Rhamnetin is a naturally occurring polyphenolic compound. In this report, experimental evidence is presented on the suppression of melanogenesis by rhamnetin using B16 murine melanoma cells (B16 cells). To document the underlying anti-melanogenic action of rhamnetin, several key biochemical mediators were quantified: superoxide (O
2•−), nitric oxide (·NO) and peroxynitrite (ONOO
−)
in vitro, and total reactive species (RS) generation, O
2•−, ·NO and ONOO
−, reduced glutathione (GSH)/GSH-to-oxidized glutathione (GSSG) ratio, prostaglandin E
2 (PGE
2) and thromboxane B
2 (TXB
2) in B16 cells. Results revealed that rhamnetin inhibited murine tyrosinase activity, suppressed melanin content and oxidative stress, reducing O
2•−,·NO and ONOO
− in vitro and total RS generation, O
2•−, ·NO and ONOO
− in B16 cells, while maintaining a well-balanced GSH/GSSG ratio in B16 cells. Results further revealed that rhamnetin suppressed key pro-inflammatory mediators such as PGE
2 and TXB
2. Thus, these results strongly indicate that rhamnetin has powerful anti-melanogenic properties through its anti-oxidative and anti-inflammatory actions.
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