title: Effect of the biologically active fragment of zonula occludens toxin, delta G, on the intestinal paracellular transport and oral absorption of mannitol.
abstract: OBJECTIVE
  Many therapeutically active agents experience low bioavailability upon oral administration due to low permeability, low solubility, interaction with efflux transporters or first pass metabolism. In general, absorption enhancers are agents that can modulate the paracellular permeability of drugs, thus, potentially increasing oral bioavailability. The objective of this study was to examine the effect of the active fragment of Zonula occludens toxin (Zot), deltaG, on the transport of a paracellular marker, mannitol, using in vitro (Caco-2 cell monolayers) and in vivo (intraduodenal administration in rats) experimental methods.
  
  
  METHODS
  The transport of [14C]mannitol with deltaG (0, 50, 80, or 100 microg/ml) was determined across Caco-2 cells. Male Sprague-Dawley rats were assigned to receive one of the following treatments: [14C] mannitol (40 microCi/kg), [14C]mannitol/deltaG (417 microg/kg), or [14C] mannitol/deltaG/Protease inhibitors (PI).
  
  
  RESULTS
  The mean (+/-S.E.M.) apparent mannitol permeability coefficients (P(app)) observed after incubation with 0, 50, 80, and 100 microg/ml deltaG were 3.5 (+/-0.4), 4.17 (+/-0.27), 4.33 (+/-0.61), and 9.94 (+/-0.24)x10(-6) cm/s. After oral administration, C(max) (3.8 x 10(-4) vs. 4.4 x 10(-4) mM) and AUC(0-6 h) (0.096 vs. 0.088 mM min), obtained for [14C]mannitol and [14C]mannitol/deltaG, respectively, were not statistically different. However, both C(max) (7.6 x 10(-4) mM) and AUC(0-6 h) (0.25 mM min) were significantly higher for the [14C]mannitol/deltaG/PI treatment.
  
  
  CONCLUSIONS
  The 12 kDa fragment of Zot, deltaG, enhanced the in vitro transport and oral absorption of the paracellular marker, mannitol, in the presence of protease inhibitors (PI).
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, 100 Penn Street, Baltimore, MD 21201, USA.
authors.forename: Noha N
authors.initials: NN
authors.lastname: Salama
authors.forename: Alessio
authors.initials: A
authors.lastname: Fasano
authors.forename: Ruliang
authors.initials: R
authors.lastname: Lu
authors.forename: Natalie D
authors.initials: ND
authors.lastname: Eddington
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D018938:Caco-2 Cells; D002772:Cholera Toxin / Q000493:pharmacokinetics* / Q000494:pharmacology; D004731:Endotoxins; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008353:Mannitol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D010446:Peptide Fragments / Q000493:pharmacokinetics / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004731:Endotoxins; D010446:Peptide Fragments; C077728:zonula occludens toxin, Vibrio cholerae; D008353:Mannitol; D002772:Cholera Toxin