Chlorophyll a - Labelled Artificial Lipid Membranes Exposed to Photo-oxidative Stress. Spectral Studies

The chlorophyll stability in biomimetic environment is the precondition for its potential application in various fields of science and technology. Its unique role, based on the specific and very diverse chemical reactivity, justifies its use in industrial technology, pharmaceutical, food and cosmetic industry, but also in medicine. In this work, two types of liposomes were prepared from saturated (dipalmitoyl phosphatidylcholine) and unsaturated (PHOSPHOLIPON 90®) lipids. The artificial lipid membranes were labeled with a natural photopigment chlorophyll a (Chla). The stability of Chla-based liposomes to in vitro induced oxidative stress by visible and UVB irradiation was examined by UV-Vis absorption spectra, and by monitoring two kind of lipid peroxidation biomarkers (conjugated dienes and TBA-MDA assay) which were quantified in order to evaluate the photodamage degree of artificial lipid membranes. Chla proved to be an effective spectral sensor to detect any damages induced by visible light and UVB irradiation on liposomes. After applied Vis/UVB radiation, Chla-liposomes suffered photodegradation which was more pronounced under UVB stress. The investigations demonstrated a closely connection between lipid peroxidation and chlorophyll degradation. The deterioration was higher in the case of biomimetic membranes made of unsaturated lipids exposed to photo-oxidative stress because of presence of double bonds in lipid molecules that decisively contribute to the formation of lipid radicals. Based on these results it can be concluded that chlorophyll behavior mechanism under the photo-oxidative stress is of crucial importance for further bio-applications.