Optimization of Enzyme-assisted Extraction and Ethanol Precipitation for Buckwheat Bee Pollen Crude Polysaccharides and their Antioxidant Activity Analysis
This study focused on the extraction of polysaccharides from buckwheat bee pollen using a composite enzyme-assisted extraction method followed by ethanol precipitation.The Box-behnken response surface methodology was employed to optimize the extraction process,and the obtained crude polysaccharides were subjected to structural identification and anti-oxidant activity analysis.The results showed that the highest extraction yeid(30.74±0.23)％was achieved using 75％ethanol at 39 ℃ when adding pectinase 0.02％,cellulase 0.03％and neutral protease 1.0％,respectively.The structure of polysaccharide was characterized by infrared spectrum,ultraviolet spectrum and high performance liquid chromatography.By infrared spectroscopy and ultraviolet light analysis,the crude polysaccharide has obvious polysaccharide characteristic abs-orption peak,and did not contain nucleic acid and protein.HPLC analysis revealed that the crude polysaccharide of buck-wheat bee pollen was mainly composed of Glc,its content was as high as 54.74％,and contained a small amount of Man,rhamnose,GlcN,GlcUA,Gal,Fuc;the monosaccharide content ratio was Man∶rhamnose∶GlcN∶GlcUA∶Glc∶Gal∶Fuc was 1.472∶1.723∶0.119∶0.129∶54.740∶11.458∶0.490.Antioxidant activity assessments of the buckwheat bee pollen crude polysaccharide showed significantly improved scavenging capabilities(p＜0.01)compared to positive controls,including buckwheat flour polysaccharides and shiitake mushroom polysaccharides,with IC50 values of(0.636±0.005)mg/mL for O2-·scavenging effect,(1.678±0.006)mg/mL for ABTS+scavenging effect,(0.734±0.003)mg/mL for DPPH free radical scavenging effect,(0.527±0.004)mg/mL for hydroxyl free radical(·OH)clearance,which was significantly better than that of buckwheat flour polysaccharide and lentinus mushroom polysaccharide(p＜0.01).
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