Effect of Salt Forms of Chitosan on In Vitro Permeability Enhancement in Intestinal Epithelial Cells (Caco-2)

Purpose: To investigate the effect of chitosan (CS) salt forms and pH condition on the transepithelial electrical resistance (TEER) of Caco-2 cell monolayer for enhanced permeability. Methods: Solutions (2 %w/v) of four different salt forms of CS-aspartate (CS-A), CS-ethylene diamine tetraacetate (CS-EDTA), CS-hydroxybenzotriazole (CS-HOBt) and CS-thiamine pyrophosphate (CS-TPP) - were prepared and tested on TEER using fluorescein isothiocyanate dextran 4,400 (FD-4) as the permeant across Caco-2 cell monolayer in both pH 6.2 and 7.4 (physiological pH) environment. Results: The results show that CS-salt solutions, at pH of 6.2, increased cell permeability in a dose-dependent manner and caused relatively reversible effects only at low doses of 0.001 - 0.010 %w/v. At CS-salt solution concentration of 0.01 %w/v, accumulation of FD-4 in the acceptor compartment was in the rank order: CS-EDTA > CS-TPP > CS-A > CS-HOBt. All CS-salt solutions significantly (p < 0.05) increased the transport of FD-4. On the other hand, at pH 7.4, only CS-EDTA at a concentration of 0.5 %w/v enhanced the transport of FD-4. CS-EDTA was also the most toxic CS salt. Conclusion: The salt forms of CS are capable of enhancing the transport of FD-4 across Caco-2 cell monolayer, with CS-EDTA the most promising of them

Oral Methylated N-Aryl Chitosan Derivatives for Inducing Immune Responses to Ovalbumin

Purpose: To investigate different structures of modified chitosan containing different chain lengths and aromatic moieties for vaccine delivery capacity. Methods: The characteristics of the modified chitosan, namely, methylated N-(4-N,Ndimethylaminobenzyl) chitosan (TM-Bz-CS), methylated N-(4-N,N-dimethylaminocinnamyl) chitosan (TM-CM-CS) and methylated N-(4-pyridinylmethyl) chitosan (TM-Py-CS), with Eqiva degree (equivalent degree) were studied by in vitro absorption enhancement on the transepithelial electrical resistance (TEER) in Caco-2 cell monolayers as well as by in vivo adjuvant activity against ovalbumin (OVA), a model antigen, via oral administration to BALB/c mice. Results: At the same concentration and pH (0.1 mg/ml, pH 7.4), TM65CM50CS exhibited the highest in vitro enhancing paracellular permeability and also the highest in vivo adjuvant activity following oral administration to mice. OVA-specific serum immunoglobulin G (IgG) antibody levels of mice that received OVA in TM65CM50CS were significantly (p < 0.05) higher than those that received OVA in TM65CS, TM56Bz42CS and TM53Py40CS. On the other hand, TM65CS and TM56Bz42CS exhibited in vitro enhancing paracellular permeability but showed no immune responses, while TM53Py40CS failed to enhance paracellular permeability and did not elicit immune responses as well. Conclusion: This study demonstrates that addition of hydrophobic moiety (dimethylaminocinnamyl) to CS backbone can increase both its absorption enhancing property and adjuvant activity. The chemical structure and the positive charge location play an important role for binding affinity, absorption enhancement and immune responses

Methylated N-(4-N,N-Dimethylaminobenzyl) Chitosan, a Novel Chitosan Derivative, Enhances Paracellular Permeability Across Intestinal Epithelial Cells (Caco-2)

The aim of this study was to investigate the effect of methylated N-(4-N,N-dimethylaminobenzyl) chitosan, TM-Bz-CS, on the paracellular permeability of Caco-2 cell monolayers and its toxicity towards the cell lines. The factors affecting epithelial permeability, e.g., degree of quaternization (DQ) and extent of dimethylaminobenzyl substitution (ES), were evaluated in intestinal cell monolayers of Caco-2 cells using the transepithelial electrical resistance and permeability of Caco-2 cell monolayers, with fluorescein isothiocyanate dextran 4,400 (FD-4) as a model compound for paracellular tight-junction transport. Cytotoxicity was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide viability assay. The results revealed that, at pH 7.4, TM-Bz-CS appeared to increase cell permeability in a concentration-dependent manner, and this effect was relatively reversible at lower doses of 0.05–0.5 mM. Higher DQ and the ES caused the permeability of FD-4 to be higher. The cytotoxicity of TM-Bz-CS depended on concentration, %DQ, and %ES. These studies demonstrated that this novel modified chitosan has potential as an absorption enhancer