Lycium barbarum polysaccharide inhibits UVA-induced melanin production by inhibiting α-MSH expression

Abstract

Objective To investigate the effect of lycium barbarum polysaccharide (LBP) on UVA-induced melanogenesis. Methods HaCaT cells and HEM cells were treated with different concentrations of LBP (0, 20, 50, 100, 200, 300, 400, 500 μg/mL). CCK8 assay was performed to assess cell proliferation, in order to obtain the most suitable concentration of LBP for subsequent study. HaCaT cells and HEM cells were treated with 300 μg/mL of LBP and (or) 20 μM N-1A after irradiation with 30 J/cm2 UVA. Tyrosinase activity was determined by L-dopa oxidation method and melanin content by NaOH analysis method. The intracellular α-MSH protein expression was measured by enzyme-linked immunosorbent assay (ELISA), and the expression levels of cellular melanogenesis-related proteins, including MITF, tyrosinase, TRP1 and TRP2, were determined by Western blot. Results Based on the results of CCK8 assay, the most suitable concentration of LBP was 300 μg/mL. Compared with UVA group, LBP significantly inhibited UVA-induced cellular tyrosinase activity (t=33.19, P=0.001) and melanin production (t=7.13, P=0.019). The ELISA results suggested that UVA irradiation promoted α-MSH protein secretion in HaCaT cells and HEM cells (t=-3.79、-3.41, P=0.043、0.046), and LBP inhibited expression levels of α-MSH protein in HaCaT cells and HEM cells (t=3.75、3.41, P=0.044、0.048). The Western blot results showed that LBP significantly downregulated the expression of the melanogenesis-related proteins, including MITF, tyrosinase, TRP1, and TRP2 induced by UVA. Conclusion LBP significantly inhibits UVA-induced melanogenesis, via regulating expression levels of α-MSH protein in HaCaT cells and HEM cells.

Keywords

• lycium barbarum polysaccharide
• ultraviolet light a
• α-msh
• melanin