Exploring separation mechanisms and lipophilicity in hydrophilic interaction chromatography conditions by thin-layer chromatography of anesthetics and adjuvant drugs as polar model compounds.

The chromatographic behavior of the selected compounds was studied under conditions of hydrophilic interaction liquid chromatography (HILIC). The effect of mobile phase composition on the retention in different chromatographic systems was systematically examined using high-performance thin-layer chromatography. The sorbents of different polarity and adsorption characteristics were selected and mixtures of water and organic solvents of various compositions, from pure water to pure organic solvent were used as mobile phases. Increasing the amount of water in the mobile phase leads to a conversion of the separation mechanism, and the retention curves have a characteristic "U" shape. The conversion between the adsorption and partition mechanisms is most likely continuous and depends on the chemical nature of separated substances, the stationary phase as well as on organic component of the mobile phase. Silica gel can be considered the most suitable stationary phase for the systematic investigation of the chromatographic behavior of the test compounds, whereas acetonitrile was the most suitable solvent. The obtained results contribute to the understanding of the dominant separation mechanism, the type, and the intensity of the interactions between separated substances with both stationary and mobile phases. Besides, the lipophilicity parameters obtained under HILIC conditions were evaluated and correlated with the calculated values.

Antibacterial Activities of Agaricus bisporus Extracts and Their Synergistic Effects with the Antistaphylococcal Drug AFN-1252.

Agaricus bisporus, commonly known as the button mushroom, has attracted attention for its biological properties, including antimicrobial activities. Here, we evaluated the efficacy of ethanolic and acetonic extracts from white and brown A. bisporus against different bacterial strains, including antibiotic-resistant strains. Bioautography and principal component analysis identified the most active antibacterial compounds for each of the tested bacteria and indicated the main markers responsible for the strain-specific effects. In addition, the mushroom extracts demonstrated a synergistic impact when combined with the antistaphylococcal antibiotic AFN-1252.

Two aspects of honeydew honey authenticity: Application of advance analytical methods and chemometrics.

Taking into account a growing market and small number of articles related to honeydew honey, a metabolomic approach associated with multivariate analysis and modelling was proposed to discriminate five varieties of honey. Advanced analytical techniques were used for determination of 20 elements, 14 carbohydrates and stable carbon isotope ratio. No chemical marker has been found within sugar compounds, but several elements (Ba, Ca, Mg, Sr, Mn, Al, Co, Ni, Se) were marked as characteristic of honey type and allow classification of three botanical origins (Abies alba, Quercus frainetto, Quercus ilex). Sugars turanose, trehalose, arabinose and raffinose, elements Ba, Sr, P, Cd and Se, and δ13C values of honey, have different concentrations in honeys of the same botanical origin but harvested in different season. In addition to a confirmation of authenticity in terms of production, the values of δ13C of protein could be a good indicator of botanical origin.

Lipophilicity assessment of ruthenium(II)-arene complexes by the means of reversed-phase thin-layer chromatography and DFT calculations.

The lipophilicity of ten ruthenium(II)-arene complexes was assessed by reversed-phase thin-layer chromatography (RP-TLC) on octadecyl silica stationary phase. The binary solvent systems composed of water and acetonitrile were used as mobile phase in order to determine chromatographic descriptors for lipophilicity estimation. Octanol-water partition coefficient, logK(OW), of tested complexes was experimentally determined using twenty-eight standard solutes which were analyzed under the same chromatographic conditions as target substances. In addition, ab initio density functional theory (DFT) computational approach was employed to calculate logK(OW) values from the differences in Gibbs' free solvation energies of the solute transfer from n-octanol to water. A good overall agreement between DFT calculated and experimentally determined logK(OW) values was established (R(2) = 0.8024-0.9658).

Correlation between structure, retention and activity of cholic acid derived cis-trans isomeric bis-steroidal tetraoxanes.

Both quantitative structure-retention (QSRR) and quantitative structure-activity relationship (QSAR) studies have been performed to correlate the molecular characteristics of seven pairs of cis-trans isomeric bis-steroidal tetraoxanes with their reversed-phase thin-layer chromatography (RPTLC) retention as well as with their antiproliferative activity. 2D and 3D molecular descriptors as whole molecule representations together with retention parameters as well as with biological activity data were subjected to the multivariate statistical analysis (principal component analysis--PCA and hierarchical cluster analysis--HCA) in order to determine the most influential factors governing the retention and activity against human cervix carcinoma (HeLa) and human malignant melanoma (Fem-X) cell lines. Both QSRR and QSAR models were built by means of the partial least-squares (PLS) statistical method. It was found that hydrogen bond donating (HBD), hydrogen bond accepting (HBAcc), hydrophilic surface percentage (%HS) and hydrophilic-lipophilic balance (HLB) exhibit the strongest influence on retention. The most prominent factors affecting antiproliferative activity of the investigated substances are those relating to the size and shape of a molecule such as: connectivity indices, refractivity (Ref), surface area (SA), molecular volume and weight, polarizability (Pol) and those regarding the ability of hydrogen bonding (HB).

Determination of the soil-water partition coefficients (logK(OC)) of some mono- and poly-substituted phenols by reversed-phase thin-layer chromatography.

In order to determine the soil-water partition coefficient for eleven mono- and poly-substituted phenolic compounds, for which there is still no literature data available, the possibility of using thin-layer chromatography (TLC) as a means for rapid and reliable logK(OC) estimation was examined. A series of chromatographically derived descriptors: R(M)(0), b, C(0) and PC1 (first principal component), calculated from retention data obtained under reversed-phase conditions, were used for the assessment of models as well as for a direct calibration procedure. The final calibration models are discussed with regard to the achieved accuracy and statistical quality, the type of descriptors used and the corresponding chromatographic conditions. The estimated logK(OC) values of the studied phenols were compared with those obtained by other means: (a) the present OECD guideline based on an HPLC technique; (b) the KOCWIN software package, available free of charge from the US Environmental Protection Agency web site and (c) general LSER models established by Nguyen and coworkers, and Poole and coworkers. The proposed method showed the best agreement with the results obtained by the OECD procedure, followed by the LSER models of Poole and Nguyen. Lower quality correlations were achieved with the KOCWIN calculated values, especially those predicted by molecular connectivity indices.