DSC and Raman study on the interaction of DDT [1,1,1-trichloro-2,2-bis( p-chlorophenyl)-ethane] with liposomal phospholipids

Abstract

In this paper, a DSC and Raman study of hydrated multilamellar DMPC (1,2-dimyristoyl- sn-glycero-3-phosphocholine) and DMPE (1,2-dimyristoyl- sn-glycero-3-phosphoethanolamine) liposomes in presence of increasing amounts of DDT is reported. The observed changes denote that DDT molecules interact with both phospholipids and that the interaction mainly involves the external part of the bilayer since the deep penetration into the hydrophobic core is prevented by the setting up of polar interactions between the three aliphatic C–Cl bonds of the trichloro group of DDT and the –N +(CH 3) 3 of DMPC or the –NH 3 + groups of DMPE molecules. This behaviour was particularly evidenced in presence of DMPE, as the insertion of DDT molecules into the central part of the bilayer seems to be completely excluded. Moreover, in DMPE liposomes the overall structure of the bilayer changes to a well defined and structured ‘phase II’ in presence of even small DDT amounts.