Depigmentation efficacy of galacturonic acid through tyrosinase regulation in B16 murine melanoma cells and a three-dimensional human skin equivalent

Sugar is a well‐known cosmetic ingredient for moisturizing skin with minimal side‐effects. Several reports have demonstrated an antimelanogenic effect of sugar in melanocytes. We evaluated the whitening efficacy of galacturonic acid (GA), the main component of pectin, as an anti‐melanogenic agent. GA significantly suppressed melanin synthesis and secretion in a concentration‐dependent manner in α‐melanocyte stimulating hormone‐treated B16 melanoma cells, and inhibited tyrosinase activity and expression at a dose of 10 mmol/L. In a three‐dimensional human skin equivalent (MelanoDerm), GA clearly brightened tissue colour. Haematoxylin and eosin and Fontana–Masson (F&M) staining of tissue sections revealed decreased melanin production without skin tissue collapse in the presence of GA. Interestingly, GA dramatically suppressed gene expression of the melanogenic proteins tyrosinase, tyrosinase‐related protein (TYRP)‐1 and microphthalmia‐associated transcription factor, but not TYRP‐2. The results support the utility of GA as an effective candidate antimelanogenic agent.