HPLC determination of a new multidrug resistance modulator (S9788) extracted from cancer cells in vitro

S9788 is a novel triazinodiaminopiperidine derivative which reverses the multidrug resistance of tumour cells to anticancer drugs. In this study, a new HPLC method was developed to determine this compound in P388 leukaemia cells. The influence of various parameters (composition and pH of the mobile phase, nature of the column) on the separation of S9788 and derivatives was investigated. Using a microsphere C18 column and the optimal mobile phase (acetonitrile-0.4 M phosphate buffer containing 0.2% triethylamine, 40:60 v/v, pH 6.5) it was possible to separate S9788 and seven hypothetical metabolites and derivatives in 15 min. The limits of detection and quantification of S9788 are 75 and 250 pg, respectively. This MDR modulator was extracted from biological media by a rapid two-step procedure which removed proteins before direct injection of the sample. Absolute recoveries ranged from 90 to 100% with a mean RSD (%) lower than 5.