BELOW: This is the inner layer of the skin called dermis and the outer surface which is visible in our eyes is the epidermis. The primary determinant of variability in human skin color is the melanin and melanocyte is a cell that synthesizes it. L-glutathione, the whitening pill"s main component, starts the lightening process in the dermis working its way out to the surface.
BELOW: This is the point where the metabolic pathway of melanin begins. As you see in the diagram GSH(reduced glutathione) intervenes the metabolism. There are certain kinds of compounds that inhibits the tyrosinase activity and L-glutathione is one of them.