Study on inhibition effect of Sargassum fusiforme polysaccharide extracts on activity of tyrosinase

Objective:To study the inhibitory effect of the Sargassum fusiforme polysaccharide (SFPS) extracts on the activity of tyrosinase for diphenolase.Methods:Extract SFPS and measure the content of polysaccharide.To investigate the effect of SFPS extracts on the diphenolase activity, the absorbance of the solution containing several concentrations of the SFPS extracts was measured at 475nm, using the L-DOPA as the substrate.Endogenous fluorescence and ANS-binding fluorescence of tyrosinase were tested with different concentrations of SFPS.Results:SFPS could obviously inhibit the activity of tyrosinase for diphenolsae.The inhibitory concentration leading to 50% activity lost (IC 50) was estimated to be (2.16±0.37) mg/mL.The results showed that SFPS was a reversible inhibitor of mushroom tyrosinase.Lineweaver-Burk plots indicated that SFPS was a mixed-type inhibitor, and its inhibition constant K_i were (4.34±0.56) mg/mL.Endogenous fluorescence and ANSbinding fluorescence test of tyrosinase indicated that SFPS combined with the tyrosinase caused significant changes in the structure.Conclusion:SFPS combined with the tyrosinase caused significant changes in the structure and reversible inhibited the activity of tyrosinase for diphenolsae in a mixed-type manner.Together these results provided a scientific basis for the design and development of new inhibitors in the future.