The extraction process, purification and characterization analyses of polysaccharides (LZJP) in Ziziphus jujuba planted in Linze County, Gansu Province were investigated, respectively. The results showed a maximum polysaccharide yield of 5.72% was achieved at a solid/liquid ratio of 1:20 g/mL for 90 min at 80 °C. Two homogenous acidic polysaccharides (LZJP3 and LZJP4) were purified successively by DEAE-52 cellulose and Sephadex G-100 column chromatography. LZJP3 is composed of one polymer with galactose while LZJP4 is made up of two different kinds of polymers with xylose and glucose by size-exclusion chromatograph combined with multi-angle laser photometer (HPSEC-LLS) and gas chromatography (GC) analysis. LZJP3 and LZJP4 were β-pyran polysaccharides with a large number of molecular globular aggregates by FT-IR (Fourier-transform infrared) and AFM (Atomic force microscopy) analysis, and the surface morphology exhibited smooth and filamentous staggered extension in the form of rod-like aggregation with SEM (Scanning electron microscopy) determination. Meanwhile, LZJP3 and LZJP4 exhibited antioxidant activities against DPPH, hydroxyl radical, hydrogen peroxide, superoxide radical and stronger reducing power in vitro with the concentration increasing. The results indicated that LZJPs were worthy of being developed further as a natural antioxidant in food and medicine industries.
Keywords: Antioxidant activity; Physicochemical characteristics; Response surface methodology; Zizyphus jujuba cv. Linzexiaozao.
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