Edaravone directly reacts with singlet oxygen and protects cells from attack.
OBJECTIVE
Protective effects of edaravone, an approved medicine for acute brain infarction in Japan, on cell death induced by singlet oxygen (1O2) were examined.


METHODS
The 1O2 scavenging activity was examined by direct analysis of near-infrared luminescence in a cell-free system and by fluorospectrometry in the presence of cells. The protective effects of edaravone on 1O2-induced cell death were examined, using rat neuronal B50 cells. Cell death was evaluated by mitochondrial respiration (MTT assay), confocal microscopy and time-lapse imaging. The chemical reaction of edaravone with 1O2 was examined by production analysis using high performance liquid chromatography (HPLC).


RESULTS
When rose Bengal (RB) in D2O was irradiated by a 514nm laser beam, the signal of 1O2 was observed. Edaravone suppressed the 1O2 signal more potently than azide, a 1O2 scavenger. When B50 cells were irradiated by 525nm green light in the RB solution, production of 1O2 and induction of cell death were observed. The fluorospectrometric study and the MTT assay revealed that 100-400microM edaravone suppressed the 1O2 production and attenuated cell death in a concentration-dependent manner. Confocal microscopy and the time-lapse imaging revealed that edaravone prevented the impairment of membrane integrity and the progression of cell death induced by 1O2. The HPLC study revealed that edaravone chemically reacted with 1O2 and changed another compound.


CONCLUSIONS
Since 1O2 is possibly involved in post-ischemic neuronal damage, the clinically approved curative effects of edaravone on acute brain infarction might be attributed to its potent 1O2 scavenging activity.
Nishinaka
Yoko
Y
School of Health Science Faculty of Medicine, Kyoto University, Kyoto, Japan.
Mori
Hiroko
H
Endo
Nobuyuki
N
Miyoshi
Takashi
T
Yamashita
Kouhei
K
Adachi
Souichi
S
Arai
Toshiyuki
T
D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002474:Cell-Free System; D002851:Chromatography, High Pressure Liquid; D000077553:Edaravone; D016166:Free Radical Scavengers / Q000494:pharmacology*; D018613:Microscopy, Confocal; D009474:Neurons / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D012395:Rose Bengal; D026082:Singlet Oxygen / Q000037:antagonists & inhibitors*; D013050:Spectrometry, Fluorescence
D016166:Free Radical Scavengers; D026082:Singlet Oxygen; D012395:Rose Bengal; D000077553:Edaravone; D000983:Antipyrine