Extraction, structural characterization and antioxidant activity of turmeric polysaccharides

This study investigated the extraction, structure and antioxidant activity of turmeric polysaccharides (TPs). A crude polysaccharide yield of 2.23 g/100 g was extracted by the hot water method. Four polysaccharide fractions (TPs-0, TPs-1, TPs-2, and TPs-3) with different molecular weights were purified by anion-exchange chromatography. Glucose, galactose and arabinose were the main polysaccharide components of TPs-0 and TPs-1, whereas TPs-2 and TPs-3 were primarily composed of rhamnose, glucose, galactose, arabinose, xylose, galacturonic acid and glucuronic acid. TPs-0 was further investigated using methylation, GC-MS and NMR, the results showed that TPs-0 comprised a main chain of α-Araf- (1 → 4) -α-Glcp- (1 → 3) -α-Arap- (1 → 3) -β-Galp- (1 → 3,6) -α-Galp- (1 → 5) -α-Araf- (1 → 3) -β-Galp- (1→R. Scanning electron microscopy analysis revealed that the characteristic morphology of different fractions. Furthermore, assays of antioxidant activity showed that any one of TPs had antioxidant effects against DPPH radical, ABTS radical cation, hydroxyl radical, among which TPS-2 was stronger. In general, the results demonstrated that TPs had great potential as a natural antioxidant in the functional food.