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Novel polysaccharide from Chaenomeles speciosa seeds: Structural characterization, α-amylase and α-glucosidase inhibitory activity evaluation

Deng, Yejun, Huang, Lixin, Zhang, Caihong, Xie, Pujun, Cheng, Jiang, Wang, Xiang, Liu, Lujie
International journal of biological macromolecules 2020 v.153 pp. 755-766
Chaenomeles speciosa, Fourier transform infrared spectroscopy, alpha-amylase, alpha-glucosidase, atomic force microscopy, cellulose, enzyme inhibition, ethanol, gel chromatography, high performance liquid chromatography, hyperglycemia, inhibitory concentration 50, methylation, molecular weight, nuclear magnetic resonance spectroscopy, scanning electron microscopy, seeds
Purification and structural characterization of a novel polysaccharide fraction from Chaenomeles speciosa seeds were investigated. After hot water extraction and ethanol precipitation, the crude polysaccharide was sequentially purified with Cellulose DEAE-52 and gel-filtration chromatography, and a highly purified polysaccharide fraction (F3) was obtained. The structure of F3 was characterized by high-performance gel permeation chromatography (HPGPC), high performance liquid chromatography (HPLC), ultraviolet-visible (UV), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectrum, together with methylation, scanning electron microscopy (SEM), atomic force microscope (AFM), and Congo-red test analysis. The results indicated that F3 was a homogeneous polysaccharide fraction with a molecular weight of 8.65 × 10⁶ Da, and it was composed of Rha, GlcA, Gal, and Ara in a molar ratio of 6.34:5.73:47.14:40.13. The backbone of F3 was consisted of →3,6)-Galp-(1→, and the side chains of F3 were composed of Araf-(1→, →4)-GlcpA-(1→, →4)-Galp-(1→ and →3)-Rhap-(1→. The hypoglycemic assays demonstrated F3 had good α-amylase and α-glucosidase inhibition activities, and their IC₅₀ values were 6.24 mg/mL and 4.59 mg/mL respectively. Thus, the polysaccharide from Chaenomeles speciose could be applied as a potential natural source in retarding postprandial hyperglycemia effects.