1995 Fiscal Year Final Research Report Summary
Joint Study on the Photodynamictherapy by Chlorophylls
| Project/Area Number |
07044127
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | University of Tsukuba |
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Principal Investigator |
KOBAYASHI Masami Insitute of Materials Science, University of Tsukba Lecturer, 物質工学系, 講師 (70234846)
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| Co-Investigator(Kenkyū-buntansha) |
TANIELIAN Ch EHICS, 教授
CHARLES Tanielian EHICS
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| Project Period (FY) |
1995
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| Keywords | Chlorophyll / Pheophorbide / Singlet oxygen / Photosensitizer / PDT |
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| Research Abstract |
Plasmid DNA has been efficiently photocleaved under anaerobic condition by water soluble phephorbides (sodium pheophorbides ; Na-Phdes) a, b and a novel coproporphyrin III with zinc (Zincphyrin) produced by Streptomyces sp. Singlet oxygen production sensitized by Na-Phdes a or b can not be observed in the aqueous media, although Zincphyrin produced singlet oxygen in ca. 17% quantum yield. Direct evidence for the electron capture from nucleic acid bases, adenine and guanine, by porphyrin-derivatives in the singlet excited states has been first obtained, by using nucleobase-attached porphyrins. A guanine-attached porphyrin showed strongest reduction of fluorescence derived from porphyrin ring, and an adenine-attached one showed secondaly strongest reduction. This is the first evidence in support the electron transfer mechanism for the exygen-independent photocleavage of DNA.Fluorescence microscopic observation has shown a rapid incorporation of Na-Phde a and Zincphyrin into nuclei, mitochondria and lysosome of human oral mucosa cells, although Na-Phde b has been incorporated only into the plasma membrane. Red fluorescence from Na-Phde a and zincphyrin has rapidly decayd durint the microscopic observation, indicating that some photochemical reactions take place in the organelle.
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