Synthesis of cationic polysaccharide derivatives and their hypocholesterolaemic capacity.

High-capacity bile acid-sequestering biopolymers with cationic polysaccharide derivatives have been developed. Cholestyramine, the bile acid sequestrant most widely used for treating hypercholesterolaemia, has unpleasant side effects because of the hydrophobic nature of its backbone. Methylan, a high-viscosity polysaccharide produced by Methylobacterium organophilum, was selected as a model polysaccharide for derivatization. Methylan was aminated to add dialkylaminoalkyl and free amino groups at hydroxyl sites in the methylan backbone, and these derivatives were quaternized to produce pH-independent cationic polyelectrolytes. The in vitro bile acid-binding capacity of quaternized DEAE-methylan was approximately 50% higher than that of cholestyramine. The bile acid-binding capacity of methylan derivatives increased with the number of carbons in the alkyl groups, indicating that hydrophobic interaction is a secondary factor for the sequestration of bile acids.