Permeation modulating properties of natural polymers - Effect of molecular weight and mucus

The permeation modulating effects of 5 natural polymers; low-ester, amidated and high-ester pectin, as well as hyaluronic acid and chitosan were tested at two different molecular weights each. The model membrane was methotrexate treated HT29 cells grown for 2 or 3 weeks, respectively, thereby differing in the amount of goblet cells and hence mucus. The pectins decreased the permeation of the paracellular marker carboxyfluorescein. Free acid groups and a high molecular weight increased this membrane protective effect. Chitosan displayed pronounced and hyaluronic acid modest permeation enhancing properties. In this case, a low molecular weight accentuated the effect. In all cases, the permeation modulating properties were reduced by mucus. (C) 2011 Elsevier B.V. All rights reserved.