Lipophenols such as palmitoyl esters of green-tea polyphenols (GTP) have been allowed for use as food additives for oxidation control. However, their digestive absorption remains unexplored. In this paper, the hydrolysis and transport characteristics of tyrosol acyl esters (TYr-Es) with various fatty acids (C12:0, C14:0, C16:0, C18:0, C18:1, and C18:2) were evaluated using the everted-rat-gut-sac model for the first time. HPLC-UV measurements demonstrated that TYr-Es were hydrolyzed to TYr, which contributed significantly to TYr transport across the sacs. The hydrolysis and transport rates correlated negatively with the chain lengths of their lipid moieties but showed a positive correlation with the degree of unsaturation. In general, all TYr-Es exhibited sustained-release behavior; therefore, the production of TYr-Es may serve as a useful way to prolong the duration of action and further improve the bioactivities of TYr.
Keywords: enzymatic synthesis; esters; everted-rat-gut sacs; hydrolysis; transport; tyrosol.