Synthesis and Bioactivity Profile of 5-<i>S</i>-Lipoylhydroxytyrosol-Based Multidefense Antioxidants with a Sizeable (Poly)sulfide Chain
作者:Lucia Panzella、Luisella Verotta、Luis Goya、Sonia Ramos、María Angeles Martín、Laura Bravo、Alessandra Napolitano、Marco d’Ischia
DOI:10.1021/jf302690c
日期:2013.2.27
Novel polyfunctionalized antioxidants, 5-S-lipoylhydroxytyrosol (1) and its disulfide 2, trisulfide 3, and tetrasulfide 4, were prepared from tyrosol and dihydrolipoic acid in the presence, when appropriate, of sulfur. Compound 1 exhibited significant activity in the ferric reducing/antioxidant power (FRAP) assay (1.60 Trolox equiv), whereas polysulfides 2-4 were more efficient in the DPPH reduction assay (88-93% reduction vs 68% by Trolox). At 10 mu M concentration, all compounds 1-4 proved to be efficient hydroxyl radical scavengers (56-69% inhibition) in a Fenton reaction assay. When administered to human HepG2 cells, 1-4 proved to be nontoxic and exhibited marked protective effects against reactive oxygen species (ROS) generation (60-84% inhibition at 1 mu M concentration) and cell damage induced by 400 mu M tert-butylhydroperoxide. All compounds 1-4 exhibited overall greater antioxidant activity than hydroxytyrosol.