Abstract:

Polysaccharides from Prophyra yezoensis (PYP) were extracted with papain and purified using DEAE
cellulose-52 and Sephadex G-100 chromatography. Four fractions named as PYP-1, PYP-2, PYP-3 and PYP-4 were
obtained, and their physicochemical properties including total sugar content, molecular weight, sulfate and uronic acid
contents and monosaccharide composition were investigated. In addition, RAW264.7 macrophage cell model was employed
to evaluate the immunomodulatory activity in vitro. Results showed that total sugar contents of PYP-2, PYP-3 and PYP-4
were 91.83%, 96.93% and 97.66%, respectively. Uronic acid contents were 19.39%, 23.77% and 18.23%, respectively, and
sulfate group contents were 18.84%, 17.63% and 18.41%, respectively. All these three polysaccharides were composed of
galactose, glucose and xylose with molecular weight of 478.6, 314.4 kD, and 417.3 kD, respectively. Pyranose ring structure
and β-type glycosidic linkages were also found in them. PYP-2, PYP-3, and PYP-4 when used at a concentration ranging
from 25 to 250 μg/mL could significantly promote the proliferation and neutral red phagocytosis of RAW264.7 macrophage
cells in vitro, suggesting the potential immunomodulatory activities of PYP-2, PYP-3, and PYP-4.

Key words: Porphyra yezoensis, polysaccharides, purification, physicochemical properties, immunomodulatory activity