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 (R_MW and ϕ₀) of studied bile acids were determined. Lipophilic parameters (R_MW and ϕ₀) were compared, both with measured partition coefficients (logP_exp) and calculated ones (AlogP_S, IAlogP, logP_KOWIN, xlogP, clogP, logP_Rekker). The most significant correlation was found between R_MW and ϕ₀ lipophilic parameters and logP_KOWIN values. IAlogP correlates with the a/m lipophilic parameters slightly more poorly than logP_KOWIN does. The values of R_MW 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.

Keywords:

• Bile acids
• RP‐HPTLC
• RP2
• Lipophilicity