Liposomes containing distamycins: Preparation, characterization and antiproliferative activity

This paper describes the production and characterization of two liposome formulations containing antitumor drugs, namely distamycin A (Dist) and a new alkyl derivative of distamycin A (C16-Dist). Egg-PC/cholesterol liposomes (4:1 molar ratio) were prepared by reverse phase evaporation technique followed by extrusion through polycarbonate filters. The encapsulation efficacy was found almost complete for C16-Dist (99.8%), whilst native distamycin A showed a lower association yield (19.0%). The in vitro antiproliferative activity of the distamycins-containing liposomes determined on human leukemic K562 cells, was 11-fold and 8-fold higher for native and alkyl derivative distamycin A respectively, if compared to that of the corresponding free drugs. Taking in consideration the obtained results, liposomal formulations could be possibly proposed to increase the activity and specificity of distamycins in experimental antitumor therapy.