Solid evidence has emerged supporting the role of nonextractable
polyphenols (NEPs) and dietary fibers (DFs) as gut microbiota modulators.
This study aims to elucidate gut microbiota-dependent release of turmeric
NEPs and examine the possible anti-inflammatory mechanism in the dextran
sulfate sodium-induced ulcerative colitis (UC) model. 1.5% DSS drinking
water-induced C57BL/6J mice were fed a standard rodent chow supplemented
with or without 8% extractable polyphenols (EPs), NEPs, or DFs for
37 days. The bound curcumin, demethoxycurcumin, and bisdemethoxycurcumin
in NEPs were released up to 181.5 ± 10.6, 65.2 ± 6.0, and
69.5 ± 7.6 μg/mL by in vitro gut microbiota-simulated fermentation
and released into the colon of NEP-supplemented mice by 5.7-, 11.0-,
and 7.8-fold higher than pseudo germ-free mice, respectively (p < 0.05). NEPs also enhanced the colonic microbiota-dependent
production of short-chain fatty acids in vitro and in vivo (p < 0.05). Interestingly, NEP feeding significantly improved
the DSS-caused gut microbiota disorder, epithelial barrier damage,
and inflammation of UC mice better than EPs or DFs (p < 0.05). Meanwhile, the pseudo germ-free mice supplemented with
NEPs failed to ameliorate UC symptoms. These findings manifest that
turmeric NEPs as macromolecular carriers exert the target delivery
of polyphenols into the colon for regulating gut microbiota to restore
the impaired gut barrier function for alleviation of inflammation.