Colonic fermentation-derived metabolites of bread crust melanoidins modulate oxidative and inflammatory responses in a 3D neuronal OGD/R model

Bread crust melanoidins are high-molecular-weight Maillard reaction products that generate bioactive metabolites during colonic fermentation. This study evaluated the effects of the colonic fermentation-derived melanoidin fraction (CFM) on redox homeostasis and HIF-1α/NF-κB/NLRP3 inflammasome signaling in a three-dimensional neuronal model of oxygen–glucose deprivation/reoxygenation (OGD/R). Bread crust melanoidins were isolated and subjected to standardized in vitro gastrointestinal and human fecal colonic fermentation. The dialyzed CFM was characterized by HPLC-DAD, GC-FID, and antioxidant assays. Its biological activity was evaluated in differentiated 3D SH-SY5Y neuronal spheroids exposed to OGD/R. Chemical characterization of CFM, a complex fermentation mixture, revealed phenolic compounds and short-chain fatty acids. OGD/R increased cell death and intracellular ROS significantly whereas CFM pretreatment reduced these responses by 41.9% and 21.6%. Notably, CFM attenuated OGD/R-induced oxidative damage, reducing 8-OHdG levels by 57.0%. CFM also modulated HIF-1α/NF-κB/NLRP3-associated responses, including reductions of 42.6% in NLRP3 and 47.2% in caspase-1 protein, together with a 51.3% reduction in the p-NF-κB/NF-κB ratio. In parallel, CFM modulated Akt/p38 MAPK/Nrf2-associated signaling, increasing the p-Nrf2/Nrf2 ratio by 44.5% relative to OGD/R. CFM also attenuated OGD/R-induced antioxidant gene expression, particularly GPX2 and HO-1, by 39.1% and 60.6%, respectively. These findings suggests that CFM modulates redox and inflammatory responses under hypoxic stress in vitro, including changes in HIF-1α/NF-κB/NLRP3- and Nrf2-associated signaling.