Inhibitory effects of phenylethanoid glycosides on melanin synthesis in cultured human epidermal melanocytes

Objective: To investigate the inhibitory effects of phenylethanoid glycosides (PhGs) derived from cistanche on melanogenesis in cultured human epidermal melanocytes, and explore the structure-activity relationship through comparison of the inhibitory effect of ten kinds of PhGs. Methods: L-dopa assay was performed to examine the effect of PhGs on tyrosinase activity. Alkaline lysis method was used to detect the content of melanin in cultured human epidermal melanocytes after treated with ten kinds of PhGs. Results: PhGs reduced tyrosinase activity in a dose-depend manner. The content of melanin was reduced by PhGs. Compared with the positive control, significant elevation was noticed in the inhibitory effect of poliumoside, 2’-acetylacteoside, acteoside, oleuropein and calceolarioside B (P < 0.01), respectively. On the contrary, the inhibitory effects of forsythoside A/B was relatively weaker compared with positive control group (P < 0.01). Conclusions: PhGs exhibit significantly inhibitory effect on melanogenesis in human epidermal melanocytes. The suppression ability is related to the number of phenolic hydroxyl and aglycone, steric hindrance, substituents on the middle glucopyranose, and the location of phenolic hydroxyl.