Search

Imatinib is a selective tyrosine kinase inhibitor, successfully used for the treatment of chronic myelogenous leukaemia and gastrointestinal stromal tumors. Binding of drugs to proteins influence their pharmacokinetic and pharmacodynamics action. In the blood, the drug is distributed in the body in the free form or bound to plasma protein. Albumin and α-1 glycoprotein (AGP) are plasma proteins with the highest affinity for drug substances. Drugs which are weak acids mainly bind to plasma albumin, while drugs that are bases have affinity for α-1 glycoprotein. The main goal of this study is to quantitatively evaluate the interaction between imatinib mesylate (IMT) and α-1 glycoprotein to characterize the nature and forces underlying the formation of a molecular complex. Relaxation experiments provide quantitative information about the relationship between the binding affinity and structure of IMT. Thus, association constant was determined as Ka = 873.36 M−1. The ITC data revealed that the binding was an entropy driven process and the association constant Ka = 3.22 × 103 M−1, with a 1:1 stoichiometry. The results obtained by NMR and ITC were complemented with a molecular docking study.

1H NMR spectroscopy was applied for the classification of a wine set, according to geographical origin and variety. The originality of the proposed approach consisted in a single uniform pH adjustment to all wine samples, in order to reduce the pH variation range but allowing to keep unaltered the wine samples fingerprint, as well as a signal treatment limited to water suppression during acquisition. No further peak alignment was performed, neither through individual pH adjustment, nor with specific software. The wine classifications were made separately on four spectral areas after exclusion of ethanol signal regions. It was found that the spectral region having the highest discrimination potential for both geographical and varietal discrimination is represented by Area 1 (5.1–9.8 ppm). In this spectral range, the separation between samples coming from different geographical areas was realized in a 100% percentage, in both initial and cross-validation procedure. For simultaneous variety classification percentages better than 99% for initial classification and 97% for cross validation procedure were achieved. Besides, the high discrimination potential, another advantage of this approach is given by a simplified working protocol which consists in an easy, rapid and affordable preparation step, making it a good candidate for laboratories which are dealing with a high number of samples.

The solvothermal polyol reaction is one of the most common methods known in the literature to synthesize magnetite nanoparticles and especially clusters. Despite this, its reaction mechanism is still not definitely determined. In the course of this work, a polyol reaction with sodium acrylate as stabilizer was used as a representative example. By using analytic tools such as TEM/SEM, XRPD, FTIR and Raman spectroscopy, XPS and magnetization measurements, the influence of several reaction parameters was examined, some of them for the first time for this type of reaction. The results detailed here have consequences for reproducibility as well as scale-up for this reaction. Using NMR techniques, the surface coating of the clusters was also analyzed. It was found that the coating consists of a variety of molecules, not just the stabilizer added in the reaction. By varying the temperature, it was possible to produce maghemite clusters instead of magnetite ones. Finally, on the basis of detailed analysis of intermediates, a possible reaction mechanism was formulated and used to explain several of the earlier findings.

Spectroscopic investigation supported by molecular modeling methods has been used to describe the inclusion complex of β-cyclodextrin (β-CD) with 1-Methyl-1-({2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-4-yl}methyl) piperidinium chloride (1MPTMPC) in solution and in solid state. The formation of inclusion complex between the β-CD and the 1MPTMPC has been investigated both in solution and in the solid state. Solution-state complexation between the 1MPTMPC and β-CD was established using 1H NMR spectroscopy and isothermal titration calorimetry (ITC). From the 1H NMR spectroscopic studies, 1:1 complex stoichiometry was deduced with an association constant (K) of 925 M−1. Using an independent binding model, the ITC technique provides a K value of the same order with the one determined by NMR and the thermodynamic parameters ΔH, ΔS and ΔG which reveals driving forces involved during complex formation. The formation of the solid inclusion compound was confirmed by X-ray powder diffraction and differential scanning calorimetry. The most probable conformation of the inclusion complex obtained through a molecular docking investigation corroborates well to ROESY experiment.

Functionalized multi-walled carbon nanotubes (MWCNTs) are potential systems for drug delivery applications like cancer therapy. By using NMR spectroscopy, we have demonstrated that 99.8% deuterated water, confined at nanoscale, splits into several components which flow with different diffusion coefficients through MWCNTs having an average diameter of 15 nm. Remarkably, we have highlighted the effect of the functionalization of MWCNTs with COOH- and NH2-molecules on the diffusion of water inside MWCNTs. Our results show that the specific choice of molecules used to functionalize the external surface of MWCNTs allows direct control of the diffusion coefficient. Raman and XPS spectroscopy were used to characterize the structure of MWCNTs after functionalization with COOH- and NH2-.

A quantitative analysis of the interaction between zidovudine (AZT) and human serum albumin (HSA) was achieved using Isothermal titration calorimetry (ITC) in combination with fluorescence and 1H NMR spectroscopy. ITC directly measure the heat during a biomolecular binding event and gave us thermodynamic parameters and the characteristic association constant. By fluorescence quenching, the binding parameters of AZT-HSA interaction was determined and location to binding site I of HSA was confirmed. Via T1 NMR selective relaxation time measurements the drug-protein binding extent was evaluated as dissociation constants Kd and the involvement of azido moiety of zidovudine in molecular complex formation was put in evidence. All three methods indicated a very weak binding interaction. The association constant determined by ITC (3.58×102M-1) is supported by fluorescence quenching data (2.74×102M-1). The thermodynamic signature indicates that at least hydrophobic and electrostatic type interactions played a main role in the binding process.

In this study we designed, synthesized and analyzed a water-soluble molecule presenting a good antioxidant and antiradical activity, namely Dihydroxy-Phenyl-Thiazol-Hydrazinium chloride (DPTH). This molecule contains 2’,4’-dihydroxyphenyl and the 2-hydrazinyl-4-methyl-thiazole fragments linked through a hydrazone and having very good antiradical scavenging, antioxidant activity and a low chelation activity in the in vitro evaluations. Knowing that, in the organism, the drugs are transported to the tissues generally bound to a plasma protein we, additionally, investigated its interaction with human serum albumin (HSA)-the main soluble protein in plasma capable of making complexes with various molecules, which deliver then, to the tissues. This binding can influence the pharmacokinetic and pharmacodynamic profile of drugs. Consequently, the interaction between DPTH and human serum albumin (HSA) was carefully examined using isothermal titration calorimetry (ITC) and T1 NMR selective relaxation time spectroscopy. According to ITC, DPTH: HSA interaction process was spontaneous and endothermic with an affinity constant Ka = 4.31 × 102 M−1 and the stoichiometry coefficient (n) was equal 1, which was subsequently confirmed by 1H NMR. Relaxation experiments provide quantitative information about the relationship between the binding affinity and structure of DPTH. Thus, association constant was determined as Ka = 9.65 × 102M −1. The results obtained by ITC and NMR were complemented with a molecular docking study.

Thiazolidine-2,4‑dione represents a key heterocyclic core in medicinal chemistry because it has the ability to bind to a wide variety of protein targets and has been intensively studied for developing bioactive multitargeting agents. The N-alkylation of imides and O-alkylation of phenols are important reactions frequently used in the synthesis of biologically active compounds, like the thiazolidine-2,4‑dione derivatives. Based on literature data, by treating (Z)-5-(4-hydroxybenzylidene)-thiazolidine-2,4‑dione with alkyl halides in a 1:1 molar ratio, either O-alkylation or N-alkylation reactions can take place. Six (Z)-5-(4-hydroxybenzylidene)-thiazolidine-2,4‑dione derivatives were synthesized by alkylating (Z)-5-(4-hydroxybenzylidene)-thiazolidine-2,4‑dione with aliphatic halogenated derivatives in alkaline environment, using a 1:1 molar ratio and then were physically and spectrally analyzed. The spectral data and the results obtained from the theoretical evaluation of the parent compound's acidity support the formation of N-alkylated derivatives in the reaction conditions.

Complexation in solution between meclofenamate sodium (MCF) and β-cyclodextrin was studied using one- and two-dimensional 1H NMR spectroscopy and molecular docking coupled with ab initio calculations. The large variation of chemical shifts from protons located inside the hydrophobic cavity of β-cyclodextrin, provided clear evidence of inclusion complexation. The stoichiometry of the inclusion complex was determined to be 1:1, using the method of continuous variation. To ascertain the solution geometry of the host–guest complex a ROESY experiment was carried out. The results suggested a preferential binding of the dichlorophenyl moiety of the guest molecule within the β-cyclodextrin cavity, conformation which also sustained by the theoretical computational investigations. The association constant of the inclusion complex was determined using 1H NMR titration method in solution followed by a non-linear least-square regression implemented in CONSTEQ, a software developed in our group. After a preliminary molecular docking investigation, the most probable conformation was subjected to ab initio calculations using SIESTA software package, to characterize more precisely the stabilization energy of the 1:1 inclusion complex.

C. albicans is the most frequently occurring fungal pathogen, and is becoming an increasing public health problem, especially in the context of increased microbial resistance. This opportunistic pathogen is characterized by a versatility explained mainly by its ability to form complex biofilm structures that lead to enhanced virulence and antibiotic resistance. In this context, a review of the known C. albicans biofilm formation inhibitors were performed and a new N-(oxazolylmethyl)-thiazolidinedione scaffold was constructed. 16 new compounds were synthesized and characterized in order to confirm their proposed structures. A general antimicrobial screening against Gram-positive and Gram-negative bacteria, as well as fungi, was performed and revealed that the compounds do not have direct antimicrobial activity. The anti-biofilm activity evaluation confirmed the compounds act as selective inhibitors of C. albicans biofilm formation. In an effort to substantiate this biologic profile, we used in silico investigations which suggest that the compounds could act by binding, and thus obstructing the functions of, the C. albicans Als surface proteins, especially Als1, Als3, Als5 and Als6. Considering the well documented role of Als1 and Als3 in biofilm formation, our new class of compounds that target these proteins could represent a new approach in C. albicans infection prevention and management.

Background and aims. Synthesis of new potential antimicrobial agents and evaluation of their lipophilicity. Methods. Ten new thiazolyl-oxadiazoline derivatives were synthesized and their structures were validated by 1 H-NMR and mass spectrometry. The lipophilicity of the compounds was evaluated using the principal component analysis (PCA) method. The necessary data for applying this method were obtained by reverse-phase thin-layer chromatography (RP-TLC). The antimicrobial activities were tested in vitro against four bacterial strains and one fungal strain. Results. The lipophilicity varied with the structure but could not be correlated with the antimicrobial activity, since this was modest. Conclusions. We have synthesized ten new heterocyclic compounds. After their physical and chemical characterization, we determined their lipophilicity and screened their antimicrobial activity.

Background and aims. In the context of the increasing phenomenon of microbial resistance to usual drugs, the development of new treatment strategies and new therapeutic protocols is a constant need. Thiazolidinedione and chromone represent two important scaffolds in medicinal chemistry due to their large pharmacological applicability. Methods. We synthesized a new 5-(chromene-3-yl)methylene-2,4-thiazolidinedione starting from 6,8-dichloro-4-oxo-4 H -chromene-3-carbaldehyde. Then, by treating with different α-bromoalkylarylketones, we obtained N -substituted derivatives. All new compounds were investigated for their antimicrobial potential, using the diffusion method, against Listeria monocytogenes ATCC 13932, Staphylococcus aureus ATCC 49444 , Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028 and Candida albicans ATCC 10231 . Three concentrations, 10 mg/ml, 5 mg/ml and 1 mg/ml of compounds were used. The results were evaluated by the measurement of the inhibition zone diameters and compared to those of gentamicin and fluconazole respectively, as reference drugs. Results. All new synthesized compounds were characterized using physico-chemical and spectrometric methods. They displayed modest to good antimicrobial activity. New molecules 8 , 9 and 10 may represent promising candidates, showing zone inhibition diameters superior to those of reference drugs. Conclusions. This work presents chemical synthesis, characterization and investigation of the antibacterial and antifungal potential of 5-(chromene-3-yl)methylene-2,4-thiazolidinedione derivatives, which may be worthy of future research for designing new chemical entities.

Assessment of interaction between β-cyclodextrin and 3-carboxy-1-[(2-phenyl-1,3-thiazol-4-yl) methyl]pyridin-1-ium iodide (3CPTMPI) in aqueous solution were investigated by isothermal titration calorimetry (ITC) and 1D and 2D 1H NMR spectroscopy at 298 K. Thermodynamic analysis using ITC revealed that the association constant of β-cyclodextrin and 3CPTMPI is 441.6 M−1 with favorable enthalpy and entropy changes. These thermodynamic parameters indicate that the binding is dominated by hydrophobic interactions, which is in agreement with inclusion complex formation. The details of β-CD/3CPTMPI molecular interaction was analyzed by 1H 2D NMR allowing the proposition of an inclusion model for 3CPTMPI into β-CD. Rotating frame NOE spectroscopy (ROESY) was used to certain the solution geometry host–guest complex. The results reveal that the 3CPTMPI molecule penetrates into β-CD cavity with both aromatic and thiazol rings. For this type of inclusion complex, the association constant K obtained by 1H NMR and ITC are in good agreement and both methods sustain a 1:1 stoichiometry.

Isotopic (δD, δ13C, and δ18O) and metal concentrations are reported for leaves, nervure, stems, and roots of N. tabacum grown in three parcels differentiated by the isotopic composition of irrigated water (deuterium enriched water, tap water, and deuterium depleted water). A linear correlation was observed between isotopic values (δD and δ18O) of water extracted from nervures and leaves with the isotopic composition of the irrigation water. The 13C-depletion in leaves was observed for all three groups in roots and stems. For the evaluation of heavy metals in N. tabacum, transfer factor values were determined. The highest values of the cadmium transfer factor, between 12.83 and 14.11 for nervure and leaves, were obtained for plants irrigated with enriched deuterium water. Also, transfer factors exceeding one were obtained for zinc in stems, nervure, and leaves from the first group. The correlations between heavy metals were made by using Pearson correlation. From cluster analysis, three groups were...

A series of 12 new thiazolidine-2,4-dione derivatives were obtained by microwave-assisted synthesis. All compounds were physicochemically characterized by quantitative elemental C, H, N, S analysis and spectral data (mass spectrometry [MS], infrared [IR], and nuclear magnetic resonance [NMR]), with the results being in agreement with the expected data. An in vitro screening performed on Candida albicans ATCC 10231 showed their moderate antifungal activity, which was further investigated by determining the minimum inhibitory concentration and minimum fungicidal concentration values for the most active compounds on four strains of Candida. The molecular docking studies, performed against a fungal lanosterol 14α-demethylase, emphasized the importance of different molecular fragments in the compounds' structures for their antifungal activity. The synthesized compounds were subjected to in silico screening for the prediction of their absorption, distribution, metabolism, excretion, and toxicity (ADMET) and molecular properties. The results of the antifungal activity assays, docking study, and ADMET predictions revealed that the synthesized compounds are potential anti- Candida agents that might act by interacting with the fungal lanosterol 14α-demethylase and could be further optimized and developed as antifungal agents.

Thiazole and bisthiazole derivatives represent a prevalent scaffold in the antimicrobial drug discovery. Therefore, we have decided to synthesize some new series of 4,5′-bisthiazoles. A total of 17 compounds were synthesized, their structural elucidation being based on elemental analysis (C,H,N,S) and spectroscopic data (MS and 1H NMR). Their in vitro antimicrobial activities were assessed against several Gram-positive and Gram-negative bacteria strains and also against one fungal strain (Candida albicans) using the difusimetric method. Some of the compounds showed modest to good antibacterial activity against Gram-negative Escherichia coli and Salmonella typhimurium and Gram-positive Staphylococcus aureus and Bacillus cereus bacterial strains. All of the synthesized compounds showed moderate to very good antifungal activity against C. albicans.

A series of new 5-(2,6-dichlorobenzylidene)thiazolidine-2,4-dione and 5-(4-methoxy-benzylidene)thiazolidine-2,4-dione derivatives (3a-h and 5a-h) were synthesized starting from 5-arylidene-thiazolidine-2,4-dione and ?-halo-ketones. The structural elucidation of the newly synthesized compounds was based on elemental analysis and spectroscopic data (MS, 1H-NMR, 13C-NMR). The synthesized compounds were screened for their antimicrobial activities against several pathogenic strains of Gram-positive and Gram-negative bacteria and one fungal strain (Candida albicans), assessed in vitro as growth inhibition diameters. Some of them displayed better inhibitory activities than that of the reference drug against the Gram-positive S. aureus, B. cereus, L. monocytogenes bacterial strains, and showed good antifungal activity against C. albicans, while the antibacterial activity against Gram-negative E. coli and S. typhimurium bacterial strains was moderate.

A total of 17 new N-substituted derivatives (2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i, 2j, 2k and 3b, 3c, 3d, 3e, 3f, 3g, 3h) of 5-((2-phenylthiazol-4-yl)methylene) thiazolidine-2,4-dione (2a) and 5-(2,6-dichloro- benzylidene)thiazolidine-2,4-dione (3a) were synthesized. The structural elucidation of the newly synthesized compounds was based on elemental analysis and spectroscopic data (MS, 1H NMR, 13C NMR), and their antimicrobial activities were assessed in vitro against several strains of Gram-positive and Gram-negative bacteria and one fungal strain (Candida albicans) as growth inhibition diameter. Some of them showed modest to good antibacterial activity against Gram-negative Escherichia coli and Salmonella typhimurium and Gram-positive Staphylococcus aureus, Bacillus cereus, and Enterococcus fecalis bacterial strains, whereas almost all the compounds were inactive against Listeria monocytogenes. All of the synthesized compounds showed moderate to very good activity against C. albicans.

The inclusion of local anesthetic drug procaine hydrochloride by β-cyclodextrin was investigated by 1D and 2D proton NMR spectroscopy and isothermal titration calorimetry (ITC) at 298 K. The stoichiometry of the complex was determinate by the method of continuous variation, using the chemical induced shift of both host and guest protons. The association constant K, of the obtained complex was calculated and found to be 293.17 M−1. Rotating frame NOE spectroscopy, was used to ascertain the solution geometry of the host–guest complex. The result reveals that the procaine molecule penetrates into the β-cyclodextrin cavity with the aromatic ring. The energetics of complexation process is investigated by ITC technique. The analysis indicates that the complexation of procaine by β-CD is an exothermic process and show that both enthalpy and entropy contribute to the binding process. The obtained value for the association constant is in good agreement with that obtained from NMR.

The complexation between the anionic forms of tolfenamic acid and flufenamic acid with β-cyclodextrin was investigated in solution by 1D and 2D proton NMR spectroscopy. The stoichiometry of the complexes was determined by the method of continuous variation using the chemical induced shifts of both the host and guest protons. An analysis of the spectroscopic data revealed that simultaneous inclusion of both rings of tolfenamic and flufenamic acids occur, giving rise each to two isomeric 1:1 complexes. The view of a bimodal binding between these two drugs and β-cyclodextrin was also supported by ROESY experiments. Using a rough approximation, we have estimated the association constants order of magnitude of the 1:1 complexes.

Twenty-three thiazolin-4-ones were synthesized starting from phenylthioamide or thiourea derivatives by condensation with α-monochloroacetic acid or ethyl α-bromoacetate, followed by substitution in position 5 with various arylidene moieties. All the synthesized compounds were physico-chemically characterized and the IR (infrared spectra), 1H NMR (proton nuclear magnetic resonance), 13C NMR (carbon nuclear magnetic resonance) and MS (mass spectrometry) data were consistent with the assigned structures. The synthesized thiazolin-4-one derivatives were tested for antifungal properties against several strains of Candida and all compounds exhibited efficient anti-Candida activity, two of them (9b and 10) being over 500-fold more active than fluconazole. Furthermore, the compounds’ lipophilicity was assessed and the compounds were subjected to in silico screening for prediction of their ADME-Tox properties (absorbtion, distribution, metabolism, excretion and toxicity). Molecular docking studies were performed to investigate the mode of action towards the fungal lanosterol 14α-demethylase, a cytochrome P450-dependent enzyme. The results of the in vitro antifungal activity screening, docking study and ADME-Tox prediction revealed that the synthesized compounds are potential anti-Candida agents that might act by inhibiting the fungal lanosterol 14α-demethylase and can be further optimized and developed as lead compounds.

Isotopic analyses are now official or standard methods in Europe and North America for routine use in testing the authenticity of several food products. These methods are based on the measurement of stable isotope content (2H, 13C, 18O) of the product or of a specific component such as an ingredient or target molecule of the product. The determinations carried out using nuclear magnetic resonance (NMR), and Isotopic Ratio Mass Spectrometry (IRMS), provide information on the botanical and geographical origin of the food product. A deuterium natural abundance quantitative NMR method (SNIF-NMR: Site-specific Natural Isotope Fractionation) was developed as an efficient and powerful tool capable of characterizing the chemical origins of organic molecules and distinguishing their biological and geographical origin. The SNIF method is based on the measurement of deuterium / hydrogen (D/H) ratios at the specific sites of the ethanol. Using these methods, we present the obtained results for a series of Romanian wines. Our results may be used like reference data set for authenticity and origin control of wines.

The complexation process between racemic flurbiprofen and β-cyclodextrin in solution was investigated by 1D and 2D proton NMR spectroscopy. In the presence of β-cyclodextrin, the aromatic protons of flurbiprofen were the most affected, suggesting a strong involvement of the phenyl groups in the inclusion mechanism. The stoichiometry of the complex was determined by the method of continuous variation, using the chemical induced shifts of both host and guest protons. The association constant, Ka of the obtained complex was calculated and found to be 2483.8 M−1. On the other hand, signals belonging to the protons associated with the carboxyl group are split in the presence of β-cyclodextrin indicating enantiomeric differentiation. Rotating frame NOE spectroscopy, (ROESY), was used to ascertain the solution geometry of the host–guest complex. The result suggested that the flurbiprofen molecule fully penetrates the β-cyclodextrin cavity with the carboxyl group protruding from the primary hydroxyl side and the phenyl group close to the secondary rim.

A series of new 1,3,4-oxadiazole/thiadiazole and 1,2,4-triazole derivatives have been synthesized starting from 2-aryl-4-methylthiazol-5-carbohydrazides and isonicotinic acid hydrazide. All the newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, and mass spectrometry. The synthesized compounds were screened for their antibacterial and antifungal activity, assessed as growth inhibition diameter. Some of them showed good antibacterial activity against gram positive Staphylococcus aureus, while the antibacterial activity against Listeria monocytogenes, Escherichia coli, and Salmonella typhymurium and antifungal activity against Candida albicans was modest. None of the tested compounds showed inhibitory activity against gram positive bacteria Enterococcus faecalis and Bacillus cereus and against gram negative bacteria Pseudomonas aeruginosa.

The inclusion of α-lipoic acid (LA) in β-cyclodextrin (β-CD) by increasing the aqueous solubility and photostability can enhance its medicinal use in the oral administration. Different preparation methods were employed to obtain an α-lipoic acid-β-cyclodextrin (LA-β-CD) inclusion complex and to determine the physical–chemical characteristics and the interactions present in this compound. The formation of the solid inclusion compound was confirmed by X-ray powder diffraction, differential scanning calorimetry (DSC) and infrared spectroscopy (FTIR). FTIR and DSC data confirm the new obtained compound. The crystalline structure of this compound belongs to the monoclinic system with four molecules in the unit cell. 1H NMR spectroscopic method was employed to study the inclusion process in aqueous solution. Job plots derived from the 1H NMR spectral data demonstrated an 1:1 stoichiometry of the inclusion complex in liquid state. 2D NMR data suggest the orientation of LA with the carboxyl group near to narrower rim of the β-CD.

In this work, a joint experimental (FT-IR, FT-Raman, NMR) and theoretical DFT study on 3-ethyl-5-methyl-2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridinedicarboxylate benzenesulphonate (amlodipine besylate) compound is reported. The experimental vibrational spectra have been assigned based on DFT calculations performed at B3LYP level of theory using the standard 6-31G(d) basis set and a uniform scaling of the calculated wave numbers. The mean deviation in reproducing the whole Raman and FT-IR spectra by B3LYP/6-31G(d) calculations is 7.7 and 6.0 cm −1 , respectively. The experimental 1 H NMR spectrum of amlodipine besylate was successfully reproduced by theoretical DFT calculations of the nuclear magnetic shielding tensors, using the GIAO method. The molecular electrostatic potential of the molecule has been calculated and used for predicting site candidates for electrophilic attack.

Experimental methods (FT-IR, Raman and NMR spectroscopies, and X-ray diffraction technique) coupled with quantum chemical calculations based on density functional theory (DFT) are used for structural and electronic characterization of 5-para-nitro-benzylidene-thiazolidine-2-thione-4-one (5pN-BTT). X-ray diffraction technique indicates that this compound crystallizes with one tetrahydrofuran (THF) solvent molecule, forming a 1:1 5pN-BTT·THF complex, in the monoclinic space group C2/c, with Z = 8 and cell parameters a = 29.496(9) A, b = 7.276(2) A, c = 14.873(4) A, α = 90.0°, β = 95.161(6)° and γ = 90.0°. The lowest energy optimized geometry of the investigated compound in gas-phase corresponds to thionic tautomer being consistent with that obtained by X-ray technique. Tautomeric equilibrium between the thione, thiol and enol forms of the compound have been considered and analyzed by theoretical methods. The continuum PCM solvation model fails to reproduce the experimental chemical shift associated with the NH proton in the thione form, but a very good correlation between experiment and theory was obtained by taking into account the specific solute–solvent interactions. Proton NMR spectrum of 5pN-BTT in DMSO solution shows an unexpected proton chemical shift at 14 ppm which is attributed to the proton bound to the nitrogen atom and explained by assuming a relatively strong hydrogen bond between 5pN-BTT and the solvent molecule, realized through NH group. The molecular vibrations of 5pN-BTT were investigated by FT-IR and FT-Raman spectroscopies and the vibrational spectrum of the solid state 5pN-BTT compound has been assigned based on DFT calculations at B3LYP level of theory using the standard 6-31G(d) basis set.

The surface-enhanced Raman scattering (SERS) spectra of 4-(2-pyridylazo)resorcinol (PAR) and its Zn(II) and Cu(II) complexes were recorded using a hydroxylamine reduced silver colloid. Molecular geometry optimization, molecular electrostatic potential (MEP) distribution and vibrational frequencies calculation were performed by density functional theory (DFT) computations for the PAR molecule and its Zn(PAR)2 metal complex. The SERS spectra of the samples prepared at PAR:metal salt 3:1 molar ratio, show mainly the spectral features of Zn(PAR)2 or Cu(PAR)2 complexes, but also spectral features of PAR molecules adsorbed to the silver surface, whereas the SERS spectra of the 1:1 molar ratio samples show exclusively the spectral features of the PAR-metal complex. Differentiation between PAR complexes with Zn(II), Cu(II), Fe(III), Mn(II) and Pb(II) is shown by the SERS spectral features of each complex.

In this work a joint experimental (FT-IR/ATR, FT-Raman) and theoretical study on N-[4-[2-[2-[4-(methanesulfonamido)phenoxy]ethyl-methyl-amino]ethyl]phenyl]methanesulfonamide (dofetilide) molecule is reported. The molecular vibrations of dofetilide were investigated by FT-IR/ATR and FT-Raman spectroscopies. The experimental spectra have been assigned based on DFT calculations at B3LYP level of theory using the standard 6-31G(d) basis set and uniform scaling of the calculated frequencies. The mean deviation in reproducing the whole Raman spectrum is 11.4 cm −1 . The molecular electrostatic potential of the molecule has been calculated and used for predicting site candidates for electrophilic attack.

The molecular vibrations of 5-(3-pyridyl-methylidene)-thiazolidine-2-thione-4-one (5-3-PMTT) were investigated by FT-IR, FT-Raman and SERS spectroscopies. In parallel, quantum chemical calculations based on density functional theory (DFT) are used to determine the geometrical, energetic and vibrational characteristics of the molecule. The three possible tautomers of 5-3-PMTT (thione, thiol and enol) have been analyzed by theoretical methods and their relative stability is discussed. The vibrational spectrum of the solid state 5-3-PMTT compound has been assigned based on DFT calculations at B3LYP level of theory using the standard 6-31G(d) basis set. The experimental vibrational bands were assigned to the calculated normal modes and a very good correlation was achieved between the experimental and theoretical data. SERS spectra suggest an important deformation of the adsorbed molecule on silver colloid surface; the six-membered ring is almost perpendicular while the thiazolidine ring lies almost parallel to Ag colloid surface. The molecular electrostatic potential of the molecule has been calculated and used for predicting site candidates of electrophilic attack.

The interaction between indomethacin and human serum albumin (HSA) was investigated by fluorescence quenching technique and UV-vis absorption spectroscopy. The results of fluorescence titration revealed that indomethacin, strongly quench the intrinsic fluorescence of HSA by static quenching and nonradiative energy transfer. The binding site number n and the apparent binding constant K(A), were calculated using linear and nonlinear fit to the experimental data. The distance r between donor (HSA) and acceptor (indomethacin) was obtained according to fluorescence resonance energy transfer (FRET). The study suggests that the donor and the acceptor are bound at different locations but within the quenching distance.

Experimental methods (NMR spectroscopy and X-ray diffraction) and quantum chemical calculations based on density functional theory (DFT) were used for structural and electronic characterization of two thiazolidine-2-thione-4-one derivatives with antimicrobial activity, namely 5-para-bromo-benzylidene-thiazolidine-2-thione-4-one (5pBr-BTT) and 5-para-fluoro-benzylidene-thiazolidine-2-thione-4-one (5pF-BTT). X-ray diffraction technique indicates that 5pBr-BTT crystallizes with one DMSO solvent molecule, forming a 1:1 5pBr-BTT·DMSO complex, in the triclinic space group P 1 ¯ , with Z = 2 and cell parameters a = 4.4597(7) A, b = 12.5508(19) A, c = 13.7270(2) A, α = 90.75(2)°, β = 96.23(2)° and γ = 97.86(3)°. The linear conformation adopted in the crystalline state is established by intermolecular hydrogen bonds formed between oxygen atoms from DMSO and the thione group. 5pF-BTT crystallizes in the monoclinic space group P21/c with Z = 4 and cell parameters a = 4.9161(4) A, b = 19.9008(17) A, c = 10.4934(9) A and β = 92.90(2)°; these molecules form a wave-like arrangement along the c axis, with direct intermolecular hydrogen bonds (HBs). The lowest energy optimized geometries of the investigated compounds in gas-phase correspond to thionic tautomers and they are consistent with those obtained by X-ray technique. Tautomeric equilibrium between the thione, thiol and enol forms of the two compounds have been considered and analyzed by theoretical methods. While crystal structures correspond to the thione forms, the investigated compounds show thione–thiol tautomerism in DMSO solution, this conclusion being supported by theoretical results obtained by using the PCM solvation model. On the other hand, the continuum PCM solvation model fails to describe the experimental chemical shift associated with the NH proton in the thione form of the two compounds, but a very good correlation between experiment and theory was obtained by taking into account the specific solute–solvent interactions.

Background and aims In the context of the increasing phenomenon of microbial resistance to usual drugs, the development of new treatment strategies and new therapeutic protocols is a constant need. Thiazolidinedione and chromone represent two important scaffolds in medicinal chemistry due to their large pharmacological applicability. Methods We synthesized a new 5-(chromene-3-yl)methylene-2,4-thiazolidinedione starting from 6,8-dichloro-4-oxo-4H-chromene-3-carbaldehyde. Then, by treating with different α-bromoalkylarylketones, we obtained N-substituted derivatives. All new compounds were investigated for their antimicrobial potential, using the diffusion method, against Listeria monocytogenes ATCC 13932, Staphylococcus aureus ATCC 49444, Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028 and Candida albicans ATCC 10231. Three concentrations, 10 mg/ml, 5 mg/ml and 1 mg/ml of compounds were used. The results were evaluated by the measurement of the inhibition zone diameters and compared to those of gentamicin and fluconazole respectively, as reference drugs. Results All new synthesized compounds were characterized using physico-chemical and spectrometric methods. They displayed modest to good antimicrobial activity. New molecules 8, 9 and 10 may represent promising candidates, showing zone inhibition diameters superior to those of reference drugs. Conclusions This work presents chemical synthesis, characterization and investigation of the antibacterial and antifungal potential of 5-(chromene-3-yl)methylene-2,4-thiazolidinedione derivatives, which may be worthy of future research for designing new chemical entities.

Sortase A inhibition is a well establish strategy for decreasing bacterial virulence by affecting numerous key processes that control biofilm formation, host cell entry, evasion and suppression of the immune response and acquisition of essential nutrients. A meta-analysis of structures known to act as Sortase A inhibitors provided the starting point for identifying a new potential scaffold. Based on this template a series of new potential Sortase A inhibitors, that contain the 2-phenylthiazole moiety, were synthesized. The physicochemical characterisation confirmed the identity of the proposed structures. Antibacterial activity evaluation showed that the new compounds have a reduced activity against bacterial cell viability. However, the compounds prevent biofilm formation at very low concentrations, especially in the case of E. faecalis. Molecular docking studies performed estimate that this is most likely due to the inhibition of Sortase A. The new compounds could be used as add-on therapies together with known antibacterial agents in order to combat multidrug-resistance enterococcal infections.