Structural characteristics and antioxidant activity of a low-molecular-weight jujube polysaccharide by ultrasound assisted metal-free Fenton reaction
Yingying Liu, Meng Yan, Hong Ji, Jianhang Guo, Miaomiao Shi, Feiliao Lai, Xiaolong Ji
Abstract
This study used an ultrasonically accelerated metal-free Fenton (H 2 O 2 -V c system) reaction to promote water-extracted degrading polysaccharides from Ziziphus Jujuba cv. Muzao (DZMP). A novel jujube polysaccharide (DPZMP3) was obtained by degradation using DEAE-Sepharose Fast Flow and Sephacryl S-100 column chromatography. Methylation analysis, HPGPC, ion chromatography, FT-IR, and NMR spectroscopies were used to clarify the chemical structures of DPZMP3. Monosaccharide compositional analysis of DPZMP3 revealed the presence of Rha, Ara, Gal, and GalA at a molar ratio of 1.00:1.49:1.60:7.68, and the HPGPC data demonstrated the average Mw of 34.3 kDa. Based on the structural and linkage research using NMR spectroscopy and GC–MS, it was determined that DPZMP3 was a homogalacturonan pectic polysaccharide with a (1 → 4)-Gal p branch at C-6 and a small amount of Ara f and Rha p residues. The ultrasonic-aided Fenton treatment did not significantly alter the structure of DPZMP3. It may also be useful for DZMP and enhancing their antioxidant activity in vitro . The current study's findings could pave the way for the food sector to use jujube polysaccharides obtained by degradation as a functional food component. • DPZMP3 was obtained by degradation via ultrasound assisted Fenton reaction. • The structures were characterized by IC, HPGPC, FT-IR, GC–MS, and NMR. • The functional groups and backbone structure did not undergo significant changes. • Ultrasound-assisted H 2 O 2 -Vc degradation enhanced the antioxidant activity of DPZMP3.