Tara Tannin Regulates Pigmentation by Modulating Melanogenesis Enzymes and Melanosome Transport Proteins Expression

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.