Asian J Beauty Cosmetol. 2007; 5(2): 239-246.
The Inhibition Effect of L-cysteine on Melanogenesis
in B16F10 Mouse Melanoma Cells
ABSTRACT
Pigmented skin disorders, including melasma, freckles and post-inflammatory hyperpigmentation,
are one of the commonest reasons for peoples and patients seeking various skin care shops and
dermatology consultation. Melanocytic cells can produce two types of pigment, pheomelanin and eumelanin,
in their specialized intracellular organelles termed melanosomes. Steps of melanin biosynthesis
catalyzed by tyrosinease, a key enzyme of melanogenesis, are common to eumelanogenesis
and pheomelanogenesis. In addition to tyrosinase, two more enzymes,tyrosinase-related protein 1
(TYRP1) and dopachrome tautomerase (DCT), are known to be involved in eumelanogenesis and/or
pheomelanogenesis. It has been reported that thiol compounds, such as cysteine and glutathione, result
in decreasing pigmentation by favoring to the pheomelanogenesis and bringing down synthesis
of eumelanin. However its mechanisms are poorly understood. In the present study, the effect of
L-cysteine on melanogenesis and expression of tyrosinase and its related proteins was examined in
a B16F10 mouse melanoma cell line model system. Cytotoxicity of L-cysteine when co-treated with
α-MSH and arbutin in B16F10 mouse melanoma cells were tested. Within a concentration range of
L-cysteine showing no cytotoxicity effects, it decreased the amount of melanin and activity of tyrosinase
in cells treated with α-MSH in a dose dependent manner. In addition, L-cysteine decreased
levels of protein expression of tyrosinase, but not either of TYRP1 or DCT in these cells. Treatment
of L-cysteine resulted in diminishing dendrite of B16F10 mouse melanoma cells. Collectively these
data show that L-cysteine has a inhibitory effect on melanin synthesis and tyrosinase activity by
down-regulation of tyrosinase protein in B16F10 mouse melanoma cells. It implies that L-cysteine
may be a good ingredient candidate for developing whiting effect cosmetic products or drugs for
hyperpigmentary disorders.
Keywords :
L-cysteine, Melanogenesis, B16F10, Tyrosinase, Hyperpigmentation
