title: Caco-2 cell methodology and inhibition of the P-glycoprotein transport of digoxin by Aloe vera juice.
abstract: The aims of this study were to carry out a thorough quality control setup for essential Caco-2 cell characteristics in P-glycoprotein (P-gp) inhibition studies and to explore if Aloe vera juice (AVJ) inhibits the bidirectional transport of the P-gp substrate digoxin (30 nm). Seven AVJ concentrations (0.00001-1.0 mg/mL), anticipated to cover a clinically relevant range, were tested and digoxin apparent permeability coefficients (Papp), net Papp values (Papp(Net)) and net flux values (J(Net)) were calculated. Relevant validation parameters for P-gp inhibition studies in Caco-2 cells are suggested to include, as a minimum, an assay linearity test with and without a known P-gp inhibitor, cell cytotoxicity testing (MTT-test) for substrates and inhibitors, and cell integrity testing by TEER and mannitol transport measurements. The question is also raised whether a minimum effect of a reference P-gp inhibitor as verapamil should be demanded. Cell cytotoxicity was seen for digoxin at concentrations >or=3 microM and for AVJ at 10 mg/mL. AVJ did not inhibit the P-gp transport of digoxin in any of the concentrations tested. This indicates that AVJ is no inhibitor of the P-gp mediated transport of digoxin in vitro if AVJ is present in clinically relevant concentrations.
authors.affiliation: Norwegian University of Science and Technology, Faculty of Medicine, Department of Cancer Research and Molecular Medicine, Trondheim, Norway. djuv@stud.ntnu.no
authors.forename: Ane
authors.initials: A
authors.lastname: Djuv
authors.forename: Odd Georg
authors.initials: OG
authors.lastname: Nilsen
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D000504:Aloe / Q000737:chemistry*; D001692:Biological Transport; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival; D004077:Digoxin / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D008517:Phytotherapy; D028321:Plant Preparations / Q000494:pharmacology*; D011786:Quality Control; D014700:Verapamil / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D028321:Plant Preparations; D004077:Digoxin; D014700:Verapamil