Lipid perturbation of liposomal membrane of dipalmitoyl phosphatidylcholine by chloroquine sulphate — a fluorescence anisotropic study

Abstract

Chloroquine sulphate (CQS) is a water-soluble anti-malarial drug having blood schizontocidal activity against Plasmodium falciparum, P. ovale, P. vivax and P. malarine. It has been reported that the lipid-soluble chloroquine base, which has similar anti-malarial and other biochemical effects, rigidifies (orders) the liposomal membrane in vivo. Here, in order to examine the lipid perturbation mechanism of CQS, we have studied the effect of incorporation of this drug into the liposomal membrane of dipalmitoyl phosphatidylcholine as measured by the fluorescence polarization of the membrane-embedded probe, 1,6-diphenyl-1,3,5-hexatriene. Our results show that the drug CQS also rigidifies the liposomal membrane even though the mechanism of the drug metabolism in vivo plays an important role. Probably the anti-malarial and other biochemical effects of CQS are exercised through this membrane rigidification.