Hydrazine swap turns riluzole metabolite into CK1δ inhibitor series
- Riluzole's main hydroxylamine metabolite still inhibited CK1δ, a kinase that phosphorylates TDP-43 in ALS, but it was chemically unstable and toxic to neuronal cells.
- Swapping the hydroxylamine for a hydrazine gave a more potent, workable benzo[d]thiazole series; branched alkyl and benzyl substituents were best tolerated overall.
- Docking and molecular dynamics pointed to an added hinge hydrogen bond with Gly86 as the source of the gain.
- The lead was ATP-competitive, engaged CK1δ directly, crossed membranes passively and showed early selectivity over GSK3β, but gave no neuroprotection in an oxidative-stress model.
💡 Points
Swapping NHOH for NHNH2 is a neat fix: it keeps the H-bond donor/acceptor pattern (and the extra Gly86 hinge contact) while dodging the labile, toxic hydroxylamine. But hydrazines carry their own liabilities (reactivity, MAO/aldehyde adducts), so cap or cyclize early. No neuroprotection despite on-target engagement means CK1δ potency alone won't carry this.