The fate of anticancer drug, ellipticine in DPPC and DMPC liposomes upon interaction with HSA: A photophysical approach

Interaction of anticancer drug, ellipticine with Human Serum Albumin (HSA) and release of this encapsulated drug from two individual liposomes namely 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) upon addition of HSA have been studied by steady state and time resolved fluorescence spectroscopy. It was observed that HSA penetrates into the liposomes through hydrophobic interaction which reduces the packing order of the lipid bi-layer and leads to a quenching in fluorescence intensity of ellipticine. DPPC is more dehydrated hence more hydrophobic due to its higher phase transition temperature (42 °C) as compared to that of DMPC (23 °C). Therefore, HSA exhibits more affinity towards DPPC than it does towards DMPC. The time resolved components revealed that penetration of HSA into liposomes results in migration of the drug molecules from liposomes to hydrophobic pocket of HSA. Incorporation of HSA in both the liposomes increases the rotational relaxation time of ellipticine. The fact confirms that HSA penetrates into the liposome and forms bigger complex.