Isolation and Structural Characterization of a Second Polysaccharide from Bulbs of Lanzhou Lily

In this study, a second water-soluble polysaccharide (designated as LDP-2) was isolated from the bulbs of Lanzhou Lily (Lilium davidii var. unicolor). Based on monosaccharide composition and methylation analysis, its structural features were investigated using a variety of characterizations, such as size-exclusion chromatography combined with laser light scattering (SEC-LLS), gas chromatography-mass spectroscopy (GC-MS), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. The results demonstrate that LDP-2 is a homogeneous heteropolysaccharide (molecular weight 6.2 × 104 Da), which includes four kinds of monosaccharides (Lyx, Man, Glc, and Gal in an approximate weight ratio of 6.74: 6.28: 76.50: 10.48). Furthermore, its morphology, thermal behavior, and preliminary hypoglycemic activities were also investigated.