A Benchmark analysis of acrylamide-derived DNA adducts in rat hepatocytes in culture measured by a new, highly sensitive method.

Acrylamide (AA) is a carcinogen formed during thermal food processing and can cause tumors in rodents while its carcinogenic potency in humans is unclear. Metabolism of AA, preferentially in the liver, leads to glycidamide (GA) forming N7-GA-guanine (N7-GA-Gua) as the major AA-derived DNA adduct in rodents. Here, a novel method allowing high sensitivity by avoidance of major matrix effects was applied to analyze N7-GA-Gua levels in nuclear DNA from rat hepatocytes in primary culture. We could thus for the first time detect a background level of 5-10 adducts/108 nucleosides in untreated hepatocytes. Incubation with AA did not result in a statistically significant increase in adduct levels over background up to a substrate concentration of 500 µM although a trend to slightly higher adduct levels was observed at and above 200 µM AA. At concentrations > 500 µM significant increases in N7-GA-Gua levels were found. When Benchmark concentration (BMC) modeling was applied to the data, non-linear concentration-response curves were obtained suggesting that AA started to cause measurable increases over background of N7-GA-Gua levels above certain concentrations only. Calculation of the composite BMCL10 (Lower Bound of a 95 % confidence interval) of a BMC leading to a 10 % increase of N7-GA-Gua levels over background resulted in a value of 6.35 µM AA after 24 h. A concentration below this value cannot be expected to lead to an increase in N7-GA-Gua of more than 10 % over the background seen in untreated hepatocytes.

Acrylamide-derived DNA adducts in human peripheral blood mononuclear cell DNA: Correlation with body mass.

Acrylamide (AA) is a carcinogen formed during thermal food processing and can cause tumors in rodents while its carcinogenic potency in humans is unclear. Metabolic conversion of AA leads to glycidamide (GA) forming N7-GA-guanine (N7-GA-Gua) as the major DNA adduct in rodents while no such adducts were found in human tissues so far. In a cohort of 56 healthy volunteers adduct levels were determined in peripheral blood mononuclear cell (PBMC) DNA and anthropometric, dietary, and biochemical parameters were measured or inquired using a questionnaire. In the majority of PBMC DNA samples the levels found were above one adduct/108 nucleosides not being correlated to dietary habits including coffee consumption, or to blood glucose levels or hemoglobin HbA1c. However, adduct levels were significantly correlated with the body mass index (BMI) and showed a continuous increase over three BMI classes. Our findings indicate a background of AA-derived DNA adducts present in humans in PBMC related to body mass rather than to certain dietary or lifestyle factors.

Crystal structure of glycidamide: the mutagenic and genotoxic metabolite of acryl-amide.

The title compound, glycidamide (systematic name: oxirane-2-carboxamide), C3H5NO2, is the mutagenic and genotoxic metabolite of acryl-amide, a food contaminant and industrial chemical that has been classified as being probably carcinogenic to humans. Synthesized via the reaction of acrylo-nitrile and hydrogen peroxide, it crystallizes with both enanti-omers occurring as two crystallographically independent mol-ecules (A and B) in the asymmetric unit. They have similar conformations with an r.m.s. deviation of 0.0809 Šfor mol-ecule B inverted on mol-ecule A. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, which lead to the formation of ß-sheet structures enclosing R 2 (2)(8) and R 4 (2)(8) loops. The ß-sheets are linked by weaker C-H⋯O hydrogen bonds, forming a supra-molecular three-dimensional structure.