A covalent resveratrol-nitroxide conjugate protects against oxidative stress-induced cellular senescence

: Cellular senescence, frequently driven by excess reactive oxygen species (ROS), is a major contributor to organismal aging. Anti-aging strategies that reduce ROS often show limited efficacy due to poor bioavailability of therapeutics, and the development of more effective anti-senescent agents remains an important research objective. In this study, we sought to integrate the activity of resveratrol (RSV), a polyphenolic antioxidant with documented anti-senescence properties, with the (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical (TEMPO), a superoxide dismutase mimetic. While RSV and TEMPO display synergistic radical-scavenging activity in chemical model systems, this effect is not reproduced in cellular environments, likely due to their divergent subcellular localization. To overcome this limitation, a hybrid molecule, termed H3, was synthesized by covalently linking RSV with TEMPO to integrate the properties of both components within a single molecular framework. H3 exhibited potent radical-trapping antioxidant activity in all chemical assays employed. In human dermal fibroblasts, H3 was non-cytotoxic and significantly attenuated multiple hallmarks of senescence, maintaining DNA replication competence and reducing the proportion of senescent cells. H3 surpassed the efficacy of RSV, TEMPO, and their equimolar mixture in preserving cellular proliferation. Under oxidative stress, H3 maintained the expression of central antioxidant enzymes, including SOD1, CAT, and HO-1. In fibroblasts induced to senescence, H3 upregulated lamin B1, PARP, SirT1, and SirT6-proteins essential for chromatin organization, genome stability, and DNA repair. As a result, H3 is an anti-senescent agent, combining direct radical-trapping activity with the ability to influence the expression of antioxidant defense and DNA repair proteins.