Melanogenesis inhibitory effect of low molecular weight fucoidan from <Emphasis Type="Italic">Undaria pinnatifida</Emphasis>

In this study, fucoidans with different molecular weight that were isolated from the brown alga Undaria pinnatifida (Phaeophyceae, Laminariales) were investigated for their ability to inhibit melanogenesis and scavenge superoxide and hydroxyl radicals. Fucoidan samples with low molecular weights of 89, 35, 17, and 6 kDa were prepared by radiation-degradation of a 378 kDa fucoidan isolated from U. pinnatifida. The inhibitory activity of fucoidan against melanin biosynthesis in B16BL6 melanoma cells was enhanced for low molecular weight samples. To investigate the increase in melanogenesis inhibition exhibited by the low molecular weight fucoidan, tyrosinase inhibition activity and radical scavenging activities were measured. There was an increase in the tyrosinase inhibition activity for low molecular weight samples. Additionally, the radical scavenging activity was increased for lower molecular weight fucoidans. These results suggest that low molecular weight fucoidans from seaweeds may have beneficial biological properties.