Antioxidant Activity and Structural Characterization of a New Polysaccharide Isolated from Stem of Flue-cured Tobacco

Abstract

A new polysaccharides fraction (PSF) was isolated from the extraction of flue-cured tobacco stem with hot water and purified through ethanol precipitation, deproteinization and Sepharose CL-6B column chromatography. Structural features of PSF were elucidated by a combination of FT-IR and GC-MS. The results revealed that PSF was heteropolysaccharide mainly consisted of mannose, arabinose, galactose and glucose. The molecular characteristics of PSF were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The SEC/MALLS analysis revealed that the PSF had an average molecular weight about 3.142 × 104 g/mol with the low polydispersity (Mw/Mn=1.247). The molecular shape of the PSF was a rigid sphere in the aqueous solution. The results of antioxidant assay showed that the PSF significantly scavenged hydroxyl (OH) and DPPH radical in a concentration-dependent manner. The results reveal that PSF is a useful antioxidant and might be available for relevant industrial application.