Rationally designed donepezil-based hydroxamates modulate Sig-1R and HDAC isoforms to exert anti-glioblastoma effects

The pursuit of activating the HDAC inhibitory template towards additional mechanisms spurred us to design dual modulators (Sig-1R agonist - HDAC inhibitor) via utilization of the core structural unit of donepezil (an FDA-approved anti-Alzheimer's agent) as a surface recognition part. Literature precedents coupled with our experience rendered us with several insights that led to the inclusion of chemically diverse linkers and hydroxamic acid (zinc-binding motif) as the other components of HDAC inhibitory pharmacophore. With this envisionment and clarity, donepezil-based HDAC inhibitory adducts were furnished and exhaustively explored for their anti-GBM efficacy. Resultantly, a magnificently potent HDAC inhibitor 10 [IC50 (HDAC6) = 2.7 nM, IC50 (HDAC2) = 0.71 μM] was pinpointed that was endowed with the ability to: i) exert cell growth inhibitory effects against Human U87MG GBM cells ii) cause death in TMZ-resistant GBM cells iii) induce subG1 arrest in GBM cells iv) prolong the survival of TMZ-resistant U87MG inoculated orthotopic mice (in-vivo studies) v) induce GBM cell apoptosis via binding to Sig-1R. Collectively, the results led to the identification of compound 10 as a tractable anti-GBM agent that deserves detailed investigation for the accomplishment of its candidature as a GBM therapeutic.