N-Oxide reduction by hemoglobin, cytochrome C and ferrous ions

Indicine N-oxide is reduced to indicine by Fe(II) ions, by enzymatically reduced cytochrome c, and by ascorbic acid in conjunction with hemin or cytochrome c. Indicine N-oxide is not reduced by native hemoglobin, but is reduced by denatured hemoglobin. Oxygen competes with indicine N-oxide for reduction by denatured hemoglobin.