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Structure and in vitro hypoglycemic activity of a homogenous polysaccharide purified from Sargassum pallidum
- Cao, Changliang, Zhang, Bin, Li, Chao, Huang, Qiang, Fu, Xiong, Liu, Rui Hai
- Food & function 2019 v.10 no.5 pp. 2828-2838
- Sargassum, arabinose, fucose, galactose, galacturonic acid, glucose, glucose transporters, glucuronic acid, glycemic effect, glycogen, glycogen (starch) synthase, hexokinase, human cell lines, insulin receptor substrate proteins, insulin resistance, mannose, molecular weight, phosphatidylinositol 3-kinase, pyruvate kinase, xylose
- This study aimed at investigating the structure, hypoglycemic activity and the underlying mechanism of a homogeneous polysaccharide (PSP-2) purified from Sargassum pallidum. Structural characterization revealed that PSP-2 with a molecular weight of 144.8 kDa was composed of fucose (21.6%), arabinose (2.5%), galactose (22.4%), glucose (2.2%), xylose (18.8%), mannose (1.2%), glucuronic acid (7.7%) and galacturonic acid (23.6%). The backbone chain of PSP-2 was composed of →1)-β-d-Xylp-(3→, →1,3)-β-l-Fucp-(4→, →1)-α-d-Galp-(6→, and →1)-α-d-GlcpNAc-(2→, and the side chains were composed of →1,3,6)-α-d-Galp-(2→, →3)-β-l-Fucp-(1,4→, β-d-GalpNAc-(1→, and α-d-Manp-(1→. In vitro hypoglycemic assays indicated that PSP-2 could significantly enhance glucose consumption, glycogen synthesis, and pyruvate kinase (PK) and hexokinase (HK) activities of insulin-resistant HepG2 cells. Furthermore, the underlying mechanistic studies revealed that PSP-2 could ameliorate insulin resistance by up-regulating the expression levels of insulin receptor substrate-1 (IRS-1), glycogen synthase (GS), phosphoinositide-3-kinase (PI3K) and glucose transporter-4 (GLUT4). These results suggested that PSP-2 may be a potential candidate for the prevention and treatment of Type 2 diabetes mellitus.