Tailored esterification of Geraniin for optimal anti-isomerization and anti-oxidation activities

Geraniin (GER), a characteristic polyphenol from the pericarp of rambutan, was severely limited in lipid systems due to its poor lipid solubility and thermal stability. In this study, geraniin oleates (GO) with different degrees of esterification were constructed firstly, which significantly enhanced the lipid solubility (104.24-244.92 %) and thermal stability (the GO-triester's initial decomposition temperature increased by 115.5 %) of GER. The nonlinear structure-activity relationships between esterification degrees and activities were also revealed. Optimal anti-isomerization (65.48 %) and anti-oxidation (27.23 %) activities were achieved by balancing the degree of modification (21-43 %) and retaining hydroxyl groups (8-11). Excessive esterification (64-86 %) led to spatial blockage and even triggered the pro-oxidant effects. The study provided a new strategy for the modification of natural polyphenols to achieve high-value.