Use of an in Vitro Digestion Model To Study the Bioaccessibility of 4-Hydroxy-2-nonenal and Related Aldehydes Present in Oxidized Oils Rich in Omega-6 Acyl Groups

Abstract

Mixtures of either sunflower oil or thermodegraded sunflower oil and a standard meal were submitted to an in vitro digestion model. The same experiment was carried out with fluid deep-frying fat and thermodegraded fluid deep-frying fat. The thermodegradation of the oil and fat was provoked by submitting them to 190 degrees C with aeration in a convection oven, and the presence in the headspace of the thermodegraded oil and fat of oxygenated alpha,beta-unsaturated aldehydes (OalphabetaUAs), such as 4-hydroxy-2-nonenal (HNE), 4-oxo-2-nonenal (ONE), and 4,5-epoxy-2-decenal (EDE), was monitored by solid phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS). The digestion products were separated by centrifugation in a lipidic phase, an aqueous phase, and a pellet phase. The headspace of these three phases was also studied by SPME/GC-MS to check if the toxic and very reactive OalphabetaUAs above-mentioned remained unaltered after the in vitro digestion process or if they had reacted with the various compounds present in the digestion products, so disappearing from the samples. With the same aim the extract in ethyl acetate of the aqueous and pellet phases, and of the lipidic phase after dilution, were studied by GC-MS. All results obtained showed that a certain proportion of the toxic OalphabetaUAs remains unaltered after digestion, dispersed in the three phases above-mentioned, and thus are bioaccessible in the gastrointestinal tract and so could reach the systemic circulation. Compounds that may originate in Maillard type reactions (2-pentylpyridine) are found among digestion products, proving that these reactions are possible in this process if adequate substrates are present. In addition, it has been shown that toxic metabolites from the synthetic antioxidant BHT, present in fat before digestion, remain unaltered after this process and could reach the systemic circulation.

2,6‐Di‐Tert‐Butyl‐Hydroxytoluene and Its Metabolites in Foods

“…Among the derived compounds generated, 5‐methyl‐7‐tert‐butyl‐2,2‐dimethyl‐2,3‐dihydrobenzo(b)furan, 2,6‐bis(1,1‐dimethylethyl)‐4‐methyl‐1‐methoxybenzene, TBP, and 2 dimeric derivatives, one of them being 2‐BHT, were tentatively identified by their mass spectra. It has to be noted that the spectra given by these authors to the 2 first compounds are very similar to those of BHT‐QM and BHT‐CHO (Fries and Püttmann ; Goicoechea and others ; Hernández and others ). The dimer 2‐BHT has also been detected in water (Fries and Püttmann ).…”

“…Although the changes undergone by BHT during in vivo digestion processes have not been studied, after submission of a fluid deep‐frying fat containing BHT and BHT‐QM to an in vitro gastrointestinal digestion model, both these were detected in the digested samples (Goicoechea and others ). These results indicate that BHT and its toxic metabolite could remain bioaccessible for intestinal absorption.…”

Usefulness of 1H NMR in assessing the extent of lipid digestion

“…Digestion experiments were carried out following the in vitro digestion model described by Versantvoort et al (2005), already employed in some previous studies (Goicoechea, Brandon, Blokland, & Guillén, 2011;Goicoechea et al, 2008). This model implies a three-step procedure which simulates digestive processes in the mouth, stomach, and small intestine by sequentially adding the corresponding digestive juices.…”

“…In recent years a great deal of attention has been paid to food digestion processes and to the estimation, by means of in vitro digestion models, of the bioaccessibility and bioavailability of certain compounds which are either toxic or beneficial for human health (Colle, Van Buggenhout, Lemmens, Van Loey, & Hendrickx, 2012;Goicoechea et al, 2008;Versantvoort, Oomen, Van de Kamp, Rompelberg, & Sips, 2005). In fact, for ethical, practical and economic reasons, in vitro approaches have emerged as powerful tools when studying the physico-chemical events that take place within the gastrointestinal tract, at least as an initial screening step (Hur, Lim, Decker, & McClements, 2011).…”

Signaling by 4-hydroxy-2-nonenal: Exposure protocols, target selectivity and degradation

“…In addition, cells/organisms may be exposed to HNE from food. HNE produced from dietary polyunsaturated fatty acids during food processing and storage [8, 9] could result in exposure of cells in the gestrointestinal tract and possibly enter circulation [10] (Fig.1). HNE features two functional groups, its carbonyl (−HC=O) and double bond (C2/C3, −C=C-) groups.…”