Capillary electrophoresis-frontal analysis for studying ligand-albumin interactions of toxicologically relevant compounds, evaluated using the RGB model.

Capillary electrophoresis-frontal analysis (CE-FA) was applied to study ligand-albumin interactions in systems of toxicological relevance. The method was initially evaluated using the warfarin-bovine serum albumin (WAR-BSA) model system, for which the obtained binding constants were consistent with literature data. It was then extended to selected coumarin derivatives, coumatetralyl (CT) and 3-hydroxycoumarin (3-HC), as well as to two synthetic cathinones, 4-methylmethcathinone (4-MMC) and 2-methylmethcathinone (2-MMC). CT showed a more complex binding pattern with BSA, whereas 3-HC was better described by a one-site model and exhibited weaker binding. Both cathinones interacted weakly with BSA, with 4-MMC showing higher affinity than 2-MMC. Temperature-dependent measurements for WAR, CT, and 3-HC enabled the determination of thermodynamic parameters, revealing different balances of enthalpic and entropic contributions to complex stabilisation. The applied CE-FA procedure was additionally evaluated using the RGB model and classified as Colorless (Gray), with a Method Brilliance value of 60.8%. The results confirm that CE-FA is a useful approach for the characterisation of ligand-albumin interactions and can be applied to compounds of toxicological interest.