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Calix[n]imidazolium as a new class of positively charged homo-calix compounds.

ABSTRACT: Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5]imidazolium. The noncovalent (C-H)(+)/?(+)-anion interactions of the imidazolium rings with anions inside and outside the cone are the stabilizing factors for crystal packing, resulting in self-assembled arrays of cone-shaped calix-imidazolium molecules. Calix[4]imidazolium senses fluoride selectively even in aqueous solutions. Calix[5]imidazolium recognizes neutral fullerenes through ?(+)-? interactions and makes them soluble in water, which could be useful in fullerene chemistry. Not only derivatization and ring expansion of calix[n]imidazolium, but also their utilization in ionic liquids, carbene chemistry and nanographite/graphene exfoliation could be exploited.

SUBMITTER: Chun Y

PROVIDER: S-EPMC3644089 | biostudies-other | 2013

REPOSITORIES: biostudies-other

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Calix[n]imidazolium as a new class of positively charged homo-calix compounds.

Chun Young Y Singh N Jiten NJ Hwang In-Chul IC Lee Jung Woo JW Yu Seong Uk SU Kim Kwang S KS

Nature communications 20130101

Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5]imidazolium. The noncovalent (C-H)(+)/π(+)-anion interactions of the imidaz ...[more]

PMID: 23653209

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Project description:Lacking an effective mechanism to safely and consistently enhance macromolecular uptake across the intestinal epithelium, prospects for successful development of oral therapeutic peptide drugs remain unlikely. We previously addressed this challenge by identifying an endogenous mechanism that controls intestinal paracellular permeability that can be activated by a peptide, termed PIP 640, which can increase cellular levels of phosphorylated myosin light chain at position S19 (MLC-pS19). Apical application in vitro or luminal application in vivo was shown to increase macromolecular solute transport within minutes that recovered completely within a few hours after removal. We now examine the nature of PIP 640-mediated permeability changes. Confluent Caco-2 cell monolayers treated with PIP 640 enhanced apical-to-basolateral (AB) transport of 4-kDa, but not 10-kDa, dextran. Expression and/or cellular distribution changes of tight junction (TJ) proteins were restricted to increased claudin-2 over a time course that correlated with an apparent shift in its distribution from the nucleus to the membrane fraction of the cell. PIP 640-mediated epithelial changes were distinct from the combined actions of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-?) and interferon gamma (IFN-?). While TNF-?/IFN-? treatment also increased MLC-pS19 levels, these cytokines enhanced AB transport for 70-kDa dextran and decreased occludin expression at TJs. Claudin-2-dependent changes induced by PIP 640 resulted in an AB transport bias for positively-charged macromolecules demonstrated in vitro using charge variants of 4-kDa dextrans and by comparing transport of salmon calcitonin to exenatide. Comparable outcomes of increased TJ localization of claudin-2 and enhanced transport of these therapeutic peptides that biased toward cationic characteristics was demonstrated in vivo following after intra-luminal injection into rat jejunum. Together, these data have shown a potential mechanism for PIP 640 to enhance paracellular permeability of solutes in the size range of small therapeutic peptides that is biased toward positively-charged solutes.

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Calix[n]imidazolium as a new class of positively charged homo-calix compounds.

Publications

Calix[n]imidazolium as a new class of positively charged homo-calix compounds.

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