Metabolic pathways of 1-butyl [3-13C]acrylate. Identification of urinary metabolites in rat using nuclear magnetic resonance and mass spectroscopy

Biotransformation of acrylates. Excretion of mercapturic acids and changes in urinary carboxylic acid profile in rat dosed with ethyl and 1-butyl acrylate

1. The excretion of urinary metabolites was studied in rat dosed intraperitoneally with ethyl acrylate and 1-butyl acrylate. 2. Physiological carboxylic acids, namely, 3-hydroxypropanoic acid, lactic acid and acetic acid were determined by hplc and may be derived from the xenobiotic acrylates. 3. A significant increase in the amounts of 3-hydroxypropanoic acid and acetic acid excreted within 24 h after dosing was found in both the ethyl acrylate and 1-butyl acrylate-exposed rats. 4. A slight increase in the excretion of lactic acid (p < 0.10) was also found in animals exposed to ethyl and 1-butyl acrylates. 5. Two mercapturic acids, N-acetyl-S-(2-carboxyethyl)cysteine and the corresponding N-acetyl-S-[(2-alkoxycarbonyl)ethyl]cysteine were formed from both acrylate esters and were determined by glc. For ethyl acrylate the conversion to mercapturic acids amounted to 11% of the administered dose, whereas for 1-butyl acrylate the corresponding conjugates decreased from 3.6% to 0.5 mmol/kg to 1.6% at 3.0 mmol/kg. 6. Mercapturic acids appear to be potential biological markers of exposure to acrylate esters. However, more sensitive methods would be required for their determination than those available at present.