Development of a 32P-Postlabeling Method for the Detection of 1,N^2-Propanodeoxyguanosine Adducts of 2-Hexenal in Vivo

2-Hexenal is an (alfa,beta)-unsaturated carbonyl compound which forms cyclic 1,N^2-propano adducts in vitro. The adduct formation in vivo was not reported by others to date. Because this type of adduct is considered promutagenic (2-hexenal is actually mutagenic and genotoxic) and humans are permanently exposed to this compound via vegetarian food, 2-hexenal may play a role in carcinogenicity. To improve the cancer risk assessment, we developed a new 32P-postlabeling technique for this compound and optimized the different steps of the postlabeling procedure. The results of the postlabeling methods are shown. A labeling efficiency of 35%, a recovery of 10% for the synthesized standards, and a detection limit of three 2-hexenal adducts per 10^8 nucleotides was achieved. After gavage of 500 mg/kg of body weight to male Fischer 344 rats, the respective DNA adducts were detected in rat liver DNA. With this study, we demonstrate in vivo adduct formation of 2-hexenal for the first time. Highest adduct levels were found 2 days after gavage, and after 4 days, the level was even higher than after I day. No adducts were detected 8 h after gavage. The respective adducts could not be found as a background in tissues of untreated rats or in calf thymus DNA at the limit of detection.