Role of thiol compounds in mammalian melanin pigmentation: Part I. Reduced and oxidized glutathione.

Evidence for the postulated role of glutathione reductase in melanin pigmentation has been obtained by determinations of the glutathione concentrations in Tortoiseshell guinea pig skin of different colors (black, yellow, red, and white). As expected, the lowest levels of reduced glutathione (GSH) were found associated with eumelanin type pigmentation, whereas the highest ones were found in the skin with phaeomelanin producing melanocytes. On the other hand, white skin of guinea pig having no active melanocytes showed GSH levels which were intermediate between those of the black and yellow areas. These results are consistent with the view that the activity of the enzyme glutathione reductase, though not primarily related to pigmentation, plays an important role in the regulation and control of the biosynthetic activity of melanocytes leading to various types of melanin pigments.