In Vitro Gastrointestinal Digestion and Microbial Hydrolysis of Hydroxytyrosol-SCFA and Tyrosol-SCFA Acyl Esters: Controlled-Release of SCFAs and Polyphenols

Phenolipids such as hydroxytyrosol-SCFA acyl esters (HTy-SEs)andtyrosol-SCFA acyl esters (TYr-SEs) with various alkyl chains lengths(C1-C4) and different isomers (branched-chain and straight-chain)were successfully synthesized. All esters were hydrolyzed by pancreaticlipase to produce polyphenols (HTy and TYr) and SCFAs (iso-butyricacid, acetic acid, propionic acid, and n-butyric acid). Moreover,HTy-SEs (and TYr-SEs) could also be hydrolyzed to free HTy (and TYr)and SCFAs by gut microbiota and Lactobacillus from mice feces. Especially, the hydrolysis rates showed positivecorrelation with the carbon skeleton length, and the hydrolysis degree(DH) of ester with a branched-chain fatty acid was weaker than thatof ester with a straight-chain fatty acid. Besides, the DH valuesof TYr -SEs were significantly higher than those of HTy-SEs. Therefore,through regulating the structures of polyphenols, carbon skeletonlengths, and isomers, controlled-release of polyphenols and SCFAsfrom phenolipids will be easily achieved.

Automated summary

Hydroxytyrosol-SCFA acyl esters (HTy-SEs) and tyrosol-SCFA acyl esters (TYr-SEs) with different alkyl chain lengths (C1-C4) and isomers (branched-chain and straight-chain) were successfully synthesized and hydrolyzed to produce polyphenols and SCFAs. The hydrolysis rates were influenced by the carbon skeleton length and the esters with branched-chain fatty acids had weaker hydrolysis degrees. Additionally, the hydrolysis degrees of TYr-SEs were significantly higher than those of HTy-SEs. Controlled-release of polyphenols and SCFAs can be easily achieved by regulating the structures of polyphenols, carbon skeleton lengths, and isomers.