Adsorption of Sodium Cholate on Cationic Dextran Gels: Comparison of Isotherm Binding Models

Magdalena Cristina Stanciu,Prisacaru Anca-Irina,Marieta Nichifor

doi:10.37358/mp.20.4.5417

Abstract

Cationic dextran hydrogels having pendent 51-59 mol% N-alkyl-N,N-dimethylammonium chloride groups were synthesized and tested as adsorbents for sodium cholate. The bile acid salt sorption by these gels was evaluated by equilibrium analysis in water and 10 mM NaCl solution. The best adsorption results were obtained with amphiphilic dextran-based gels having two types of pendant ammonium chloride groups with different polarities. Experimental adsorption data for all polymers fitted good with Langmuir, Dubinin-Raduskevich and Temkin models over the entire range of ligand concentrations. The maximum experimental adsorption capacity of dextran sorbents for sodium cholate was in the range 850-1075 mg/g.

Highlights

Hypercholesteremia is one of the more important factors of risk for cardiovascular disease, a health problem that has an impact on millions of people throughout the world, mainly in the developed countries
The goal of this study was the investigation of the influence of dextran hydrogels chemical composition and swelling porosity on sodium cholate adsorption
Hydrogel synthesis An efficient BAS must have structural characteristics which enable an enhancement of hydrogel

Summary

Introduction

Hypercholesteremia is one of the more important factors of risk for cardiovascular disease, a health problem that has an impact on millions of people throughout the world, mainly in the developed countries. BAS, were used for long time as cholesterol lowering agent [1,2,3,4,5]. BAS are cationic polymeric hydrogels that bind mainly by electrostatic interactions the conjugated bile acid salts in the small intestine and remove them from enterohepatic circulation by excretion. First (Cholestyramine®, Colestipol®)[7,8,9] and second generation (Colextran®, Colesevelam®, Colestilan®) [7,10,11,12,13] of commercial BAS have reduced efficacy due to low binding capacity to trihydroxy acids, complexation with fat-soluble vitamins, a decrease in some drugs absorption and GI distress (indigestion, nausea and constipation). Good results were obtained using dextran-based hydrogels bearing one type of pendant quaternary ammonium groups with long-chain alkyl substituents [19, 22,23,24]

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Conclusion