Oxidative Stress Studies on Lipid Model Membranes

The living organisms are known to be often exposed to oxidative stress due to the action of most of environmental factors: the exposure to athmospheric oxygen (O2), the pollution, the ozone and the ultraviolet radiation level increasing. The consequence of this fact is the biomolecules (proteins, nucleic acids and lipids) damaging. The oxidative stress mainly affects the membranous systems of aerobic cells and the consequently oxidative damage is associated with the peroxidation reactions in membrane lipids. Thus, the use of the liposomes as cell model membranes is an important tool for oxidative stress studies. The liposomes with chlorophyll a (Chla) are excellent models for biomembranes and are successfully used to study the interactions of different agents inside the bilayer structures. The chlorophyll is an important photopigment, but insufficient exploited in biotechnological applications. The strong visible absorption and fluorescence of Chla allow its use as a sensor for the interactions at molecular level and as a fluorescence marker; it reflects certain aspects of the supramolecular structure of the lipid phase: fluidity, lipid and liposomes aggregation [1]. It is known that the chlorophyll has antioxidant properties. Derivatives of chlorophyll a were found to be more effective radical quenchers than those of chlorophyll b [2]. This is why we utilised in our studies the Chla.