Oxidative stress-inducing carbonyl compounds from common foods: Novel mediators of cellular dysfunction

Background: The general increase in reactive oxygen species generated from glucose-derived advanced glycation endproducts (AGEs) is among the key mechanisms implicated in tissue injury due to diabetes. AGE-rich foods could exacerbate diabetic injury, at least by raising the endogenous AGE. Materials and Methods: Herein, we tested whether, prior to ingestion, diet-derived AGEs contain species with cell activating (TNFα), chemical (cross-linking) or cell oxidative properties, similar to native AGEs. Glutathione (GSH) and GSH peroxidase (GPx) were assessed after exposure of human umbilical vein endothelial cell (HUVECs) to affinity-purified food-AGE extracts, each exposed to 250°C, for 10 min, along with synthetic AGEs. Results: Animal product-derived AGE, like synthetic methylglyoxal-bovine serum albumin (MG-BSA), AGE-BSA, and AGE-low density lipoprotein (AGE-LDL), induced a dose- and time-dependent depletion of GSH (↓60-75%, p < 0.01) and an increase in GPx activity (↑500-600%, p < 0.01), consistent with marked TNFα and cross-link formation (p < 0.05); this contrasted with the low bioreactivity of starch/vegetable AGE-extracts, which was similar to that of control BSA and CML-BSA and BSA (p:NS). Anti-AGE-R1,2,3 and -RAGE IgG each inhibited cell-associated ¹²⁵I-dAGE by ∼30-55%; GSH/GPx were effectively blocked by N-acetyl-cysteine (NAC, 800 uM, p < 0.01) and aminoguanidine-HCl (AG, 100uM, p < 0.01). Conclusion: Thus, food-derived AGE, prior to absorption, contain potent carbonyl species, that can induce oxidative stress and promote inflammatory signals.