Document Detail


Ascorbic acid offsets the inhibitory effect of bioactive dietary polyphenolic compounds on transepithelial iron transport in Caco-2 intestinal cells.
MedLine Citation:
PMID:  21430251     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We previously reported that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) at high concentration nearly blocked intestinal iron transport across the enterocyte. In this study, we aimed to determine whether small amounts of EGCG, GSE, and green tea extract (GT) are capable of inhibiting iron absorption, to examine if ascorbic acid counteracts the inhibitory action of polyphenols on iron absorption, and to explore the mechanisms of polyphenol-mediated apical iron uptake and basolateral iron release. An(55)Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT using Caco-2 intestinal cells. Polyphenols were found to inhibit the transepithelial (55)Fe transport in a dose-dependent manner. The addition of ascorbic acid offset the inhibitory effects of polyphenols on iron transport. Ascorbic acid modulated the transepithelial iron transport without changing the apical iron uptake and the expression of ferroportin-1 protein in the presence of EGCG. The polyphenol-mediated apical iron uptake was inhibited by membrane impermeable Fe(2+) chelators (P < 0.001), but at a low temperature (4°C), the apical iron uptake was still higher than the control values at 37°C (P < 0.001). These results suggest that polyphenols enhance the apical iron uptake partially by reducing the conversion of ferric to ferrous ions and possibly by increasing the uptake of polyphenol-iron complexes via the energy-independent pathway. The present results indicate that the inhibitory effects of dietary polyphenols on iron absorption can be offset by ascorbic acid. Further studies are needed to confirm the current findings in vivo.
Authors:
Eun-Young Kim; Soo-Kyung Ham; Daniel Bradke; Qianyi Ma; Okhee Han
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2011-03-23
Journal Detail:
Title:  The Journal of nutrition     Volume:  141     ISSN:  1541-6100     ISO Abbreviation:  J. Nutr.     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-04-21     Completed Date:  2011-07-18     Revised Date:  2013-06-30    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  828-34     Citation Subset:  IM    
Affiliation:
Department of Nutritional Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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MeSH Terms
Descriptor/Qualifier:
Ascorbic Acid*
Biological Transport / drug effects
Caco-2 Cells
Catechin / adverse effects,  analogs & derivatives,  antagonists & inhibitors,  metabolism
Cation Transport Proteins / metabolism
Cell Polarity
Cold Temperature
Diet / adverse effects*
Dietary Supplements / adverse effects
Enterocytes / drug effects,  metabolism*
Flavonoids / adverse effects*,  antagonists & inhibitors,  metabolism
Grape Seed Extract / adverse effects,  antagonists & inhibitors,  metabolism
Humans
Intestinal Absorption*
Iron Chelating Agents / pharmacology
Iron Radioisotopes
Iron, Dietary / metabolism*
Oxidation-Reduction
Phenols / adverse effects*,  antagonists & inhibitors,  metabolism
Plant Extracts / adverse effects,  antagonists & inhibitors,  metabolism
Polyphenols
Tea / chemistry
Grant Support
ID/Acronym/Agency:
R21 AT005006-01A1/AT/NCCAM NIH HHS; R21AT005006/AT/NCCAM NIH HHS
Chemical
Reg. No./Substance:
0/Cation Transport Proteins; 0/Flavonoids; 0/Grape Seed Extract; 0/Iron Chelating Agents; 0/Iron Radioisotopes; 0/Iron, Dietary; 0/Phenols; 0/Plant Extracts; 0/Polyphenols; 0/Tea; 0/metal transporting protein 1; 154-23-4/Catechin; 50-81-7/Ascorbic Acid; BQM438CTEL/epigallocatechin gallate
Comments/Corrections

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