Structural properties and bioactivities of pectic polysaccharides isolated from soybean hulls
Hong Song, Lin Han, Zunqing Zhang, Yixue Li, Lina Yang, Danshi Zhu, Shengnan Wang, Yutang He, He Liu
Abstract
The purpose of this study was to investigate the structural characteristic and its antioxidant of a pectic polysaccharide (ASP-3A) extracted and purified from soybean hulls. Results of structural and morphological characterization according to high-performance gel-permeation chromatography, methylation analysis and nuclear magnetic resonance spectroscopy etc. showed that ASP-3A was composed of rhamnose, galactose, galacturonic acid, arabinose, xylose, glucuronic acid, glucose, mannose, and glucosamine hydrochloride with molar ratios of 1.000 : 0.745: 0.570 : 0.189: 0.135 : 0.098: 0.036 : 0.036: 0.008. ASP-3A was mainly consisted of 4)-α-D-GalAp-(1→ and β-D-Glap-(1 → 4)-α-L-Rha-(1→, with branch consisting principally of α-L-Araf-(1 → 5)-α-L-Araf-(1→, which suggested that ASP-3A was a pectin polysaccharide including homogalacturonan (HG) and rhamnogalacturonan I (RG-I) domain. ASP-3A exhibited dose-dependent antioxidant activities in superoxide anion radical, hydroxy radical, ABTS•+ and DPPH• scavenging assays with SC50 values of 1.083 ± 0.060, 2.507 ± 0.387, 1.677 ± 0.027 and 1.325 ± 0.002 mg/mL, respectively. ASP-3A alleviated oxidative stress induced by CCl4 through enhancing antioxidant capacity of hepatocytes via NRF2/ARE pathway. This study provides information useful for screening natural polysaccharide-based antioxidants in soybean hulls.