Identification of Highly Promising Antioxidants/Neuroprotectants Based on Nucleoside 5′-Phosphorothioate Scaffold. Synthesis, Activity, and Mechanisms of Action

With a view to identify novel and
biocompatible neuroprotectants, we designed nucleoside 5′-thiophosphate
analogues, 6–11. We identified 2-SMe-ADP­(α-S), 7A, as a most promising neuroprotectant. 7A reduced
ROS production in PC12 cells under oxidizing conditions, IC50 of 0.08 vs 21 μM for ADP. Furthermore, 7A rescued
primary neurons subjected to oxidation, EC50 of 0.04 vs
19 μM for ADP. 7A is a most potent P2Y1-R agonist, EC50 of 0.0026 μM. Activity of 7A in cells involved P2Y1/12-R as indicated by
blocking P2Y12-R or P2Y1-R. Compound 7A inhibited Fenton reaction better than EDTA, IC50 of 37
vs 54 μM, due to radical scavenging, IC50 of 12.5
vs 30 μM for ADP, and Fe­(II)-chelation, IC50 of 80
vs >200 μM for ADP (ferrozine assay). In addition, 7A was stable in human blood serum, t1/2 of 15 vs 1.5 h for ADP, and resisted hydrolysis by NPP1/3,
2-fold vs ADP. Hence, we propose 7A as a highly promising
neuroprotectant.