Antioxidative capacity of C60 (buckminsterfullerene) and newly synthesized fulleropyrrolidine derivatives encapsulated in liposomes

Abstract

C(60) (buckminsterfullerene or fullerene C(60)) has been recognized an efficient free-radical scavenger. Owing to its high antioxidative capacity, C(60) and its derivatives have a great potential for application in biological systems where prevention of oxidative cell damage is desirable. However, poor solubility of native C(60) in water represents a major drawback for its use in biological systems. In order to increase the efficiency of delivery of fullerenes to target tissues it is of great interest to enhance their water solubility by developing hydrophilic organoderivatives of C(60) with retained antioxidative properties, and/or by encapsulating fullerenes in biocompatible liposomes. In the present study, using EPR spin-trapping and spin-labelling techniques, we investigated the antioxidative capacity of C(60) and newly synthesized fulleropyrrolidine derivatives Q-C(60) [N-methyl-(2-quinolyl)fulleropyrrolidine(60)] and I-C(60) [N-methyl-(2-indolyl)fulleropyrrolidine(60)] encapsulated in multilamellar phospholipid liposomes. The capacity for removal of (*)OH (hydroxyl radical) and O2(*-) (superoxide radical) and for the prevention of lipid peroxidation should be stressed as the most relevant biological antioxidative parameters. When these parameters for novel organofullerenes were compared with the the performance of C(60), Q-C(60) and I-C(60) showed similar, or even better, antioxidative characteristics. However, further research is required to establish the toxicity of these derivatives and their antioxidant efficacy in vivo.