Search

The objective of current work was to explore the potential anti-diabetic mechanisms of Hizikia fusifarme polysaccharide (HFP) in type 2 diabetic rats. The carbohydrate loading experiment illustrated that HFP supplement could reduce blood sugar fluctuations caused by eating through inhibiting the hydrolysis of starch in mice. The analysis of typically diabetic symptoms and serum profiles showed that oral administration of HFP could mitigate hyperglycemia, insulin resistance, dyslipidemia, chronic inflammation and oxidative stress in rats. The 16s rRNA gene sequencing analysis indicated that HFP treatment could restore beneficial composition of gut flora in diabetic rats, and the correlation analysis revealed that the improvement of diabetes is closely related to the modification of gut flora by HFP intervention. Furthermore, the RT-qPCR and western blotting analysis clarified that HFP administration could increase glycogen storage in liver and skeletal muscle of diabetic rats through activating IRS/PI3K/AKT/GLUT signaling pathway and restrain gluconeogenesis via affecting the relative expression of Egr-1 and PEPCK genes.

Three algal polysaccharides (APs) were acquired from Scagassum (SCP), Sargassum fusiforme(Harv.) Setch. (SFP) and Macrocystis pyrifera(L.)Ag. (MAP) by hot water extraction, and their structural characterization and antidiabetic activity were investigated in high fat diet and streptozotocin-induced type 2 diabetic rats. The results revealed that there were obvious differences in extraction yield, molecular weight, compositions of monosaccharide and organic element, molecular morphology, rheological properties and the contents of total sugar, protein, uronic acid and sulfate of SCP, MAP and SFP. SFP had the highest extraction yield, the contents of total sugar and uronic acid and the smallest molecular weight. Congo red assay indicated that all polysaccharides had no triple-helix structure. Oral administration of APs prominently restrained loss of weight and increase of water intake (P .05), and also significantly controlled the increase of levels of blood glucose, triglyceride (TG) and total cholesterol (TC) in diabetic rats (P 0 .05). Diabetic rats treated with SCP had the highest high density lipoprotein cholesterol (HDL-C) level (P .05), similar to those in normal group. MAP and SCP showed positive effect in improving the low density lipoprotein cholesterol (LDL-C) level of diabetic rats (P .05). Meanwhile, the increased ALT and BUN contents caused by the liver and kidney damages were markedly ameliorated in the diabetic rats with APs intervention (P .05). As a consequence, APs could be promising candidates as natural medicines and functional foods for the improvement of diabetes and its complications.

Sargassum fusiforme polysaccharides (SFPs), including SFP-3-40, SFP-3-60, SFP-3-80, SFP-7-40, SFP-7-60, SFP-7-80, SFP-10-40, SFP-10-60, and SFP-10-80, were extracted at different pH (3, 7, and 10), and then precipitated with graded precipitation of 40%, 60% and 80% (v/v) ethanol solution, respectively. Their physicochemical properties and α-glucosidase inhibitory activity were determined. Results showed that SFPs significantly differed in the contents of total sugar, protein, uronic acid, sulfate, the zeta potential, and molecular weight distribution. SFPs, including SFP-10-40, SFP-10-60, and SFP-10-80, had bigger absolute zeta potential value and higher respective average molecular weight in the same ethanol concentration precipitate. All samples were mainly composed of fucose, glucuronic acid, and mannose with different molar ratios. The extraction pH and precipitation ethanol solution concentration caused little changes in functional groups, but significantly altered surface morphology of SFPs. Congo red test revealed that all polysaccharides were not helical polysaccharides. Rheological measurements indicated that SFPs were pseudoplastic fluids and showed elastic behavior of the gel. Except SFP-3-40 and SFP-3-60, all other samples had a stronger α-glucosidase inhibitory activity than that of acarbose. The inhibition type of SFPs against α-glucosidase varied owing to different extraction pH and precipitation ethyl concentration. This study shows that extraction pH can significantly affect the structure and hypoglycemic activity of SFPs and provide a data support for the scientific use of Sargassum fusiforme in industrial production.

Honey-processed Astragalus is a dosage form of Radix Astragali processed with honey, which exhibits better efficacy of tonifying Qi than the raw product. Polysaccharides are its main water-soluble active components. This work was designed to study the structural differences of homogeneous honey-processed Astragalus polysaccharides (HAPS3a) and Astragalus polysaccharides (APS3a) and their effects on colitis mice. The results showed that HAPS3a (Mw = 2463.5 kDa) and APS3a (Mw = 3373.2 kDa) differed in molecular weight, monosaccharide compositions, glycosidic bonds and degree of branching (DB). Notably, the molar ratios of galactose and galacturonic acid in HAPS3a were 22.66% and 33.24%, while those in APS3a were 11.87% and 49.55%, respectively. The uronic acid residues 1,4-β-GalpA and 1,6-α-GlcpA of the backbone in APS3a were converted into the corresponding neutral residues in HAPS3a after honey processing. The different DB of HAPS3a (15.35%) and APS3a (25.13%) suggested that the chain conformation became smoother. The anti-inflammatory effects on colitis mice revealed that HAPS3a exhibited better effects than APS3a by protecting intestinal mucosa, regulating the expression of cytokines and influencing microbiota diversity. Taken together, the differences in anti-inflammatory activity might be related to structural differences caused by honey processing. Our findings have laid a foundation for the processing mechanism of Astragalus.

Three algae polysaccharides (APs) extracted from Ascophyllum nodosum (ANP), Fucus vesiculosus (FVP) and Undaria Pinnatifida (USP) significantly differed in the zeta potential, water and oil holding capacity, monosaccharide composition, organic element composition, molecular weight distribution, microstructure and rheological properties. Antidiabetic effects of APs were compared by oral intervention at the dose of 400 mg/kg·body weight/day in high sugar and fat diets and streptozotocin injection induced type 2 diabetic rats. The analysis of body weight, water intake, fasting blood glucose, insulin, oral glucose tolerance, blood lipid indicators (including total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and free fatty acid (FFA)), liver function indexes (involving alanine aminotransferase (ALT) and aspartate aminotransferase (AST)) and renal function profiles (comprising uric acid (UA) and urea nitrogen (BUN)) showed that APs possessed obvious antidiabetic activities, and FVP showed better effects in controlling the levels of FFA, AST, ALT, UA and BUN. Intervention of FVP reduced the total bile acid (TBA) level and elevated high density lipoprotein cholesterol (HDL-C) level of diabetic rats. Histomorphological observation further demonstrated that APs, especially FVP, could attenuate liver and kidney damage caused by diabetes. This study concluded that the antidiabetic effects of ANP, FVP and USP were distinctly different, which might be attributed to their different chemical structures. Therefore, the structure-activity relationship and antidiabetic mechanism of APs will be our future research direction.

Two polysaccharide fractions (SFPs, designated as respectively SFP-1 and SFP-2) were acquired from Sargassum fusiforme by ultrasound-assisted enzymatic extraction, and their physicochemical properties and hypoglycemic and hypolipidemic effects were investigated. Structural analysis indicated that SFPs were obvious different in the zeta potential, molecular weight distribution, characteristic organic group, microstructure and the contents of total sugar, uronic acid, sulfate and moisture. SFPs consisted of fucose, mannose, rhamnose, glucose, galactose and glucuronic acid with different molar ratios. Congo red test explained that SFPs had no triple-helix structure. SFP-1 exhibited lower viscosity due to its lower molecular weight. Regarding to hypoglycemic and hypolipidemic effects, oral administration of SFPs prominently restrained loss of body weight and increase of water intake, and also significantly controlled the increase of levels of fasting blood glucose, triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), uric acid (UA), urea nitrogen (BUN), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of diabetic rats, and SFP-2 showed better effects in controlling fasting blood glucose, ALT, UA and BUN levels. Intervention of SFP-2 reduced the levels of insulin, FFA and TBA of diabetic rats. Histomorphological observation further demonstrated that SFPs could attenuate liver and kidney damage caused by hyperglycemia and hyperlipidemia. Data indicated that SFPs, especially SFP-2, significantly improved hyperglycemia, hyperlipidemia and liver and kidney function of diabetic rats.