Lipids of membranes: Chemistry, biological role and applications as drug carriers

Abstract

The lipids are a wide and heterogeneous class of natural products. They are considered as essential biomolecules for the structure and function in living cells. The classification of lipids is not so simple. Many systems have been proposed in the recent literature in order to classify the lipids. This review article deals with the structure and classification of the main lipid classes that are taking part in the membrane structure, [glycerolipids ( i.e. glycerophospholipids and glyceroglycolipids), sphingolipids ( i.e. shingophospholipids and shingoglycolipids), sterols], their biological role and their applications as drug carriers. Glycerolipids and sphingolipids have a hydrophilic polar group and a hydrophobic carbon chain, they are characterized as amphiphilic and they can form lipid bilayers in water. The presence of sterols in membrane can influence their thermotropic behavior, resulting in the stabilization of the bilayer. This report underlines the thermodynamic and thermotropic properties of model lipidic membranes, their formation to lipidic drug carriers, their encapsulation efficiency and their physicochemical stability. Additionally, paradigms concerning bioactive natural products ( i.e. diterpenes and flavonoids) encapsulating into lipidic drug carriers such as liposomes, are underlined.