On the other hand, inhibition of
tyrosinase (TYR, EC 1.
A: It takes 12-16 weeks in some cases to see the effects of
tyrosinase inhibitors.
The binding of melanocyte-stimulating hormone to the melanocortin 1 receptor sets in motion melanogenesis by activating
tyrosinase in melanocytes.
Laccase and
Tyrosinase activity was induced 142% and 166 % respectively.
16 It inhibits melanin synthesis by inhibiting L-DOPA to interact with
tyrosinase in the process of melanin production.
Antioxidant (DPPH radical scavenging, reducing power (CUPRAC and FRAP), phosphomolybdenum and metal chelating (ferrozine method)) and enzyme inhibitory activities (cholinesterase (Elmann's method),
tyrosinase (dopachrome method), [alpha]-amylase (iodine/potassium iodide method) and [alpha]-glucosidase (chromogenic PNPG method)) determined by the method described by Zengin et al.
66,67] During melanogenesis,
tyrosinase is responsible for the conversion of L-tyrosine to L-DOPA and subsequently to dopaquinone, then the pathway bifurcates to produce eumelanin or phaeomelanin.
It inhibits
tyrosinase, the main pigment forming enzyme.
In the previous works, the leaf extract of mangosteen was found to stimulate melanin synthesis and enhance
tyrosinase activity [1] while its stem-bark extract showedcytotoxic activity against colon cancer cells [2].
4,5] have shown that cultured human melanocytes express oestrogen receptors and estradiol increases the levels of
tyrosinase,
tyrosinase-related-protein 1 and 2, the enzymes involved in human eumelanogenesis within normal human melanocytes.
Autoimmune hypothesis is the most widely accepted, because autoantibodies to melanocytes and
tyrosinase have been demonstrated and owing to the usual association of vitiligo with other autoimmune diseases.
Expression of
tyrosinase was revealed in some of these cells by dopa reaction.
