bound more strongly to HSA than 3-PBA (1.42 × 105 L mol-1) in subdomain ⅡA (site I). It was found by isothermal titration calorimetry that the metabolites and HSA spontaneously combined mainly through hydrogen bond and van der Waals interaction. Ultraviolet absorption spectra and circular dichroism spectra showed that the metabolites caused slight changes in the microenvironment and conformation of HSA. The above results were proved by molecular docking. The toxicity properties of the metabolites were further analyzed by software, and 4-F-3-PBA was found to be more toxic than 3-PBA. Considering the high exposure level of these metabolites in food, the environment and human body, it is necessary to further explore the toxicity of PIs metabolites.

Lipophilicity and ADMET Analysis of Quinoline-1,4-quinone Hybrids

Lipophilicity is one of the basic properties of a potential drug determining its solubility in non-polar solvents and, consequently, its ability to passively penetrate the cell membrane, as well as the occurrence of various pharmacokinetic processes, including adsorption, distribution, metabolism, excretion, and toxicity (ADMET). Heterocyclic compounds containing a nitrogen atom play a significant role in the search for new drugs. In this study, lipophilicity as well as other physicochemical, pharmacokinetic and toxicity properties affecting the bioavailability of the quinolone-1,4-quinone hybrids are presented. Lipophilicity was determined experimentally as well as theoretically using various computer programs. The tested compounds showed low values of experimental lipophilicity and its relationship with the type of 1,4-quinone moiety. Introduction of the nitrogen atom reduced the lipophilicity depending on the position at the 5,8-quinolinedione moiety. The bioavailability of the tested compounds was determined in silico using the ADMET parameters. The obtained parameters showed that most of the hybrids can be used orally and do not exhibit neurotoxic effects. Similarity analysis was used to examine the relationship between the ADMET parameters and experimental lipophilicity. The ability of hybrids to interact with biological targets was characterized by global reactivity descriptors. The molecular docking study showed that the hybrids can inhibit the BCL-2 protein.

Preparation and antioxidant activity of novel chitosan oligosaccharide quinolinyl urea derivatives

In the present study, four new chitosan oligosaccharide derivatives bearing quinolinyl urea groups were synthesized by reaction between 2-methoxyformylated chitosan oligosaccharide and aminoquinoline. The chitosan oligosaccharide derivatives were characterized by Fourier Transform Infrared (FTIR) and 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy. The obtained results confirmed that chitosan oligosaccharide quinolinyl urea derivatives were successfully synthesized. Meanwhile, the antioxidant activities of different chitosan oligosaccharide derivatives were examined in vitro. Experimentally, it was demonstrated that chitosan oligosaccharide quinolinyl urea derivatives had superior antioxidant activity compared with chitosan oligosaccharide and the antioxidant effects were concentration-dependent. Especially, when the concentration was 1.6 mg/mL, their superoxide anion radical scavenging rates could reach to 72.35 ± 0.49%, 100.00 ± 0.21%, 84.63 ± 0.49%, and 87.22 ± 0.32%, respectively. And the hydroxyl radical scavenging rates could reach to 100.00 ± 0.82%, 98.49 ± 4.08%, 100.00 ± 5.76%, and 92.07 ± 5.10%. In addition, the cytotoxic activity of the prepared chitosan derivatives against L929 cells was determined by CCK-8 assay. The cell survival rates were all higher than 90%, which intuitively indicated that the samples had almost no cytotoxicity. The findings indicated that the enhanced antioxidant property and biocompatibility of these chitosan oligosaccharide quinolinyl urea derivatives could enlarge the scope of the application of chitosan oligosaccharide, particularly as an antioxidant in food packaging, biomedical, pharmaceutical, cosmetics industries and other fields.