Oxyresveratrol from mulberry (Morus alba L.) ameliorates post-inflammatory hyperpigmentation in vitro by anti-melanogenesis, inhibiting melanosome transfer, and providing photoprotection

Abstract

Mulberry (Morus alba L.) twigs are a traditional Chinese medicine and edible agricultural by-product. Oxyresveratrol (OXY) is one of the natural resorcinol-type polyphenols obtained from mulberry twigs with anti-melanogenesis effects. This study aimed to investigate the ameliorative effects and mechanisms of OXY on post-inflammatory hyperpigmentation (PIH) in vitro. The results of DPPH radical scavenging and tyrosinase inhibition assays showed that OXY exhibited potent antioxidant and tyrosinase inhibitory activities. In human melanocytes, OXY significantly down-regulated protein expression related to melanin synthesis and transport. A molecular docking study suggested that OXY could inhibit these GTPases (RAB27A, RAC1, and CDC42) activities in melanosome transfer processes. Furthermore, OXY significantly reduced inflammatory factor secretion, promoted human β-defensin production, and up-regulated the expression of barrier proteins in UVB-induced human keratinocytes. This research indicated that the OXY from mulberry twigs has potential applications in ameliorating PIH through its antioxidant, anti-melanogenic, melanosome transport inhibition, anti-inflammatory, and photoprotective properties.

Keywords

• Oxyresveratrol
• Mulberry twig
• Post‐inflammatory hyperpigmentation
• Melanogenesis
• Melanin transport
• Skin barrier