Water-Soluble Polysaccharides from Leaves of Abelmoschus esculentus: Purification, Characterization, and Antioxidant Activity

Two water-soluble polysaccharides were obtained from the leaves of Abelmoschus esculentus using aqueous extraction and purification with DEAE-52 and Sephadex G-100. AEP-11 (1.9 × 105 Da) consisted of D-arabinose, D-xylose, D-glucose, D-mannose, and D-galactose in a 2.9:3.1:0.3:0.4:3.4 ratio. AEP-22 (1.6 × 106 Da) consisted of D-arabinose, xylose, D-mannose, and galactose in a 4.7:0.8:0.6:3.9 ratio. AFM and Congo red indicated that the enhanced flexibilities of AEP-11 and AEP-22 chains could lead to agglomerated morphologies and may further confirm random coils instead of triple helical conformations. CD revealed the presence of disordered structure in AEP-22 compared with the ordered structure in AEP-11. In antioxidant activity assay, AEP, AEP-11, and AEP-22 all exhibited strong radical-scavenging capacities (AEP > AEP-11 > AEP-22) and obvious reducing power.