Effects of substitution sites and acyl chain length on antioxidant capacity and bioaccessibility of high-active resveratrol monoesters in vitro

Resveratrol monoesters, synthesized by esterifying with lipophilic groups, excel in lipophilicity, antioxidant activity, and bioavailability. This study selectively acylated resveratrol at 3-OH and 4’-OH using lipozyme RMIM (from Rhizomucor miehei ). Seven 3-resveratrol monoesters (3-RC 2:0 – 18:0 ) and seven 4’-RC 2:0 – 18:0 were prepared, purified and identified. Their antioxidant capacity and bioaccessibility were innovatively studied, focusing on substitution and acyl chain length effects. Results showed that 3-RC 2:0 – 18:0 consistently outperformed 4’-RC 2:0 – 18:0 in SET assays for antioxidant activity. Notably, 4’-RC 2:0 – 8:0 performed better oxygen radical absorption capacity than 3-RC 18:0 . 3-RC 2:0 even showed better ABTS radical scavenging capacity than Trolox and TBHQ. 3-RC 2:0 /RC 4:0 displayed higher antioxidant efficacy than medium- and long-chain counterparts, excluding 3-RC 16:0 . In the gastric and intestinal phases, 4’-RC 2:0 – 18:0 showed slightly higher retention due to enhanced lipophilicity compared to 3-RC 2:0 – 18:0 . RC 2:0 /RC 12:0 – 18:0 showed better retention properties during digestion. In summary, 3-RC 2:0/16:0 exhibited exceptional antioxidant capacity and digestive stability. These findings suggest resveratrol derivatives' potential in lipid-based foods, pharmaceuticals, and cosmetics.