Plant‑Based Nutraceutical Formulation Modulates the Human Gut Microbiota and Ferulic Acid Esterase Activity During In Vitro Fermentation.

Oxidative stress is an imbalance between free reactive oxygen species and antioxidant defences leading to neurological and
other chronic disorders. The interaction between food and gut microbiota and their metabolites significantly reduces oxidative
stress and influences host physiology and metabolism. This process mainly involves enzymes that hydrolyse complex
polysaccharides and produce metabolites. Ferulic acid esterases (FAE) one of the most important enzymes of the gut microbiome,
release ferulic acid from feruloylated sugar ester conjugates, that occur naturally in grains, fruits, and vegetables.
FA is crucial in combating oxidative stress resulted from free radical formation. This study investigated the effect of two
plant-based nutraceutical formulations, cereal-millet-based (PC1) and fruit-vegetable-based (PC2), on gut microbiota and the
production of FAE, short chain fatty acids (SCFA) and other small metabolites in in vitro fermentation using human faecal
samples. After in vitro fermentation, both nutraceutical formulations increased the abundance of Bifidobacterium, Lactobacillus,
Prevotella, Feacalibacteria, and Clostridium leptum. Furthermore, they induced the production of FAE, xylanase
and pectinase enzymes, SCFA and other small metabolites, resulting in increased antioxidation activity of the fermentate.
PC1 stimulated FAE and xylanase production more effectively. These results demonstrated a positive correlation between
the feruloylated nutraceutical formulation and the production of FAE and other accessory enzymes, suggesting that PC1 and
PC2 stimulate the proliferation of the FAE-producing microbial consortium of the gut microbiome and therefore, increase
FA and SCFA concentration. From this study it is evident that FA-rich plant-based formulation can be used as a prophylactic
nutraceutical supplement to alleviate oxidative stress by modulating the gut microbiota.