Bioanalysis of aplidine, a new marine antitumoral depsipeptide, in plasma by high-performance liquid chromatography after derivatization with trans-4'-hydrazino-2-stilbazole

A sensitive bio-analytical assay in plasma of the depsipeptide aplidine is reported, based on reversed-phase liquid chromatography and fluorescence de tection of the trans-4'-hydrazino-2-stilbazole (4'H2S) derivative of the an alyte. Ar ambient temperature, two conformations of the depsipeptide are ob served in solution due to cis-trans isomerism at the proline-pyruvoyl pepti de bond. Aplidine is isolated from the matrix by solid-phase extraction on an octadecyl modified silica stationary phase. After evaporation of the ace tone eluate, a derivatization with 4'H2S is performed in a water-acetonitri le mixture at pH 4. The reaction mixture is injected directly into the chro matograph and the analyte is quantified by fluorescence detection at 410 an d 560 nm for excitation and emission, respectively. The method has been val idated in the 2-100 ng/ml-range, 2 ng/ml being the lower limit of quantific ation. Precision and accuracy both meet the current requirements for a bioa nalytical assay. The identity of the 4'H2S reaction products of aplidine ha ve been confirmed by mass spectrometric analysis. Finally, the method has b een employed for a pilot pharmacokinetic study of aplidine in mice which de monstrated its usefulness for pharmacological research. (C) 1999 Elsevier S cience B.V. All rights reserved.