MIRELA ENACHE, ANA MARIA TOADER SPECTROSCOPIC STUDY OF THE INTERACTION OF ANTICANCER DRUG MITOXANTRONE WITH SODIUM CHOLATE AGGREGATES The focus of the present work is to investigate the interaction of anticancer drug mitoxantrone with sodium cholate (NaC) bile salt in phosphate buffer (pH 7.4) and carbonate buffer (pH 10) by UV-Visible absorption spectroscopy. The results indicate that mitoxantrone may bind to NaC monomers and micelles through electrostatic and hydrophobic interactions and the interaction with NaC induces the dissociation of dimers and higher aggregates of mitoxantrone. The stoichiometric ratio, binding constant, micelle/water partition coefficient and the corresponding thermodynamic parameters for binding and partitioning processes were estimated from the monomer absorbance changes occurred as a result of the interaction between mitoxantrone and NaC micelles. The binding process of mitoxantrone to NaC micelles is spontaneous and entropy controlled over the range of studied temperatures, at both pH values. The partition process of mitoxantrone between micellar and bulk aqueous phases is spontaneous and entropy controlled at pH 7.4 but enthalpy controlled at pH 10.
Keywords: mitoxantrone, bile salts, micelles, binding constant, partition coefficient