Characteristic Interactions of Propolis with Liposomal Phospholipids as a Membrane Model

Abstract

Natural products are invaluable resource of anticancer drug discovery. They generally viewed as safe but weak, within the framework of nanotechnology, they can serve as template for potent anticancer drugs. This work first evaluated the cytotoxic activity of different propolis extracts (water, hydroalcohol, ethanol and hexane) in a number of cancer cell lines, then the solid nanoparticles from the organic solvent extracts were prepared and their cytotoxicity was evaluated as well. Finally, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes were prepared from the most cytotoxic organic solvent extract and their cytotoxicity was also evaluated. All results collectively showed that hexane extract and its solid nanoparticles as well as its liposomal form exhibited high cytotoxic activity. DPPC/DOPC-hexane extract cytotoxicity was selectively dependent on the cell line and DOPC liposomal form was characterized by reduced IC50 compared with the other preparations/extracts, the average IC50 was 165.8 ± 3 µg/ml. The antiproliferative activity of propolis was associated with multiple modes of actions including apoptosis and nitric oxide production. As indicated by the HPLC and FTIR results, it is functioning in many propolis ingredients rather than a single component; and influenced by the presence of more lipophilic components within the extract. These results may have an impact on the multidrug resistivity issue.