Purification and analysis of the composition and antioxidant activity of polysaccharides from Helicteres angustifolia L.

The antioxidant activity of polysaccharides has attracted tremendous research interest in recent years. In this study, we aimed to investigate the antioxidant properties of Helicteres angustifolia L. polysaccharides (HALP) that was acquired by water extraction and alcohol precipitation using ultrasound-assisted method with decolorization and protein removal. The polysaccharides were then successively purified using chromatography on DEAE-cellulose and Sephadex S-300 columns with two major fractions: HALPs1-1 and HALPs2-1. The physicochemical properties, structural characterization, and antioxidant activities of these fractions were investigated. The results indicated that HALPs1-1 was a glucan with an average molecular weight of 151.70 kDa, and HALPs2-1 was composed of glucuronic acid with an average molecular weight of 114.81 kDa. Infrared spectroscopies and iodine potassium iodide tests showed that the HALP were acid α-pyranoses. The antioxidant activities of the polysaccharide fractions (HALP, HALPs1-1, and HALPs2-1) were evaluated in vitro. The results suggested that HALPs2-1 had the highest scavenging activities for ABTS, hydroxyl and DPPH radicals than other polysaccharides. Taken together, the results of this study suggested that polysaccharides from Helicteres angustifolia L. could be used as novel potential antioxidants.