Structural characterization and bioactivities of a glucomannan-based polysaccharide (AGP-1) from Arundina graminifolia

• Extraction condition of Arundina graminifolia polysaccharide was optimized by RSM. • AGP-1 was mainly composed of mannose, glucose and galactose with Mw of 494.3 kDa. • AGP-1 revealed excellent ABTS scavenging capacity and α-glucosidase inhibitory effect. This work aims to explore and characterize the functional polysaccharide of Arundina graminifolia . The extraction process of the crude Arundina graminifolia polysaccharides (AGP) was optimized using response surface methodology (RSM). The maximum yield of AGP reached 10.2 % under the optimal conditions of extracting 84.7 min at 96.0 °C, and liquid-material ratio of 27.5 mL/g. Meanwhile, AGP-1, the purified polysaccharide, was obtained using DEAE-Cellulose52 and Sephadex G-200 chromatography, and its structure was analyzed and confirmed by multiple chromatographic and spectroscopic techniques. It was indicated that AGP-1 (Mw 494.3 kDa) was a glucomannan-based polysaccharide mainly consisted of mannose, glucose and galactose at a molar ratio of 10:7:1, and its structure skeleton contained glycosyl residues of Glc p -(1→, →4)-Man p -(1→, →4)-Glc p -(1→, →3,4)-Gal p -(1→ and →4,6)-Gal p -(1→. Distinct from the β-1,4 glycosidic linkage bonds of other glucomannans, AGP-1 was infrequently linked by α-1,4 glycosidic bonds between monosaccharides of mannose and glucose with a specific molar ratio of 3:2. Furthermore, it was found that AGP-1 exhibited strong DPPH, ABTS, and hydroxyl radicals scavenging abilities, along with excellent inhibition of α-glucosidase activity in vitro. Our finding indicated that AGP-1 possessed a potential as natural antioxidant and hypoglycemic product.