C₇₀-Carboxyfullerenes as Efficient Antioxidants to Protect Cells against Oxidative-Induced Stress

Oxidative stress induced by excessive production of reactive oxygen species (ROS) has been implicated in the etiology of many human diseases. Acquiring a highly efficient antioxidant with good biocompatibility is of significance in eliminating the deleterious effect induced by the oxidative stress. Herein, we address our efforts on investigating the cytoprotective effect of carboxyfullerenes on H₂O₂-injured cells. Meanwhile, the uptake and intracellular location of carboxyfullerenes were studied. The results show that C₇₀-carboxyfullerenes (dimalonic acid C₇₀ fullerene (DF₇₀) and trimalonic acid C₇₀ fullerene (TF₇₀)) exhibit an obviously protective effect against oxidative stress on C2C12 cells at concentrations as low as 2.5 μmol L^–1, whereas C₆₀-carboxyfullerenes (dimalonic acid C₆₀ fullerene (DF₆₀) and quadri-malonic acid C₆₀ fullerene (QF₆₀)) show a protective effect at relatively higher concentration (40 μmol L^–1). The molecular structure of carboxyfullerenes and the physiological state of cells play an important role in the different cytoprotective capability. Further study reveals that DF₇₀ and TF₇₀ could enter into cells and mainly localize into the lysosome, which possibly involves the protective mechanism by stabilizing lysosome. The use of a significantly low concentration of C₇₀-carboxyfullerene as the antioxidative agent will benefit the therapeutic approaches aiming at alleviating ROS-induced injuries such as muscle disorder and arthritis.