Glycine hydroxamate inhibits tyrosinase activity and melanin contents through downregulating cAMP/PKA signaling pathways

Among the eight amino acid hydroxamates tested, Glycine hydroxamate (GH) was the best inhibitor of mushroom tyrosinase (TYR). With l-tyrosine as substrate, the GH inhibition of the monophenolase activity of the mushroom TYR was noncompetitive. GH decreased not only TYR protein expression, but also melanin content, tyrosinase-related protein (TRP)-1, TRP-2, and microphthalmia-associated transcription factor (MITF) expression in B16F10 melanoma cells while in the presence of α-melanocyte-stimulating hormone (α-MSH). GH also significantly decreased the isobutylmethylxanthine (IBMX)-induced increase in melanin content, which was not prevented by the ERK inhibitor PD98059. These results suggest GH has the potential for use in cosmetic hypopigmentation.