Mixed-strain probiotic fermentation of Aronia melanocarpa attenuates neuroinflammation and oxidative stress in microglial and neuronal cells.

UNLABELLED: Microbial fermentation can enhance the bioactivity of plant-derived phytochemicals through biotransformation of phenolic compounds. This study compared unfermented, single-strain fermented (SFA), and mixed-strain fermented (MFA) Aronia melanocarpa extracts for their phytochemical characteristics and neuroprotective effects using BV-2 microglial and HT22 neuronal cell models. Probiotic fermentation altered the anthocyanin composition of aronia extracts, increasing cyanidin aglycone while decreasing glycosylated anthocyanins, accompanied by enhanced antioxidant activity. Among the tested extracts, MFA exhibited the strongest biological activity. In BV-2 cells, MFA suppressed lipopolysaccharide-induced inflammatory responses by reducing nitric oxide production, pro-inflammatory cytokines, and NF-κB nuclear translocation. In HT22 cells, MFA protected against H2O2-induced oxidative injury by reducing reactive oxygen species and lipid peroxidation, restoring the Bax/Bcl-2 balance, and promoting Nrf2 nuclear translocation. Collectively, these findings indicate that mixed-strain probiotic fermentation enhances the neuroprotective potential of aronia through modulation of neuroinflammatory and oxidative stress pathways, highlighting its potential as a neuroprotective functional food ingredient. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s10068-026-02260-3.