Neuroprotective Tri- and Tetracyclic BChE Inhibitors Releasing Reversible Inhibitors upon Carbamate Transfer

Tri- and tetracyclic nitrogen-bridgehead compounds were designed and synthesized to yield micromolar cholinesterase (ChE) inhibitors. Structure-activity relationships identified potent compounds with butyrylcholinesterase selectivity. These compounds were selected as starting points for the design and synthesis of carbamate-based (pseudo)irreversible inhibitors. Compounds with superior inhibitory activity and selectivity were obtained and kinetically characterized also with regard to the velocity of enzyme carbamoylation. Structural elements were identified and introduced that additionally showed neuroprotective properties on a hippocampal neuronal cell line (HT-22) after glutamate-induced intracellular reactive oxygen species generation. We have identified potent and selective pseudoirreversible butyrylcholinesterase inhibitors that release reversible inhibitors with neuroprotective properties after carbamate transfer to the active site of cholinesterases.