Solvent and structural effects on the UV absorption spectra of N-(substituted phenyl)-2-cyanoacetamides.

UV absorption spectra of N-(substituted phenyl)-2-cyanoacetamides have been recorded in the range 200-400 nm in the set of selected solvents. The solute-solvent interactions were analyzed on the basis of linear solvation energy relationships (LSER) concept proposed by Kamlet and Taft. The effects of substituents on the absorption spectra were interpreted by correlation of absorption frequencies with Hammett substituent constant, σ. It was found that substituents significantly change the extent of conjugation. Furthermore, the experimental findings were interpreted with the aid of ab initio B3LYP/6-311G(d,p) method. Electronic energies was calculated by the use of 6-311++G(3df,3pd) methods with standard polarized continuum model (PCM) for inclusion of the solvent effect.

RP TLC data in correlation studies with in silico pharmacokinetic properties of benzimidazole and benztriazole derivatives.

Reversed-phase thin-layer chromatographic (RP TLC) retention constants for a newly designed series benzimidazole/benztriazole with expected biological activity were determined as parameters of their lipophilicity and this series was recognized as congeneric. Pharmacokinetic descriptors of the compounds investigated were calculated in silico with the use of the established drug design software. The bioactivity descriptors, which are assumed to predicted drug absorption, distribution, metabolism, elimination and toxicity (ADMETox) in humans, were correlated with retention constants and good statistical parameters were obtained. Multiple regression analysis which was introduced suggested that the absorption through different epithelial membranes (intestinal, blood-brain or erythrocyte membrane) and distribution process depend on retention constants (as measure of lipophilicty) and total polar surface area and molar weight/volume of the analyte. Finally, the compounds with halogen substituent (compounds A4/A7 and A5/A8 in Table 1), were suggested as the best drug candidates, because of their predicted proper pharmacokinetics and have been proposed for further biological tests.

HPTLC chromatography of androstene derivates. Application of normal phase thin-layer chromatographic retention data in QSAR studies.

The chromatographic behavior of seven 16-oximino derivatives of 3beta-hydropxy-5-androstene have been investigated using the normal-phase (NP) HPTLC chromatographic mode of the type silica-non-polar diluent (benzene)-polar modifier (acetonitrile, ethyl acetate, or dioxane). The linear relationship between the retention constants (R(M)) and the logarithm of the organic modifier content in the mobile phase allowed for the calculation of R(M)0 values. The influence of substituent in the molecule on extrapolated retention data is discussed. To better understand the retention mechanism in the separation of androstene compounds, the functional group contributions (tauX) were compared with Hansch substituent constants (pi). An attempt to quantitate the lipophilicity of the investigated compounds using normal phase thin-layer chromatographic R(M)0 value was made. Also, the relative lipophilicity values determined previously by RPC as well as activity were compared with NPC data.