Inhibition effects of Eucalyptus globules Labill. essential oil against tyrosinase

Essential oils derived from Eucalyptus globules Labill. (EGEOs) represent a significant class of bioactive metabolites with broad applications in medicinal and pharmaceutical industries. Despite their various biological activities, the potential of EGEOs to inhibit tyrosinase, a key enzyme in melanin biosynthesis, remains unexplored. Then, this study delineates the inhibitory effects of EGEOs on tyrosinase. Our findings indicated that EGEOs acted as one reversible and non-competitive inhibitor toward tyrosinase, presenting an inhibition rate of 59.6% (10 mg/ml). Circular dichroism (CD) spectral analysis suggested that EGEOs induced conformational changes in tyrosinase, potentially disrupting its catalytic function. The binding of EGEOs to tyrosinase, as evidenced by ANS binding assays, led to the exposure of hydrophobic regions within the enzyme, further impairing its activity. Molecular docking studies illustrated the specific interactions between the major metabolite of EGEOs, 1,8-cineole, and tyrosinase. Moreover, the impact of EGEOs on melanin production was assessed in B16F10 melanoma cells, demonstrating a significant reduction in intracellular melanin content upon EGEOs treatment. Collectively, these results suggested EGEOs as one promising natural tyrosinase inhibitor with potential applications in treating hyperpigmentation and associated skin disorders.