Excretion of 2,3-dihydroxy-propionamide (OH-PA), the hydrolysis product of glycidamide, in human urine after single oral dose of deuterium-labeled acrylamide.

A dose of 0.99 mg d(3)-acrylamide (d(3)-AA) (13.2 µg/kg body weight) was ingested by a healthy male volunteer. Urine samples were collected over a period of 46 h after the intake and analyzed for the hydrolysis product of glycidamide (GA), 2,3-dihydroxy-propionamide (OH-PA), a metabolite of the toxicologically relevant oxidative AA metabolism pathway; 5.4% of the administered d(3)-AA dose was eliminated as OH-PA within 46 h after ingestion. Therefore, OH-PA represents a major metabolite of the oxidative metabolism pathway. Elimination kinetics of OH-PA is similar to the oxidative metabolites N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-cysteine (GAMA) and N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-cysteine (iso-GAMA). The major excretion of d(3)-OH-PA took place between 8 and 22 h with the highest urinary d(3)-OH-PA concentration (c (max)) of 69.3 µg/L urine, 18 h (t (max)) postdose. OH-PA (5.4%), together with the other known urinary metabolites of the oxidative pathway GAMA (4.6%) and iso-GAMA (0.8%), represents 10.8% of the total AA dose. The share of the oxidative pathway metabolites is much smaller than the share of the reductive pathway metabolite N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA) that represents 51.7% of the ingested d(3)-AA dose. However, this new quantitative human data on OH-PA together with the previous data on the other oxidative pathway metabolites are of special importance when evaluating the carcinogenic potential of AA and when comparing human data with data from animal studies.

N-Acetyl-S-(1-carbamoyl-2-hydroxy-ethyl)-L-cysteine (iso-GAMA) a further product of human metabolism of acrylamide: comparison with the simultaneously excreted other mercaptuic acids.

The N-acetyl-S-(1-carbamoyl-2-hydroxy-ethyl)-L: -cysteine (iso-GAMA) could be identified as a further human metabolite of acrylamide. In this study, we report the excretion of d(3)-iso-GAMA in human urine after single oral administration of deuterium labelled acrylamide (d(3)-AA). One healthy male volunteer ingested a dose of about 1 mg d(3)-AA which is equivalent to a dose of 13 microg/kg bodyweight. Over a period of 46 h the urine was collected and the d(3)-iso-GAMA levels analysed by LC-ESI-MS/MS. The excretion of iso-GAMA begins five hours after application. It rises to a maximum concentration (c (max)) of 43 microg/l which was quantified in the urine excreted after 22 h (t (max)). The excretion pattern is parallel to that of the major oxidative metabolite N-acetyl-S-(2-carbamoyl-2-hydroxy-ethyl)-L-cysteine (GAMA). Total recovery of iso-GAMA was about 1% of the applied dose. Together with N-acetyl-S-(2-carbamoylethyl)-L: -cysteine (AAMA) and GAMA, 57% of the applied dose is eliminated as mercapturic acids. The elimination kinetics of the three mercapturic acids of AA are compared. We show that dietary doses of acrylamide (AA) cause an overload of detoxification via AAMA and lead to the formation of carcinogenic glycidamide (GA) in the human body.

Hemoglobin adducts and mercapturic acid excretion of acrylamide and glycidamide in one study population.

The aim of this study was to determine the relationship between the oxidative and reductive metabolic pathways of acrylamide (AA) in the nonsmoking general population. For the first time both the blood protein adducts and the urinary metabolites of AA and glycidamide (GA) were quantified in an especially designed study group with even distribution of age and gender. The hemoglobin adducts N-carbamoylethylvaline (AAVal) and N-( R, S)-2-hydroxy-2-carbamoylethylvaline (GAVal) were detected by GC-MS/MS in all blood samples with median levels of 30 and 34 pmol/g of globin, respectively. Concentrations ranged from 15 to 71 pmol/g of globin for AAVal and from 14 to 66 pmol/g of globin for GAVal. The ratio GAVal/AAVal was 0.4-2.7 (median = 1.1). The urinary metabolites were determined by LC-MS/MS. Of all urine samples examined 99% of N-acetyl- S-(2-carbamoylethyl)- l-cysteine (AAMA) levels and 73% of N-( R/ S)-acetyl- S-(2-carbamoyl-2-hydroxyethyl)- l-cysteine (GAMA) levels were above the LOD (1.5 microg/L). Concentrations ranged from