Sequential extraction, characterization and antioxidant activity of polysaccharides from Fritillaria pallidiflora Schrenk

In this paper, Fritillaria pallidiflora schrenk polysaccharides were extracted with different methods and isolated by anion-exchange and gel-permeation chromatography. Physicochemical properties, structural characteristics and antioxidant activities were investigated for the first time. The polysaccharides composed of glucose, galactose, arabinose, xylose, mannose and rhamnose with different molar ratio and molecular weight. Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis exhibited the presence of key functional groups of polysaccharides whereas scanning electron microscopy analysis revealed the characteristic morphology of different fractions. The thermogravimetric analysis manifested the thermal stability of polysaccharides. The reducing power and antioxidant activities of polysaccharides were evaluated in vitro. Among them, the acidic fraction FPSP-H2-1 has a strong antioxidant effect against DPPH, hydroxyl and ABTS free radicals. The results revealed the polysaccharide's important role as potential natural antioxidant agents during the investigation and application of bioactive polysaccharide.