Investigation of Nicotianamine and 2' Deoxymugineic Acid as Enhancers of Iron Bioavailability in Caco-2 Cells.

Jesse T Beasley,Alexander A T Johnson,Jonathan J Hart,Raymond P Glahn,Elad Tako

doi:10.3390/nu11071502

Jesse T Beasley, Alexander A T Johnson + Show 3 more

Open Access

https://doi.org/10.3390/nu11071502

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Abstract

Nicotianamine (NA) is a low-molecular weight metal chelator in plants with high affinity for ferrous iron (Fe2+) and other divalent metal cations. In graminaceous plant species, NA serves as the biosynthetic precursor to 2′ deoxymugineic acid (DMA), a root-secreted mugineic acid family phytosiderophore that chelates ferric iron (Fe3+) in the rhizosphere for subsequent uptake by the plant. Previous studies have flagged NA and/or DMA as enhancers of Fe bioavailability in cereal grain although the extent of this promotion has not been quantified. In this study, we utilized the Caco-2 cell system to compare NA and DMA to two known enhancers of Fe bioavailability—epicatechin (Epi) and ascorbic acid (AsA)—and found that both NA and DMA are stronger enhancers of Fe bioavailability than Epi, and NA is a stronger enhancer of Fe bioavailability than AsA. Furthermore, NA reversed Fe uptake inhibition by Myricetin (Myr) more than Epi, highlighting NA as an important target for biofortification strategies aimed at improving Fe bioavailability in staple plant foods.

Highlights

Iron (Fe) possesses unique redox properties that are critical to fundamental biological processes such as cellular respiration and photosynthesis [1]
These results demonstrate that NA > deoxymugineic acid (DMA) > Epi in the promotion of Fe uptake into Caco-2 cells
As ferritin formation was similar in the ‘Fe control’ at both 4 μM and 40 μM, it is likely that maximum Fe solubility is exceeded somewhere between 4 μM and 40 μM Fe in the absence of any Fe bioavailability enhancer (Figures 1 and 2)

Summary

Introduction

Iron (Fe) possesses unique redox properties that are critical to fundamental biological processes such as cellular respiration and photosynthesis [1]. Fe is largely unavailable for plant uptake under aerobic or calcisol (high pH) conditions (representing ~30% of arable land), due to the formation of insoluble ferric (Fe3+ ) ion precipitates [2]. As well as negatively impacting on plant growth, inadequate plant Fe uptake translates to human Fe deficiency, as plants provide a major gateway for Fe into human food systems [3]. Plants have evolved sophisticated mechanisms to absorb. Non-graminaceous plants such as common bean (Phaseolus vulgaris L.) reduce soil Fe3+ ions to the more soluble ferrous (Fe2+ ) form for uptake into plant roots [4]. Graminaceous plants such as bread wheat (Triticum aestivum L.)

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