TY - JOUR
T1 - Luteolin as reactive oxygen generator by X-ray and UV irradiation
AU - Toyama, Michiru
AU - Mori, Takashi
AU - Takahashi, Junko
AU - Iwahashi, Hitoshi
N1 - Funding Information:
To investigate ROS generation mechanisms, we performed studies using electron spin resonance with support from Prof. Emiko Yanase and Ms. Sakina Hayashi. We thank Mr. Hideo Katayama, Daikin Industries Ltd., and Dr. Masaki Misawa, AIST for the revision of this manuscript. We would like to thank Editage ( www.editage.jp ) for English language editing. This work was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI Grant no. 25293270 .
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2018/5
Y1 - 2018/5
N2 - Non-toxic X-ray-responsive substances can be used in the radiosensitization of cancer, like porphyrin mediated radiotherapy. However, most X-ray-responsive substances are toxic. To find novel non-toxic X-ray-responsive substances, we studied the X-ray and UV reactivity of 40 non-toxic compounds extracted from plants. Dihydroethidium was used as an indicator to detect reactive oxygen species (ROS) generated by the compounds under X-ray or UV irradiation. We found that 13 of the investigated compounds generated ROS under X-ray irradiation and 17 generated ROS under UV irradiation. Only 4 substances generated ROS under both X-ray and UV. In particular, luteolin exhibited the highest activity among the investigated compounds; therefore, the ROS generated by luteolin were thoroughly characterized. To identify the ROS, we employed a combination of ROS detection reagents and their quenchers. O2·- generation by luteolin was monitored using dihydroethidium and superoxide dismutase (as an O2·- quencher). OH· and 1O2 generation was determined using aminophenyl fluorescein with ethanol (OH· quencher) and Singlet Oxygen Sensor Green® with NaN3 (1O2 quencher), respectively. Generation of O2·- under X-ray and UV irradiation was observed; however, no OH· or 1O2 was detected. The production of ROS from luteolin is surprising, because luteolin is a well-known antioxidant.
AB - Non-toxic X-ray-responsive substances can be used in the radiosensitization of cancer, like porphyrin mediated radiotherapy. However, most X-ray-responsive substances are toxic. To find novel non-toxic X-ray-responsive substances, we studied the X-ray and UV reactivity of 40 non-toxic compounds extracted from plants. Dihydroethidium was used as an indicator to detect reactive oxygen species (ROS) generated by the compounds under X-ray or UV irradiation. We found that 13 of the investigated compounds generated ROS under X-ray irradiation and 17 generated ROS under UV irradiation. Only 4 substances generated ROS under both X-ray and UV. In particular, luteolin exhibited the highest activity among the investigated compounds; therefore, the ROS generated by luteolin were thoroughly characterized. To identify the ROS, we employed a combination of ROS detection reagents and their quenchers. O2·- generation by luteolin was monitored using dihydroethidium and superoxide dismutase (as an O2·- quencher). OH· and 1O2 generation was determined using aminophenyl fluorescein with ethanol (OH· quencher) and Singlet Oxygen Sensor Green® with NaN3 (1O2 quencher), respectively. Generation of O2·- under X-ray and UV irradiation was observed; however, no OH· or 1O2 was detected. The production of ROS from luteolin is surprising, because luteolin is a well-known antioxidant.
KW - Luteolin
KW - Radiosensitizer
KW - Reactive oxygen species (ROS)
KW - X-ray
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U2 - 10.1016/j.radphyschem.2017.12.022
DO - 10.1016/j.radphyschem.2017.12.022
M3 - Article
AN - SCOPUS:85041458885
SN - 0969-806X
VL - 146
SP - 11
EP - 18
JO - Radiation Physics and Chemistry
JF - Radiation Physics and Chemistry
ER -
