Tissue sites of uptake of C-14-labeled C-60

This paper describes the in vivo behavior and potential metabolism of C-60 and a more water-soluble quaternary ammonium salt-derivatized C-60. In both cases, a C-14-labeled fullerene core was utilized for the target molecules that were intravenously injected into female Sprague-Dawley rats. The C-14-labeled C-60 (*C-60) was rapidly (within 1 min) cleared from the circulation and the majority of the *C-60 accumulated in the liver (90-95%). *C-60 was not eliminated from the liver over the 120-h period of this study. Our results also suggest that C-60 is not metabolized by the typical oxidative patterns characteristic of other polycyclic aromatics. Therefore, although not acutely toxic, use of C-60, or its derivatives that could be cleaved back to the parent C-60 in vivo, would likely lead to long-term fullerene accumulation in the liver. The uptake of *C-60 and C-14-labeled ammonium salt-derivatized C-60 (1) by human keratinocytes in vitro showed that while both *C-60 and 1 are readily taken up by cells, 1 accumulates more slowly. Additionally, while C-60, at rather high concentrations (2.0 mu M) and over extended periods of time (8 days), is able to inhibit the growth of human keratinocytes by about 50%, this effect showed little, if any, photoinducability. (C) 1996 Academic Press, Inc.