Analogues of N-hydroxy-N′-phenylthiourea and N-hydroxy-N′-phenylurea as inhibitors of tyrosinase and melanin formation

A series of N-hydroxy-N′-phenylthiourea and N-hydroxy-N′-phenylurea analogues were prepared and evaluated as inhibitors of tyrosinase and melanin formation. The most active analogue 1 inhibited mushroom tyrosinase with an IC50 of around 0.29 μM and also retained a substantial potency in cell culture by reducing pigment synthesis by 78%. Therefore, compound 1 could be considered as a promising candidate for preclinical drug development for skin hyperpigmentation application.