Molecular characteristics of partially hydrolyzed fucoidans from sporophyll of Undaria Pinnatifida and their in vitro anticancer activity

Abstract

The effects of molecular characteristics on the anticancer activity of fucoidans were investigated after hydrolysis by copper acetate and then fractionation with 30 and 5kDa membranes, which produced three fucoidan fractions: F >₃₀K, F ₅₋₃₀K and F <5K. The F >30K and F 5-30K consisted of mostly carbohydrate (58.2-61.3%) and sulphate (31.7-35.5%) with small amounts of proteins (1.2-6.4%). However, the major constituents of F <5K were sulphate (31.8%) and ash (37.5%) with smaller amounts of carbohydrate (15.5%) and protein (1.2%). The molecular weights (M w) of F >30K, F 5-30K and F <5K, obtained by a light scattering technique, were 262, 5.6 and 1.6kDa, respectively. The observed anticancer activities were 18.0-28.5% for F >30K, 19.2-57.5% for F 5-30K and 26.5-36.5% for F <5K, respectively, in the concentration range of 0.2-0.8mg/mL. The results suggest that the anticancer activity of fucoidans could be considerably improved by lowering their M w and by improving the binding properties of sulphate groups possibly through changing the molecular conformation.