Separation, preliminary characterization, and moisture-preserving activity of polysaccharides from Ulva fasciata

Sulfated polysaccharide (UFP(31)) extracted from the marine algae Ulva fasciata (UFP) was a heteropolysaccharide, and consisted of rhamnose, xylose, and glucose in a ratio of 1:0.46:0.27 with a (1 → 4)-linked glycosyl backbone. The rheology of UFP(31) solution has been investigated by steady shear and small amplitude oscillatory experiments. The effects of concentration, temperature, and time were systematically investigated. Steady-shear rheological measurement in a range of shear rate (1-1000 s(-1)) exhibited that UFP(31) has a Newtonian behavior in diluted solutions (1.0%, 3.0%, and 5.0%, w/v), dilatant flow behavior at higher concentrations (7.0% and 9.0%, w/v). Specifically, UFP(31) solution (7%, w/v) exhibited antithixotropic behavior. In small amplitude oscillatory experiments, both the storage modulus (G') and the loss modulus (G") of UFP(31) solution (7%, w/v) increased with frequency swept but G' increased more quickly. As a consequence, G' tends to overcome G" at 2.7 Hz. The capability of moisture-absorption and moisture-retention of the polysaccharide was also respectively examined gravimetrically in comparison with those of glycerol. It revealed that UFP(31) exhibited a higher ability both in the moisture-absorption and moisture-retention test throughout the entire experiment. These results clearly establish the possibility that UFP(31) could be employed as a new material of nature moisturizer.