EVALUATION OF LIPOPHILICITY OF PIPERAZINE DERIVATIVES BY THIN LAYER CHROMATOGRAPHY AND PRINCIPAL COMPONENT ANALYSIS

Abstract

The lipophilic character of a series of active anticonvulsant N-substituted amides of α-piperazine-γ-hydroxybutyric was studied. The classical R_Mo- values were measured by means of reversed thin layer chromatography using a mixture of methanol, TRIS buffer, and acetic acid as the solvent system and compared with the factors scores obtained by principal component analysis based also on the TLC retention data. The significant correlation between the R_Mo- values and slopes (the specific hydrophobic surface areas) usually indicated that this group of N-substituted amides could be considered as a homologous series of compounds independent of their structural heterogeneity. It is emphasized, once again, that this procedure can not be a rational and objective way for congeneric studies because there is always a high correlation between slope and intercept. The reliability of the factor scores values as lipophilicity indices is shown by their high correlation with the classical R_Mo-values. In addition, the “lipophilicity chart” described by the first two components will have the effect of separating compounds from each other most effectively from the congeneric aspect point of view.

Finally, a better correlation was observed between scores corresponding to the first principal component and the partition coefficients (log P) of the amides, calculated by using the Prolog P module of the Pallas system.

Acknowledgments