Tyrosinase Inhibition
Definition
The mechanism by which mercury compounds and some other skin-lightening agents achieve depigmentation: mercury binds to the sulphydryl (cysteine) group at the active site of tyrosinase, the copper-containing enzyme that catalyses the first and rate-limiting steps of melanin biosynthesis (tyrosine to DOPA to dopaquinone).
- Agent
- Mercury compounds and other skin-lightening agents
- Target
- Sulphydryl group at tyrosinase active site
- Enzyme role
- Catalyses tyrosine to DOPA to dopaquinone
- Result
- Reduced melanin biosynthesis (depigmentation)
Common questions
Why is tyrosinase inhibition the mechanism forensic chemists look for when investigating illegal skin-lightening cosmetics?+
Confirming that a product's active ingredient binds and blocks the tyrosinase active site, rather than working by some other bleaching mechanism, supports linking detected mercury or banned compound levels to the depigmentation effect the product was marketed for, which matters for labeling and safety enforcement.
Why are mercury-based skin lighteners banned in most jurisdictions despite being effective tyrosinase inhibitors?+
Mercury absorbed through the skin accumulates systemically and is neurotoxic and nephrotoxic, so the depigmentation benefit is outweighed by chronic poisoning risk, which is why regulators test cosmetics for mercury content rather than relying on the manufacturer's ingredient declaration.
Related terms
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