| Okra is favored by the vast number of consumers,widely cultivated,and rich in resources.In this study,okra was used as raw materials,studying on optimization of okra polysaccharide extraction,and the crude polysaccharides were isolated and purified,and the structural characterisation,physicochemical properties and anti fatigue activity of polysaccharides were investigated.The main results are as follows:the extraction process of polysaccharides from okra was established and optimized by response surface methodology.The results suggested that the optimal extraction conditions were extraction time of 2.75 h,extraction temperature of 90? and pH of 2.1.Under the above optimized conditions,the yield of polysaccharides was 29.77%.The crude polysaccharide was isolated and purified by DEAE-52 cellulose chromatography.AEP-1 obtained by eluting with distilled water and AEP-2 obtained by eluting with 0.3 mol/L NaCl.AEP-1 is white flocculent solids,and AEP-2 is flaxen flocculent solids,both of them are soluble in water,insoluble in high concentrations of ethanol and other organic solvents;And do not contain starch,phenols,protein or nucleic acid,but the content of uronic acid is high.And the infrared spectra determined that they are two polysaccharides with pyran structure;HPLC analysis showed that AEP-1 and AEP-2 are polysaccharides were relatively homogeneous,and the molecular weight AEP-1 is 5×103 Da,the molecular weight of AEP-2 is 2×106 Da;AEP-1 is mainly composed of 6 kinds of monosaccharides: rhamnose,mannose,glucuronic acid,galacturonic acid,glucose and arabinose,the proportion is 1.0?0.9?3.5?3.5?11.7?1.0;AEP-2 is mainly composed of 5 kinds of monosaccharides: mannose,rhamnose,galactose,glucose and galactose,the proportion is 1.0?8.0?3.2?1.2?15.0.Based on the combination of methylation and GC-MS instrumental analysis,the bond types of two components were analyzed: Detection of 8 residues in AEP-1,and they are T-Glcp1?,?4-Glcp1?,?3-Galp1?,?6-Glcp1?,?4-Galp1?,?2,4-Manp1?,?2-Araf1???2,4-Rhap1?;Detection of 8 residues in AEP-2,and they are?3,6-Galp1?,?2-Rhap1?,T-Galp1?,T-Glcp1?,?6-Glcp1?,?4-Galp1?,?2,4-Manp1???2,4-Rhap1?.The anti-fatigue activity of polysaccharides from okra were studied by animal experiments.There is no significant effect on body weight of mice by feeding okra polysaccharides.And okra polysaccharides improved the swimming ability of mice(8.1-148.2%),retarding the accumulation of BLA(12.9%-40.0%)and SUN(6.6%-24.5%),and enhancing liver glycogen levels(25.6%-102.4%).In addition,the effects appeared to be dose-related.On the whole,the anti fatigue activity of AEP-1 is stronger than that of AEP-2,significantly better than the crude polysaccharides,AEP-1 and AEP-2 may be the main active anti-fatigue functional substance of okra polysaccharides in substance.The reason for the stronger anti fatigue activity of AEP-1 is that the molecular weight is small,which is beneficial for the body to absorb or take effect in the body,and uronic acid has obvious effect on fatigue function. |
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