Photodynamic membrane lipid peroxidation

Abstract The supramolecular composites containing fullerenes C60 immobilized at nanosilica were used for the design of the molecular systems that can be an effective agent in cancer photodynamic therapy (PDT). In particular, it was shown that photoexcited fullerene C60-containing composites decrease viability of transformed cells, intensify the process of lipid peroxidation (LPO) in cell membranes and accumulation of low-molecular weight DNA fragments, and also decrease the activity of electron-transport chain of mitochondria. 

Photosensitive liposomes may contain a photosensitizer that can induce peroxidation of the membrane lipids by type I and/or type II photodynamic sensitization (Srinath and Jain, 1994). In the type I process, the electronically excited sensitizer reacts directly with the lipids. The result is the formation of radicals that can react further with molecular oxygen or other components present at the reaction site. In the type II process, the electronically excited sensitizer reacts directly with molecular oxygen via energy transfer to produce singlet oxygen. 

The antioxidant behavior of astaxanthin has been demonstrated in vivo as well. In Haematococcus algae, astaxanthin is accumulated as part of a stress response, and it is believed to protect cellular DNA from photodynamic damage. This carotenoid also protects lipids from peroxidation in trout and salmon. In chicks, astaxanthin supplementation suppressed the formation of lipid peroxides in the plasma. Significant biological antioxidant effects have been observed in vitamin E-deficient rats fed an astaxanthin-rich diet these include protection of mitochondrial function and inhibition of peroxidation of erythrocyte membranes. In two independent studies, lipid peroxidation in the seram and liver of astaxanthin-fed rats treated with carbon tetrachloride was... 

The membrane of an erythrocyte comprises intricately linked lipid and protein components. Therefore, liposomes made without structural proteins cannot be fully satisfactory model systems. Nevertheless, a-terthienyl induced photodynamic membrane damage in glucose-containing liposomes, probably through lipid peroxidation 185). The modification of the membrane properties was revealed by leakage of glucose trapped in the liposomes. 

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