Photophysical and photodynamical study of ellipticine: an anticancer drug molecule in bile salt modulated in vitro created liposome

Abstract

The entrapment of anticancer drug ellipticine in the dipalmitoylphosphocholine (DPPC) liposome and its release by addition of three different bile salts, namely sodium deoxycholate, cholate and taurocholate, have been studied by steady state and time resolved fluorescence spectroscopy. We found that the release of the drug from a liposome depends on the degree of penetration of bile salts. Among the three bile salts, deoxycholate was most effective in releasing the drug from the hydrocarbon core of the liposome because of its high insertion ability owing to its maximum hydrophobicity. The time resolved studies revealed that with addition of bile salt to the liposome solution, ellipticine molecules were removed from the hydrocarbon core and were entrapped in an interfacial region of liposomes by electrostatic interaction. This led to an increase in the shorter lifetime component. On the other hand, the longer lifetime component decreased because bile salts wet the hydrocarbon core of the liposome by carrying hydrogen bonded water. Entrapment of ellipticine in the interfacial region was also supported by an increase in the rotational relaxation time with addition of bile salt.