First Dual AK/GSK-3β Allosteric Inhibitors Endowed with Antioxidant Properties as Multifunctional, Potential Neuroprotective Agents

The manuscript deals with the design, synthesis and biological evaluation of novel benzoxazinone-based and indole-based compounds as multifunctional neuroprotective agents. These compounds inhibit human adenosine kinase (hAK) and human glycogen synthase kinase 3 beta (hGSK-3β) enzymes. Computational analysis based on a molecular docking approach underlined the potential structural requirements for simultaneously targeting both proteins' allosteric sites. In silico hints drove the synthesis of appropriately decorated benzoxazinones and indoles (5a-s, and 6a-c) and biochemical analysis revealed their behavior as allosteric inhibitors of hGSK-3β. For both our hit 4 and the best compounds of the series (5c,l and 6b) the potential antioxidant profile was assessed in human neuroblastoma cell lines (IMR 32, undifferentiated and neuronal differentiated), by evaluating the protective effect of selected compounds against H2O2 cytotoxicity and reactive oxygen species (ROS) production. Results showed a strong efficacy of the tested compounds, even at the lower doses, in counteracting the induced oxidative stress (50 μM of H2O2) and in preventing ROS formation. In addition, the tested compounds did not show any cytotoxic effect determined by the LDH release, at the concentration range analyzed (from 0.1 to 50 μM). This study allowed the identification of compound 5l, as the first dual hAK/hGSK-3β inhibitor reported to date. Compound 5l, which behaves as an effective antioxidant, holds promise for the development of new series of potential therapeutic agents for the treatment of neurodegenerative diseases characterized by an innovative pharmacological profile.