Caco-2 cell methodology and inhibition of the P-glycoprotein transport of digoxin by Aloe vera juice

Phytother Res. 2008 Dec;22(12):1623-8. doi: 10.1002/ptr.2536.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / antagonists & inhibitors
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / drug effects
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • Aloe / chemistry*
  • Biological Transport
  • Caco-2 Cells
  • Cell Membrane Permeability / drug effects
  • Cell Survival
  • Digoxin / metabolism*
  • Humans
  • Models, Biological
  • Phytotherapy
  • Plant Preparations / pharmacology*
  • Quality Control
  • Verapamil / pharmacology


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Plant Preparations
  • Digoxin
  • Verapamil