Table 2 Courtesy [9] Origins of reactive oxygen species (ROS) and cellular location

Nicotinamide adenine dinucleotide reduced (NADH)

NADH Oxidase NADH / NAD ⁺ (mitochondrion, cytosol)

NADH + 2O₂ → NAD⁺ + H⁺ + 2O ₂ ^- (Super Oxide)

Nicotinamide adenine dinucleotide phosphate reduced (NAD(P)H)

NAD(P)H Oxidase NAD(P)H / NAD(P) ⁺ (membrane)

NAD(P)H + 2O₂ → NAD(P)⁺ + H⁺ + 2O ₂ ^- (Super Oxide)

Super oxide dismutase (SOD):

MnSOD = Mitochondrial SOD

CuZnSOD = Intracellular (cytosolic) SOD

EcSOD = Extracellular SOD

O₂^- + SOD → H₂O₂ (hydrogen peroxide)

Fenton Reaction: H₂O₂ + Fe⁺⁺ → -OH' (the hydroxyl radical) * + Fe⁺⁺⁺ + OH^-

Haber-Weiss Reaction: H₂O₂ + O₂^- → -OH^- (the hydroxyl radical) + O₂ +OH^-

Peroxynitrite: origins of reactive nitrogen species (RNS)

O₂^- is consumed. Nitric oxide (NO) is also consumed in this process with the creation of reactive nitrogen species (RNS).

O₂^- +NO → ONOO^- (peroxynitrite) + tyrosine → nitrotyrosine

O₂^- +NO → ONOO^- (peroxynitrite) + arginine → nitroarginine

Nitroarginine competes for arginine in the formation of eNO.

Nitrotyrosine reflects redox stress and leaves an indelible measurable footprint.

NO: the good; O₂^-: the bad; ONOO^-: the ugly [122, 9]