Structure features and in vitro hypoglycemic activities of polysaccharides from different species of Maidong

Structures and in vitro hypoglycemic activities of polysaccharides from different species of Maidong were studied. The primary structures of polysaccharides were elucidated on the basis of GC, GC–MS, infrared, NMR and periodate oxidation-Smith degradation. Liriope spicata polysaccharide (LSP), Ophiopogon japonicus polysaccharide (OJP) and Liriope muscari polysaccharide (LMP) were composed of β-fructose and α-glucose. The average molecular weights of LSP, OJP and LMP were 4742, 4925 and 4138 Da with polydispersity indexes of 1.1, 1.2 and 1.1, respectively. The backbones of polysaccharides were formed by Fruf-(2→, →2)-Fruf-(6→, →6)-Glcp-(1→ and →1, 2)-Fruf-(6→ with a molar ratio of 5.0:18.2:1.0:5.3 (LSP), 6.8:15.8:1.0:5.8 (OJP), 8.3:12.3:1.0:3.9 (LMP), respectively. The RT-PCR and western blot analysis indicated that LSP, LMP and OJP increased the expression of PI3K, AKT, InsR, PPARγ and decreased the expression of PTP1B in mRNA level and protein level in IR HepG2 cells. Furthermore, glucose consumption was increased after treated with polysaccharides. These results revealed that LSP, OJP and LMP had potential anti-diabetic effects.