Figure 1 : Redox Cycle of Methylene Blue and Hemoglobin In vivo.

Red arrow –reduction          MetHgb Fe3+: methemoglobin
Blue arrow –oxidation          OxyHgb Fe2+: oxyhemoglobin
Red –reduced compound   G6PD: Gucose 6 phosphate dehydrogenase
Blue –oxidized compound    NADPH: Nicotinamide adenine dinucleotidephosphate
e-electron

Lee et al.Journal of Anesthesiology and Clinical Science  2016 5:4DOI : 10.7243/2049-9752-5-4