How come L112 BIOPOLYMER from
CHITOSAN SPEC L112 CHARACTERISTICS
STUDY: CHITOSANS OF INTEREST
Chitosan, a polyglucosamine derived from chitin by deacetylating chitin molecule. It is a cellulose-like polymer located mainly in exoskeletons of arthropods (e.g. crabs, shrimps, lobsters and insects) and squidpen. Chemically and physiologically, the compound can be defined as a dietary polysaccharide fiber which cannot be hydrolyzed by digestive enzymes of humans. The ability of chitosan, a glucosamine polymer formed by deacetylating chitin, is known to interact with hydrophobic compounds such as cholesterol, triglycerides, fatty and bile acids and reduce their absorption or reentry into the mucosal cells of animals and man. Part of this property is likely related to the positive charge of the amide group at pH’s less than 6.5 and its ability to be dissolved at low pH and form a viscous gel at higher pH’s. Chitosan’s capacity to bind bile acids, which consequently reduces the enterohepatic recycling, provides a favorable means of reducing plasma cholesterol. In addition, chitosan forms complex salts that bind to or associate with the triglycerides, fatty acids and other sterol compounds. By means of ionic binding or other associations such as entrapment of hydrophobic compounds, clear evidence indicates that measurable reduction of fat absorption occurs with chitosan feeding. This physiological property to reduce fat absorption has been tested in animal models, clinical studies and the physical properties of fat-binding interactions have also been supported through in vitro laboratory studies. It has exhibited a potent hypocholesterolaemic activity in rats. However, its hypocholesterolaemic mechanism is still unclear. Under different reaction conditions, chitosans with different physicochemical properties can be prepared. Degree of deacetylation (DD) and molecular weight (MW) of chitosan are two important characteristics which greatly affect its chemical and physiological five properties. chitosan is the only abundant cationic polymer having an amino group in its chemical structure and the DD is a characteristic greatly different from those of other dietary fibers. Higher DD reflects more free amino groups in the chitosan molecule and more positive charge in chitosan solution. A previous study showed that the hypocholesterolemic activity of chitosan was better when DD was high (90%deacetylated), which might be due to the electrostatic force between chitosan and anion substances (such as unesterified fatty acid and bile acid) and also cholesterol. MW and size of chitosan is proportional to its viscosity. Entrapment caused by a viscous chitosan would reduce the absorption of fat and cholesterol in diet. Possibly, weight-lowering and hypocholesterolemic mechanisms would be similar to that of certain dietary fibers, guar gum and pectin. Nevertheless, the relationship between the MW of chitosan and its hypocholesterolemic effect is still controversy and under discussion. a recent study has shown that binding capacities of chitosans with bile acids and triglycerides had no correlation with DD in vitro. Essentially, the chitosan has been promoted as an effective, natural nutraceutical to reduce absorption of dietary fat and cholesterol, eventually leading to reduce body weight and blood cholesterol. Our investigations of the chitosans with different positive charges and molecular size will be beneficial in prevention of obesity and cardiovascular disease.
The study was performed in vitro to investigate fat-binding capacity of the chitosans having different molecular size and degree of deacetylation. Cholesterol and bile acid-binding activity of the chitosans were also included. Penetration of the chitosans into intestinal epithelial cells was assayed in vitro.