Promising Schiff bases in antiviral drug design and discovery

Highly Sensitive and Selective Detection of Hg2+ ions and Antibacterial Activity Using a Schiff-base Derivative

A simple and highly effective Schiff-base fluorescent chemosensor (S1) was synthesized and characterized by 1HNMR and fluorescence spectroscopy. The synthesized chemosensor was applied for the selective and sensitive detection of Hg2+ ions. The chemosensor exhibited a strong 'turn-on' fluorescence response in a CH3OH/H2O (1:9, v/v) solution due to complex formation (S1-Hg2+) which block photo induce electron transfer (PET). The chemosensor showed significant sensitivity with very low detection limit of 2.0 ppb, making it suitable for trace-level Hg2+ detection. Furthermore, the S1-Hg2+ complex demonstrated excellent antibacterial activity against various Gram-positive and Gram-negative bacterial strains, broadening its utility beyond sensing. This dual-functional system offers significant potential in environmental and biomedical applications.

Electronic, structural and nonlinear optical investigation of manganese carbonyl complexes of isatin derivatives by DFT

CONTEXT

Isatin-Schiff bases have wide applications in chemistry. The π conjugated electronic system and heterocylic structure of these materials make them valuable for use as photosensitized materials. The delocalization of π-electrons throughout the structure causes the UV-vis absorption spectra to shift to longer wavelengths. In this study, the isatin manganese carbonyl complex shifted the UV-vis absorption wavelength to a longer wavelength (vis. 400-700 nm) compared with our previous studies. The isatin derivatives (ISE (3[4-ethyl(phenyl)imino][indoline-2-one]), ISB (3[4-butly(phenyl)imino][indoline-2-one])) and their Mn carbonyl complexes MnISE ((ISE)Mn(CO)3), and, MnISB ((ISB)Mn(CO)3) were investigated via density functional theory (DFT) in different solvent media. The most stable complexes were found in medium polarity THF. The calculated HOMO-LUMO energy gap shows that the charge transfer occurs within the molecule. The HOMO-LUMO energy gap was increased with increasing solvent polarity for all investigated compounds. The smaller energy gap indicates that charge transfer occurs within the Mn(II) complex, in contrast to ISE and ISB, which exhibit larger energy gaps. As a result, the maximum absorption of Mn complexes shifts to the visible region. MnISB has the smallest HOMO-LUMO energy gap in THF. Additionally, the global reactivity parameters indicated that the MnISE complex has the highest electrophilicity index. DFT calculations have also been performed to investigate polarizability and first-order hyperpolarizability of these compounds. In water, the ISE had higher NLO values than the other structures did. These results indicate that all the studied molecules in different solvents could be good candidates for use in photosensitized and nonlinear optical materials.

METHODS

Geometries were determined at the DFT level via the LANL2DZ basis set for Mn and cc-PVTZ for other atoms in the molecules with the B3LYP functional. The UV-vis absorption spectra and HOMO-LUMO energies of ISE, ISB, and their Mn complexes were calculated by Time-dependent DFT (TDDFT) with CAM-B3LYP using the same basis sets. The UV-vis absorption spectra of ISE were also measured in acetonitrile and compared with the calculated spectra, which were consistent with the experimental results. All calculations were repeated in different solvents with the polarizable continuum model (PCM).

Synthesis, crystal structure, and antiviral evaluation of new imidazopyridine-schiff base derivatives: in vitro and in silico anti-HIV studies

A series of Imidazo[1,2-a]pyridine-Schiff base derivatives were synthesized and characterized using 1H NMR, 13C NMR, Mass Spectrometry and FTIR techniques, and the structure of 4a was further confirmed through single-crystal X-ray diffraction analysis. Density Functional Theory (DFT) has been used to investigate the structural and electronic properties. The synthesized compounds were evaluated in vitro for their antiviral activity against human immunodeficiency virus type-1 (HIV-1) and human immunodeficiency virus type-2 (HIV-2) in MT-4 cells. Compound 4a displayed EC50 values of 82,02 and 47,72 μg ml-1 against HIV-1 and HIV-2, respectively. Molecular docking studies were conducted to gain insights into the interaction mechanism of the synthesized compounds with HIV-1 reverse transcriptase. ADME analysis suggested acceptable pharmacokinetic profiles, though solubility remains a limitation for these compounds, highlighting the need for further structural modifications to enhance bioavailability and therapeutic potential.

Glowing discoveries: Schiff base-cyanostilbene probes illuminating metal ions and biological entities

Schiff bases featuring cyanostilbene units have emerged as versatile and highly effective probes for the selective detection of various metal ions as well as biologically important species. This review comprehensively highlights recent advances in the development and application of the probes, which exhibit remarkable Aggregation-Induced Emission (AIE), Twisted Intramolecular Charge Transfer (TICT), and Excited-State Intramolecular Proton Transfer (ESIPT) properties. These unique structural characteristics facilitate their potential applications in the detection of biologically important metal ions such as Zn2+, Fe3+, Cu2+, Hg2+ and Co2+ ions with high sensitivity and selectivity. Furthermore, these probes have demonstrated significant potential in the recognition of vital biological species, including arginine, hydrazine and hypochlorite (ClO-). The present review discusses the underlying detection mechanisms, emphasizing the role of the Schiff base and cyanostilbene moieties for the selective detection of particular biologically important entities. Moreover, this discussion highlights the practical applications, problems, and future directions in this fast-growing field, emphasizing the vital importance of these probes in both analytical chemistry and bioassays.

Molecular docking, derivatization, characterization and biological assays of amantadine

Background: Derivatization has been tremendously utilized in the field of drug discovery for optimizing the pharmacological properties and improving safety, efficacy and selectivity.Methodology: Schiff's bases (AD1-AD11) are synthesized through amantadine condensation with different aldehydes and ketones. Fourier transform infrared, 1H NMR, 13C NMR, TLC, liquid chromatography mass spectrometry analysis, in silico studies, molecular docking and antiviral activity through hemagglutinin test were performed for evaluation of new compounds.Results: AD2, 3 and 9-11 showed greater antiviral activity than the parent drug. Among all derivatives, AD2 and AD3 exhibited good potential against α-amylase while AD7 and AD10 showed stronger inhibition against α-glucosidase.Conclusion: So, it is concluded that the most potent derivatives can be used as lead compounds in novel drug design of antiviral antidiabetic agents.

Synthesis and Biological Activity of New Hydrazones Based on N-Aminomorpholine

The data on the synthesis of N-aminomorpholine hydrazones are presented. It is shown that the interaction of N-aminomorpholine with functionally substituted benzaldehydes and 4-pyridinaldehyde in isopropyl alcohol leads to the formation of corresponding hydrazones. The structure of the synthesized compounds was studied by 1H and 13C NMR spectroscopy methods, including the COSY (1H-1H), HMQC (1H-13C) and HMBC (1H-13C) methodologies. The values of chemical shifts, multiplicity, and integral intensity of 1H and 13C signals in one-dimensional NMR spectra were determined. The COSY (1H-1H), HMQC (1H-13C), and HMBC (1H-13C) results revealed homo- and heteronuclear interactions, confirming the structure of the studied compounds. The antiviral, cytotoxic, and antimicrobial activity of some synthesized hydrazones were investigated. It is shown that 2-((morpholinoimino)methyl)benzoic acid has a pronounced viral inhibitory property, comparable in its activity to commercial drugs Tamiflu and Remantadine. A docking study was performed using the influenza virus protein models (1930 Swine H1 Hemagglutinin and Neuraminidase of 1918 H1N1 strain). The potential binding sites that are complementary with 2-((morpholinoimino)methyl)benzoic acid were found.

The H2Valdien derivatives regulate the epithelial-mesenchymal transition of hepatoma carcinoma cells through the Hedgehog signaling pathway

This research delves into the influence of H2Valdien derivatives on the proliferation, migration, and apoptosis induction in hepatoma carcinoma cells (HepG2, Huh-7, and SMMC-7721), with a specific emphasis on inhibiting epithelial-mesenchymal transition (EMT) through modulation of the Hedgehog (Hh) signaling pathway. Utilizing the cell counting kit-8 method, flow cytometry, TUNEL assay, wound healing, and transwell assays, we observed a dose-dependent growth arrest and apoptosis induction in HepG2, Huh-7, and SMMC-7721 cells. Notably, H2Valdien derivatives exhibited a capacity to reduce migration and invasion, impacting the expression of EMT-associated proteins such as N-cadherin, vimentin, and E-cadherin. Mechanistically, these derivatives demonstrated the inhibition of the Hh signaling pathway by inactivating Sonic Hh (Shh) and smoothened proteins. This study underscores the robust antiproliferative and apoptosis-inducing effects of H2Valdien derivatives on hepatoma carcinoma cells and elucidates their regulatory role in EMT through modulation of the Hh signaling pathway, providing valuable insights for potential therapeutic interventions.

Synthesis of Novel [{(2-Amino-5-Nitro-N-[(E)-Thiophen-2-yl-Methylidene]Aniline-κ3N1:N4:S)(Sulphato-κ2O1:O3)}Zinc(II)] Complex with Physico-Chemical and Biological Perspective Exploration: A Combined Experimental and Computational Studies

A novel metal complex was synthesized using freshly prepared 2-Amino-5-nitro-N-[(E)-thiophen-2-yl-methylidene]aniline ligand with Zn (II) sulphate heptahydrate in a 1:1 molar ratio. The ligand and the complex were characterized using different spectroscopic techniques, and the complex was assigned a distorted square pyramidal geometry. Additionally, DNA binding assays and antibacterial activity were used to assess the biological perspectives for the synthesized complex, including the ligand and complex which was further confirmed by molecular docking. Fluorescence Spectroscopy, viscosity measurement, and adsorption measurement were used to investigate the interaction of the Zn (II) complex with CT-DNA. A comparative in vitro antibacterial activity study against Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, and Staphylococcus aureus strains were studied with free ligand and Zn (II) metal complex. The stable geometry of the complex was additionally established through computational simulation utilizing density functional theory, which was followed by the calculation of several electronic properties. The ADMET characteristics of the complex and ligand were also assessed using ADMET analysis. The in-silico ADMET properties pointed to a significant drug-likeness feature in the synthesized compounds, based on the Lipinski criteria.

Synthesis and Spectroscopic Characterization of Schiff Base Metal Complexes, Biological Activity, and Molecular Docking Studies

New cobalt(II), copper(II), and zinc(II) Schiff metal complexes were synthesized by the condensation reaction of 4-nitrobenzene-1,2-diamine with 3-4-(diethylamino)-2-hydroxybenzaldehyde. Fourier transform infrared, nuclear magnetic resonance, ultraviolet-visible, electron paramagnetic resonance, and high-resolution electrospray ionization mass spectrometry and powder X-ray diffraction were used to characterize the synthesized H2L and its metal complexes. Conductance measurements, magnetic moment estimation, and metal estimation have all been determined and discussed. The electrochemical properties of the synthesized compounds have been determined and discussed using cyclic voltammetry. The molecular structures of H2L and its metal complexes have been optimized using the B3LYP functional and the 6-31G (d,p) basis set, and their parameters have been discussed. The quantum chemical properties of these synthesized compounds have been predicted through charge distribution and molecular orbital analysis. The biological properties of the synthesized compounds' antioxidant, antifungal, and antibacterial activity have been studied and discussed. Furthermore, H2L and its complexes have been docked with HER2-associated target proteins in breast cancer.

Synthesis, Characterizations, and Quantum Chemical Investigations on Imidazo[1,2-a]pyrimidine-Schiff Base Derivative: (E)-2-Phenyl-N-(thiophen-2-ylmethylene)imidazo[1,2-a]pyrimidin-3-amine

In this study, (E)-2-phenyl-N-(thiophen-2-ylmethylene)imidazo[1,2-a]pyrimidin-3-amine (3) is synthesized, and detailed spectral characterizations using 1H NMR, 13C NMR, mass, and Fourier transform infrared (FT-IR) spectroscopy were performed. The optimized geometry was computed using the density functional theory method at the B3LYP/6-311++G(d,p) basis set. The theoretical FT-IR and NMR (1H and 13C) analysis are agreed to validate the structural assignment made for (3). Frontier molecular orbitals, molecular electrostatic potential, Mulliken atomic charge, electron localization function, localized orbital locator, natural bond orbital, nonlinear optical, Fukui functions, and quantum theory of atoms in molecules analyses are undertaken and meticulously interpreted, providing profound insights into the molecular nature and behaviors. In addition, ADMET and drug-likeness studies were carried out and investigated. Furthermore, molecular docking and molecular dynamics simulations have been studied, indicating that this is an ideal molecule to develop as a potential vascular endothelial growth factor receptor-2 inhibitor.

Preparation of gelatin-chitosan bilayer film loaded citral nanoemulsion as pH and enzyme stimuli-responsive antibacterial material for food packaging

The responsive release of enzymes, pH, temperature, light and other stimuli is an effective means to reduce the loss of volatile active substances and control the release of active ingredients. The purpose of this study is to design a simple and rapid method to synthesize a multifunctional bilayer membrane, which has good mechanical properties, long-lasting pH and enzyme dual sensitive sustained release properties, and excellent antibacterial activity. The citral nanoemulsion was prepared by ultrasonic method, then the chitosan solution loaded with nanoemulsion was assembled on the gelatin film, and the uniform and smooth gelatin-chitosan bilayer film was successfully prepared. Compared with the control group, the bilayer film loaded with nanoemulsion showed better barrier performance, mechanical properties and antibacterial activity.