Isolation, purification, structural characterization, and hypoglycemic activity assessment of polysaccharides from Hovenia dulcis (Guai Zao)

Hovenia dulcis polysaccharides (HDPs) have a variety of important biological activities associated with potential applications in food engineering, pharmacy science, and health care. Herein, we isolated and purified polysaccharides from H. dulcis. Chemical composition analysis revealed that the purified polysaccharides (HDPs-2A) were composed of different molar ratios of mannose, Rha, GalA, GlcA, Glc, Gal, and Ara and had a molecular weight of 372.91 kDa. The structure of HDPs-2A was assessed by FT-IR, periodate oxidation, Smith degradation, methylation analysis, and NMR, allowing us to determine that the backbone of HDPs-2A is composed primarily of →5)-α-L-Araf-(1→, →5)-α-L-Araf-(1→, →3,5)-α-L-Araf-(1→, →6)-β-D-Galp-(1→, →3,6)-β-D-Galp-(1→, T-β-D-Galp, →3)-β-D-Galp-(1→, and T-α-D-Glcp. The results of atomic force microscopy (AFM) showed that HDPs-2A present an irregular polymer particle morphology in water. X-ray diffraction (XRD) results showed that HDPs-2A have a single crystal structure. Finally, we demonstrated that HDPs-2A have a good therapeutic effect on a rat model of type 2 diabetes.