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Oxidation of melatonin by singlet molecular oxygen (O 2 ( 1 Δ g )) produces N 1 ‐acetyl‐ N 2 ‐formyl‐5‐methoxykynurenine
Author(s) -
Almeida Eduardo A.,
Martinez Glaucia R.,
Klitzke Clécio F.,
Medeiros Marisa H. G.,
Mascio Paolo Di
Publication year - 2003
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1034/j.1600-079x.2003.00066.x
Subject(s) - melatonin , singlet oxygen , chemistry , mass spectrometry , oxygen , bromine , singlet state , molecule , electrospray ionization , antioxidant , analytical chemistry (journal) , nuclear chemistry , chromatography , organic chemistry , excited state , medicine , physics , nuclear physics
It has been shown that melatonin exhibits antioxidant properties. Chemical structures of some of the products formed by the interaction of melatonin with reactive oxygen and nitrogen species have been elucidated. Despite some evidence that the reaction of melatonin with singlet molecular oxygen (O 2 ( 1 Δ g )) produces N 1 ‐acetyl‐ N 2 ‐formyl‐5‐methoxykynurenine (AFMK), it has not been fully documented. In this investigation, melatonin was oxidized by photosensitization with methylene blue or by a clean chemical source of O 2 ( 1 Δ g ), the thermodecomposition of N , N ′‐di(2,3‐dihydroxypropyl)‐1,4‐naphtalenedipropanamide (DHPNO 2 ). The resulting product was characterized by high performance liquid chromatography, coupled to electrospray ionization mass spectrometry and also by 1 H, 13 C and dept135 nuclear magnetic resonance spectroscopy. An isotopically labeled DHPN 18 O 2 was also prepared and used as a chemical source of labeled 18 [O 2 ( 1 Δ g )] to unequivocally characterize the end product. The results uncovered by this work confirm the hypothesis that oxidation of melatonin by O 2 ( 1 Δ g ) produces AFMK.