Fullerene (C
60, C
70, etc.) is an effective photosensitizer and its utilization as a pharmacophore for photo-chemotherapy of tumors has received considerable attention. We developed a method to solubilize fullerenes into water with polyvinylpyrrolidone (PVP) as a detergent. By using thus prepared aqueous fullerene solutions, we have clarified a series of biological activities of fullerene under photoirradiation which include DNA-cleavage, hemolysis, mutagenicity, cancerinitiation, and cell-toxicity. A newly synthesized C
60 derivative with an acridine moiety as a DNA-chelating function showed much more effective DNA-cleaving activity in the presence of NADH. Visible-light irradiation of PVP-solubilized C
60 in water in the presence of NADH as a reductant and molecular oxygen resulted in the formation of O
2·
-, which was detected by the EPR spin-trapping method. Formation of O
2·
-was also evidenced by the direct observation of a characteristic signal of O
2·
-by the use of a low-temperature EPR technique at 77 K. On the other hand, no formation of
1O
2 was observed by the use of TEMP as a
1O
2 trapping agent. No near-IR luminescence of
1O
2 was also observed in the aqueous C
60/PVP/O
2 system. These results suggest that photoinduced bioactivities of the PVP-solubilized fullerene are caused not by
1O
2, but by reduced oxygen species (O
2·
-, ·OH) which are generated by the electron-transfer reaction of C
60·
- with molecular oxygen
抄録全体を表示