Metabolism and Distribution of [2,3-¹⁴C]Acrolein in Sprague-Dawley Rats

Abstract

The metabolites of [2,3-14C]acrolein in the urine and feces of Sprague-Dawley rats were identified after either intravenous administration in saline at 2.5 mg/kg or oral administration by gavage as an aqueous solution as either single or multiple doses at 2.5 mg/kg or as a single dose of 15 mg/kg. Selected urine and feces samples were pooled by sex and collection interval and profiled by combinations of reverse-phase, anion-exchange, cation-exchange, and ion-exclusion high-performance liquid chromatography (HPLC). Feces were also profiled by size-exclusion chromatography. Metabolites were identified by comparison with well-characterized standards by HPLC and by mass spectrometry. The urinary metabolites were identified as oxalic acid, malonic acid, N-acetyl-S-2-carboxy-2-hydroxyethylcysteine, N-acetyl-S-3-hydroxypropylcysteine, N-acetyl-S-2-carboxyethylcysteine, and 3-hydroxypropionic acid. The fecal radioactivity from the oral dose groups was partitioned into methanol-soluble, water-soluble, and insoluble radioactivity, some of which could be liberated by dilute acid hydrolysis. HPLC analysis of these extracts revealed no discrete metabolites. Size-exclusion chromatography indicated a molecular weight range of 2,000 to 20,000 Da for the radioactivity, which was unaffected by hydrolysis at reflux with 6 M acid or base. This radio-activity was thought to be a homopolymer of acrolein, which was apparently formed in the gastrointestinal tract. The pathways of acrolein metabolism were epoxidation followed by conjugation with glutathione, Michael addition of water followed by oxidative degradation, and glutathione addition to the double bond either following or preceding oxidation or reduction of the aldehyde. The glutathione adducts were further metabolized to the mercapturic acids.

Toxicology and risk assessment of acrolein in food

“…The tissue contents (measured as radioactivity) were minimal (o1.2%). They were higher after intravenous administration [3].…”

Acrolein scavengers: Reactivity, mechanism and impact on health

“…The conjugated ACR-GSH is then further metabolized by mitochondrial and cytosolic aldehyde and alcohol dehydrogenase to form novel metabolites. One of the major metabolites has been identified as 3-hydroxypropylmercapturic acid (3-HPMA) in laboratory animals [41,42] and in urine of cigarette smokers [43]. However, the reports of application of exogenous GSH as an approach to counteract ACR are scarce.…”

Metabolic fate of endogenous molecular damage: Urinary glutathione conjugates of DNA-derived base propenals as markers of inflammation

“…This scenario seems unlikely given our observations that 3a-d appeared only for Tp, 3e increased significantly with Tp administration and 3e increased significantly following treatment with bleomycin, an agent that is highly specific for cleaving DNA to produce base propenals (26). The background production of 3e is unlikely to involve malondialdehyde or acrolein, because malondialdehyde is metabolized mainly to CO 2 (35,36), whereas acrolein is mainly excreted as the monoacetylcysteine adduct in vivo (37,38). Even if malondialdehyde metabolism to CO 2 is not quantitative, malondialdehyde does not form GSH conjugates under biologically relevant conditions (39), due to a nonelectrophilic beta-carbon caused by resonance effects with the adjacent oxyanion and the fact that the oxyanion is a very poor leaving group (39).…”