Reducing Compounds Equivocally Influence Oxidation during Digestion of a High-Fat Beef Product, which Promotes Cytotoxicity in Colorectal Carcinoma Cell Lines

We studied the formation of malondialdehyde, 4-hydroxy-nonenal, and hexanal (lipid oxidation products, LOP) during in vitro digestion Of a cooked low-fat and high-fat beef product in response to the addition of reducing compounds. We also investigated whether higher LOP in the digests resulted in a higher cyto- and genotoxicity in Caco-2, HT-29 and HCT-116 cell lines. High-fat compared to low-fat beef digests contained approximately 10-fold higher LOP concentrations (all P < 0.001), and induced higher cytotoxicity (P < 0.001). During digestion of the high-fat product, phenolic acids (gallic, ferulic, chlorogenic, and caffeic acid) displayed either pro-oxidant or antioxidant behavior at lower and higher doses respectively, whereas ascorbic acid was pro-oxidant at all doses, and the lipophilic reducing compounds (alpha-tocopherol, quercetin, and silibinin) all exerted a clear antioxidant effect. During digestion of the low-fat product, the hydrophilic compounds and quercetin were antioxidant. Decreases or increases in LOP concentrations amounted to 100% change versus controls.