Use of multivariate mathematical methods for the evaluation of retention data matrices.
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Chromatography↗
Biomedical subjects
E Forgács
Publications and source records attributed to E Forgács.
Charge transfer chromatographic study of the binding of commercial pesticides to various albumins.
The interaction of 28 commercial pesticides with human and bovine serum albumin as well as with egg albumin was studied by charge-transfer reversed-phase thin-layer chromatography and the relative strength of the interaction was calculated. Only one pesticide interacted with egg albumin whereas the majority of pesticides bound both to bovine and human serum albumins. Stepwise regression analysis proved that the hydrophobicity parameters of pesticides exert a significant impact on their capacity to bind to serum albumins. These findings support the hypothesis that the binding of pesticides to albumins may involve hydrophilic forces occurring between the corresponding apolar substructures of pesticides and amino acid side chains. No linear correlation was found between the capacities of human and bovine serum albumins to bind pesticides.
Albumins↗
Binding of anticancer drugs to human serum albumin studied by reversed-phase chromatography.
The interaction of eight commercial anticancer drugs with human serum albumin (HSA) was studied by charge-transfer reversed-phase thin-layer chromatography in neutral, acidic, basic and ionic environments (NaCl and CaCl2) and the relative strength of interaction was calculated. Each drug interacted with HSA in a neutral environment, and the pH and the presence of mono- and divalent cations markedly affected the strength of interaction. The capacity of anticancer drugs to interact with HSA depended considerably on their molecular structure. Various multivariate statistical methods such as principal component analysis and cluster analysis indicated that the steric parameters of anticancer drugs have a considerable impact on their capacity to bind to HSA. The influence of electronic parameters on the HSA-drug interaction was of secondary importance.
Antineoplastic Agents↗
Determination of hydrophobicity of non-homologous series of anticancer drugs by reversed-phase high-performance liquid chromatography.
The hydrophobicity and specific hydrophobic surface area of 21 commercial anticancer drugs were determined by reversed-phase high-performance liquid chromatography on an octadecyl-silica column using methanol-water mixtures as eluents. Linear correlations were calculated between the log k' values and the methanol concentration of the eluent, the intercept and slope were considered as the best estimation of the hydrophobicity and specific hydrophobic surface area. The relationship between retention characteristics and physicochemical parameters of drugs was evaluated by multivariate mathematical statistical methods, such as principal component analysis followed by two-dimensional non-linear mapping, varimax rotation and by cluster analysis. Anticancer drugs can be well separated by reversed-phase HPLC. Various multivariate mathematical statistical calculations indicate that the retention of the investigated drugs is mainly governed by hydrophobic and steric parameters. The results suggest that the use of principal component analysis followed by two-dimensional non-linear mapping is superior to cluster analysis for the evaluation of large retention data matrices.
Antineoplastic Agents↗
Use of principal component analysis for the evaluation of the retention behaviour of monoamine oxidase inhibitory drugs on beta-cyclodextrin column.
The retention of 17 monoamine oxidase inhibitory drugs (proparlgylamine derivatives) were determined on a beta-cyclodextrin polymer (beta CDP)-coated silica column using ethanol-0.05 M K2HPO4 (6:4 v/v) as the eluent. The relative strength of interaction between the drugs and a water soluble beta-cyclodextrin polymer was determined by charge-transfer chromatography carried out on reversed-phase TLC layers. The relationship between capacity factors, physicochemical parameters and inclusion complex forming capacity of the monoamine oxidase inhibitory drugs were evaluated by stepwise regression analysis and by principal component analysis (PCA) followed by two-dimensional nonlinear mapping and varimax rotation. Calculations indicated that the retention of monoamine oxidase inhibitory drugs on beta CDP column is mainly governed by their steric and lipophylic parameters. Significant linear correlations were found between the corresponding coordinates of varimax rotation and two-dimensional nonlinear maps proving the suitability of both methods for the reduction of dimensionality of complicated data matrices.
Chemical Phenomena↗
Interaction of taxol and other anticancer drugs with alpha-cyclodextrin.
The interaction between 23 anticancer drugs and alpha-cyclodextrin (alpha-CD) was studied by reversed-phase charge-transfer thin-layer chromatography and the relative strength of interaction was calculated. As alpha-CD has smaller cavity than beta- and tau-CD it interacted only with 10 anticancer drugs proving the relatively poor complex forming capacity of alpha-CD. The hydrophobicity of host-guest inclusion complex was always different from that of the uncomplexed drug suggesting that the complex formation may influence the uptake, absorption, half-life etc. of the original drug. The inclusion forming capacity of drugs differed considerably according to their chemical structure. The intensity of interaction significantly depended on the hydrophobicity of the guest molecule proving the preponderant role of hydrophobic interactions in inclusion complex formation.
Antineoplastic Agents↗
Binding of amino acids to the cationic surfactant cetyltrimethylammoniumbromide.
The interaction of amino acids with the cationic surfactant cetyltrimethylammoniumbromide (CTAB) was studied by charge transfer reversed-phase thin-layer chromatography and the relative strength of interaction was calculated. In the majority of cases the surfactant has a negligible effect on the hydrophobicity of amino acids. Only the binding of Arg, Glu, Gly, Leu, Lys, Met, Nle, Phe Trp, Tyr and Val to the surfactant was observed, however, the strength of interaction was fairly low. The hydrophobicity of the amino acid side chains significantly influenced the strength of interaction. The findings support the hypothesis that the binding of cationic surfactants to proteins involves more than one amino acid residues and that the hydrophobic forces have a considerable impact on the interaction.
Amino Acids↗
Retention behaviour of some barbituric acid derivatives on a polyethylene-coated silica column.
The retention of 45 barbituric acid derivatives was determined on a polyethylene-coated silica column (PEE) in unbuffered methanol-water eluent mixtures. Each derivative showed a symmetric peak shape in each eluent and the capacity factor decreased monotonously with increasing concentration of methanol in the eluent. Stepwise regression analysis indicated that the retention of barbituric acid derivatives is mainly governed by the molecular lipopholicity and, to a lesser extent, by steric effects of the various substituents. This finding indicates that the polyethylene-coated silica behaves as a real reversed-phase chromatographic support with slightly different retention characteristics.
Barbiturates↗
Relationship between the hydrophobic physicochemical parameters and biological activity of some monoamine oxidase inhibitory drugs.
The MAO-B inhibitory effect of 11 propargylamine derivatives was determined in rat brain and rat liver and the concentration causing 50% inhibition (IC50) was calculated. The hydrophobic (lipophilicity, specific hydrophobic surface area) and hydrophilic (adsorption capacity on slightly acidic and alkaline surfaces, specific hydrophilic surface area on the same surfaces) physicochemical parameters of the MAO inhibitory drugs were determined by various adsorptive and reversed-phase chromatographic techniques. Stepwise regression analysis proved that only the hydrophilic parameters describing the interaction of drugs with alkaline surfaces exert a significant impact on the biological activity. These results make probably the direct interaction between the alkaline hydrophilic substructures of drugs and the secondary carboxyl groups of the target enzyme.
Animals↗
[Significance of blood picture changes in the diagnosis of neonatal sepsis].
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Bacterial Infections↗
Reversed-phase chromatographic study of the binding of polychlorinated biphenyls to cyclodextrins and sodium dodecylsulphate.
The binding of polychlorinated biphenyls (PCBs) to hydroxypropyl-beta-cyclodextrin (HP-beta-CD), tau-cyclodextrin (tau-CD) and sodium dodecylsulphate (SDS) was studied by reversed-phase thin-layer chromatography and the relative strength of interaction was calculated. HP-beta-CD and SDS did not bind to PCBs making it unlikely that these compounds modify the adsorption capacity or decomposition rate of PCBs. Each PCB formed inclusion complexes with tau-cyclodextrin. The inclusion-forming capacity of PCBs increased with an increase in the number of chloro substitutions in the molecule, indicating that tau-CD can be successfully used for the modification of the physicochemical and biochemical characteristics of PCBs. The linear correlation between the hydrophobicity and specific hydrophobic area of PCBs indicated that they can be considered as a homologous series of compounds.
Chemical Phenomena↗
Effect of support characteristics on the reversed-phase retention behaviour of a non-homologue series of anticancer drugs.
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Antineoplastic Agents↗
Effect of column temperature and nitrogen flow rate on the separation of cis-permethrinic acid isomers on a (2,3,6-tri-O-methyl)-beta-cyclodextrin coated capillary column.
The separation efficiency of a capillary column coated with (2,3,6-tri-O-methyl)-beta-cyclodextrin was determined at the temperature and flow rate ranges of 80-120 degrees C and 0.3-1.5 mL/min respectively using (+) and (-) cis-permethrinic acid methylesters as test compounds. The dependence of the retention differences, sum of peak widths and separation factor on the temperature and flow rate was calculated with step regression analysis. The column exhibited acceptable isomer separation capacity at each temperature and flow rate proving the excellent separation power of the cyclodextrin coating. The differences between the retention times of isomers depended on the logarithm and on the reciprocal value of temperature, the effect of flow rate was negligible. The sum of their peak widths depended reciprocally on the temperature and logarithmically on the flow rate, the impact of temperature being higher than that of flow rate. The significant impact of the reciprocal value of temperature can be explained by the inclusion complex formation between cyclodextrin and cis-permethrinic acid methylester isomers. The resolution depended on the square of column temperature and flow rate, indicating local optimums at each temperature and flow rate.
Chromatography, Gas↗
Use of liquid chromatography for the determination of interactions between bioactive compounds.
Molecular interactions can be easily determined both by thin-layer and high performance liquid chromatography. The theory and practice of the determination of molecular interactions and the various methods for the calculation of complex stability are presented. Examples of the application of liquid chromatographic methods for the measurements of molecular interactions are also discussed.
Chemical Phenomena↗
Dependence of the retention of some barbituric acid derivatives on a porous graphitized carbon column on their physicochemical parameters.
The retentions of 45 barbituric acid derivatives were determined on a porous graphitized carbon column (PGC) in unbuffered methanol-water eluent mixtures at various organic phase concentrations and the retention data were correlated with the various hydrophobic and electronic parameters of barbituric acid derivatives. Each derivative showed symmetric peaks in each eluent proving the good separation characteristics of the PGC column without buffering the eluent. Significant linear correlations were found between the logk' value and the concentration of the organic mobile phase in the eluent. Stepwise regression analysis indicated that the retention of barbituric acid derivatives is mainly governed by the electronic parameters, and the lipophilicity of various substituents did not affect significantly the retention, although the eluents were typical reversed-phase eluents.
Barbiturates↗