Tyrosinase is an oxidoreductase enzyme which catalyzes o-hydroxylation of monophenols into their corresponding o-diphenols. It also oxidizes o-diphenols to the corresponding oquinones using molecular oxygen. Due to the high chemical activity, o-quinones participate in further chemical reactions and form macromolecules known as melanin which are the core substances of natural pigment of skin, eyes, and hair [1]. The synthesis of o-diphenols is a potentially valuable catalytic ability and thus tyrosinase has attracted a lot of attention with respect to industrial applications. Various dermatological disorders, such as melanoma, age spots, and sites of actinic damage arise from the accumulation of an excessive level of epidermal pigmentation originated from hyper activity of tyrosinase. In addition, unfavorable enzymatic browning of plant-derived phenolic compounds by tyrosinase causes a decrease in nutritional quality and economic loss of food products [2]. Consequently, a great deal of research has been directed toward finding compounds that can inhibit tyrosinase activities. Based on the scientific literature in this field, some 5-hydroxy pyrimidine derivatives were designed to work as analogues of tyrosinase substrates.

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