title: N-alkylation of highly quaternized chitosan derivatives affects the paracellular permeation enhancement in bronchial epithelia in vitro.
abstract: This study describes the structure-activity relationship for carefully characterized N-alkyl-N-quaternary chitosan derivatives as permeation enhancers for drugs that are mainly absorbed through the paracellular pathway, such as macromolecular drugs and hydrophilic drugs, in a well defined bronchial epithelial cell line. The O-methyl free derivatives used in the study were fully trimethylated (100%) N,N,N-trimethyl chitosan (TMC) and N-propyl-(QuatPropyl), N-butyl-(QuatButyl) and N-hexyl (QuatHexyl)-N,N-dimethyl chitosan, with 85-91% degree of quaternization. The fully trimethylated TMC, from 0.25mg/ml, decreased transepithelial electrical resistance (TER) in a reversible manner and enhanced the permeation of the macromolecule FITC-dextran 4kDa (FD4) 2-5 fold. TMC did not cause any alterations in the tight junction (TJ) protein claudin-4 or in F-actin architecture. QuatHexyl was the most effective polymer to produce enhanced permeation and decreased TER from 0.016mg/ml. Nevertheless, this enhanced permeation was accompanied by reduced viability and dissociation of F-actin and claudin-4 proteins. The structure-activity relationship suggests that more lipophilic derivatives show more permeation enhancement, TJ disassembly, and less viability in the order of hexyl≈butyl>propyl>methyl and demonstrates that the permeation effect is not only mediated by permanent positive charge but also by the extent of N-alkylation. These results are relevant to elucidate the structural factors contributing to the permeation enhancement of chitosan derivatives and for potential use in pulmonary applications.
authors.affiliation: Faculty of Pharmaceutical Sciences, School of Health Sciences, University of Iceland, Reykjavik, Iceland.
authors.forename: Berglind Eva
authors.initials: BE
authors.lastname: Benediktsdóttir
authors.affiliation: Biomedical Center, School of Health Sciences, University of Iceland, Reykjavík, Iceland.
authors.forename: Thórarinn
authors.initials: T
authors.lastname: Gudjónsson
authors.affiliation: Department of Pulmonary Medicine, Landspitali - The National University Hospital of Iceland, Reykjavík, Iceland.
authors.forename: Ólafur
authors.initials: Ó
authors.lastname: Baldursson
authors.affiliation: Faculty of Pharmaceutical Sciences, School of Health Sciences, University of Iceland, Reykjavik, Iceland. Electronic address: mmasson@hi.is.
authors.forename: Már
authors.initials: M
authors.lastname: Másson
mesh_terms: D000478:Alkylation; D001980:Bronchi / Q000166:cytology / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D048271:Chitosan / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D004337:Drug Carriers / Q000737:chemistry / Q000493:pharmacokinetics; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D010539:Permeability; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000493:pharmacokinetics; D013329:Structure-Activity Relationship; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism
chemical_list: D004337:Drug Carriers; D000644:Quaternary Ammonium Compounds; D048271:Chitosan
keywords: Airway drug delivery; Chitosan; N-quaternary derivatives; Permeation enhancement; TMC; Tight junctions