Alginate-inulin-chitosan based microspheres alter metabolic fate of encapsulated quercetin, promote short chain fatty acid production, and modulate pig gut microbiota.

Quercetin loaded alginate microspheres, fabricated with the inclusion of inulin as a prebiotic source and chitosan as protective coating (ALINCH-Q), were subjected to in vitro colonic fermentation using pig fecal microbiota, with empty microspheres ALINCH-E, unencapsulated quercetin UQ and media only Blank as parallel studies. ALINCH-Q altered quercetin biotransformation towards higher production of 3-hydroxyphenylpropionic acid and 3-hydroxyphenylacetic acid, and further metabolism of 3,4-dihydroxyphenylacetic acid and 4-hydroxyphenylacetic acid compared to UQ. In addition, ALINCH-Q but not ALINCH-E or UQ significantly promoted SCFAs production compared to Blank. Furthermore, the ALINCH-Q microspheres altered the microbial compositions, increased the relative abundance of Lactobacillus, Turicibacter, Eubacterium, and Clostridium, while decreased that of the potentially pathogenic Enterococcus. The results suggest an interplay between the dietary fiber matrix and quercetin in producing these effects, and that ALINCH-Q could serve as a potential targeted delivery vehicle for quercetin to exert beneficial biological effects in the colon.