Dual-acting small molecules : subtype-selective cannabinoid receptor 2 agonist/butyrylcholinesterase inhibitor hybrids show neuroprotection in an Alzheimer's disease mouse model

We present the synthesis and characterization of merged human butyrylcholinesterase (hBChE) inhibitor/cannabi-noid receptor 2 (hCB2R) ligands for the treatment of neuro-degeneration. In total, 15 benzimidazole carbamates were synthesized and tested for their inhibition of human cholines-terases, also with regard to their pseudoirreversible binding mode and affinity toward both cannabinoid receptors in radioligand binding studies. After evaluation in a calcium mobilization assay as well as a beta-arrestin 2 (beta arr2) recruitment assay, two compounds with balanced activities on both targets were tested for their immunomodulatory effect on microglia activation and regarding their pharmacokinetic properties and blood-brain barrier pene-tration. Compound 15d, containing a dimethyl carbamate motif, was further evaluated in vivo, showing prevention of A beta 25-35-induced learning impairments in a pharmacological mouse model of Alzheimer's disease for both short-and long-term memory responses. Additional combination studies proved a synergic effect of BChE inhibition and CB2R activation in vivo.