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•New coumarine derivatives and palladium(II) complexes were synthesized.•Characterized by microanalysis, infrared, 1H and 13C NMR spectroscopy.•Monocrystal X-ray structural analysis ...and DFT calculations.•Antimicrobial activity for ligands and complexes is investigated.
The five coumarin derivatives 3-(1-(2-hydroxypropylamino)ethylidene)-chroman-2,4-dione (L1), 3-(1-(phenylamino)ethylidene)-chroman-2,4-dione (L2), 3-(1-(o-toluidino)ethylidene)-chroman-2,4-dione (L3), 3-(1-(m-toluidino)ethylidene)-chroman-2,4-dione (L4), 3-(1-(2-mercaptoethylamino)ethylidene)-chroman-2,4-dione (L5) and its corresponding complexes 3-(1-(2-hydroxypropylamino)-ethylidene)-chroman-2,4-dione-palladium(II) (C1), 3-(1-(phenylamino)-ethylidene)-chroman-2,4-dione-palladium(II) (C2), 3-(1-(o-toluidino)-ethylidene)-chroman-2,4-dione-palladium(II) (C3), 3-(1-(m-toluidino)ethylidene)-chroman-2,4-dione-palladium(II) (C4), 3-(1-(2-mercaptoethylamino)ethylidene)-chroman-2,4-dione-palladium(II) (C5), were synthesized and characterized with microanalysis, infrared, 1H and 13C NMR spectroscopy. The proposed structures of ligands L3 and L4 were confirmed on the basis of the X-ray structural study. The ligands and their complexes were tested for their in vitro antimicrobial activity against 17 species of bacteria and fungi. Testing is performed by the microdilution method, with the minimum inhibitory concentration (MIC) and the minimum microbicidal concentration (MMC) being determined.
Coumarin N-acylhydrazone derivatives were synthesized in the reaction of 3-acetylcoumarin and different benzohydrazides in the presence of molecular iodine as catalyst and at room temperature. All ...reactions were rapidly completed, and products were obtained in good to excellent yields. It is important to emphasize that four products were reported for the first time in this study. The obtained compounds were subjected to evaluation of their in vitro antioxidative activity using DPPH, ABTS, and FRAP methods. It was shown that products with a catechol moiety in their structure are the most potent antioxidant agents. The thermodynamic parameters and Gibbs free energies of reactions were used to determine the most probable mechanism of action. The results of in silico examination emphasize the need to take solvent polarity and free radical species into account when examining antiradical action. It was discovered by using computational approaches that HAT and SPLET are competitive molecular pathways for the radical scavenging activity of all compounds in polar mediums, while the HAT is the dominant mechanism in non-polar environments.
Spectral assignments done on the best-fit basis comparison of the experimentally obtained and theoretically calculated vibrational spectra of fisetin match quite well indicating DFT calculations as ...very accurate source of normal mode assignments.
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► The experimental and theoretical research in fisetin structure is performed.
► The assignments of the bands are proposed on the basis of fundamentals.
► Description of the largest vibrational contributions to the normal modes is given. ► The Raman spectra of baicalein and quercetin were used for qualitative comparison.
This paper addresses experimental and theoretical research in fisetin (2-(3,4-dihydroxyphenyl)-3,7-dihydroxychromen-4-one) structure by means of experimental IR and Raman spectroscopies and mechanistic calculations. Density Functional Theory calculations, with M05-2X functional and the 6-311+G (2df, p) basis set implemented in the Gaussian 09 package, are performed with the aim to support molecular structure, vibrational bands’ positions and their intensities. Potential energy distribution (PED) values and the description of the largest vibrational contributions to the normal modes are calculated. The most intense bands appear in the 1650–1500
cm
−1 wavenumber region. This region involves a combination of the C
O, C2
C3 and C–C stretching vibrational modes. Most of the bands in the 1500–1000
cm
−1 range involve C–C stretching, O–C stretching and in-plane C–C–H, C–O–H, C–C–O and C–C–C bending vibrations of the rings. The region below 1000
cm
−1 is characteristic to the combination of in plane C–C–C–H, H–C–C–H, C–C–C–C, C–C–O–C and out of plane O–C–C–C, C–C–O–C, C–C–C–C torsional modes. The Raman spectra of baicalein and quercetin were used for qualitative comparison with fisetin spectrum and verification of band assignments. The applied detailed vibrational spectral analysis and the assignments of the bands, proposed on the basis of fundamentals, reproduced the experimental results with high degree of accuracy.
•The (E)-3-(1-((4‑hydroxy-3-methoxyphenyl)amino)-ethylidene)chromane-2,4‑dione (L1) and (E)−3-(1-((3‑hydroxy-4-methoxyphenyl)-amino)ethylidene) chromane-2,4‑dione (L2) was synthesized and ...characterized.•The crystallographic structure of the L1 was analyzed.•The interactions between newly synthesized compounds and human serum albumin investigated by fluorescence and absorption spectroscopy.•The inhibitory nature of L1 and L2 against the human serum albumin was investigated by molecular docking and molecular dynamic simulations.
Two 4-hydroxycoumarin derivatives: (E)-3-(1-((4‑hydroxy-3-methoxyphenyl)amino) -ethylidene)chromane-2,4‑dione (L1) and (E)-3-(1-((3‑hydroxy-4-methoxyphenyl)-amino)ethylidene) chromane-2,4‑dione (L2), were prepared and structurally characterized by spectroscopic techniques in combination with the B3LYP-D3BJ theoretical method. The interactions between newly synthesized compounds and human serum albumin (HSA) were investigated under physiological conditions at 296,303, and 310 K by fluorescence and absorption spectroscopy, molecular docking, and molecular dynamic simulations. The results of absorption and fluorescence spectral analysis showed that ligands quenched HSA fluorescence through a static process. The corresponding thermodynamic parameters ΔH0, ΔS0, and ΔG0 were calculated according to Van't Hoff's equation. The obtained results indicated that compounds bind spontaneously to HSA mainly by van der Waals's forces and through hydrogen bonds. Ligand-competitive displacement experiments, using known site-specific ligands for HSA's binding sites (I and II) suggest that ligands had a higher affinity for site I (subdomain IIA). The results of the computational analysis follow the experimental data, and the obtained results suggest that the investigated compounds show a good binding affinity according to the HSA receptor, which will be useful for future studies related to rational drug design.
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The equilibrium geometries and chemical reactivities of the novel coumarine derivative, 3-1-(3-hydroxypropylamino)ethylidenechroman-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.
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•New ligands and corresponding palladium(II) complexes were synthesized.•Characterized by microanalysis, IR, 1H and 13C NMR spectroscopy, DFT calculations.•Antimicrobial activity for ...ligands and complexes were investigated.
A series of four new ligands of general formula R2-S,S-eddtrp·2HCl (L1–L4) and their palladium(II) complexes of general formula PdCl2(R2-S,S-eddtrp) (C1–C4) where R = ethyl, 1-propyl, 1-butyl and 1-pentyl; S,S-eddtrp·2HCl = ethylenediamine-N,N′-di-(3,3′-1H-indol-3yl)propionic acid dihydrochloride have been synthesized and characterized by elemental microanalysis, infrared, 1H and 13C NMR spectroscopy. The proposed structures of all compounds were examined by density functional theory (DFT). The ligands (L1–L4) and Pd(II) complexes (C1–C4) were screened for their antimicrobial activity against 19 microorganisms and minimum inhibitory concentrations (MIC) and minimum microbicidal concentration (MMC) were determinated. All tested ligands and complexes exhibited the highest antimicrobial activity on Escherichia coli ATCC 25922, being in range or higher than positive control, tetracycline.
Naturally occurring flavonoid molecules, i.e. fisetin (2-(3,4-dihydroxyphenyl)-3,7-dihydroxychromen-4-one) and baicalein (5,6,7-trihydroxy-2-phenyl-4 H -chromen-4-one), have been investigated ...experimentally and theoretically for their ability to scavenge hydroxyl and superoxide anion radicals. The reaction enthalpies for the reaction of fisetin and baicalein with selected radical species, related to three mechanisms of free radical scavenging activity (HAT, SET-PT and SPLET), are calculated using the M05-2X/6-311+G(d,p) model. The calculated energy requirements indicated the preferred radical scavenging mechanisms in polar protic and aprotic solvents.
Density functional theory calculations were performed to evaluate the antioxidant activity of baicalein. The conformational behaviors of both the isolated and the aqueous-solvated species (simulated ...with the conductor-like polarizable continuum solvation model) were analyzed at the M052X/6-311 + G(d,p) level. The most stable tautomers of various forms of baicalein displayed three IHBs between O4 and OH5, O5 and OH6, and O6 and OH7. The most stable tautomer of the baicalein radical was obtained by dehydrogenating the hydroxyl at C6, while the most stable anion tautomer was obtained by deprotonating the C7 hydroxyl in gaseous and aqueous phases. The expected antioxidant activity of baicalein was explained by its ionization potentials (IPs) and homolytic O–H bond dissociation enthalpies (BDEs), which were obtained via the UM052X optimization level of the corresponding radical species. Heterolytic O–H bond cleavages (proton dissociation enthalpies, PDEs) were also computed. The calculated IP, BDE, and PDE values suggested that one-step H-atom transfer, rather than sequential proton loss–electron transfer or electron transfer–proton transfer, would be the most favorable mechanism for explaining the antioxidant activity of baicalein in the gas phase and in nonpolar solvents. In aqueous solution, the SPLET mechanism was more important.
Figure
Spin density map of the most stable baicalein radical form
The palladium(II) complex decreased viability of U251 human glioma and B16 mouse melanoma cells in a dose and time dependent manner, while its ligand exhibited only moderate cytotoxicity.
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•New coumarine derivative and palladium(II) complex were synthesized.•Characterized by microanalysis, infrared, 1H and 13C NMR spectroscopy.•Monocrystal X-ray structural analysis and DFT calculations.•Cytotoxicity for ligand and complex is investigated.
The new coumarine derivative, 3-(1-(3-hydroxypropylamino)ethylidene)chroman-2,4-dione, and corresponding palladium(II) complex have been synthesized and characterized by microanalysis, infrared, 1H and 13C NMR spectroscopy. The structure of the ligand, solved using a monocrystal X-ray structural analysis, consists of two crystallographic different pseudocentrosymmetrically related molecules of 3-(1-(3-hydroxypropylamino)ethylidene)chroman-2,4-dione, while the structure of the square-planar palladium(II) complex was proposed on the basis of DFT calculations. The palladium(II) complex decreased viability of U251 human glioma and B16 mouse melanoma cells in a dose and time dependent manner, while its ligand exhibited only moderate cytotoxicity.
Fisetin (3,3',4',7-tetrahydroxyflavone) has been investigated for its ability to bind iron in a wide range of pH values of acetate and phosphate buffered solutions. To assess the relevant ...interactions of iron with fisetin, combined spectroscopic (UV/visible, Raman, MS) and theoretical approaches were used. The chelation sites, stoichiometry, stability and the dependence of the complexes structures on pH were defined. The results pointed to the formation of two iron-fisetin complexes with stoichiometries of 1 : 1 and 1 : 2, depending on the pH. Results of vibrational analysis and theoretical calculations implicated the 3-hydroxyl-4-carbonyl group as a chelating site in acidic media while catechol (3'-hydroxyl-4'-hydroxyl) group was identified as the chelating group in neutral and alkaline media. Determined relative, conditional, stability constants with iron-fisetin were in the range from 6 × 10(4) dm(3) mol(-1) to 7 × 10(9) dm(6) mol(-2). Competition experiments demonstrated that fisetin bound iron less strongly than EDTA and citric acid under the investigated experimental conditions. Rate constant values calculated for the fast step of the DPPH reduction for fisetin and the iron-fisetin complex are k(1) = 225.75 dm(3) mol(-1) s(-1) and k(1) = 658.00 dm(3) mol(-1) s(-1). These values fit within the interval of the rate constant values which are typical for antioxidants which have a single polyphenolic nucleus. The equilibrium geometries, optimized at the B3LYP/6-311 + G(d,p) and M06/6-311 + G(d,p) levels of theory, predicted structural modifications between the ligand molecule in the free state and in the complex structure. The theoretical model has been validated by both vibrational and electronic spectroscopies.
