Glycine Inhibits Melanogenesis in Vitro and Causes Hypopigmentation in Vivo

The study demonstrated that glycine inhibited melanogenesis in B16F0 melanoma cells and hair follicle melanogenesis in C57BL/6J mice. Glycine treatment (1—16 mM) for 72 hours reduced α-MSH-induced melanogenesis in a concentration-dependent manner without affecting cell proliferation. In mice, glycine (1250 or 2500 mg/kg) administered for 5 days prevented decreases in L* and C* values and reduced tyrosinase protein levels and melanin content in the skin. These effects were similar to those observed with kojic acid and hydroquinone treatments. The findings suggested that glycine's hypopigmenting effect was due to the down-regulation of tyrosinase protein levels.