Physicochemical, rheological properties, and hypoglycemic activities of polysaccharides from Hemerocallis citrina Baroni leaves and stems

Hemerocallis citrina Baroni ( H. citrina Baroni) is widely used in the food and medical industries. However, a comprehensive evaluation of the physicochemical, rheological properties, and hypoglycemic activities of its various parts has not yet been reported. In this study, we extracted polysaccharides from the leaves (HCLP) and stems (HCSP) of H. citrina Baroni. The physicochemical properties were investigated using high-performance gel permeation chromatography (HPGPC), high performance liquid chromatography (HPLC), Congo red experiment, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), thermogravimetric (TG), and scanning electron microscopy (SEM). HCSP exhibited higher total sugar contents, uronic acids, protein, total phenol, and flavonoid contents than HCLP. However, the HCSP extraction yield (2.54 ± 0.68%) was lower than that of HCLP (6.34 ± 0.75%). Both polysaccharides were mainly composed of Mannose (Man) and galactose (Gal), but their contents varied significantly; HCSP contained more glucosamine (GlcN), rhamnose (Rha), arabinose (Ara), gluconic acid (GlcA), galacturonic acid (GalA) and glucose (Glc) than HCLP. The results showed that both HCSP and HCLP displayed macromolecular characteristics with a triple-helix structure. The thermal stability was stronger in HCLP than in HCSP. The rheological results showed that HCLP and HCSP exhibited a pseudoplastic fluid behavior. Compared to HCSP, HCLP had a stronger ability to inhibit α -glucosidase and enhance glucose consumption in HepG2 cells, attributed to its superior thermal stability and higher molecular weight ( M w ). These results indicated that polysaccharides from the leaves and stems of H. citrina Baroni have potential as functional foods and hypoglycemic drugs.