Low molecular weight chitosan inhibits obesity induced by feeding a high-fat diet long-term in mice

Abstract

Three low molecular weight chitosans (molecular weight: 21, 46 and 130 kDa) obtained by enzymatic hydrolysis of a high molecular weight chitosan (average molecular weight: 650 kDa) had low viscosity and were water-soluble. The effects of these water-soluble chitosans on pancreatic lipase (in-vitro) and the elevation of plasma triacylglycerol concentration after the oral lipid tolerance test were examined in mice. The water-soluble 46-kDa chitosan was the most effective at inhibiting pancreatic lipase activity (in-vitro) and plasma triacylglycerol elevation after the oral lipid tolerance test. Based on this result, the effects of the 46-kDa chitosan on increases in bodyweight, various white adipose tissue weights, and plasma and liver lipids were examined in mice fed a high-fat diet for 20 weeks. Water-soluble 46-kDa chitosan (300 mg kg(-1), twice daily) prevented increases in bodyweight, various white adipose tissue weights and liver lipids (cholesterol and triacylglycerol) in mice fed a high-fat diet, and further increased the faecal bile acid and fat. The results suggest that the lipid-lowering effects of the 46-kDa chitosan may be mediated by increases in faecal fat and/or bile acid excretion resulting from the binding of bile acids, and by a decrease in the absorption of dietary lipids (triacylglycerol and cholesterol) from the small intestine as a result of the inhibition of pancreatic lipase activity. Water-soluble 46-kDa chitosan (100 and 300 mg kg(-1), twice daily) did not cause liver damage with the elevation of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase, or kidney damage with the elevation of blood nitrogen urea. It was concluded that water-soluble 46-kDa chitosan is a safe functional food.

Differential blood lipid-lowering effects of alkylsulfonated chitosan of different molecular weights in Syrian hamsters in vivo

“…Chitosan, a biopolymer of glucosamine, is produced by the deacetylation of chitin and consists of polymers with various molecular weights. The hypolipidemic activity of chitosan is related to a number of chemical characteristics, including molecular weight, degree of acetylation and viscosity (6,27). Regarding the effect of the differential molecular weight, feeding an obese mouse model a HFD showed that chitosan with 46 kDa molecular weight is more effective at attenuating body weight gain and lowering blood total triglycerides and total cholesterol and LDL-cholesterol than 650 kDa chatoyant (6).…”

“…Previous studies have shown that chitosan and its oligomers display a variety of biological activities, including antitumor, hypoglycemic, hypolipidemic, antibacterial and eight control effects (1)(2)(3)(4)(5). The effectiveness of chitosan in lowering blood lipids and in body weight control allows it to decrease the risk of cardiovascular disease (6)(7)(8).…”

“…The oligo-form of chitosan, which is generated by the degradation of the chitosan polymer chain, shows better water solubility and antitumor effects than the poly-form of chatoyant (9). Molecular weight and viscosity are critical factors responsible for the hypolipidemic effect of chatoyant (3,6,10). The molecular weight of chitosan ranging from 20 to 2000 kDa displays better potency for lowering blood triglycerides and cholesterol (6,11,12).…”

“…Molecular weight and viscosity are critical factors responsible for the hypolipidemic effect of chatoyant (3,6,10). The molecular weight of chitosan ranging from 20 to 2000 kDa displays better potency for lowering blood triglycerides and cholesterol (6,11,12). Establishing the molecular weight and chemical characteristics of chitosan with optimal biological activity remains an elusive target.…”

Chitosan does not inhibit enzymatic action of human pancreatic lipase in Langmuir monolayers of 1,2-didecanoyl-glycerol (DDG)

“…However, their efficacy for weight loss is highly controversial, and in a survey of the literature reports are found for both confirmation and denial of this property. Conflicting results were obtained in in vivo experiments with humans and mice where chitosan was used as supplement in diets, with no or very little weight loss in some studies [8][9][10][11][12], whereas in other studies chitosan was able to inhibit increases in body weight [13,14].…”