Unexpected formation of N-methylfulleropyrrolidines by the reaction of fullerene and gossypol and their bioactivity

Reaction of fullerene, sarcosine and gossypol through the Prato reaction resulted in some unexpected N-methylfulleropyrrolidines. These fulleropyrrolidines were fully characterized via rigorous structure determination through multiple spectral experiments, which included 1D, 2D NMR, FT-IR, MS and X-ray crystallography. During the reaction, gossypol decomposed into benzaldehyde which was successfully detected as a new intermediate through GC-MS. In an in vitro assay of NO radical induced apoptosis in 3T3L1 cells, N-methylfulleropyrrolidine (2) and N-methyl-2,2-dimethylfulleropyrrolidine (3) showed dose dependent and stronger radical scavenging activities than the parent fullerene.