Increasing the in vitro bile acid binding capacity of diethylaminoethylcellulose by quaternization

Diethylaminoethylcellulose (DEAE-cellulose) was quaternized with methyl iodide (DEAE-cellulose-CH3I), and its in vitro binding capacity for sodium glycocholate, at room temperature, in water, Tris-HCl buffer (0.0015-0.0050 M, pH 7.0), and aqueous NaCl (0.0025 M) was determined by reversed-phase HPLC. Quaternization increased the in vitro bile salt binding capacity of DEAE-cellulose. On a molar basis, the binding capacity was greater than that of cholestyramine, a cholesterol-lowering agent. Increasing the ionic strength of the medium decreased the binding capacities, as expected if ionic interactions are important. However, conversion of DEAE-cellulose-CH3I to its chloride form did not change the binding capacity. The bile salt binding capacity of DEAE-cellulose-CH3I was similar for both sodium cholate and sodium glycocholate.