Characterization of Antioxidant and Anti-inflammatory Activities of Bioactive Fractions Recovered from a Glucose-lysine Maillard Reaction Model System

A glucose-lysine (Glu-Lys) Maillard reaction mixture heated at 121°C for 60 min was processed by ultrafiltration, ethyl acetate extraction, and semi-preparative HPLC to recover a bioactive fraction, termed F3. F3, characterized by spectral analysis to contain three distinct components, inhibited NO and IL-8 by 70 and 61%, respectively, at a concentration of 50 μg/ml in inflamed Caco-2 cells induced by IFN-γ and phorbol 12-myristate 13-acetate (PMA). F3 significantly (P < 0.05) down-regulated several genes involved in nuclear factor kappa B (NF-κB) signaling pathway. These genes included the cytokine receptors, TNFRSF10A and TNFRSF10B; receptor-associated proteins, IRAK2 and TICAM1; the inhibitor κB kinase, IKBKE; the NF-κB inhibitor, NFKBIA; and the NF-κB subunits, REL, RELA, and RELB. F3 also down-regulated the NF-κB responsive genes IL-8, NOS2, and ICAM1, attenuated the gene expression of peroxidases such as DUOX1 and DUOX2, and relieved the down-regulated GCFHR that are involved in the biosynthesis of NO and TROAP, a gene suppressed by NO. The anti-inflammatory activity of F3 was mediated through multiple processes that included regulation of gene expressions involved in NF-κB signaling, the inhibition of IL-8 and iNOS translation, a decrease in NO synthesis and attenuating oxidative stress in inflamed Caco-2 cells. Our results show that MRP components have the potential to suppress inflammation in IFN-γ and PMA-induced Caco-2 cells.