Inhibitory effects of Na7PMo11CuO40 on mushroom tyrosinase and melanin formation and its antimicrobial activities

• A novel tyrosinase inhibitor and antimicrobial is studied.
• Apply Na7PMo11CuO40 decreased the melanin content in B16 melanoma cells.
• Extended the use of polyoxometalates in the fields of food preservation and depigmentation.

Keggin-type Cu-substituted phosphomolybdic acid (Na7PMo11CuO40, abbreviated as PMo11Cu) was synthesized and characterized. The inhibitory effects of PMo11Cu on mushroom tyrosinase and melanin formation in B16 melanoma cells were studied. The results showed that PMo11Cu could strongly inhibit the activity of tyrosinase, and it was reversible and competitive inhibitor. The IC50 value was estimated to be 0.48 mM for diphenolase activity. PMo11Cu also exhibited inhibitory effects on cell viability, cellular tyrosinase activity and melanin formation in B16 melanoma cells at concentrations ranging from 0 to 200 μM for 24 h. Furthermore, the antimicrobial activities of PMo11Cu against Sarcina lutea, Staphylococcus aureus, Bacillus subtilis and Escherichia coli were investigated. The results showed that PMo11Cu had an obvious antimicrobial activities, and it was more effective against two kinds of coccus than two kinds of bacillus. This study may provide theoretical basis for designing novel effective mushroom tyrosinase inhibitors and extend the use of polyoxometalates in the fields of food preservation and depigmentation.

Electrophoretic analysis of the inhibitory effect of PMo11Cu on the diphenolase activity of mushroom tyrosinase. Mushroom tyrosinase is a tetrameric glycoprotein copper containing metalloenzyme. Figure A is a gel map of SDS–PAGE for the analysis of the molecular weight of mushroom tyrosinase, figure B showed that the color of the tyrosinase activity staining bands became gradually shallow until they disappeared with the increasing of inhibitor concentration. The figures confirmed that PMo11Cu could potently inhibit the activity of tyrosinase.Figure optionsDownload as PowerPoint slide