Cell Biology and Toxicology

, Volume 28, Issue 6, pp 369–381 | Cite as

The effect of oxidative stress upon the intestinal uptake of folic acid: in vitro studies with Caco-2 cells

  • Mafalda R. Couto
  • Pedro Gonçalves
  • Telmo Catarino
  • João R. Araújo
  • Ana Correia-Branco
  • Fátima Martel
Original Research


Folic acid (FA) is a vitamin essential for normal cellular functions, growth, and development. Because humans cannot synthesize this micronutrient, it must be obtained from dietary sources through intestinal absorption. The intestinal tract is a major target for oxidative stress. Our aim was to investigate the effect of oxidative stress upon the uptake of FA by Caco-2 cells. Oxidative stress was induced by exposure of the cells to tert-butyl hydroperoxide (TBH) for 1 h. TBH (3,000 μM) induced an increase in biomarkers of oxidative stress, while maintaining cell viability and proliferation. In relation to the apical uptake of 3H-FA, TBH (3,000 μM) reduced the cellular accumulation of 3H-FA (10 nM), although the characteristics (kinetics, pH dependence, and inhibitory profile) of 3H-FA uptake were not changed. This effect was associated with a decrease in the mRNA steady-state levels of proton-coupled folate transporter and folate receptor alpha and of the efflux transporter multidrug resistance protein 2. Moreover, TBH (3,000 μM) did not affect the noncarrier-mediated apical uptake of 3H-FA. Finally, the effect of TBH upon 3H-FA apical uptake was not dependent on protein kinase A, protein kinase C, mitogen-activated protein kinases, phosphoinositide 3-kinase, nuclear factor kappa B, and protein tyrosine kinases, but was completely prevented by dietary polyphenols (resveratrol, quercetin, and EGCG). These results suggest that oxidative stress at the intestinal level may result in a reduction in the intestinal absorption of dietary FA and that polyphenolic dietary components may offer protection against oxidative stress-induced inhibition of intestinal FA absorption.


Folic acid Membrane transport Oxidative stress Polyphenols tert-butyl hydroperoxide 



This work was supported by FCT, COMPETE, QREN, and FEDER (PTDC/SAU-OSM/102239/2008). The authors wish to thank Prof. Maria João Pinho (Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal) for her help concerning MRP2 primer design and Dr. Joana Marques (Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal) for the donation of the β-actin primer pair.


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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Mafalda R. Couto
    • 1
  • Pedro Gonçalves
    • 1
  • Telmo Catarino
    • 1
  • João R. Araújo
    • 1
  • Ana Correia-Branco
    • 1
  • Fátima Martel
    • 1
  1. 1.Department of Biochemistry (U38-FCT), Faculty of MedicineUniversity of PortoPortoPortugal

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