Encapsulation of polyphenols in pH-responsive micelles self-assembled from octenyl-succinylated curdlan oligosaccharide and its effect on the gut microbiota.

ABSTRACT

An amphiphilic polymer based on octenyl succinic anhydride-modified curdlan oligosaccharide (MCOS) was synthesized. The critical micelle concentration of MCOS was 3.91 µg·mL-1. MCOS could self-assemble into spherical micelles with a particle size of 230.1 nm and a zeta potential of - 37.9 mV. When used for polyphenol encapsulation, the loading capacity of curcumin and quercetin-co-encapsulated micelles was higher than that of single-polyphenol encapsulated micelles. In vitro gastrointestinal release test showed that the MCOS micelle presented a pH-dependent release, released a little polyphenol in simulated gastric fluid, but presented sustained release in the simulated intestinal fluid. The gastrointestinal-digested polyphenol-loaded micelles exhibited excellent antioxidant ability. In vitro human fecal fermentation indicated that the MCOS carrier could promote the production of short-chain fatty acids by gut microbiota and exhibited the highest relative abundance of Megamonas. In addition, the supplementation of curcumin and quercetin-co-loaded MCOS micelles increased the relative abundance of Bifidobacterium and inhibited the growth of Escherichia_Shigella. These findings indicated that the MCOS carrier can be potentially used for the colon-targeted delivery of hydrophobic polyphenols due to its pH-responsive property.