OXIDATIVE DAMAGE-INDUCED BY THE FULLERENE C-60 ON PHOTOSENSITIZATION IN RAT-LIVER MICROSOMES

We have examined the ability of a commonly used fullerene, C-60, to in duce oxidative damage on photosensitization using rat liver microsomes as model membranes. When C-60 was incorporated into rat liver microso mes in the form of its cyclodextrin complex and exposed to UV or visib le light, it induced significant oxidative damage in terms of (1) lipi d peroxidation as assayed by thiobarbituric acid reactive substances ( TBARS), lipid hydroperoxides and conjugated dienes, and (2) damage to proteins as assessed by protein carbonyls and loss of the membrane-bou nd enzymes. The oxidative damage induced was both time- and concentrat ion-dependent. C-60 plus light-induced lipid peroxidation was signific antly inhibited by the quenchers of singlet oxygen (O-1(2)), beta-caro tene and sodium azide, and deuteration of the buffer-enhanced peroxida tion. These observations indicate that C-60 is an efficient inducer of peroxidation and is predominantly due to O-1(2). Biological antioxida nts such as glutathione, ascorbic acid and alpha-tocopherol significan tly differ in their ability to inhibit peroxidation induced by C-60. O ur studies, hence, indicate that C-60, on photosensitization, can indu ce significant lipid peroxidation and other forms of oxidative damage in biological membranes and that this phenomenon can be greatly modula ted by endogenous antioxidants and scavengers of reactive oxygen speci es. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.