Elisabet Fernández-García

Developing an emulsifier system to improve the bioaccessibility of carotenoids.

Food emulsion designs, with the aim of delivering lipophilic bioactive compounds, should include an estimate of their bioaccessibility to support the claimed effect. With this goal in mind, in vitro digestion models and experimental design of mixtures were used as analytical tools to measure this parameter and to optimize the formulation of an O/W emulsion, including carotenoids as functional ingredients. Two experimental stages were applied. First, a screening phase was completed to detect the critical factors that exerted a significant effect on the response (bioaccessibility). During this phase, we observed that the response was modified mainly by secondary effects such as synergies and antagonisms of the emulsifying mixture. A group of four emulsifiers was selected at this phase to perform the second experimental stage, the optimization phase. This allowed us to obtain the mixture that produced the maximum carotenoid bioaccessibility. This formulation had emulsifying properties of the liposugars, acyl- and polyacyl-glycerides, as well as the synergistic effect arising from the combination of materials; this maximized the response. The analytical approach applied in this work is of interest for food designers for screening and controlling the bioaccessibility of bioactive compounds in a given matrix and, consequently, selecting the formulation conditions for higher bioaccessibilities.

Manganese Redistribution by Calcium-stimulated Vesicle Trafficking Bypasses the Need for P-type ATPase Function

Background: Yeast is a model system for the study of mechanisms governing eukaryotic Golgi-Mn2+ homeostasis. Results: We provide evidence that calcium stimulates ER and late endosome/trans- to cis-Golgi manganese delivery and bypasses the need for Pmr1. Conclusion: Vesicle trafficking promotes organelle-specific ion interchange and cytoplasmic metal detoxification. Significance: Our findings open new perspectives on chemical modifiers of Hailey-Hailey disease. Regulation of intracellular ion homeostasis is essential for eukaryotic cell physiology. An example is provided by loss of ATP2C1 function, which leads to skin ulceration, improper keratinocyte adhesion, and cancer formation in Hailey-Hailey patients. The yeast ATP2C1 orthologue PMR1 codes for a Mn2+/Ca2+ transporter that is crucial for cis-Golgi manganese supply. Here, we present evidence that calcium overcomes the lack of Pmr1 through vesicle trafficking-stimulated manganese delivery and requires the endoplasmic reticulum Mn2+ transporter Spf1 and the late endosome/trans-Golgi Nramp metal transporter Smf2. Smf2 co-localizes with the putative Mn2+ transporter Atx2, and ATX2 overexpression counteracts the beneficial impact of calcium treatment. Our findings suggest that vesicle trafficking promotes organelle-specific ion interchange and cytoplasmic metal detoxification independent of calcineurin signaling or metal transporter re-localization. Our study identifies an alternative mode for cis-Golgi manganese supply in yeast and provides new perspectives for Hailey-Hailey disease treatment.

In Vitro Intestinal Absorption of Carotenoids Delivered as Molecular Inclusion Complexes with β-Cyclodextrin Is Not inhibited by High-Density Lipoproteins

This study analyzed the assimilation efficiency of carotenoids when they are delivered as inclusion complexes with beta-cyclodextrin (CyDIC) in water. The in vitro assimilation model used was the brush border membrane vesicles (BBMV) system in which the BBMVs were incubated with CyDIC. Carotenoid suspensions in Tween were used as a reference. Regardless of the form in which the carotenoids were delivered to the BBMV preparation, a higher assimilation efficiency was observed for carotenes than for the xanthophyll lutein. At the highest donor solution concentration, supplying carotenoids in CyDIC produced a significant increase in carotenoid assimilation compared to the corresponding carotenoid suspensions in Tween. The assimilation process using CyDIC takes place by means of a dissociation process in which the carotenoids are released from the beta-cyclodextrin to later be assimilated. At the highest concentration of CyDIC in the donor solution, the dissociation equilibrium will be shifted toward the free forms of the complex, thus increasing the amount of carotenoids available for assimilation. In another set of experiments, the effect of high-density lipoproteins as activity inhibitors for the receptors involved in carotenoid assimilation was analyzed. In carotenoid suspensions in Tween, with an inhibitor, a significant decrease in the assimilated quantity compared was observed with values reached without the inhibitor. Lutein presented the most significant decrease (70%). The fact that complete inhibition was not reached suggests that both simple and facilitated diffusion contributes to the assimilation process. When the donor solution composed of CyDIC and inhibitor was added, significant increases were observed in beta-carotene and lycopene assimilation for all concentrations and in lutein for the highest concentration. This effect is due to the exchange between lipoprotein lipid components and CyDIC, which promotes the dissociation and liberation processes of the carotenoid, which then becomes available for assimilation.