Characterization of reactive oxygen species generated by protoporphyrin IX under X-ray irradiation

Junko Takahashi, Masaki Misawa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)


As a possible radiosensitizer candidate having biological compatibility, oncotropic property, and X-ray activation capability, contribution of protoporphyrin IX (PpIX) to enhanced generation of reactive oxygen species (ROS) under X-ray and UV irradiations were examined. To identify the kinds of ROS, 2-[6-(4-amino)phenoxy-3H-xanthen-3-on-9-yl] benzoic acid (APF) and dihydroethidium (DHE) were used together with ethanol as a hydroxyl radical (OH{radical dot}) quencher. All of the three species of our interest (OH{radical dot}, superoxide radical (O2{radical dot}-), and singlet oxygen (1O2)) were enhanced by PpIX under X-ray and UV irradiations in addition to those by radiolysis and photolysis. Its enhancement factors exceeded 1.7 depending on the concentrations of PpIX from 1.5 to 15.0 μg/ml.

Original languageEnglish
Pages (from-to)889-898
Number of pages10
JournalRadiation Physics and Chemistry
Issue number11
Publication statusPublished - 2009 Nov
Externally publishedYes


  • Photodynamic therapy
  • Photosensitizer
  • Protoporphyrin
  • Radiosensitizer
  • Radiotherapy
  • Reactive oxygen species
  • X-ray

ASJC Scopus subject areas

  • Radiation


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