Optimization of important early ADME(T) parameters of NADPH oxidase-4 inhibitor molecules.

Through their reactive oxygen species (ROS) producing function, NADPH oxidase (NOX) enzymes have been linked to several oxidative stress related diseases. In our recently published paper [1] we have already shown the NOX4 inhibitory effect of diverse, molecule sub-libraries and their biological importance. We also presented our work connected to potential anti-tumour molecules and the relationship between their biological activity and physico-chemical properties [2]. As an extension of these studies further physico-chemical and biological investigation has been carried out on a molecule group included NOX4 inhibitory chromanone compounds. Here we describe the optimization of early ADME(T) parameters determining lipophilicity, phospholipophilicity and permeability linked to structure-activity relationship. We prove that optimal lipo- and phospholipophilicty can be also determined in case of NOX4 inhibitors and a comparison will be made between the chemically similar isochromanone and chromanone molecular libraries. It will be also shown how to predict the effect of different substituents on permeability, lipo- and phospholipophilicity and also the biological differences between anti-tumour molecules and NOX4 inhibitors according to their penetration ability.

Characterisation of mixed lithium dodecyl sulphate/lithium perfluorooctanesulphonate pseudo-stationary phases in MEKC.

Lipophilicity and methylene selectivity of mixed pseudo-stationary phases (PSPs) (containing lithium dodecyl sulphate (LDS) and lithium perfluorooctanesulphonate (LiPFOS) in different molar ratios) applied in MEKC have been investigated. Micellar proportion (t(prop,mic), a quantity expressing that how much time is spent by the analyte in the micellar phase related to its whole migration time), CLOGP(50) value (showing the value of hydrophobicity of a molecule spending exactly 50% of its migration time in the PSP) and methylene selectivity have been determined for different LDS/LiPFOS mixed phases. Values of the above-mentioned parameters have been determined for analytes with different chemical structures (alkylbenzene and alkylphenone homologous series, alcohols). Good linear correlation was obtained between either the micellar proportion, CLOGP(50), or methylene selectivity and the phase composition for the mixed phases. Lipophilicity and methylene selectivity of the mixed LDS/LiPFOS PSPs can be calculated and can continuously be changed by mixing the two single phases (LDS and LiPFOS) in the appropriate (and calculable) portion.

Lipophilicity and antiproliferative activity profiling of 2-benzylidencycloalkanones.

High performance liquid chromatographic (HPLC) method has been developed to separate the members of a library including 24 benzylidenecycloalkanone-type structures and to characterize their lipophilicity. The experimental lipophilicity data (k) of the compounds have been compared with their calculated lipophilicity parameters (CLOGP). In general, good correlations between the measured and calculated lipophilicities have been found and these results were in good accordance with our previously data obtained in case of structurally related molecular libraries. In addition, cytotoxicity screening has been performed to determine the antiproliferative activity of these compounds. Some of the investigated compounds possessed noticeable inhibitory potential. Based on the correlation between the antiproliferative activity and experimentally determined lipophilicity of the molecules investigated, limited structural demands to obtain more potent compounds can be exhibited to support the synthetic design.

Micellar proportion: a parameter to compare the hydrophobicity of the pseudostationary phases or that of the analytes in micellar electrokinetic chromatography.

Micellar proportion, t(prop,mic) = t(mic)/t(m), a quantity expressing how much time is spent by the analyte in the micellar phase related to its whole migration time (t(m)) has been introduced by utilizing the micellar phase residence time (t(mic)). The t(prop,mic) values have been determined for analytes of different chemical structures (alkyl benzene and alkyl phenone homologous series, alcohols, strongly hydrophobic peptides) studied by micellar elektrokinetic chromatography (MEKC) using various cationic and anionic pseudostationary phases. A good linear correlation was obtained between t(prop,mic) and the calculated hydrophobicity (CLOGP) of the analytes for all pseudostationary phases (CLOGP = A.logt(prop,mic) + B). Considering a given pseudostationary phase, t(prop,mic) as a relative quantity is a suitable parameter to characterize and compare experimentally the behavior of the various analytes in MEKC. Applying a set of probe molecules with known hydrophobicity, the CLOGP(50) value (showing the value of hydrophobicity of a virtual molecule spending exactly 50% of its migration time in the pseudostationary phase) has been calculated for each pseudostationary phase applied here. This experimentally determinable numerical value (characterizing the pseudostationary phase) can be utilized to compare the hydrophobicity and hence retention ability of the pseudostationary phases. The t(prop,mic) value was found to be applicable to compare the methylene selectivity of the different pseudostationary phases as well: logt(prop,mic) = A.Z + B, where Z is the number of carbon atoms of the alkyl chain in the alkyl benzene homologous series.

Separation of anti-tumor peptides by capillary electrophoresis in organic solvent containing background electrolytes.

Connections between the calculated and measured electrophoretic mobilities (nu(ep)) determined by capillary electrophoresis as well as connections between the measured and calculated diffusion coefficients of anti-tumor peptides have been investigated in background electrolytes (BGEs) containing different organic solvents (acetonitrile, methanol, ethanol and isopropanol). Comparison of the electrophoretic mobility (nu(ep)) values revealed discrepancies between the measured and calculated values. However, no change in the migration order or selectivity could be expected from the calculated nu(ep) values, variation of both properties was observed applying organic solvents as BGE modifiers. Experimental determination of the diffusion coefficient suggested that the effect of the organic solvents is not restricted to the change of the BGE viscosity. The reason for the discrepancy between the measured and calculated mobility values might be the possible conformation and/or solvation changes of the peptide caused by the different organic solvents.

Evaluation of lipophilicity and antitumour activity of parallel carboxamide libraries.

Searching for molecules possessing antitumour activity, a parallel molecule library of aromatic carboxamides has been designed and synthesised. This work resulted in a "thiophene" sub-library containing a thiophene core and of a "furoyl" sub-library with a furoyl core, respectively. In both sub-libraries substitutions were carried out with six different groups resulting in six pairs of compounds differing in only the heteroatom of aromatic ring of the cores. To study the importance of the type of cores and the specific substitutions in relation to their lipophilicity and antitumour activity, lipophilicity of carboxamides was determined by chromatographical data (log k') and by software calculated parameters (CLOGP). Pairs of compounds were tested for their ability to inhibit the proliferation of the A431 cells by MTT assay. The isosteric molecule pairs were successfully separated. Our results showed that the experimentally determined (log k') and the calculated (CLOGP) lipophilicity parameters correlated well with each other. Furthermore, lipophilicity values of the thiophene sub-library were always higher than those in the furoyl sub-library. Moreover, compounds of the thiophene sub-library were more active than their respective furoyl pairs in our MTT antiproliferative assay. From these observations we can conclude that the higher the lipophilicity values the higher the antitumour activity of the carboxamides synthesised. Therefore, determination of lipophilicity by measuring the log k' or by calculating the CLOGP values of the carboxamide sub-libraries may help to predict their biological activities.

Relationship between lipophilicity and antitumor activity of molecule library of Mannich ketones determined by high-performance liquid chromatography, clogP calculation and cytotoxicity test.

A series of Mannich ketones were synthesized in order to study the relative importance of structure and specific substitutions in relation to their lipophilicity and antitumor activity. Substitutions were carried out with morpholinyl, pirrolidinyl, piperidyl and tetrahydro-isoquinolyl groups in various positions on three different skeletons. Lipophilicity of Mannich ketones was characterised by chromatography data (log k') and by software calculated parameters (clogP). Compounds were tested on their ability to inhibit the proliferation of the A431 human adenocarcinoma cell line evaluated by MTT and apoptosis assays. The results suggest that the higher the lipophilicity values (log k' and clogP), the higher the antitumor and apoptotic activity of Mannich ketones. Determination of lipophilicity by measuring the log k' or by calculating the clogP values of the compounds may help to predict their biological activities.