“Twin peaks”: Searching for 4-hydroxynonenal urinary metabolites after oral administration in rats

Abstract

4-Hydroxynonenal (HNE) is a cytotoxic and genotoxic lipid oxidation secondary product which is formed endogenously upon peroxidation of cellular n-6 fatty acids.However, it can also be formed in food or during digestion, upon peroxidation of dietary lipids. Several studies have evidenced that we are exposed through food to significant concentrations of HNE that could pose a toxicological concern. It is then of importance to known how HNE is metabolized after oral administration. Although its metabolism has been studied after intravenous administration in order to mimick endogenous formation, its in vivo fate after oral administration had never been studied.In order to identify and quantify urinary HNE metabolites after oral administration in rats, radioactive and stable isotopes of HNE were used and urine was analyzed by radio-chromatography (radio-HPLC) and chromatography coupled with High Resolution Mass Spectrometry (HPLC–HRMS).Radioactivity distribution revealed that 48% of the administered radioactivity was excreted into urine and 15% into feces after 24 h, while 3% were measured in intestinal contents and 2% in major organs, mostly in the liver. Urinary radio-HPLC profiles revealed 22 major peaks accounting for 88% of the urinary radioactivity. For identification purpose, HNE and its stable isotope [1,2-13C]-HNE were given at equimolar dose to be able to univocally identify HNE metabolites by tracking twin peaks on HPLC–HRMS spectra. The major peak was identified as 9-hydroxy-nonenoic acid (27% of the urinary radioactivity) followed by classical HNE mercapturic acid derivatives (the mercapturic acid conjugate of di-hydroxynonane (DHN-MA), the mercapturic acid conjugate of 4-hydroxynonenoic acid (HNA-MA) in its opened and lactone form) and by metabolites that are oxidized in the terminal position. New urinary metabolites as thiomethyl and glucuronide conjugates were also evidenced. Some analyses were also performed on feces and gastro-intestinal contents, revealing the presence of tritiated water that could originate from beta-oxidation reactions.

Formation of 4‐Hydroxy‐2‐Trans‐Nonenal, a Toxic Aldehyde, in Thermally Treated Olive and Sunflower Oils

“…It accumulates in the body and is difficult to remove (Esterbauer, Schaur, & Zollner, 1991). Keller, Baradat, Jouanin, Debrauwer, and Guéraud (2015) used radiolabeled HNE to track the HNE metabolism in rats after oral administration. It was reported that HNE originating from the diet was metabolized in vivo and incorporated into the cecum, liver, small intestine, colon, kidneys, stomach, and also into the brain and heart.…”

4-Hydroxynonenal (HNE), a Toxic Aldehyde in Fried Chicken from Fast Food Restaurants and a Grocery Store

“…These products include various lipophilic aldehydes such as alkanals, alkenals, alkadienals and hydroxyalkenals and these compounds are readily absorbed from the diet [10] [11] [12] [13]. One class of aldehydes, the toxic 4-hydroxyalkenals, generated from lipid peroxidation of unsaturated FA are of special importance because of their reactivity to biomolecules [14] [15]. The cytotoxicity of 4-hydroxynonenal (HNE) [16] has been found to be formed from the oxidation of n-6 FA, including linoleic acid [12] [15] [17] which is high in polyunsaturated fatty acids (PUFA).…”

A Diet with 3% of Energy from a Mixture of Omega-3 Fatty Acids Significantly Increases <i>in Vivo</i> Lipid Peroxidation in Postmenopausal Women

“…The work of Esterbauer and colleagues established that such 4-hydroxyalkenals were highly reactive and could bind with most amino acids, and that HNE had been implicated in the etiology of atherosclerosis, diabetes, and neurodegenerative diseases [2]- [4]. In addition to vitamin E deficiency and impaired endogenous antioxidant systems, a diet high in PUFA would be expected to increase total lipid peroxidation within an organism [5]- [9]. Previous research from our laboratory demonstrated that heating methyl linolenate, formed from the omega-3 (n − 3) PUFA α-linolenic acid (ALA, 18:3 n − 3), yielded detectable quantities of HHE [10], but limited human research had documented its production via in vivo lipid peroxidation following n − 3 consumption [11].…”