A novel soluble β-1,3-D-glucan Salecan reduces adiposity and improves glucose tolerance in high-fat diet-fed mice

Salecan is a recently identified water-soluble viscous extracellular beta-1,3-D-glucan polysaccharide from an Agrobacterium species. It is a high-molecular-mass polymer (about 2 x 10(6) Da) and composed of a linear chain of glucosyl residues linked through a repeat unit of seven beta-(1,3) and two alpha-(1,3) glucosidic bonds. In the present study, we examined the effects of dietary Salecan fed at 2 and 5% in a high-fat diet (64% energy) in C57BL/6J mice. After 6 weeks, mice fed 2 and 5% Salecan had significantly lower body weight, fat mass and percentage of body fat mass compared with those fed a high-fat cellulose (control) diet. Both the Salecan groups significantly and dose-dependently improved glucose tolerance, with a 9 and 26% reduction of glucose AUC, respectively. Liver and adipose tissue weights were also significantly decreased by the Salecan treatment. Supplementation with 5% Salecan led to lower serum TAG, total cholesterol (TC) and HDL-cholesterol (52, 18 and 19 %, respectively) and lower hepatic TAG by 56% and TC by 22% compared with the high-fat cellulose control group. Dietary Salecan intake caused an obvious elevation of fat in the faeces. Supplementation with Salecan disturbed bile acid-promoted emulsification and reduced the size of emulsion droplets in vitro. These results indicate that Salecan decreases fat absorption, improves glucose tolerance and has biologically important, dose-related effects on reducing high-fat diet-induced obesity.