Lipophilicity of Selected Bile Acids as Determined by TLC. III. Investigations on RP2 Stationary Phase

Abstract

The following bile acids: cholic acid (C), glycocholic acid (GC), glycodeoxycholic acid (GDC), chenodeoxycholic (CDC), deoxycholic acid (DC), lithocholic acid (LC), and glycolithocholic acid (GLC) were investigated with the use of reversed phase thin‐layer chromatography on RP2 plates (E. Merck, # 1.13726) using methanol‐water, organic mixture (acetonitrile‐methanol 50:50, v/v)‐water, acetone‐water, dioxane‐water in different volume compositions as mobile phases. The chromatographic parameters of lipophilicity (RMW and ϕ0) of studied bile acids were determined. Lipophilic parameters (RMW and ϕ0) were compared, both with measured partition coefficients (logPexp) and calculated ones (AlogPS, IAlogP, logPKOWIN, xlogP, clogP, logPRekker). The most significant correlation was found between RMW and ϕ0 lipophilic parameters and logPKOWIN values. IAlogP correlates with the a/m lipophilic parameters slightly more poorly than logPKOWIN does. The values of RMW and ϕ0 lipophilic parameters obtained on both, RP2 and RP18W plates with the use of the a/m mobile phases, indicate that the investigated bile acids may be listed in order of decreasing lipophilicity as follows: LC>DC≈CDC≈GLC>C≈GDC>GC.