Biological activity of water-soluble fullerenes. Structural dependence of DNA cleavage, cytotoxicity, and enzyme inhibitory activities including HIV-protease inhibition

Two different classes of water-soluble fullerene derivatives, detergent-type and sphere-type, were synthesized. The derivatives were evaluated for their biological activities including cytotoxicity, DNA cleavage, and inhibition of HIV-protease and other enzymes. Both classes of compounds display generally similar behavior except for their cytotoxicity spectra against several cell lines. The fullerene derivatives bearing N-methylpyrrole were found to be photo-inactive with respect to DNA cleaving activity and cytotoxicity. A study on the kinetics for the inhibition of HIV-protease with detergent type derivative revealed that the compound is a potent fullerene-based HIV protease inhibitor, inhibiting the enzyme activity in a reversible and competitive manner with a K-i value of 0.32 mu M.