Two dimensional separation schemes for investigation of the interaction of an anticancer ruthenium(iii) compound with plasma proteins

Abstract

On-line 2-dimensional size exclusion/anion exchange chromatography was coupled to inductively coupled mass spectrometry with dynamic reaction cell technology (SEC-IC-ICP-MS) in order to characterize the interaction of the ruthenium-based anticancer drug KP1019 with human plasma proteins in vitro and, for the first time, in vivo. In SEC-ICP-MS studies the drug was found to bind exclusively to the protein fraction of 60–80 kDa in human plasma samples (clinical study/phase 1). The respective size fraction was collected and subsequently analyzed by reversed phase chromatography coupled to electrospray mass spectrometry (LC-ESI-MS) confirming the presence of the two well known transporter proteins, i.e. human serum albumin (HSA) and transferrin (Tf). Hence, for in vivo investigation of KP1019 interaction with HSA and Tf a fully automated SEC-IC-ICP-MS approach was applied. The stoichiometry of the KP1019 protein binding was determined through the molar Ru/S ratio. Human apo-Tf standards incubated with different stoichiometric equivalents of KP1019 were used for species-specific and species-unspecific calibration of the molar Ru/S ratio. Competitive in vitro incubation of KP1019 to both HSA and Tf for ca. 10 h showed that via the transferrin pathway.