Topical skin-lightening agents used for the treatment of melasma

Agent	Mechanism of action
Hydroquinone	Tyrosinase inhibition
Azelaic acid	Tyrosinase inhibition
Kojic acid	Tyrosinase inhibition
Ascorbic acid	Inhibition of reactive oxygen species
Retinoids	Downregulation of tyrosinase, increased epidermal turnover
Corticosteroids	Anti-inflammatory and nonselective inhibition of melanogenesis
Niacinamide (nicotinamide)	Inhibition of melanosome transfer
Licorice extract	Melanin dispersion, tyrosinase inhibition
Undecylenoyl phenylalanine	Antagonist of alpha-melanocyte-stimulating hormone, beta-adrenergic, stem cell receptors
4-N-butylresorcinol	Tyrosinase inhibition, antioxidant, anti-inflammatory
Soy	Inhibits melanosome transfer to keratinocytes
Arbutin	Tyrosinase inhibition
Glucosamine	Inhibition of tyrosinase activation
Mequinol	Tyrosinase inhibition
Cysteamine	Radio protector (via direct scavenging effects of hydroxy radicals), tyrosinase peroxidase inhibition
Deoxyarbutin	Tyrosinase inhibition
Flutamide	Blocks action of endogenous/exogenous testosterone by binding to androgen receptor
N-acetylglucosamine	Inhibition of tyrosinase glycosylation
Methimazole	Potent peroxidase inhibitor, blocks melanin synthesis
Aleosin	Tyrosinase inhibition

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