Quantitative analysis of 23-hydroxybetulinic acid, a novel anticancer substance, in the cellular environment of a human colon adenocarcinoma cell line for cellular pharmacokinetic studies

In order to study the cellular distribution and kinetics of a new anticancer substance, 23-hydroxybetulinic acid, a simple, reproductive and sensitive high-performance liquid chromatography/mass spectrometric (HPLC/MS) method was developed to quantify its trace concentration in cell suspension and cell culture medium. This method involved a liquid-liquid extraction with diethyl ether and a subsequent analysis performed on a Shimadzu LCMS 2010A system which contained an electrospray ionization interface. Separation was achieved by HFLC on a Zorbax Extend-C18 column with gradient elution using a mix of acetonitrile and water containing triethylamine and acetate-triethylamine as the mobile phase. A total analytical run was achieved within 6.5 min and the calibration curve was linear over a wide concentration range of 1.0-1000.0 nM for both cell suspension and culture medium. Intra- and inter-batch accuracy and precision were acceptable for both matrices. The described assay method was successfully applied to cellular pharmacokinetic studies in a human colon adenocarcinoma cell line (Caco-2) and its application of measuring the cellular concentrations of 23-hydroxybetunilic acid could be extended to different cultured cell lines.