Acute and chronic effects of some dietary bioactive compounds on folic acid uptake and on the expression of folic acid transporters by the human trophoblast cell line BeWo Elisa Keating 4 , Clara Lemos, Pedro Gonc ¸alves, Fa ´tima Martel Department of Biochemistry (U38-FCT), Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal Received 12 June 2006; received in revised form 12 January 2007; accepted 17 January 2007 Abstract Folic acid (FA) is a vitamin that acts as a coenzyme in the biosynthesis of purine and pyrimidine precursors of nucleic acids, which are critically important during pregnancy. Our group has previously shown that both reduced folate carrier (RFC1) and folate receptor a (FRa) seem to be involved in the uptake of [ 3 H]folic acid ([ 3 H]FA) by a human trophoblast cell line (BeWo) and by human primary cultured cytotrophoblasts. Our aim was to study the interaction between FA and some nutrients/bioactive substances. For this, we tested the acute and chronic effects of some dietary compounds on [ 3 H]FA apical uptake and on the expression of both RFC1 and FRa mRNA in BeWo cells. Our results show that [ 3 H]FA uptake was significantly reduced by acute exposure to epicatechin, isoxanthohumol (1–400 AM) or theophylline (0.1– 100 AM); isoxanthohumol seemed to act as a competitive inhibitor, whereas epicatechin and theophylline caused an increase in both K m and V max . On the other hand, [ 3 H]FA uptake was significantly increased by chronic exposure to xanthohumol, quercetin or isoxanthohumol (0.1– 10 AM), and this increase does not seem to result from changes in the level of RFC1 or FRa gene expression. Moreover, [ 3 H]FA uptake was significantly reduced by chronic exposure to ethanol (0.01%). This reduction seems to be, at least in part, due to a reduction in FRa expression. These results are compatible with an association between a deficient FA supply to the placenta/fetus and ethanol toxicity in pregnancy. D 2008 Elsevier Inc. All rights reserved. Keywords: Folic acid; Reduced folate carrier; Folate receptor; Ethanol; Polyphenols; Methylxanthines 1. Introduction Folic acid (pteroylglutamate; FA) is the parent structure of a large family of B-vitamin coenzymes known as folates. Various coenzymes of FA facilitate the transfer of one- carbon units in reactions leading to the synthesis of methionine, thymidine and purine nucleotides, which are crucial in processes such as cell division. For this reason, FA is critically important for normal fetal development during pregnancy, as demonstrated by the well-established associ- ation between maternal FA deficiency and pregnancy complications such as preeclampsia [1,2] and a higher incidence of fetal neural tube defects (NTDs) [1]. Peri- conceptional supplementation with FA is now widely accepted as a strategy for reducing the risk of NTDs [3–5]. Knowing that FA in food or supplementation is ingested together with other nutrients and bioactive substances and that the developing fetus obtains FA from the maternal blood through the placenta, it is of major importance to study the interactions between FA and those nutrients/substances that may improve or inhibit FA absorption at the placental level. So, our aim was to determine the effect of bioactive substances present in alcoholic and nonalcoholic beverages on FA placental uptake by testing the acute and chronic effects of these substances on [ 3 H]folic acid ([ 3 H]FA) uptake by BeWo cells. One of the substances tested was ethanol because it is the most frequently used drug worldwide [6] and its consump- tion is not uncommon during pregnancy. For example, in the United States, between the years 2003 and 2004, 11% of pregnant women aged 15–44 years reported alcohol use and 4.5% reported binge drinking during the prior month. Nevertheless, heavy alcohol use was relatively rare (0.5%) among pregnant women [7,8]. Among the wide variety of 0955-2863/$ – see front matter D 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jnutbio.2007.01.007 4 Corresponding author. Department of Biochemistry, Faculty of Medicine, 4200-319 Porto, Portugal. Tel.: +351 22 551 36 24; fax: +351 22 551 36 24. E-mail address: keating@med.up.pt (E. Keating). Journal of Nutritional Biochemistry 19 (2008) 91 – 100 Available online at www.sciencedirect.com