Abstract
The areas of melanic pigmentation were found to contain much thiamine and riboflavin. Thiamine and riboflavin detected in these areas are mostly in the free form and flavinmononucleotide. The role of thiamine played in melanogenesis was further investigated. Thiamine, added to tyrosine-tyrosinase reaction is assumed to act as follows: it interferes in the action of dopa or dopaquinone, inhibits the production of dopa, extends the lag period of this reaction, and is in itself oxidized to thiamine disulfide.
The inhibitory action of thiamine in melanogenesis would not be so strong as that of reducing agents, such as ascorbic acid or cysteine; it would be just enough to adjust the progress of melanogenesis in such a way that it may not proceed too fast.
