Abstract: Chitosan in a range of molecular weight has the anti-hyperlipoidenmia effect owing to its ability to bind bile salt in gastrointestinal tract. Water-soluble chitosan with molecular weight of 8 000 was prepared and reacted with diethylaminoethyl chloride and dimethylamino(1-methyl)ethyl chloride to afford diethylaminoethyl chitosan(DEAE-chitosan) and dimethylaminoisopropyl chitosan(DMAIP-chitosan) respectively. DEAE-chitosan was methylated with methyl iodide to give the ammonium-containing chitosan(DEMAE-chitosan). The binding capacities of the water-soluble chitosan and its derivatives to taurocholate and glycocholate as bile salts were investigated in vitro. Through changing the factors of bile salts concentration, medium pH value, deacetylation degrees of the soluble chitosan and so on the influence of the binding capacity was studied on soluble chitosan to bile salts. The results indicated that the binding capacity of the soluble chitosan to bile salts was mainly depended on its cationic structure. The taurocholate binding capacities of chitosan, DEAE-chitosan at an initial taurocholate concentration of 10 mmol/L are 2\^04 and 2.83 mmol/g. The binding capacities are increased about 40% by the latter. The glycocholate binding capacities of chitosan, DEMAE-chitosan at an initial glycocholate concentration of 10 mmol/L are 1.65 and 3.34 mmol/g. The results indicated that the introduction of amino or ammonium groups onto chitosan could increase the binding capacity to bile salts.

Key words: Soluble chitosan, Chitosan modification, Bile salts, Sodium taurocholate, Sodium glycocholate