Search

In the present manuscript, three different 4,7-dihydroxycoumarin derivatives were prepared and structurally characterized by crystallographic and spectroscopic techniques in combination with the B3LYP-D3BJ theoretical method. Cytotoxic and antimicrobial activities of investigated compounds were screened against different cell lines and microorganisms. HCT-116 cells were most sensitive to the 3-(1-(2-hydroxyphenyl)amino) ethylidene)-2,4-dioxochroman-7-yl acetate derivative, while the best antimicrobial activity against Bacillus subtilis ATCC 6633 was shown by 3-(1-(2-hydroxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate. The molecular docking study for all compounds with important epidermal growth factor receptors (EGFR) was performed. The results indicate that the largest contribution to the binding energy is through conventional hydrogen bonds.

Objectives: New tributyltin(IV) complexes containing the carboxylate ligands 3-(4-methyl-2-oxoquinolin-1(2H)-yl)propanoic acid (HL1) and 2-(4-methyl-2-oxoquinolin-1(2H)-yl)acetic acid (HL2) have been synthesized. Methods: Their structures have been determined by elemental microanalysis, FT-IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy and X-ray diffraction study. A solution state NMR analysis reveals a four-coordinated tributyltin(IV) complex in non-polar solvents, while an X-Ray crystallographic analysis confirms a five-coordinated trigonal-bipyramidal geometry around the tin atom due to the formation of 1D chains. A theoretical structural analysis was performed by optimization employing B3LYP-D3BJ functional and 6-311++G(d,p)/def2-TZVP(Sn) basis sets for H, C, N, O/Sn, respectively. The interactions between tin(IV) and surrounding atoms were examined by QTAIM approach. The in vitro antiproliferative activity of the synthesized compounds was evaluated by MTT and CV assays versus MCF-7 (human breast adenocarcinoma), HCT116 (human colorectal carcinoma), A375 (human melanoma), 4T1 (mouse breast carcinoma), CT26 (mouse colon carcinoma) and B16 (mouse melanoma) tumor cell lines. Results: Both synthesized compounds (nBu3SnL1 and nBu3SnL2) exerted powerful micromolar IC50 cytotoxicity values and demonstrated high selectivity toward malignant cells. Both experimental drugs affected cell adhesion and induced anchorage independent apoptosis, a favorable type of cell death with an essential role in cancer dissemination prevention. The BSA-binding affinity of the obtained organotin compounds was followed by spectrofluorometric titration and molecular docking simulations. Conclusions: The tributyltin(IV) compounds selectively induce anoikis-like cell death in A375 cells, also highlighting the importance of the organic moiety on the tin(IV) ion in the mechanism of action. [ABSTRACT FROM AUTHOR]

Background: The aim of this research is the synthesis and characterization of coumarin-palladium complex and the investigation of the cytotoxicity of both the ligand and the complex. Methods: The palladium(II) complex (CC) was obtained in the reaction between (E)-3-(1-((4-hydroxy-3-methoxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl-acetate (CL) and potassium-tetrachloropalladate(II) and characterized using IR and NMR spectra, experimentally and theoretically. Cytotoxicity of CL and CC were determined for human cervical carcinoma HeLa, ovarian cancer A2780, hormone dependent breast cancer MCF7, and colorectal cancer HCT116 lines. The interaction of investigated compounds with HSA was followed by spectrofluorimetric method. The binding mechanism in the active pocket was assessed via molecular docking simulations. Results: A low mean absolute error between experimental and theoretical data proved that the optimized structure corresponded to the experimental one. Both compounds showed a satisfactory selectivity index towards neoplastic cells. The binding affinity of tested compounds to the HSA were confirmed. The molecular docking showed a much lower change in the Gibbs free energy of binding for CC compared to CL. Conclusions: The obtained results revealed that CL and CC exhibit significant effects on several cancer cell lines and good binding properties to HSA, while molecular docking discovered that CC has the most pronounced activity against alpha-fetoprotein. [ABSTRACT FROM AUTHOR]

The pyridoxal-semicarbazone (PLSC) ligand and its transition metal complexes have shown significant biological activity. In this contribution, a novel nickel(II)-PLSC complex, [Ni(PLSC)(SO4)(H2O)2], was obtained, and its structure was determined by X-ray crystallographic analysis, FTIR, and UV-VIS spectroscopy. The sulfate ion is directly coordinated to the central metal ion. The intermolecular stabilization interactions were examined using Hirshfeld surface analysis. The crystal structure was optimized by a B3LYP functional using two pseudopotentials for nickel(II) (LanL2DZ and def2-TZVP) together with a 6-311++G(d,p) basis set for non-metallic atoms. The experimental and theoretical bond lengths and angles were compared, and the appropriate level of theory was determined. The stabilization interactions within the coordination sphere were investigated by the Quantum Theory of Atoms in Molecules (QTAIM). The antioxidant activity towards hydroxyl and ascorbyl radicals was measured by EPR spectroscopy. The interactions between Human Serum Albumin (HSA) and the complex were examined by spectrofluorimetric titration and a molecular docking study. The mechanism of binding to DNA was analyzed by complex fluorescence quenching, potassium iodide quenching, and ethidium bromide displacement studies in conjunction with molecular docking simulations. [ABSTRACT FROM AUTHOR]

Nickel transition metal complexes have shown various biological activities that depend on the ligands and geometry. In this contribution, six Ni(II) nitrate complexes with pyridoxal-semi, thiosemi, and isothiosemicarbazone ligands were examined using theoretical chemistry methods. The structures of three previously reported complexes ([Ni(PLSC)(H2O)3]∙2NO3−, [Ni(PLTSC)2] ∙2NO3−∙H2O, and [Ni(PLITSC)(H2O)3]∙2NO3−) were investigated based on Hirshfeld surface analysis, and the most important stabilization interactions in the crystal structures were outlined. These structures were optimized at the B3LYP/6-311++G(d,p)(H,C,N,O,(S))/LanL2DZ(Ni) level of theory, and the applicability was checked by comparing theoretical and experimental bond lengths and angles. The same level of theory was applied for the optimization of three additional structures, ([Ni(PLSC)2]2+, [Ni(PLTSC)(H2O)3]2+, and [Ni(PLITSC)2]2+). The interactions between selected ligands and Ni(II) were examined using the Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) approaches. Particular emphasis was placed on interactions between oxygen, sulfur, and nitrogen donor atoms and Ni(II). Human Serum Albumin (HSA) and the DNA-binding properties of these complex cations were assessed using molecular docking simulations. The presence of water molecules and various substituents in the thermodynamics of the processes was demonstrated. The results showed significant effects of structural parameters on the stability and reactivity towards important biomolecules. [ABSTRACT FROM AUTHOR]

New Cu(II) complexes with pyridoxal-aminoguanidine (PLAG) ligands and different counterions (SO42− and NO3−) were prepared and their crystal structures were solved by the X-ray crystallography. The geometries of the obtained complexes significantly depended on the counterions, leading to the square-pyramidal structure of [Cu(PLAG)NO3H2O]NO3 (complex 1) and square-planar structure of [Cu(PLAG)H2O]SO4 (complex 2). The intermolecular interactions were examined using the Hirshfeld surface analysis. The theoretical structures of these complexes were obtained by optimization at the B3LYP/6-311++G(d,p)(H,C,N,O,S)/LanL2DZ(Cu) level of theory. The Quantum Theory of Atoms in Molecules (QTAIM) was applied to assess the strength and type of the intramolecular interactions and the overall stability of the structures. The interactions between the complexes and transport proteins (human serum albumin (HSA)) and calf thymus DNA (CT-DNA) were examined by spectrofluorometric/spectrophotometric titration and molecular docking. The binding mechanism to DNA was assessed by potassium iodide quenching experiments. The importance of counterions for binding was shown by comparing the experimental and theoretical results and the examination of binding at the molecular level. [ABSTRACT FROM AUTHOR]

Ru(II)‐arene compounds are being investigated as anticancer agents due to the biocompatibility of ruthenium and their structural diversity. Two newly synthesized Ru(II) complexes, [RuCl(η6‐p‐cymene)(3‐DNPH)] (chlorido(η6‐p‐cymene)(3‐nitrophenylhydrazine‐k2N,N′)ruthenium(II)) (1) and [RuCl(η6‐p‐cymene)(3‐CNPH)] (chlorido(3‐chlorophenylhydrazine‐k2N,N′)(η6‐p‐cymene)ruthenium(II)) (2), are experimentally (IR, NMR) and theoretically (B3LYP/6‐31+G(d,p)(H,C,N,Cl)/LanL2DZ(Ru)) characterized. Experimental and theoretical values of 1H and 13C chemical shifts and position of the most intense vibrational bands showed high correlation coefficients and low mean absolute errors, proving the predicted structure and applicability of the selected level of theory. Cell viability studies performed on MDA‐MB‐468, BT‐474, and PC3 cells using MTT and CV assay indicated the activity of the second complex similar to the activity of cisplatin towards BT‐474 breast cancer cells. The spectrofluorimetric measurements of Bovine Serum Albumin showed the binding process's spontaneity of complexes and protein, with a binding energy of around −30 kJ mol−1. Detailed molecular docking analysis allowed the elucidation of the binding mechanism through specific intermolecular interactions. Both compounds showed a higher affinity towards BSA than naproxen and cisplatin. Molecular docking simulations proved the spontaneity of the complexes binding to DNA. Based on these promising results, further biological examinations of these compounds are advised. [ABSTRACT FROM AUTHOR]

Vanadium complexes have gained considerable attention as biologically active compounds. In this contribution, three previously reported dioxovanadium(V) complexes with pyridoxal semicarbazone, thiosemicarbazone, and S-methyl-iso-thiosemicarbazone ligands are theoretically examined. The intermolecular stabilization interactions within crystallographic structures were investigated by Hirshfeld surface analysis. These experimental structures were optimized at the B3LYP-D3BJ/6-311++G(d,p)(H,C,N,O,S)/def2-TZVP(V) level of theory, and crystallographic and optimized bond lengths and angles were compared. High correlation coefficients and low mean absolute errors between these two data sets proved that the selected level of theory was appropriate for the description of the system. The changes in structures and stability were examined by adding explicit solvent molecules. The Quantum Theory of Atoms in Molecules (QTAIM) was employed to analyze the intramolecular interactions with special emphasis on the effect of substituents. A good correlation between electron density/Laplacian and interatomic distance was found. Through molecular docking simulations towards Bovine Serum Albumin (BSA), the binding affinity of complexes was further investigated. The spontaneity of binding in the active position of BSA was shown. Further experimental studies on this class of compounds are advised. [ABSTRACT FROM AUTHOR]

A novel trimethyltin(IV) complex (Me3SnL), derived from 3-(4-methyl-2-oxoquinolin-1(2H)-yl)propanoate ligand, has been synthesized and characterized by elemental microanalysis, UV/Vis spectrophotometry, FT-IR and multinuclear (1H, 13C and 119Sn) NMR spectroscopies. Furthermore, the structure of the ligand precursor HL was solved using SC-XRD (single-crystal X-ray diffraction). The prediction of UV/Vis and NMR spectra by quantum-chemical methods was performed and compared to experimental findings. The protein binding affinity of Me3SnL towards BSA was determined by spectrofluorometric titration and subsequent molecular docking simulations. Me3SnL has been evaluated for its in vitro anticancer activity against three human cell lines, MCF-7 (breast adenocarcinoma), A375 (melanoma) and HCT116 (colorectal carcinoma), and three mouse tumor cell lines, 4T1 (breast carcinoma), B16 (melanoma) and CT26 (colon carcinoma), using MTT and CV assays. The strong inhibition of A375 cell proliferation, ROS/RNS upregulation and robust lipid peroxidation lead to autophagic cell death upon treatment with Me3SnL. [ABSTRACT FROM AUTHOR]

Ruthenium(II)–arene complexes have gained significant research interest due to their possible application in cancer therapy. In this contribution two new complexes are described, namely [{RuCl(η6-p-cymene)}2(μ-Cl)(μ-1-N,N′-naphthyl)]X (X = Cl, 1; PF6, 2), which were fully characterized by IR, NMR, and elemental microanalysis. Furthermore, the structure of 2 in the solid state was determined by a single crystal X-ray crystallographic study, confirming the composition of the crystals as 2·2MeOH. The Hirshfeld surface analysis was employed for the investigation of interactions that govern the crystal structure of 2·2MeOH. The structural data for 2 out of 2·2MeOH was used for the theoretical analysis of the cationic part [{RuCl(η6-p-cymene)}2(μ-Cl)(μ-1-N,N′-naphthyl)]+ (2a) which is common to both 1 and 2. The density functional theory, at B3LYP/6-31+G(d,p) basis set for H, C, N, and Cl atoms and LanL2DZ for Ru ions, was used for the optimization of the 2a structure. The natural bond orbital and quantum theory of atoms in molecules analyses were employed to quantify the intramolecular interactions. The reproduction of experimental IR and NMR spectra proved the applicability of the chosen level of theory. The binding of 1 to bovine serum albumin was examined by spectrofluorimetry and molecular docking, with complementary results obtained. Compound 1 acted as a radical scavenger towards DPPH• and HO• radicals, along with high activity towards cancer prostate and colon cell lines. [ABSTRACT FROM AUTHOR]

New Ni (II) and Cu (II) complexes with pyridoxal-semicarbazone were synthesized and their structures were solved by X-ray crystallography. This analysis showed the bis-ligand octahedral structure of [Ni(PLSC-H)2]·H2O and the dimer octahedral structure of [Cu(PLSC)(SO4)(H2O)]2·2H2O. Hirshfeld surface analysis was employed to determine the most important intermolecular interactions in the crystallographic structures. The structures of both complexes were further examined using density functional theory and natural bond orbital analysis. The photocatalytic decomposition of methylene blue in the presence of both compounds was investigated. Both compounds were active toward E. coli and S. aureus, with a minimum inhibition concentration similar to that of chloramphenicol. The obtained complexes led to the formation of free radical species, as was demonstrated in an experiment with dichlorofluorescein-diacetate. It is postulated that this is the mechanistic pathway of the antibacterial and photocatalytic activities. Cyclic voltammograms of the compounds showed the peaks of the reduction of metal ions. A molecular docking study showed that the Ni(II) complex exhibited promising activity towards Janus kinase (JAK), as a potential therapy for inflammatory diseases, cancers, and immunologic disorders. [ABSTRACT FROM AUTHOR]

In the current study, the interaction mechanisms between protonated neurotransmitters: octopamine (4-(2-amino-1-hydroxyethyl)phenol) and norepinephrine (4-[(1R)-2-amino-1- hydroxyethyl]benzene-1,2-diol) with the ß-1 adrenergic receptor (ß1AR) were examined by molecular docking, molecular dynamics (MD) simulations and MM/PBSA free energy calculations. The investigated receptor belongs to the G-protein coupled receptor group. The investigation was carried out at physiological pH=7.4. It was estimated that both compounds exist in the protonated form in the water at physiological pH. It was found that both protonated neurotransmitters established similar interactions with amino acid residues of the receptor, such as salt bridges, conventional hydrogen bonds, p-s, and T-shaped p-p interactions, as shown by molecular docking simulations. As the initial structures for MD simulation with a total time of 10ns the most stable docking structures were used. The presented results are expected to provide some useful information for the design of specific ß1AR agonists. [ABSTRACT FROM AUTHOR]

Abstract The coumarin–orthoaminophenol derivative was prepared under mild conditions. Based on crystallographic structure, IR and Raman, 1H and 13C NMR spectra the most applicable theoretical method was determined to be B3LYP-D3BJ. The stability and reactivity parameters were calculated, in the framework of NBO, QTAIM and Fukui functions, form the optimized structure. This reactivity was then probed in biological systems. The antimicrobial activity towards four bacteria and three fungi species was examined and activity was proven. In vitro cytotoxic effects, against human epithelial colorectal carcinoma HCT-116 and human healthy lung MRC-5 cell lines, of the investigated substance are also tested. Compound showed significant cytotoxic effects on HCT-116 cells, while on MRC-5 cells showed no cytotoxic effects. The effect of hydroxy group in ortho -position on the overall reactivity of molecule was examined through molecular docking with Glutathione-S-transferases. Graphical Abstract Unlabelled Image Highlights • The cumarine derivative with o -aminophenol was synthesized under mild conditions. • The structure and spectroscopic properties of compound 3 are confirmed by DFT. • The MIC and IZ values of 3 are comparable to the commercially active drugs • Investigated substance revealed surprising effect on cancer cells HCT-116. • Possible interactions between 3 and Glutathione-S-transferase were revealed by MD. [ABSTRACT FROM AUTHOR]

[Display omitted] • The radical scavenging study of BOH towards HO• was investigated by the DFT method. • The SOMO showed that the PCET is dominant mechanism for H atom abstraction. • Six positions in BOH structure were active for radical adduct formation with HO•. • The kinetically preferred pathway for the anionic species is electron transfer. • Molecular docking confirmed inhibitory effectiveness of BO− to the GLOI receptor. Baicalein (BOH) is an essential flavone molecule with proven significant scavenging activity towards various reactive species, although the actual mechanism has not been fully elucidated. Three common mechanisms: Hydrogen Atom Abstraction (HAA), Radical Adduct Formation (RAF), and Electron Transfer (EA), for the reaction between BOH and HO• have been investigated thermodynamically and kinetically in water and penthylethanoate. Based on the pKa values of BOH, the percentages of various acid-base species were estimated and subsequently incorporated into the described procedures. Changes in Gibbs free energy of HAA reactions demonstrated the spontaneity of hydrogen transfer from each OH group of BOH with reaction rates of 1.8 × 107 and 7.5 × 104 M−1 s−1. This process occurred through Proton Coupled-Electron Transfer (PCET) mechanism. Reactions involving RAF processes were operable in six places, with rate constants ranging from 4.8 × 104 to 3.0 × 108 M−1 s−1. Reaction rates calculated for electron transfer from anionic species (BO-) were the kinetically most favorable reaction pathway of the order of 109 M−1 s−1, which unequivocally shows that these reactions are diffusion controlled. These results shed new light on BOH chemistry and its possible medical use. The molecular docking analysis was performed to identify the inhibition potency of the baicalein-anion against Glyoxalase I (GLOI) receptor. This study demonstrated that molecular docking analysis is an important tool for evaluating the interactions of biologically significant compounds, particularly their many acid-base forms. [ABSTRACT FROM AUTHOR]

The equilibrium geometries and chemical reactivities of the novel coumarine derivative, 3-[1-(3-hydroxypropylamino)ethylidene]chroman-2,4-dione, in water and benzene were investigated. The Fukui parameters, calculated by the Natural and Atoms in Molecules charges, were determined for all atoms in both phases. The most potent sites for the electrophilic, nucleophilic, and radical attack are discussed. Molecular docking analysis was carried out to identify the potency of inhibition of the title molecule against human cartilage proteins. The inhibition activity was obtained for ten conformations of ligand inside protein. This study proved that the Fukui indices can be used as the reactivity descriptors for the novel substances with inhibitory activity. Graphical abstract: [ABSTRACT FROM AUTHOR]

In this contribution, four new compounds synthesized from 4-hydroxycoumarin and tyramine/octopamine/norepinephrine/3-methoxytyramine are characterized spectroscopically (IR and NMR), chromatographically (UHPLC-DAD), and structurally at the B3LYP/6-311++G*(d,p) level of theory. The crystal structure of the 4-hydroxycoumarin-octopamine derivative was solved and used as a starting geometry for structural optimization. Along with the previously obtained 4-hydroxycoumarin-dopamine derivative, the intramolecular interactions governing the stability of these compounds were quantified by NBO and QTAIM analyses. Condensed Fukui functions and the HOMO-LUMO gap were calculated and correlated with the number and position of OH groups in the structures. In vitro cytotoxicity experiments were performed to elucidate the possible antitumor activity of the tested substances. For this purpose, four cell lines were selected, namely human colon cancer (HCT-116), human adenocarcinoma (HeLa), human breast cancer (MDA-MB-231), and healthy human lung fibroblast (MRC-5) lines. A significant selectivity towards colorectal carcinoma cells was observed. Molecular docking and molecular dynamics studies with carbonic anhydrase, a prognostic factor in several cancers, complemented the experimental results. The calculated MD binding energies coincided well with the experimental activity, and indicated 4-hydroxycoumarin-dopamine and 4-hydroxycoumarin-3-methoxytyramine as the most active compounds. The ecotoxicology assessment proved that the obtained compounds have a low impact on the daphnia, fish, and green algae population. [ABSTRACT FROM AUTHOR]

• The 3-(1- m -chloridoethylidene)-chromane-2,4‑dione was characterized by x-ray structural analysis. • The 3-(1- m -chloridoethylidene)-chromane-2,4‑dione was characterized by spectroscopic and DFT methods. • The hirshfeld surface analysis of 3-(1- m -chloridoethylidene)-chromane-2,4‑dione was performed. • The electronic structure of 3-(1- m -chloridoethylidene)-chromane-2,4‑dione was examined using a quantum chemical approach. • The inhibitory nature of 3-(1- m -chloridoethylidene)-chromane-2,4‑dione against the adenosine A 2A (ADORA 2A) receptor was investigated by molecular docking and dynamics. The coumarin derivative, 3-(1- m -chloridoethylidene)-chroman-2,4‑dione, was previously synthesized by a conventional method. Detailed structural characterization of the obtained compound was performed by using X-ray crystallography and vibrational analysis. Experimental data were confirmed by the optimization of a structure employing three common functionals (B3LYP-D3BJ, M06–2X, and APF-D) in combination with a 6–311+ G (d,p) basis set. Low values of the average absolute error and the high values of the correlation coefficient for bond lengths and angles, proved that B3LYP-D3BJ could be used for the structural and spectral analysis. The stability of the investigated compound was determined by Fukui functions, NBO, and QTAIM analyses along with various reactivity parameters. The special emphasis in the discussion was put on the role of a chlorine atom for the overall stability and reactivity by comparison with 3-(1-(phenylamino)ethylidene)-chromane-2,4‑dione. In silico simulations with Adenosine A 2 a receptors (ADORA 2A), were performed using molecular docking and dynamics methods for both coumarin derivatives. The thermodynamic parameters and specific interactions proved the importance of chlorine atom for possible biological activity. [ABSTRACT FROM AUTHOR]

• The 3-acetyl-4‑hydroxy‑2-oxo-2H-chromen-7-yl acetate (3AcHyC) was synthesized and characterized. • The crystallographic structure of the 3AcHyC was analyzed. • The hirshfeld surface analysis of 3AcHyC was performed. • The electronic structure of 3AcHyC was examined using a quantum chemical approach. • The inhibitory nature of 3AcHyC against the TDP1 receptor was investigated by molecular docking. In the present study, the structural, spectroscopic (FT-IR, NMR, and UV–Vis) and electronic properties of newly synthesized 3-acetyl-4‑hydroxy‑2-oxo-2H-chromen-7-yl acetate (3AcHyC) were determined by experimental and theoretical methods. The structural parameters (bond lengths and angles) were calculated using the B3LYP-D3BJ/6–311++ G (d,p) theoretical model and compared with the experimentally determined crystal structure of the investigated compound. Hirshfeld surfaces and fingerprint plots analysis were used to find and analyze the percentage of intermolecular interactions in the crystal structure of the investigated compound. The calculated FT-IR frequencies were determined from the same theoretical model and matched with experimental data. The NMR chemical shifts (1H and 13C) were recorded in the CDCl 3 solution and compared with theoretically determined spectra. The UV–Vis absorption spectrum was analyzed and compared with the spectrum calculated by Time-Dependent Density Functional Theory (TD-DFT). The obtained and compared spectroscopic data demonstrated that applied level theory reproduces well the experimental results. Furthermore, to examine the electronic structure of the studied molecule, the Natural Bond Orbitals (NBOs), the Quantum Theory of Atoms in Molecules (QTAIM), Non-linear Optical parameter (NLO), and Mapped Molecular Electrostatic Potential (MEP) surface analyses were also performed with the same level of theory. Furthermore, results of in silico molecular docking calculations, indicate the stability as well as favorable binding interactions between the investigated compound and the Tyrosyl DNA-Phosphodiesterase 1 (TDP1) active site. Also, the results indicate that the investigated compound is a favorable precursor in the synthesis of new coumarin derivatives with potentially significant biological and pharmacological properties. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• A suitable level of theory for the description of octopamine is B3LYP-D3BJ/6−311 G(d,p). • Additional OH group influences the scavenging reaction rates and thermodynamics. • The dominant mechanism of DPPH and ABTS scavenging is SPLET. • Additional bonds are present in β1/β2- adrenergic receptors-norepinephrine complex. • Protein complexes have similar flexibility, interatomic distances and compactness. Octopamine is a neurotransmitter in invertebrates and a phenol analog of norepinephrine. The crystallographic and spectral (UV–visUV, and NMR) characteristics of octopamine were investigated experimentally and theoretically by applying appropriate level of theory, B3LYP-D3BJ/6-311++G(d,p), which reproduced well the experimental bond lengths and angles. The intramolecular interactions governing the stability of conformers were described by NBO and QTAIM analyses. The antiradical potencies of octopamine and norepinephrine towards DPPH and ABTS+ were examined with special emphasis on the preferred mechanism and effect of catechol moiety. Several techniques were used to distinguish Hydrogen Atom Transfer (HAT) and Proton Coupled Electron Transfer (PCET) mechanisms for reaction with DPPH. The calculated rate constants of the reactions with both radicals showed that Sequential Proton Loss Electron Transfer (SPLET) mechanism was dominant both thermodynamically and kinetically, with values of thermodynamic functions and rate constants clearly proving the importance of the second hydroxyl group in structure. The Molecular Docking and afterward Molecular Dynamics calculations of formed complexes between octopamine/norepinephrine with β1- and β2- adrenergic receptors examined in details the interactions that lead to the formation of stable complexes. The number of strong interactions of amino acids with norepinephrine was higher, but the absence of hydroxyl group in octopamine did not lead to a significant change in the type of interactions and stability. The formed complexes showed higher flexibility of amino acids, similar compactness of structure as proteins and increased interatomic distances of the backbone when compared to pure proteins. [ABSTRACT FROM AUTHOR]

Calculations based on the density functional theory, with the B3LYP functional and the 6-311++G(d,p) basis set, were performed with the aim of confirming the molecular structure and spectroscopic characteristics of kaempferol, a naturally occurring flavonoid molecule. The electronic structure of kaempferol was examined using NBO analysis. The assigning of the experimentally obtained IR and Raman spectra was performed after the best-fit-based comparison with theoretical spectra. The 13C and 1H NMR experimental spectra were related to the theoretically obtained values of the chemical shifts determined by the GIAO method. The correlation coefficient and the average absolute error values proved B3LYP-D3 to be an adequate method in describing the NMR parameters of kaempferol. Molecular docking analysis was carried out in order to identify the potency of inhibition of the title molecule against human procalcitonin. The inhibition activity was obtained for 10 conformations of ligand inside the protein. [ABSTRACT FROM AUTHOR]

In this study, the analysis of vibrational spectra and electronic structure of 3-(1- m -toluidinoethylidene)-chromane-2,4-dione (L1) and its corresponding palladium (II) complex (C1) was employed to characterize the spectroscopic behavior and molecular structure of the investigated compounds by applying B3LYP-D3BJ/6-311+G(d,p) level of theory. Hirshfeld surface analysis of the intermolecular interactions in crystal structure L1 was performed. The AIM and NBO analyses were used to understand the type, nature, and strength of intramolecular interactions and to examine the electronic structure of the studied molecules. The calculation of HOMO and LUMO energies was applied in order to present the charge transfer within the molecule. The computational molecular docking studies of title compounds was performed with special emphasis on differences in binding of ligand and complex. Image 1 • The vibrational spectroscopic analysis of 3-(1- m -toluidinoethylidene)-chromane-2,4-dione (L1) and its Pd (II) complex (C1) were employed. • The Hirshfeld surface analysis of L1 was performed. • The electronic structure of L1 and C1 was examined using a quantum chemical approach. • Inhibitory nature of L1 and C1 against CDK2 receptor was investigated by molecular docking. [ABSTRACT FROM AUTHOR]

• (E)-N'-(2,5-dimethoxybenzylidene)picolinohydrazide (DBP) single crystal was synthesised by recrystallization method. • DBP crystal was characterized by XRD, FTIR, Raman, NMR and UV–vis spectra. • The structure of DBP was optimized by B3LYP, CAM-B3LYP, B3PW91, M05-2X, and M06-2X with the 6-311++G(d,p) basis set. • NBO, HOMO-LUMO, QTAIM and molecular docking analyses were made and discussed. • Nonlinear optical behavior was confirmed by Z-scan analysis. Schiff bases and hydrazides are groups of compounds with important biological activities. In this contribution, (E)-N'-(2,5-dimethoxybenzylidene)picolinohydrazide (DBP) was synthesized and characterized by X-ray crystallography, IR, Raman, UV–vis and NMR spectroscopies. The Hirshfeld surface analysis was performed to investigate the interactions within the crystal package. The structure of DBP was optimized by several functionals (B3LYP, CAM-B3LYP, B3PW91, M05-2X, and M06-2X) in conjunction with the 6-311++G(d,p) basis set. The suitable level of theory was determined based on the comparison between experimental and theoretical bond lengths and angles (M06-2X/6-311++G(d,p)). The Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) approaches were used for the quantification of the interaction strengths within a structure. The experimental IR and Raman peaks were assigned based on the calculated one, with the aid of the Potential Energy Distribution (PED) analysis. The 1H and 13C NMR signals were also assigned when compared to the calculated ones. The reproducibility of the experimental results proved that a suitable level of theory was obtained. The experimental UV–vis spectra consisted of a wide peak between 200 and 450 nm, while the most prominent theoretical transitions were located at 324, 231, and 213 nm. The nonlinear optical (NLO) studies Z-scan experiment allowed the determination of the nonlinear absorption coefficient and nonlinear refractive index, thus proving that DBP can be used as NLO material. Various reactivity descriptors of DBP and its analogs were computed and the reactivity was checked towards Cyclin-Dependent Kinase 2 protein, with the influence of structural parameters explained. [Display omitted] [ABSTRACT FROM AUTHOR]

• Structure of (E)-2-(2,5-dimethoxybenzylidene)hydrazinecarbothioamide was obtained. • A suitable level of theory for the structural optimization is M05-2X/6-311++G(d,p). • IR, Raman and NMR spectra are assigned based on optimized structure. • Stacked dimer has the highest interaction energy determined by DFT, NBO, and QTAIM. • Favorable interactions with Polo-like Kinase 1 were shown by molecular docking. Thiosemicarbazides are an important class of compounds with pronounced biological activities. In this contribution, the crystallographic structure of (E)-2-(2,5-dimethoxybenzylidene)hydrazinecarbothioamide (DBH) was described, and further spectroscopic studies (IR, Raman, 1H, and 13C NMR) studies were performed. Several density functional theory functionals (B3LYP, CAM-B3LYP, APFD, PBEPBE, M05-2X, and M06-2X) in conjunction with 6-311++G(d,p) were applied for the optimization of the structure. The highest resemblance to the crystallographic structure was obtained for structure optimized at M05-2X/6-311++G(d,p) level of theory. This structure was further used for the prediction of IR, Raman, and NMR spectra. The detailed vibrational and NMR analysis, with the most prominent bands assigned, proved that the experimental and theoretical spectra match well and that the obtained level of theory was suitable for the description of structure. Special emphasis was put on the analysis of dimers of DBH and water/DMSO- DBH structures to examine specific interactions. Natural Bond Orbital (NBO) and Quantum Atoms in Molecules (QTAIM) theories were applied for the quantification of the strength of these interactions. The most active positions were outlined through the calculation of the Fukui functions. A molecular docking study of DBH was performed towards Polo-like Kinase 1 (PLK1) to investigate the potential antitumor activity and the results were compared to volasertib. Specific interactions and binding affinities of monomers and dimers of DBH were discussed. [ABSTRACT FROM AUTHOR]