Catalysis-based specific detection and inhibition of tyrosinase and their application

Abstract

Tyrosinase is an important enzyme in controlling the formation of melanin in melanosome, and plays a key role in the pigmentation of hair and skin. The abnormal expression or activation of tyrosinase is associated with several diseases such as albinism, vitiligo, melanoma and Parkinson disease. Excessive deposition of melanin could cause diseases such as freckles and brown spots in the human body, and it is also closely related to browning of fruits and vegetables and insect molting. Detecting and inhibiting the activity of tyrosinase is of extraordinary value in the progress of diagnosis and treatment of these diseases. Therefore, many selective optical detection probes and small molecular inhibitors have been developed, and have made significant contributions to the basic and clinical research on these diseases. In this paper, the detection and inhibition of tyrosinase and their application in whitening products are reviewed, with special emphasis on development of fluorescent probes and inhibitors. Hopefully, this review will help design more efficient and sensitive tyrosinase probes and inhibitors, as well as shed light on novel treatment of diseases such as melanoma.

Keywords: Detection probe; Inhibitors; Melanin; Melanoma; Tyrosinase.

Graphical abstract

Fig. 1

The process of melanin biosynthesis catalyzed by tyrosinase.

Fig. 2

E_oxy/E_met/E_deoxy forms of oxidation state of tyrosinase. Monophenol cycle and bisphenol cycle catalytic mechanism. E_oxyM: monophenolase E_oxy complex, E_oxyD: diphenolase E_oxy complex, E_metD: diphenolase E_met complex.

Fig. 3

Schematic representation of three main types of probes for tyrosinase activity detection.

Fig. 4

Structures of tyrosinase fluorescent probes; fluorophore and WH are in green and purple, respectively.

Fig. 5

(A) Schematic diagram for detection of tyrosinase by probe Pr12 and melanoma imaging in the mouse model. (B) Images of B16F10 cells with different treatments (a-d); (e) relative intensity values obtained from panels (a-d) in B. (C) Images for 3-day-old zebrafishes with different treatments (a-d); (e) relative intensity values obtained from panels (a-d) in C. Reproduced with permission from Ref. [36]. Copyright 2018 American Chemical Society.

Fig. 6

(A) The proposed reaction mechanisms of Pr14 with tyrosinase. (B) Confocal fluorescence images of B16 cells with different treatments (a-c); (d) relative intensity values obtained from panels (a-c) in B. (C) Fluorescence images of 3-day-old zebrafishes with different treatments (a-c); (d) relative intensity values obtained from panels (a-c) in C. Reproduced with permission from Ref. [38]. Copyright 2016 John Wiley and Sons.

Fig. 7

The proposed sensing mechanism for the tyrosinase induced enzymatic activation of Pr21.

Fig. 8

Structure of the main classes of flavonoids.

Fig. 9

Structure of the main inhibitors of tyrosinase.