Antioxidant Activities Of Polysaccharide Fractions With Different Molecular Masses Extracted From Dendrobium Huoshanense

Total polysaccharides(ST) from the seedlings of Dendrobium huoshanense C.Z.Tang et S.J.Cheng.was dissolved in deionised water and then continuously deposited by ethanol with final concentrations of 40%,50%,60%and 80%to obtain different polysaccharides fractions of S1,S2,S3 and S4.The average molecular weight,monosaccharide components and structure information were determined by HPLC,GC-MS and FT-IR,respectively. Total polysaccharide and four fractions were evaluated on their antioxidant activities in vitro.Fractions of S1 and S4 showed good potential for scavenging DPPH,ABTS,·OH, H₂O₂ and NO,inhibiting lipid peroxidation,reducing power and DNA damage.The average molecular weight distributions of S1,S2,S3,S4 and ST were 316,168 Da,307,411 Da,85,892 Da,252,189 Da and 479,352 Da,respectively.According to GC-MS analysis, the total polysaccharides and its fractions were all composed of glucose(Glu),galactose (Gal),mannose(Man) and arabinose(Ara),of which the molar ratio was 100.0:21.0:613:16.7 for S1,100.0:22.2:5.6:6.3 for S2,100.0:21.0:16.4:12.2 for S3, 100.0:11.5:59.8:30.3 for S4 and 100.0:31.7:28.5:17.9 for ST.The uronic acid contents evaluated in the five different polysaccharide fractions ranged from 1%to 4.5%.The figure of IR revealedβ-configurations existing in different polysaccharide fractions.These results indicated that the antioxidant abilities of different polysaccharide fractions might be related to the molecular weight and structural information.Moreover,S1 and S4 might be exploited as potential antioxidants of natural bioactive macromolecules...