Partition coefficients in octanol-water and liquid chromatographic behavior of eight oxygenated triterpenes which are paired stereo- and positional isomers

The chromatographic behavior of eight lanostanoid triterpenes, which are four pairs of C-3 epimers and two pairs of C-3/C-15 positional isomers, were determined by reverse-phase high performance liquid chromatography (RP-HPLC). In the mobile phase systems of acetonitrile-water-acetic acid, methanol-water-acetic acid, and tetrahydrofuran-water-acetic acid, these triterpenes showed a very good linear relationship between capacity factors (k') and volume fractions of organic modifiers. The partition coefficients (Poet) of these triterpenes in 1-octanol/water and capacity factors (k') in RP-HPLC, when both expressed in logarithm, correlated linearly. This study showed that RP-HPLC is an effective method to evaluate the molecular hydrophobicity of multi-functional compounds which are stereo- and positional isomers.