Anti-melanogenenic and anti-inflammatory effect of Hibiscus syriacus anthocyanin-rich extracts

Abstract

Hibiscus syriacus is the national flower of South Korea and grows in a wide climatic range from mild to tropical temperature. The bark and roots of H. syriacus have been used to cure diarrhea and bacterial infection, and its seed are effective to fever and cold. Recently, native flowers of H. syriacus possesses promising potential as a new edible source and colorants with various anthocyanins. However, the function of anthocyanins isolated from H. syriacus has been determined. In the current study, we, for the first time, evaluated whether H. syriacus varieties, Pulsae and Paetanshim, anthocyanin-rich extract (PS and PTS, respectively) inhibits melanin biogenesis. Our results showed that PS and PTS did not strongly downregulate mushroom tyrosinase activity in vitro; but significantly decreased the extracellular and intracellular melanin production in B16F10 cells accompanied by the inhibition of α-melanocyte-stimulating hormone (α-MSH)-induced microphthalmia-associated transcription factor (MITF) and tyrosinase expression. We also found that PS and PTS attenuated pigmentation in α-MSH-stimulated zebrafish larva without any severe toxicity. Furthermore, PS and PTS activated the phosphorylation of extracellular signal-regulated kinase (ERK) and a specific ERK inhibitor, PD98059, resulted in the recovery of intracellular and extracellular melanin downregulation induced by PS and PTS in B16F10 cells and of melanogenesis in zebrafish larvae. PS and PTS possess 17 specific anthocyanins, which mostly target dual specificity protein phosphastase 7 (DUSP7) according to molecular docking prediction. These findings suggest that anthocyanins from PS and PTS inhibit melanogenesis in vitro and in vivo by activating the ERK signaling pathway.