However,thesafety oflong-term use of this plasmin inhibitor has never been adequately demonstrated. Another interesting agent is glutathi- one, a cysteine-glycine-glutamate tri-peptide, which exerts several effects on melanogenesis through dif- ferent mechanisms involving the functions and cellu- lar transport of tyrosinase, the rate-limiting step enzyme in melanin formation (2). Importantly, it is well-knownthatwhenglutathioneorcysteineisadded to melanocytes or melanoma cell lines, the melano- genetic pathway is shifted from eumelanin towards pheomelanin formation