Hw. Zhang et al., THE REACTION OF MELATONIN WITH PEROXYNITRITE - FORMATION OF MELATONINRADICAL-CATION AND ABSENCE OF STABLE NITRATED PRODUCTS, Biochemical and biophysical research communications (Print), 251(1), 1998, pp. 83-87
Peroxynitrite is capable of hydroxylating and nitrating aromatic speci
es. However, nitromelatonin is not found as a final product when melat
onin was allowed to react with peroxynitrite either in the presence or
absence of added bicarbonate. In the absence of bicarbonate, the two
major products formed are 6-hydroxymelatonin and 5-methoxy-2-hydro-pyr
roloindole, and the latter is the only major product with excess bicar
bonate. A transient purple intermediate with a maximum absorbance at a
bout 520 nm is observed upon mixing solutions containing peroxynitrite
and melatonin. These observations indicate that the melatoninyl radic
al cation is formed in the peroxynitrite/melatonin reaction, providing
a direct evidence for the one-electron oxidation ability of peroxynit
rite. The melatoninyl radical cation also is observed with excess bica
rbonate. (C) 1998 Academic Press.