Extraction, characterization and antioxidant activity evaluation of polysaccharides from Smilacina japonica

Three polysaccharides of uniform molecular weight designated as SJP1-1, SJP2-1, and SJP3-1 from Smilacina japonica were studied in this paper. Respectively, their specific optical rotations were −45°, −75°, and −35°, their polysaccharide contents were 89.22%, 93.05%, and 59.83%, their relative average molecular weights were 1.87 × 105 Da, 1.04 × 105 Da, and 1.36 × 104 Da. Three polysaccharides were all composed mainly of the three monosaccharides mannose, glucose, and galactose, which together in SJP1–1, SJP2–1, and SJP3–1 respectively made up 96.34%, 98.23%, and 91.67% of the total polysaccharide. The polysaccharide structure was maintained mostly by β-glucose (1 → 3), β-glucose (1 → 4), α-mannose (1 → 3), and α-galactose (1 → 4) glycosidic linkages. Scanning electron microscopy showed that SJP1–1, SJP2–1, and SJP3–1 were smooth uniform microspheres with diameters of 10–20 μm that combined to form both uniformly dispersed particles and blocky structures. Finally, antioxidant assay showed that these polysaccharides all had a strong ability to scavenge ·OH and DPPH· radicals, with the effects of purified polysaccharides being greater than those of crude polysaccharides. This first report on the properties of these polysaccharides provides a basis for further studies to shed light on the medical properties of Smilacina japonica.