Background: Red meat consumption is associated with an increased risk of colon cancer. Animal studies show that heme, found in red meat, promotes preneoplastic lesions in the colon, probably due to the oxidative properties of this compound. End products of lipid peroxidation, such as 4-hydroxynonenal metabolites or 8-iso-prostaglandin-F 2 A (8-iso-PGF 2 A), could reflect this oxidative process and could be used as biomarkers of colon cancer risk associated with heme intake. Methods: We measured urinary excretion of 8-iso-PGF 2 A and 1,4-dihydroxynonane mercapturic acid (DHN-MA), the major urinary metabolite of 4-hydroxynonenal, in three studies. In a short-term and a carcinogenesis long-term animal study, we fed rats four different diets (control, chicken, beef, and blood sausage as a high heme diet). In a randomized crossover human study, four different diets were fed (a 60 g/d red meat

Free radical reactions are involved in the pathogenesis of numerous diseases, so there is a real need to develop biomarkers that reflect these reactions in vivo. 4-Hydroxy-2-nonenal (HNE) is a major product of the lipid peroxidation process that is a consequence of free radical reactions. We present here the development and validation of an enzyme immunoassay (EIA) of the major urinary metabolite of HNE, namely 1,4-dihydroxynonane-mercapturic acid (DHN-MA). EIA allowed direct measurement of DHN-MA in rat urine with good sensitivity (0.02 ng/ml) and precision (intraassay CV = 5.7%). Recovery was complete (99-102%). Cross-reactivity was very low with 1,4-dihydroxynonene and with different mercapturic acids except with one other HNE urinary metabolite. Good correlation (EIA = 0.79 x LC/MS + 14.03, r = 0.877, p < 10(-8)) was obtained between EIA and liquid chromatography/mass spectrometry (LC/MS) quantitation when analyzing urine samples of rats with different oxidative status, due to treatment with either BrCCl(3) or trinitrobenzene sulfonic acid, which are known to induce hepatic lipid peroxidation or colon inflammation, respectively.

The objective of our study was to compare the information obtained through the use of three different urinary biomarkers of lipoperoxidation during the time course of a bromotrichloromethane (BrCCl3) induced oxidative stress in rats. These biomarkers were malondialdehyde (MDA) measured by LC/MS after derivatization, the isoprostane 8-iso-PGF2alpha measured by enzyme immunoassay and 1,4-dihydroxynonene mercapturic acid (DHN-MA), the major 4-hydroxynonenal urinary metabolite [1], measured by LC-MS. Male Wistar rats received a single dose of 100 microL/kg BrCCl3 per os and lipid peroxidation was estimated every day for a 4-day-period after treatment. MDA, 8-iso-PGF2alpha and DHN-MA significantly increased in response to BrCCl3 treatment for this period of time, and DHN-MA showed the main increase during the 24-48 h period after treatment.