Dual-Acting Small Molecules: Subtype-Selective Cannabinoid Receptor 2 Agonist/Butyrylcholinesterase Inhibitor Hybrids Show Neuroprotection in an Alzheimer’s Disease Mouse Model

Abstract

We present the synthesis and characterization of merged human butyrylcholinesterase (hBChE) inhibitor/cannabinoid receptor 2 (hCB2R) ligands for the treatment of neurodegeneration. In total, 15 benzimidazole carbamates were synthesized and tested for their inhibition of human cholinesterases, 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 β-arrestin 2 (βarr2) 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 penetration. Compound 15d, containing a dimethyl carbamate motif, was further evaluated in vivo, showing prevention of Aβ25–35-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.

Novel Dual-Acting Hybrids Targeting Type-2 Cannabinoid Receptors and Cholinesterase Activity Show Neuroprotective Effects In Vitro and Amelioration of Cognitive Impairment In Vivo

“…This result was not entirely unexpected, because with increasing structural complexity and thus the potential type/number of drug-receptor interactions, a receptor agonist can often turn into an antagonist or inverse agonist. Examples of this structure-dependent shift of functional activity have already been reported in various receptor systems by us and others. , …”

“…In the last 15 years, many promising multitarget-directed ligands (MTDLs) have been identified and developed at the preclinical level. The discovery of MTD-drugs is one of the hot topics and one of the most active fields in the search for new molecules against AD. − …”

“…Examples of this structure-dependent shift of functional activity have already been reported in various receptor systems by us 47 and others. 20,48 Lipophilicity and Related Druglike Properties. The lipophilicity of the studied molecules 4a−g, 7, and 12, considered a critical physicochemical property encoding information on the inter-and intramolecular forces affecting both drug transport through lipid structures, which is somewhat related to ADMET parameters, and interactions with target proteins, was calculated using three different software programs (see Methods section and Tables S1 and S2 and Figure S6 in Supporting Information).…”

The selective butyrylcholinesterase inhibitor UW‐MD‐95 shows symptomatic and neuroprotective effects in a pharmacological mouse model of Alzheimer's disease

“…As the neurodegenerative process in AD is protean 5 and affects complex interacting toxic pathways between extracellular space, neurons, and glial cells, 59 , 60 BChE may represent a promising target per se but also for multi‐target ligands. 61 , 62 …”

A Comprehensive Exploration of the Multifaceted Neuroprotective Role of Cannabinoids in Alzheimer's Disease Across a Decade of Research

“…Spatz et al [54] focused on synthesizing and investigating hybrid molecules acting as CB2R agonists and BChE antagonists. Among the compounds they synthesized, 15d (with IC50 BChE= 0.62 μM, EC50 CB2R= 244 nM) and 21d (with IC50 BChE= 0.15 μM, EC50 CB2R= 1.3 μM) (Scheme 3) demonstrated considerable promise.…”