Superoxide Oxidises Catecholamines

The oxidation of catecholamines by the hydroperoxidase activity of lipoxygenase (EC 1.13.11.12) is documented by Rosei et al. (1994) and NOnez-Delicado et al. (1996). o-Diphenols are easily studies spectrophotometrically since, when oxidised, they render coloured compounds, quinones, or their corresponding aminochromes. In the case of isoprenaline the maximum of the oxidation product was developed at 490 nm (NOnez-Delicado et al. 1999), which corresponds to that of the aminochrome product (Jim nez et al. 1985, NOnez-Delicado et al. 1996). 

The macrophage migration inhibitory factor (MIF) converted the oxidised catecholamines 3,4-dihydroxyphenylaminechrome, epinephrinechrome, and norepinephrinechrome to 5,6-dihydroxyindole, 3,5,6-trihydroxy-l-methylindole, and 3,5,6-trihydro-xyindole, respectively (Matsunaga et al. 1999). These products are precursors of neuromelanin (Smythies 1996, DTschia and Prota 1997), a pig- 

---