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Open Access Research

Mn bioavailability by polarized Caco-2 cells: comparison between Mn gluconate and Mn oxyprolinate

Chiara Foglieni1, Mariangela Cavarelli1, Mariarosaria Piscopiello2, Alessandro Fulgenzi3 and Maria Elena Ferrero3*

Author Affiliations

1 Viral Evolution and Transmission Unit, San Raffaele Scientific Institute, Milan, Italy

2 INSPE, San Raffaele Scientific Institute, Milan, Italy

3 Department of Human Morphology "Città Studi", Università degli Studi di Milano, Milan, Italy

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Nutrition Journal 2011, 10:77  doi:10.1186/1475-2891-10-77

Published: 25 July 2011

Abstract

Background

Micronutrient inadequate intake is responsible of pathological deficiencies and there is a need of assessing the effectiveness of metal supplementation, frequently proposed to rebalance poor diets. Manganese (Mn) is present in many enzymatic intracellular systems crucial for the regulation of cell metabolism, and is contained in commercially available metal supplements.

Methods

We compared the effects of two different commercial Mn forms, gluconate (MnGluc) and oxyprolinate (MnOxP). For this purpose we used the polarized Caco-2 cells cultured on transwell filters, an established in vitro model of intestinal epithelium. Since micronutrient deficiency may accelerate mitochondrial efficiency, the mitochondrial response of these cells, in the presence of MnGluc and MnOxP, by microscopy methods and by ATP luminescence assay was used.

Results

In the presence of both MnOxP and MnGluc a sustained mitochondrial activity was shown by mitoTraker labeling (indicative of mitochondrial respiration), but ATP intracellular content remained comparable to untreated cells only in the presence of MnOxP. In addition MnOxP transiently up-regulated the antioxidant enzyme Mn superoxide dismutase more efficiently than MnGluc. Both metal treatments preserved NADH and βNADPH diaphorase oxidative activity, avoided mitochondrial dysfunction, as assessed by the absence of a sustained phosphoERK activation, and were able to maintain cell viability.

Conclusions

Collectively, our data indicate that MnOxP and MnGluc, and primarily the former, produce a moderate and safe modification of Caco-2 cell metabolism, by activating positive enzymatic mechanisms, thus could contribute to long-term maintenance of cell homeostasis.