Original Paper Pharmacology	Planta Med 2007; 73: 27-32 DOI: 10.1055/s-2006-951745
© Georg Thieme Verlag KG Stuttgart · New York
Inhibition of Folic Acid Uptake by Catechins and Tea Extracts in Caco-2 Cells
N. Ceren Alemdaroglu1, Siegfried Wolffram2, Jean-Paul Boissel3, Ellen Closs3, Hildegard Spahn-Langguth4, Peter Langguth1
1 Institute of Pharmacy, Johannes Gutenberg-University, Mainz, Germany 2 Institute of Animal Nutrition and Physiology, University of Kiel, Kiel, Germany 3 Department of Pharmacology, Johannes Gutenberg-University, Mainz, Germany 4 Faculty of Pharmacy and Biotechnology, German University in Cairo (GUC), New Cairo City, Egypt

Abstract

In this present study it was aimed to determine whether the catechins contained in green tea and the whole extracts of Camellia sinensis (Theaceae) inhibit the uptake of folic acid by Caco-2 cell monolayers. Our results indicate that (-)-epigallocatechin 3-gallate (EGCG) and (-)-epicatechin 3-gallate (ECG) inhibit cellular folic acid uptake with IC₅₀ values of 34.8 μmol/L and 30.8 μmol/L, respectively. Furthermore, green and black tea extracts were also found to inhibit folic acid uptake with IC₅₀ values of approximately 7.5 and 3.6 mg/mL, respectively. According to these results, simultaneous intake of tea and folic acid may inhibit intestinal folic acid absorption. The consequences with respect to the folate status of the body will need to be examined in vivo.

Abbreviations

EGCG:(-)-epigallocatechin-3-gallate

ECG:(-)-epicatechin-3-gallate

EGC:(-)-epigallocatechin

EC:(-)-epicatechin

MTX:methotrexate

DHFR:dihydrofolate reductase

RFC:reduced folate carrier

FRα:folate receptor alpha

FRβ:folate receptor beta

Key words

Camellia sinensis - Theaceae - folic acid - tea - catechin - uptake