An alkali-extracted polysaccharide from Zizyphus jujuba cv. Muzao: Structural characterizations and antioxidant activities

An acidic polysaccharide (SAZMP3) was isolated from jujube fruit residues by alkaline extraction and purified with DEAE-Sepharose Fast Flow and Sephacryl S-300 column chromatography. The structural characterizations of SAZMP3 were determined by high-performance gelpermeation chromatography, gas chromatography, Fourier transform infrared spectroscopy, methylation analysis, NMR spectroscopy, scanning electron microscopy, and atomic force microscopy. The results determined SAZMP3 was an acidic polysaccharide mainly contained rhamnose, galactose, and galacturonic acid with a molecular weight of 9.37 kDa and its backbone might mainly be composed of 1,4-α-D-GalAp with side chains of 1,3-β-D-Galp, 1,3,5-linked Araf, 1,2,4-α-L-Rhap and terminals of 1-linked Araf, 1-linked Rhap, 1-linked Galp by methylation and NMR analysis. Besides, SAZMP3 has shown potential antioxidant activity in scavenging free radicals suggesting that it is an antioxidant agent, which might contribute to the functional food qualities of jujube fruit.