Identification of a Novel Selenium-containing Compound,Selenoneine,
as the Predominant Chemical Form of Organic Selenium in the Blood of Bluefin
Tuna |
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Authors: | Yumiko Yamashita Michiaki Yamashita |
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Institution: | From the National Research Institute of Fisheries Science, Fukuura, Yokohama 236-8648, Japan |
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Abstract: | A novel selenium-containing compound having a selenium atom in the imidazole
ring,
2-selenyl-Nα,Nα,Nα-trimethyl-l-histidine,
3-(2-hydroseleno-1H-imidazol-5-yl)-2-(trimethylammonio)propanoate,
was identified from the blood and other tissues of the bluefin tuna,
Thunnus orientalis. The selenium-containing compound was
purified from the tuna blood in several chromatographic steps. High resolution
mass spectrometry and nuclear magnetic resonance spectroscopy showed that the
exact mass of the M+H]+
ion of the compound was 533.0562 and the molecular formula was
C18H29N6O4Se2. Its
gross structure was assigned as the oxidized dimeric form of an ergothioneine
selenium analog in which the sulfur of ergothioneine is replaced by selenium.
Therefore, we named this novel selenium-containing compound
“selenoneine.” By speciation analysis of organic selenium
compounds using liquid chromatography inductively coupled plasma mass
spectrometry, selenoneine was found widely distributed in various tissues of the
tuna, with the highest concentration in blood; mackerel blood contained similar
levels. Selenoneine was measurable at 2–4 orders of magnitude lower
concentration in a limited set of tissues from squid, tilapia, pig, and chicken.
Quantitatively, selenoneine is the predominant form of organic selenium in tuna
tissues. |
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Keywords: | Amino Acid Antioxidant Glutathione Oxidative Stress Radicals Reactive Oxygen Species (ROS) Selenium Zebrafish Betaine Ergothioneine |
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