Synthesis, Structural Characterization, Cytotoxicity, and Protein/DNA Binding Properties of Pyridoxylidene-Aminoguanidine-Metal (Fe, Co, Zn, Cu) Complexes

Pyridoxylidene-aminoguanidine (PLAG) and its transition metal complexes are biologically active compounds with interesting properties. In this contribution, three new metal-PLAG complexes, Zn(PLAG)(SO4)(H2O)].∙H2O (Zn-PLAG), [Co(PLAG)2]SO4∙2H2O (Co-PLAG), and [Fe(PLAG)2]SO4∙2H2O) (Fe-PLAG), were synthetized and characterized by the X-ray crystallography. The intermolecular interactions governing the stability of crystal structure were compared to those of Cu(PLAG)(NCS)2 (Cu-PLAG) within Hirshfeld surface analysis. The structures were optimized at B3LYP/6-31+G(d,p)(H,C,N,O,S)/LanL2DZ (Fe,Co,Zn,Cu), and stability was assessed through Natural Bond Orbital Theory and Quantum Theory of Atoms in Molecules. Special emphasis was put on investigating the ligand's stability and reactivity. The binding of these compounds to Bovine and Human serum albumin was investigated by spectrofluorometric titration. The importance of complex geometry and various ligands for protein binding was shown. These results were complemented by the molecular docking study to elucidate the most important interactions. The thermodynamic parameters of the binding process were determined. The binding to DNA, as one of the main pathways in the cell death cycle, was analyzed by molecular docking. The cytotoxicity was determined towards HCT116, A375, MCF-7, and A2780 cell lines. The most active compound was Cu-PLAG due to the presence of PLAG and two thiocyanate ligands.

The Effect of Metal Ions (Fe, Co, Ni, and Cu) on the Molecular-Structural, Protein Binding, and Cytotoxic Properties of Metal Pyridoxal-Thiosemicarbazone Complexes

Thiosemicarbazones and their transition metal complexes are biologically active compounds and anticancer agents with versatile structural properties. In this contribution, the structural features and stability of four pyridoxal-thiosemicarbazone (PLTSC) complexes with Fe, Co, Ni, and Cu were investigated using the density functional theory and natural bond orbital approach. Special emphasis was placed on the analysis of the donor atom-metal interactions. The geometry of compounds and crystallographic structures were further examined by Hirshfeld surface analysis, and the main intermolecular interactions were outlined. It has been shown that the geometry and the number of PLTSC units in the structure determine the type and contribution of the specific interactions. The binding of all four complexes to bovine and human serum albumin was investigated through spectrofluorometric titration. The dependency of the thermodynamic parameters on the present metal ion and geometry was explained by the possible interactions through molecular docking simulations. The binding of complexes to DNA, as one of the possible ways the compounds could induce cell death, was examined by molecular docking. The cytotoxicity was measured towards HCT116, A375, MCF-7, A2780, and MCF5 cell lines, with Cu-PLTSC being the most active, as it had the highest affinity towards DNA and proteins.

The Electronic Effects of 3-Methoxycarbonylcoumarin Substituents on Spectral, Antioxidant, and Protein Binding Properties

Coumarin derivatives are a class of compounds with pronounced biological activities that depend primarily on the present substituents. Four 3-methoxycarbonylcoumarin derivatives with substituents of different electron-donating/electron-withdrawing abilities (Br, NO₂, OH, and OMe) were investigated structurally by NMR, IR, and UV-VIS spectroscopies and density functional theory methods. The appropriate level of theory (B3LYP-D3BJ/6-311++G(d,p) was selected after comparing similar compounds' experimental and theoretical structural parameters. The natural bond orbital and quantum theory of atoms in molecules were employed to investigate the intramolecular interactions governing stability. The electronic effects of substituents mostly affected the aromatic ring that the substituents are directly attached to. The antioxidant properties were investigated by electron paramagnetic resonance spectroscopy towards HO^•, and the percentages of reduction were between 13% (6-Br) and 23% (6-OMe). The protein binding properties towards transport proteins were assessed by spectrofluorimetry, molecular docking, and molecular dynamics (MD). The experimentally determined binding energies were well reproduced by molecular docking, showing that the spontaneity of ibuprofen binding was comparable to the investigated compounds. The flexibility of HSA in MD simulations depended on the substituents. These results proved the importance of electronic effects for the protein binding affinities and antioxidant properties of coumarin derivatives.

Alizarin as a potential protector of proteins against damage caused by hydroperoxyl radical

Alizarin is a natural anthraquinone molecule with moderate antioxidative capacity. Some earlier investigations indicated that it can inhibit osteosarcoma and breast carcinoma cell proliferation by inhibiting of phosphorylation process of ERK protein (extracellular signal-regulated kinases). Several mechanisms of deactivation of one of the most reactive oxygen species, hydroperoxyl radical, by alizarin are estimated: hydrogen atom abstraction (HAA), radical adduct formation (RAF), and single electron transfer (SET). The plausibility of those mechanisms is estimated using density functional theory. The obtained results indicated HAA as the only thermodynamically plausible mechanism. For that purpose, two possible mechanistic pathways for hydrogen atom abstraction are studied in detail: hydrogen atom transfer (HAT) and proton-coupled electron transfer (PCET). Water and benzene are used as models of solvents with opposite polarity. To examine the difference between HAT and PCET is used kinetical approach based on the Transition state theory (TST) and determined rate constants (k). Important data used for a distinction between HAT and PCET mechanisms are obtained by applying the Quantum Theory of Atoms in Molecules (QTAIM), and by the analysis of single occupied molecular orbitals (SOMOs) in transition states for two examined mechanisms. The molecular docking analysis and molecular dynamic are used to predict the most probable positions of binding of alizarin to the sequence of ApoB-100 protein, a protein component of plasma low-density lipoproteins (LDL). It is found that alizarin links the nitrated polypeptide forming the π-π interactions with the amino acids Phenylalanine and Nitrotyrosine. The ability of alizarin to scavenge hydroperoxyl radical when it is in a sandwich structure between the polypeptide and radical species, as the operative reaction mechanism, is not significantly changed concerning its antioxidant capacity in the absence of polypeptide. Therefore, alizarin can protect the polypeptide from harmful hydroperoxyl radical attack, positioning itself between the polypeptide chain and the reactive oxygen species.

Kinetics and mechanism of amino acid derived 2-thiohydanoin formation reactions

The reaction of allyl isothiocyanate with some common natural protein amino acids (glycine, L-alanine, L-valine, L-leucine and L-phenylalanine) was monitored. 1H NMR spectroscopy is used as a practical tool in...

Synthesis, Crystallographic Structure, Theoretical Analysis, Molecular Docking Studies, and Biological Activity Evaluation of Binuclear Ru(II)-1-Naphthylhydrazine Complex

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.

In Silico Prediction of the Toxicity of Nitroaromatic Compounds: Application of Ensemble Learning QSAR Approach

In this work, a dataset of more than 200 nitroaromatic compounds is used to develop Quantitative Structure-Activity Relationship (QSAR) models for the estimation of in vivo toxicity based on 50% lethal dose to rats (LD₅₀). An initial set of 4885 molecular descriptors was generated and applied to build Support Vector Regression (SVR) models. The best two SVR models, SVR_A and SVR_B, were selected to build an Ensemble Model by means of Multiple Linear Regression (MLR). The obtained Ensemble Model showed improved performance over the base SVR models in the training set (R² = 0.88), validation set (R² = 0.95), and true external test set (R² = 0.92). The models were also internally validated by 5-fold cross-validation and Y-scrambling experiments, showing that the models have high levels of goodness-of-fit, robustness and predictivity. The contribution of descriptors to the toxicity in the models was assessed using the Accumulated Local Effect (ALE) technique. The proposed approach provides an important tool to assess toxicity of nitroaromatic compounds, based on the ensemble QSAR model and the structural relationship to toxicity by analyzed contribution of the involved descriptors.

Numerical modelling of WNT/β-catenin signal pathway in characterization of EMT of colorectal carcinoma cell lines after treatment with Pt(IV) complexes

BACKGROUND AND OBJECTIVE

Colorectal cancer (CRC) is at the top of the most common cancer types in the world, with significant mortality rates among both men and women. Deregulation of Wnt/β-catenin pathway and cell-cell junctions' components, acquisition of invasive phenotype, epithelial-mesenchymal transition (EMT) and invasion are important for development and progression of colorectal cancer. Numerical simulation presents method for estimation of the Wnt pathway via its individual components in cells, thus providing information about EMT, migratory and invasive potential. By using this numerical model, the effectiveness of treatment in EMT suppression can be assessed. Furthermore, the model can be adapted to ``every'' cell type, application time or duration of treatment can be also modified.

METHODS

We characterized colorectal cancer (CRC) cell lines (HCT-116, SW-480) from the aspect of EMT, via markers β-catenin and E-cadherin using numerical modeling. To confirm the numerical model, cells were treated with sublethal concentrations of platinum(IV) complexes and their ligands. We confirmed β-catenin regulated expression of mesenchymal markers: N-cadherin, Vimentin and MMP-9, and decreased E-cadherin expression. Treatment-induced changes were determined in the protein expression of tested markers and results showed cell-specific responses. Molecular docking was performed to investigate exact effects of treatments on E-cadherin and β-catenin in cell-cell junctions and individually in tested cells.

RESULTS

The application of the numerical model via β-catenin and E-cadherin (experimentally measured), is largely valid for the categorization of EMT progression in cells. This numerical modeling better characterizes cells with single cell migration, higher expression of mesenchymal markers, and advanced mesenchymal phenotype like HCT-116 cell line. The model was validated for the treatments and results show HCT-116 cells as more sensitive to applied compounds, among which ligands were more potent in reducing migration and invasiveness. Anti-migratory/invasive effects were due to increased E-cadherin, cytoplasmic β-catenin expression and suppressed mesenchymal markers. In silico methods showed higher affinity of tested chemicals towards free β-catenin, which is the key for regulation of migratory/invasive potential.

CONCLUSIONS

Our study shows that, no matter individual properties of cell lines and EMT degree, de novo formation of intercellular junctions stands in the basis of anti-migratory/invasive process.

In vitro, in vivo and in silico evaluation of the anti-inflammatory potential of Hyssopus officinalis L. subsp. aristatus (Godr.) Nyman (Lamiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal properties of hyssop have been used in traditional medicine since ancient times, inter alia, in diseases/conditions with an inherent inflammatory process.

AIM OF THE STUDY

Accordingly, the aim of this study was to investigate the anti-inflammatory properties of hyssop herb preparations (essential oil and methanol extracts) in vivo, in vitro and in silico.

MATERIALS AND METHODS

For in vitro testing of essential oils and extracts of hyssop herb, the cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzyme assays were used. In vivo anti-inflammatory potential of the extracts (at doses of 50, 100 and 200 mg/kg) was assessed using the carrageenan-induced rat paw edema test. Molecular docking and dynamics were used for in silico testing of the inhibitory activity of chlorogenic (CA) and rosmarinic (RA) acids, as the dominant compounds in the tested methanol extracts against COX-1 and COX-2 enzymes.

RESULTS

Significant inhibitory activity was shown in the COX-2 test regarding extracts (essential oils did not exhibit any significant activity). Namely, all analyzed extracts, at a concentration of 20 μg/mL, showed a percentage of inhibition of COX-2 enzyme (54.04-63.04%), which did not indicate a statistically significant difference from the positive control of celecoxib (61.60%) at a concentration of 8.8 μM. In vivo testing showed that all methanol extracts of hyssop herb, at the highest test dose of 200 mg/kg in the third and fourth hours, after carrageenan administration, exhibited a statistically significant (p < 0.05) inhibitory effect on the increase in rat paw edema in relation to control. This activity is comparable or higher in relation to the reference substance, indomethacin, at a concentration of 8 mg/kg. The preliminary in silico results suggest that investigated compounds (RA and CA) showed better inhibitory activity against COX-1 and COX-2 than standard non-steroidal anti-inflammatory drug (NSAID), ibuprofen, as evident from the free binding energy (ΔG_bind in kJ mol^-1). The binding energies of the docked compounds to COX-1 and -2 were found to be in the range between -47.4 and -49.2 kJ mol^-1. Ibuprofen, as the one NSAID, for the same receptors targets, showed remarkably higher binding energy (ΔG_bind = -31.3 kJ mol^-1 to COX-1, and ΔG_bind = -30.9 kJ mol^-1 to COX-2).

CONCLUSION

The results obtained not only support the traditional use of hyssop herb in inflammatory conditions in folk medicine, but also open the door to and the need for further in vivo testing of extracts in order to examine the molecular mechanism of anti-inflammatory activity in living systems and possibly develop a new anti-inflammatory drug or supplement.

Motoric Abilities of Basketball Players According to Different Ranks of Competition and Playing Positions

Basketball is a complex sports game, interrupted by the constant change of defense and offense, and it is a combination of cyclic and most often acyclic movements. Since basketball involves sudden and intense changes in the movement direction, high frequencies of initiating dribbling and movement in posture, stoppings, and physical contact allowed by game rules, there is a link between the abilities needed for successful basketball playing and playing positions. This research aimed to determine the differences in motoric abilities, i.e. the change of direction speed, explosive strength, and running speed of basketball players who compete in different ranks of the competition in relation to the playing positions. The sample of 25 basketball players was divided into two subsamples in relation to the rank of the competition (elite and sub-elite). Eleven motoric ability tests were used in the study (change of direction speed – four tests, explosive strength – four tests, and running speed – three tests). Applying the analysis of variance (ANOVA and MANOVA), differences in motoric abilities were determined between basketball players of different ranks of a competition in relation to the playing positions in the team. Based on the results, a conclusion was reached that the players differ in favor of a higher rank of a competition in the tested abilities, namely those ones who play in the forward position. It can be inferred that a higher rank of a competition requires better quality preparation and players who differ in tactical thinking and better performance of measured abilities.

Mechanism of Antiradical Activity of Newly Synthesized 4,7-Dihydroxycoumarin Derivatives-Experimental and Kinetic DFT Study

Coumarin derivatives have proven beneficial biological activities, but the mechanism of their radical scavenging potency is not fully understood. In this study, the antiradical capacity of two newly synthesized 4,7-dihydroxycoumarin derivatives: (E)-3-(1-((3-hydroxy-4-methoxyphenyl)amino)-ethylidene)-2,4-dioxochroman-7-yl acetate (A-3OH) and (E)-3-(1-((4-hydroxy-3-methoxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate (A-4OH) towards HO• were examined by Electron Paramagnetic Resonance (EPR) Spectroscopy and Density Functional Theory (DFT). The compounds were fully characterized by the elemental microanalysis, IR, and NMR spectroscopies. The effect of pH on the acid-base equilibria is separately discussed and the predominant species at the physiological pH were determined. Several common mechanisms (Hydrogen Atom Transfer (HAT), Single-Electron Transfer followed by Proton Transfer (SET-PT), Sequential Proton Loss followed by Electron Transfer (SPLET), Radical Adduct Formation (RAF), and Intramolecular Hydrogen Atom Abstraction (iHAA)) of radical scavenging were investigated based on thermodynamic and kinetic parameters. EPR results indicated that both compounds significantly reduce the amount of present HO•. The results of the kinetic DFT study demonstrated that both compounds predominantly exhibit antiradical capacity through HAT and SPLET mechanisms. The estimated overall rate constants (koverall) proved that A-4OH shows better antioxidant capacity than A-3OH which is well-correlated with the results obtained by EPR measurement.

Theoretical Study of Radical Inactivation, LOX Inhibition, and Iron Chelation: The Role of Ferulic Acid in Skin Protection against UVA Induced Oxidative Stress

Ferulic acid (FA) is used in skin formulations for protection against the damaging actions of the reactive oxygen species (ROS) produced by UVA radiation. Possible underlying protective mechanisms are not fully elucidated. By considering the kinetics of proton-coupled electron transfer (PCET) and radical-radical coupling (RRC) mechanisms, it appears that direct scavenging could be operative, providing that a high local concentration of FA is present at the place of ^•OH generation. The resulting FA phenoxyl radical, after the scavenging of a second ^•OH and keto-enol tautomerization of the intermediate, produces 5-hydroxyferulic acid (5OHFA). Inhibition of the lipoxygenase (LOX) enzyme, one of the enzymes that catalyse free radical production, by FA and 5OHFA were analysed. Results of molecular docking calculations indicate favourable binding interactions of FA and 5OHFA with the LOX active site. The exergonicity of chelation reactions of the catalytic Fe²⁺ ion with FA and 5OHFA indicate the potency of these chelators to prevent the formation of ^•OH radicals via Fenton-like reactions. The inhibition of the prooxidant LOX enzyme could be more relevant mechanism of skin protection against UVA induced oxidative stress than iron chelation and assumed direct scavenging of ROS.

Impact of the phenolic O–H vs. C-ring C–H bond cleavage on the antioxidant potency of dihydrokaempferol

In order to correctly estimate hydrogen atom abstraction from polyphenols, kinetic analysis including suitable tunneling effects should be mandatory.

Antioxidative potential of ferulic acid phenoxyl radical

The vast majority of previous studies dealing with antioxidant potency of (poly)phenols does not investigate the fate of phenoxyl radical obtained after single free radical scavenging. We investigated possible pathways of inactivation of ferulic acid phenoxyl radical (FAPR) using DFT method. Direct coupling with a set of 10 physiologically important free radicals, H-atom donation and dimerization were analysed by estimation of Gibbs free energy changes related to these processes. The former two processes are thermodynamically feasible to inactivate more dangerous free radicals such as hydroxyl, alkoxyl and carbon-centered radicals. Among dimerization reactions, the least energy demanding is formation of C-5-C-5 dimer of ferulic acid (FA), which has higher antiradical potency than FA itself. Obtained results reveal that FAPR, a priori considered as stable and unreactive, may contribute to the overall antioxidant activity of FA. This is a beneficial behavior, which makes FA a particularly valuable protector against oxidative stress. Hence, the contribution of phenoxyl radicals to the antioxidant activity of (poly)phenolic compounds should be taken into account, what has been scarcely considered until now.

Comparative antiradical activity and molecular Docking/Dynamics analysis of octopamine and norepinephrine: the role of OH groups

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.

Structural characterization of kaempferol: a spectroscopic and computational study

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.

Synthesis, spectroscopic characterization (FT-IR, FT-Raman, and NMR), quantum chemical studies and molecular docking of 3-(1-(phenylamino)ethylidene)-chroman-2,4-dione

The experimental and theoretical investigations of structure of the 3-(1-(phenylamino)ethylidene)-chroman-2,4-dione were performed. X-ray structure analysis and spectroscopic methods (FTIR and FT-Raman, ¹H and ¹³C NMR), along with the density functional theory calculations (B3LYP functional with empirical dispersion corrections D3BJ in combination with the 6-311 + G(d,p) basis set), were used in order to characterize the molecular structure and spectroscopic behavior of the investigated coumarin derivative. Molecular docking analysis was carried out to identify the potency of inhibition of the title molecule against human's Ubiquinol-Cytochrome C Reductase Binding Protein (UQCRB) and Methylenetetrahydrofolate reductase (MTHFR). The inhibition activity was obtained for ten conformations of ligand inside the proteins.

Antiradical activity of catecholamines and metabolites of dopamine: theoretical and experimental study

The importance of molecules with antiradical potency that are produced in the human body has significantly increased. Among others, neurotransmitters and their metabolites act as the first line of defense against oxidative stress in the peripheral endocrine and the central nervous systems. Dopamine (DO), epinephrine (EP), norepinephrine (NE), l-DOPA, catechol, and three metabolites of dopamine (3-methoxytyramine (3-MT), homovanillic acid (HO), and 3,4-dihydrophenylacetic acid (DOPAC)) were investigated for their antiradical potency via computational methods and DPPH assay. Density functional theory calculations were used to determine the most probable reaction mechanism based on the thermodynamic parameters. These results suggested that hydrogen atom transfer (HAT)/proton-coupled electron transfer (PCET) and sequential proton loss electron transfer (SPLET) mechanisms are preferable in polar solvents. Several techniques were employed to differentiate between HAT and PCET mechanisms via examination of the transition state structures. Kinetic studies of HAT/PCET and electron transfer (ET) reactions, the second step of SPLET, have proven that ET is much faster for an order of 10⁵-10⁶. Based on this, it was concluded that SPLET was the dominant mechanism for the antiradical activity towards DPPH radicals in polar solvents. The findings suggest that all the investigated molecules can be classified as excellent antiradical scavengers, except for 3-MT and homovanillic acid.

Antioxidative mechanisms in chlorogenic acid

Although chlorogenic acid (5CQA) is an important ingredient of various foods and beverages, mechanisms of its antioxidative action have not been fully clarified. Besides electron spin resonance experiment, this study includes thermodynamic and mechanistic investigations of the hydrogen atom transfer (HAT), radical adduct formation (RAF), sequential proton loss electron transfer (SPLET), and single electron transfer - proton transfer (SET-PT) mechanisms of 5CQA in benzene, ethanol, and water solutions. The calculations were performed using the M06-2X/6-311++G(d,p) level of theory and CPCM solvation model. It was found that SET-PT is not a plausible antioxidative mechanism of 5CQA. RAF pathways are faster, but HAT yields thermodynamically more stable radical products, indicating that in acidic and neutral media 5CQA can take either HAT or RAF pathways. In basic environment (e.g. at physiological pH) SPLET is the likely antioxidative mechanism of 5CQA with extremely high rate.

Variability of sweat chloride concentration in subjects with cystic fibrosis and G551D mutations

INTRODUCTION

Sweat chloride concentration, a biomarker of CFTR function, is an appropriate outcome parameter in clinical trials aimed at correcting the basic CF defect. Although there is consensus on a cut-off value to diagnose CF, we have only limited information on the within subject variability of sweat chloride over time. Such information would be useful for sample size calculations in clinical trials. Therefore, we retrospectively analyzed repeated sweat chloride values obtained in patients with G551D mutation(s) assigned to placebo in an ivacaftor interventional trial.

METHODS

In subjects with G551D at least 12years of age, a pilocarpine sweat test using Macroduct collector was taken on both arms at 8 time points over 48weeks. We explored 1062 pilocarpine sweat test values obtained in 78 placebo patients of the VX08-770-102 trial.

RESULTS

Mean overall sweat chloride value (all patients, all tests, n=1062) was 100.8mmol/L (SD 12.7mmol/L). Using a multilevel mixed model, the between-subject standard deviation (SD) for sweat chloride was 8.9mmol/L (95% CI 7.4-10.6) and within-subject SD was 8.1mmol/L (95% CI 7.5-8.7). Limits of repeatability for repeat measurements were -19.7 to +21.6mmol/L using values from one arm, and -13.3 to 11.8mmol/L using mean of values obtained at 4 test occasions. Sample size calculations showed that the minimal treatment effect on sweat chloride concentration that can be demonstrated for a group of 5 patients is around 15mmol/L, using a cross-over design and combinations of 4 tests for each phase of the trial.

CONCLUSION

Although the sweat test is considered a robust measure, sweat chloride measurements in patients with CF and a G551D mutation had an inherent biological variability that is higher than commonly considered. Further analyses of placebo group data are crucial to learn more about the natural variability of this outcome parameter.

The preferred radical scavenging mechanisms of fisetin and baicalein towards oxygen-centred radicals in polar protic and polar aprotic solvents

The flavonoids fisetin and baicalein have been investigated for their ability to scavenge certain anion radicals.

PM6 and DFT study of free radical scavenging activity of morin

Flavonoids have long been recognised for their general health-promoting properties, of which their antioxidant activity may play an important role. In this work, we have studied the properties of flavonoid morin using semiempirical and density functional theory (DFT) methods in order to validate the application of the recently developed parametric method 6 (PM6). Reaction enthalpies related to mechanisms of free radical scavenging by flavonoid morin were calculated by DFT and PM6 methods in gas-phase, water, DMSO and benzene. It has been shown that fast semiempirical PM6 method can mimic results obtained by means of more accurate time consuming DFT calculations. Thermodynamically favoured mechanism depends on reaction medium: SPLET (sequential proton loss electron transfer) is preferred in water and DMSO, and HAT (hydrogen atom transfer) is predominant in gas-phase. In benzene these two mechanisms are competitive.

Application of comparative vibrational spectroscopic and mechanistic studies in analysis of fisetin structure

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 CO, C2C3 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.

Mechanistic study of the structure-activity relationship for the free radical scavenging activity of baicalein

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.

[Ileal conduit--quality of life]

Removal of the urinary bladder--cystectomy--imposes the problem of urine derivation. The most sophisticated forms of urinary derivation imply those where the continent urinary reservoir is anastomosed to the urethra. One of these is Came's enteroplasty. In our hospital this technique was applied on 52 patients. Postoperative complications and obtained results suggest that this form of urinary derivation is an important step forward not only to incontinent forms of derivation, but to non-orthotopic continent urinary derivations, as well. All patients in our series were very successful in reintegration into the normal life, i.e. they were able to achieve a high quality of life after otherwise mutilating surgical procedure.

[Renal tubular function in patients with nephrolithiasis]

The aim of the study was to establish the frequency of tubular dysfunction in 59 patients with nephrolithiasis, of whom 52 had unilateral and 7 bilateral calculosis. Before the study urinary infection was cured in all patients. Renal function was normal in all subjects. Hypercalcaemia was present in 8 patients, and hypercalciuria in 17 subjects. Phosphate clearance (CPO4) was increased in 40 patients, and had the same number of patients, decreased tubular reabsorbtion of phosphate (TRP). In 31 patients increased CPO4 and decreased percent of TRP was present. Renal threshold phosphate concentration was decreased in 17 patients. High fraction excretion of sodium was observed in 37 patients, while urine sodium level was higher than normal only in 4 patients. Decreased ability of renal acidification of urine was found in 5 patients, and decreased renal concentration ability in 10 subjects. The most common finding in the observed patients was the phosphate excretion defect usually accompanied with defect of calcium excretion, and defect of urine acidification.

[Analysis of intracranial aneurysms from autopsy material]

The analysis of 44 intracranial aneurysms found at 7.687 autopsies is performed. The largest number of aneurysms was of congenital (secular) type, then, of arteriosclerotic type while inflammatory and traumatic aneurysms were very rare. The elastic and reticular fibres in the aneurysmal wall and the normal arteries of the base of the brain were identified by a standard and special staining. Significantly decreased quantity and disturbed distribution of the reticular fibres were found in the congenital aneurysms which was considered to be a consequence of degenerative processes. The finding of the preserved elastic internal lamina in the wall of the congenital aneurysm and its absence or fragmentation in cases of arteriosclerotic aneurysms suggest the different etiology and pathogenesis of these aneurysms.

[Tuberculous inflammation of the synovial membrane]

Four patients with tuberculous synovitis of the large joints are reported in whom primary tuberculous process has not been confirmed as a possible foci of spreading of the acidoresistant bacilli. The authors, describing in details the histologic picture of tuberculous synovitis, point out the importance of an early biopsy of the synovial membrane and obligatory microbiological confirmation of the established diagnosis.

[Morphologic characteristics of surgically removed menisci]

The authors have analysed histologically and histochemically 88 surgically removed damaged menisci of which 8 were studied by the electron microscope. Of the total number of the analysed cases only 20 had the anamnesis specific for meniscus trauma while in the rest meniscus was damaged spontaneously. The age of the operated patients ranged from 16 to 50 years, the majority being from 20 to 25 years old. The authors have reported that the morphological examinations of the damaged menisci have shown that the main cause of the ruptured menisci was destruction of the collagenous fibres of the menisci and severe mucoid degeneration of their tissues with the increasing number of the elastic fibres at the site of the destructed collagenous fibres. The histochemical examinations have shown that the basic meniscus substance contains chodroitin sulfate mucopolysaccharides which, according to their opinion, were secreted by the choindroid cells.