Dual-Acting Cholinesterase–Human Cannabinoid Receptor 2 Ligands Show Pronounced Neuroprotection in Vitro and Overadditive and Disease-Modifying Neuroprotective Effects in Vivo

Abstract

We have designed and synthesized a series of 14 hybrid molecules out of the cholinesterase (ChE) inhibitor tacrine and a benzimidazole-based human cannabinoid receptor subtype 2 (hCB2R) agonist and investigated them in vitro and in vivo. The compounds are potent ChE inhibitors, and for the most promising hybrids, the mechanism of human acetylcholinesterase (hAChE) inhibition as well as their ability to interfere with AChE-induced aggregation of β-amyloid (Aβ), and Aβ self-aggregation was assessed. All hybrids were evaluated for affinity and selectivity for hCB1R and hCB2R. To ensure that the hybrids retained their agonist character, the expression of cAMP-regulated genes was quantified, and potency and efficacy were determined. Additionally, the effects of the hybrids on microglia activation and neuroprotection on HT-22 cells were investigated. The most promising in vitro hybrids showed pronounced neuroprotection in an Alzheimer’s mouse model at low dosage (0.1 mg/kg, i.p.), lacking hepatotoxicity even at high dose (3 mg/kg, i.p.).

Structure and therapeutic uses of butyrylcholinesterase: Application in detoxification, Alzheimer's disease, and fat metabolism

“…Compound 7 was predicted by an in vitro parallel artificial membrane permeation assay (PAMPA‐BBB) to be able to penetrate BBB through passive diffusion. Dolles et al 154 previously obtained a benzimidazole‐based selective cannabinoid receptor subtype 2 (CB 2 R) agonist 8 (Figure 8) with good BChE inhibitory activity, and in 2019, Scheiner et al 155 further modified tacrine with compound 8 to give a series of MTDLs. The administration of CB 2 R agonists could suppress the activation of microglia and thus reduce the production of neurotoxic factors 156 .…”

Multidirectional in vitro and in cellulo studies as a tool for identification of multi-target-directed ligands aiming at symptoms and causes of Alzheimer’s disease

“…Tacrine is a widely used scaffold in the AD therapy research 40 . It provides compounds with reliable inhibitory activity against cholinesterases, its derivatives are repeatedly reported as Aβ aggregation inhibitors 18 , 22 , 41 , 42 and dual inhibitors of self-induced Aβ and tau aggregation potent in in vitro assays and living cells 43 . On the downside of the tacrine-based multifunctional ligands is the fact that very often they lack drug-likeness, mostly due to their high molecular weight, exceeded of limits logP values or potential toxicity.…”

Breakthroughs in Medicinal Chemistry: New Targets and Mechanisms, New Drugs, New Hopes–6

“…The hybrids exhibited significant inhibitory effects towards cholinesterase activity and Aβ40 and Aβ42 aggregation, and concomitant partial agonist activity towards the human cannabinoid receptor subtype 2. Furthermore, the compound 2-(4-ethoxybenzyl)-1-isopentyl-N-(2-((2-((1,2,3,4-tetrahydroacridin-9-yl)amino)ethyl)disulfaneyl)ethyl) -1H-benzo[d]imidazole-5-carboxamide exerted significant, concentration-dependent, neuroprotective effects in murine hippocampal neurons and prevented Aβ25-35-induced short-and long-term memory impairment in mice [3]. Notably, animal studies did not show any evidence of hepatotoxicity, a common complication during treatment with tacrine [4].…”

“…Targeting multiple pathways involved in the onset and the progression of the disease might increase the success rate of drug discovery and development programs [2]. Scheiner et al report the synthesis of a series of hybrid molecules that are based on the cholinesterase inhibitor tacrine and a benzimidazole-based human cannabinoid receptor subtype 2 agonist [3]. The hybrids exhibited significant inhibitory effects towards cholinesterase activity and Aβ40 and Aβ42 aggregation, and concomitant partial agonist activity towards the human cannabinoid receptor subtype 2.…”