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Abnormal overexpression of tyrosinase activity can lead to the production of hyperpigmentation in human skin and enzymatic browning in fruits and vegetables. Herein, the inhibition and mechanism of the H3PMo12O40 and two transition metal‐substituted Keggin‐type polyoxometalates (Na7PMo11CoO40 and Na7PMo11ZnO40) on tyrosinase were studied by kinetics and molecular modeling. Kinetic studies indicated that all compounds had more potent inhibitory activities than standard arbutin, and H3PMo12O40 (IC50 = 0.443 ± 0.006 mm) is ~15‐fold stronger inhibition than arbutin. Additionally, all compounds inhibited tyrosinase in a reversible competitive manner. Intriguingly, molecular modeling elucidated that three compounds competitively bind to tyrosinase mainly through more interactions with Cu2+ ions and the amino acid residue capable of forming cation‐π and hydrogen bonding, forming a reversible non‐covalent complex. Molecular simulation study correlated well with the biological activity of three compounds in vitro. This work provided new insights into design and synthesis of polyoxometalates as tyrosinase inhibitors in the field of medicine, cosmetic, and food.

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Two Keggin-type polyoxometalates (POMs) containing glycine, (HGly) PW O and (HGly) SiW O , were synthesized and evaluated as mushroom tyrosinase inhibitors. The spectrophotometric method results showed that both (HGly) PW O and (HGly) SiW O could strongly inhibit the diphenolase activity of the tyrosinase and that their inhibition mechanisms were reversible. Their half-inhibition concentration values were estimated to be 1.55 and 1.39 mmol/L, respectively. The inhibition kinetics analysis by Lineweaver-Burk plots indicated that (HGly) PW O was an uncompetitive inhibitor with K = 0.046 mmol/L, whereas (HGly) SiW O was a noncompetitive inhibitor with K = K = 2.17 mmol/L. This study may help to extend the application of POMs in the fields of medicine and food preservation.