Relationship between melanin content and superoxide dismutase (SOD) activity in the liver of various species of animals

The scavenger effect of melanin and of superoxide-dismutase (SOD) activity on superoxide anion has been showwn. In tis work we show the relationship between melanin content and SOD activity in livers containing different quantities of melanin which were taken from various species of animals. The mitochondrial SOD activity disappears when the melanin content in the liver is very high; moreover it increase, in the liver of various species of animals, examined, proportionally to the decrease of melanin content. No significant variation of the SOD activity localized in the soluble fraction has been detected when related to the melanin content. We think that in the pigmented liver the antioxidant activity of the melanin could mimic part of the function of SOD. The loss of MnSOD activity could be mediated by a low intracellular level of superoxide anion due to the scavenger effect of melanin on superoxide anion;in fact, it is well known that the biosynthesis of MnSOD is induced by intracellular levels of superoxide anion.