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 degrees 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 mu g/ml in inflamed Caco-2 cells induced by IFN-gamma and phorbol 12-myristate 13-acetate (PMA). F3 significantly (P < 0.05) down-regulated several genes involved in nuclear factor kappa B (NF-kappa B) signaling pathway. These genes included the cytokine receptors, TNFRSF10A and TNFRSF10B; receptor-associated proteins, IRAK2 and TICAM1; the inhibitor kappa B kinase, IKBKE; the NF-kappa B inhibitor, NFKBIA; and the NF-kappa B subunits, REL, RELA, and RELB. F3 also down-regulated the NF-kappa B 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-kappa B 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-gamma and PMA-induced Caco-2 cells.