Diet-gut microbiome interaction and ferulic acid bioavailability: implications on neurodegenerative disorders.

PURPOSE OF THE REVIEW: Ferulic acid (FA), which occurs naturally as the feruloylated sugar ester in grains, fruits, and vegetables, is critical for combating oxidative stress and alleviating neurodegenerative diseases resulting from free radical-generated protein aggregates in brain cells. However, FA cannot be absorbed in conjugated form. Therefore, strategies to improve the bioavailability of FA are gaining more importance. Ferulic acid esterases (FAE) of the gut microbiota are critical enzymes that facilitate FA release from feruloylated sugar ester conjugates and influence systemic health. This review provides insight into a nutrition-based approach to preventing neurodegenerative disorders such as Alzheimer's and Parkinson's by altering the diversity of FAE-producing gut microbiota. RECENT FINDINGS: The human gut is a niche for a highly dense microbial population. Nutrient components and the quality of food shape the gut microbiota. Microbiota-diet-host interaction primarily involves an array of enzymes that hydrolyse complex polysaccharides and release covalently attached moieties, thereby increasing their bio-accessibility. Moreover, genes encoding polysaccharide degrading enzymes are substrate inducible, giving selective microorganisms a competitive advantage in scavenging nutrients. Nutraceutical therapy using specific food components holds promise as a prophylactic agent and as an adjunctive treatment strategy in neurotherapeutics, as it results in upregulation of polysaccharide utilisation loci containing fae genes in the gut microbiota, thereby increasing the release of FA and other antioxidant molecules and combat neurodegenerative processes.

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.

Prophylactic effect of pectic oligosaccharides against poly I: C- induced virus-like infection in BALB/c mice.

Pectin oligosaccharides (POS) are pectin-derived prebiotics that exerts anti-inflammatory effects on the host and stimulates an innate immune response. The role of POS in protective immunity against viral infections is not very obvious. Therefore, the prophylactic effect of POS in the mouse model induced by Poly I: C mimicking viral infection was examined. Mice fed POS showed a significant (p ≤ .05) increase in IgG, sIgA, IgA, IL-12, and a significant (p ≤ .05) decrease in the concentration of pro-inflammatory cytokines IL-5, IL-6, IL-13 and IL-17 in lung and blood serum after Poly I: C stimulation. However, the control group could not inhibit pro-inflammatory cytokines. POS also promoted the growth of the Lactobacillus, Prevotella, Rilenellaceae, and Lachanospiraceae groups. Therefore, this study demonstrate that POS has the potiential to protect against viral inflammation by altering gut microbiota and activating mucosal immunity. PRACTICAL APPLICATIONS: POS is 2-10 mer oligomers of pectin. The human gastrointestinal tract lacks the enzyme to break down POS. They are fermented by gut bacteria in the colon and stimulate the proliferation of specific gut bacteria that are positively correlated with the production of anti-inflammatory cytokines and SCFA. POS also stimulates the secretion of IgA, which inhibits bacterial and viral adhesion and protects the host. Therefore, POS can be used as a functional food ingredient in food to stimulate a specific group of gut bacteria and enhance preventive immunity.