Abstract
The skin color is imparted by the pigment melanin produced in the melanosomes of
melanocytes, through the catalytic action of melanogenesis enzymes tyrosinase,
tyrosinase-related protein 1, and dopachrome tautomerase. Disruptions in the
melanogenesis process may result to hypopigmentation, as observed in cutaneous
postinflammatory conditions. Here, the bioactivity of tara tannin, specifically
on melanogenesis, was evaluated in vitro using human epidermal
melanocytes (HEM) and B16F10 murine melanoma cells in order to determine the
possibility that it may be used as a treatment against hypopigmentation. The
melanin content of tara tannin-treated B16F10 cells and the expression level of
melanogenesis enzymes and melanosome transport proteins were determined. To
elucidate the underlying mechanism of tara tannin’s effect on
melanogenesis, DNA microarray analysis was performed. Tara tannin significantly
increased melanogenesis in both murine and human pigment cell models by
upregulating melanogenesis-associated enzymes’ (tyrosinase,
tyrosinase-related protein 1, and dopachrome tautomerase) protein and mRNA
expression levels, as well as the melanosome transport proteins (myosin Va and
RAB27A) expression, both attributed to increased microphthalmia-associated
transcription factor (MITF) expression. Global gene expression analysis results
revealed the modulation of genes (p≤0.05; fold-change ≥2.0 and
≤−2.0) that are under the transcriptional regulation of MITF and
genes relevant for MAPK signaling, metabolic pathways, and cell cycle. Tara
tannin has a significant effective melanogenesis-promoting effect, making it a
potential therapeutic agent against hypopigmentation disorders. This is the
first report on the melanogenesis regulatory effect of tara tannin in
vitro.
Key words
melanogenesis - tara tannin - melanosome - Microphthalmia-Associated Transcription Factor (MITF)
