Structural Insight and in vitro Free Radical Scavenging Capacity of Arabinogalactan Polysaccharides from the Peels of Punica granatum

The juice extracted from Punica granatum L. fruit has been used for ages as an important functionalfood that can endow with healthcare benefits besides fundamental nutritional food that we intake.Although demonstration of antioxidant activity has been shown here, the target molecule responsiblefor this phenomenon remains unidentified. In this present work, we report a structural insight andantioxidant activity of its polysaccharide (PF-1), purified from water extract (WE) by precipitationwith ethanol, ethanol soluble fraction (PF-2) and acetone extracted fraction (PF-3). The purifiedpolysaccharide (PF-1) contains mainly arabinose, galactose together with lesser amount of rhamnoseand glucose residues, and the molecular mass was determined 180 kDa. This fraction consists ofT-(1,5)- and (1,3,5)-linked Araf; T-(1,6)- and (1,3,6)-linked Galp alongside (1,2,4)-linked Rhap residues.The glucan is found to be β-(1→3)-linked glucopyranosyl residues with a molecular mass of 9 kDa.The in vitro antioxidant activity of the active fractions was determined by using1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), hydroxyl radicalscavenging and total antioxidant activity (TAA) assays. The arabinogalactan showed the highestpotential among the polysaccharides. This work involves an economically viable simple extractionmethod and reports promising antioxidant capacity. The studies suggest that this polysaccharide fromPunica granatum L. fruit could be a natural antioxidant.