Inhibitor Report for: bis9-(-)-nor-meptazinol

Alzheimer's disease (AD) is the main type of dementia and is characterized by progressive memory loss and a notable decrease in cholinergic neuron activity. As classic drugs currently used in the clinic, acetylcholinesterase inhibitors (AChEIs) restore acetylcholine levels and relieve the symptoms of AD, but are insufficient at delaying the onset of AD. Based on the multi-target-directed ligand (MTDL) strategy, bis-(-)-nor-meptazinol (BIS-MEP) was developed as a multi-target AChEI that mainly targets AChE catalysis and the beta-amyloid (Abeta) aggregation process. In this study, we bilaterally injected Abeta oligomers and ibotenic acid (IBO) into the hippocampus of ICR mice and then subcutaneously injected mice with BIS-MEP to investigate its therapeutic effects and underlying mechanisms. According to the results from the Morris water maze test, BIS-MEP significantly improved the spatial learning and memory impairments in AD model mice. Compared with the vehicle control, the BIS-MEP treatment obviously inhibited the AChE activity in the mouse brain, consistent with the findings from the behavioral tests. The BIS-MEP treatment also significantly reduced the Abeta plaque area in both the hippocampus and cortex, suggesting that BIS-MEP represents a direct intervention for AD pathology. Additionally, the immunohistochemistry and ELISA results revealed that microglia (ionized calcium-binding adapter molecule 1, IBA1) and astrocyte (Glial fibrillary acidic protein, GFAP) activation and the secretion of relevant inflammatory factors (TNFalpha and IL-6) induced by Abeta were decreased by the BIS-MEP treatment. Furthermore, BIS-MEP showed more advantages than donepezil (an approved AChEI) as an Abeta intervention. Based on our findings, BIS-MEP improved spatial learning and memory deficits in AD mice by regulating acetylcholinesterase activity, Abeta deposition and the inflammatory response in the brain.

Alzheimer's disease (AD) is a multifaceted neurodegenerative disorder which is characterized by the progressive deterioration of cognition and the emergence of behavioral and psychological symptoms in aging patients. Given that the clinical effectiveness of acetylcholinesterase inhibitors (AChEIs) has still been questioned due to dubious disease-modifying effects, the multi-target directed ligand (MTDL) design has become an emerging strategy for developing new drugs for AD treatment. Bis(9)-(-)-nor-meptazinol (Bis-Mep) was firstly reported by us as a novel MTDL for both potent cholinesterase and amyloid-beta aggregation inhibition. In this study, we further explored its AChE inhibition kinetic features and cognitive amelioration. Bis-Mep was found to be a mixed-type inhibitor on electric eel AChE by enzyme kinetic study. Molecular docking revealed that two "water bridges" located at the two wings of Bis-Mep stabilized its interaction with both catalytic and peripheral anionic sites of AChE. Furthermore, subcutaneous administration of Bis-Mep (10, 100 or 1000ng/kg) significantly reversed the scopolamine-induced memory deficits in a typical bell-shaped dose-response manner. The maximal cognitive amelioration of Bis-Mep was achieved at 100ng/kg, comparable with the effect of a reference drug Huperzine A at 1mg/kg and also the relevant AChE inhibition in brain. These findings suggested that Bis-Mep might be a promising dual-binding AChE inhibitor for potential AD therapeutics.

A bis-(-)-nor-meptazinol derivative in which the two meptazinol rings are linked by a nonamethylene spacer is a novel acetylcholinesterase inhibitor that inhibits both catalytic activity and Abeta peptide aggregation. The crystal structure of its complex with Torpedo californica acetylcholinesterase was determined to 2.7 A resolution. The ligand spans the active-site gorge, with one nor-meptazinol moiety bound at the "anionic" subsite of the active site, disrupting the catalytic triad by forming a hydrogen bond with His440N(epsilon2), which is hydrogen-bonded to Ser200O(gamma) in the native enzyme. The second nor-meptazinol binds at the peripheral "anionic" site at the gorge entrance. A number of GOLD models of the complex, using both native TcAChE and the protein template from the crystal structure of the bis-(-)-nor-meptazinol/TcAChE complex, bear higher similarity to the X-ray structure than a previous model obtained using the mouse enzyme structure. These findings may facilitate rational design of new meptazinol-based acetylcholinesterase inhibitors.

Alzheimer's disease (AD) is the main type of dementia and is characterized by progressive memory loss and a notable decrease in cholinergic neuron activity. As classic drugs currently used in the clinic, acetylcholinesterase inhibitors (AChEIs) restore acetylcholine levels and relieve the symptoms of AD, but are insufficient at delaying the onset of AD. Based on the multi-target-directed ligand (MTDL) strategy, bis-(-)-nor-meptazinol (BIS-MEP) was developed as a multi-target AChEI that mainly targets AChE catalysis and the beta-amyloid (Abeta) aggregation process. In this study, we bilaterally injected Abeta oligomers and ibotenic acid (IBO) into the hippocampus of ICR mice and then subcutaneously injected mice with BIS-MEP to investigate its therapeutic effects and underlying mechanisms. According to the results from the Morris water maze test, BIS-MEP significantly improved the spatial learning and memory impairments in AD model mice. Compared with the vehicle control, the BIS-MEP treatment obviously inhibited the AChE activity in the mouse brain, consistent with the findings from the behavioral tests. The BIS-MEP treatment also significantly reduced the Abeta plaque area in both the hippocampus and cortex, suggesting that BIS-MEP represents a direct intervention for AD pathology. Additionally, the immunohistochemistry and ELISA results revealed that microglia (ionized calcium-binding adapter molecule 1, IBA1) and astrocyte (Glial fibrillary acidic protein, GFAP) activation and the secretion of relevant inflammatory factors (TNFalpha and IL-6) induced by Abeta were decreased by the BIS-MEP treatment. Furthermore, BIS-MEP showed more advantages than donepezil (an approved AChEI) as an Abeta intervention. Based on our findings, BIS-MEP improved spatial learning and memory deficits in AD mice by regulating acetylcholinesterase activity, Abeta deposition and the inflammatory response in the brain.

Alzheimer's disease (AD) is a multifaceted neurodegenerative disorder which is characterized by the progressive deterioration of cognition and the emergence of behavioral and psychological symptoms in aging patients. Given that the clinical effectiveness of acetylcholinesterase inhibitors (AChEIs) has still been questioned due to dubious disease-modifying effects, the multi-target directed ligand (MTDL) design has become an emerging strategy for developing new drugs for AD treatment. Bis(9)-(-)-nor-meptazinol (Bis-Mep) was firstly reported by us as a novel MTDL for both potent cholinesterase and amyloid-beta aggregation inhibition. In this study, we further explored its AChE inhibition kinetic features and cognitive amelioration. Bis-Mep was found to be a mixed-type inhibitor on electric eel AChE by enzyme kinetic study. Molecular docking revealed that two "water bridges" located at the two wings of Bis-Mep stabilized its interaction with both catalytic and peripheral anionic sites of AChE. Furthermore, subcutaneous administration of Bis-Mep (10, 100 or 1000ng/kg) significantly reversed the scopolamine-induced memory deficits in a typical bell-shaped dose-response manner. The maximal cognitive amelioration of Bis-Mep was achieved at 100ng/kg, comparable with the effect of a reference drug Huperzine A at 1mg/kg and also the relevant AChE inhibition in brain. These findings suggested that Bis-Mep might be a promising dual-binding AChE inhibitor for potential AD therapeutics.

The strategy of dual binding site acetylcholinesterase (AChE) inhibition along with metal chelation may represent a promising direction for multi-targeted interventions in the pathophysiological processes of Alzheimer's disease (AD). In the present study, two derivatives (ZLA and ZLB) of a potent dual binding site AChE inhibitor bis-(-)-nor-meptazinol (bis-MEP) were designed and synthesized by introducing metal chelating pharmacophores into the middle chain of bis-MEP. They could inhibit human AChE activity with IC(50) values of 9.63uM (for ZLA) and 8.64uM (for ZLB), and prevent AChE-induced amyloid-beta (Abeta) aggregation with IC(50) values of 49.1uM (for ZLA) and 55.3uM (for ZLB). In parallel, molecular docking analysis showed that they are capable of interacting with both the catalytic and peripheral anionic sites of AChE. Furthermore, they exhibited abilities to complex metal ions such as Cu(II) and Zn(II), and inhibit Abeta aggregation triggered by these metals. Collectively, these results suggest that ZLA and ZLB may act as dual binding site AChEIs with metal-chelating potency, and may be potential leads of value for further study on disease-modifying treatment of AD.

A bis-(-)-nor-meptazinol derivative in which the two meptazinol rings are linked by a nonamethylene spacer is a novel acetylcholinesterase inhibitor that inhibits both catalytic activity and Abeta peptide aggregation. The crystal structure of its complex with Torpedo californica acetylcholinesterase was determined to 2.7 A resolution. The ligand spans the active-site gorge, with one nor-meptazinol moiety bound at the "anionic" subsite of the active site, disrupting the catalytic triad by forming a hydrogen bond with His440N(epsilon2), which is hydrogen-bonded to Ser200O(gamma) in the native enzyme. The second nor-meptazinol binds at the peripheral "anionic" site at the gorge entrance. A number of GOLD models of the complex, using both native TcAChE and the protein template from the crystal structure of the bis-(-)-nor-meptazinol/TcAChE complex, bear higher similarity to the X-ray structure than a previous model obtained using the mouse enzyme structure. These findings may facilitate rational design of new meptazinol-based acetylcholinesterase inhibitors.

Bis-(-)-nor-meptazinols (bis-(-)-nor-MEPs) 5 were designed and synthesized by connecting two (-)-nor-MEP monomers with alkylene linkers of different lengths via the secondary amino groups. Their acetylcholinesterase (AChE) inhibitory activities were more greatly influenced by the length of the alkylene chain than butyrylcholinesterase (BChE) inhibition. The most potent nonamethylene-tethered dimer 5h exhibited low-nanomolar IC 50 values for both ChEs, having a 10 000-fold and 1500-fold increase in inhibition of AChE and BChE compared with (-)-MEP. Molecular docking elucidated that 5h simultaneously bound to the catalytic and peripheral sites in AChE via hydrophobic interactions with Trp86 and Trp286. In comparison, it folded in the large aliphatic cavity of BChE because of the absence of peripheral site and the enlargement of the active site. Furthermore, 5h and 5i markedly prevented the AChE-induced Abeta aggregation with IC 50 values of 16.6 and 5.8 microM, similar to that of propidium (IC 50 = 12.8 microM), which suggests promising disease-modifying agents for the treatment of AD patients.

Molecular docking has been performed to investigate the binding mode of (-)-meptazinol (MEP) with acetylcholinesterase (AChE) and to screen bis-meptazinol (bis-MEP) derivatives for preferable synthetic candidates virtually. A reliable and practical docking method for investigation of AChE ligands was established by the comparison of two widely used docking programs, FlexX and GOLD. In our hands, we had more luck using GOLD than FlexX in reproducing the experimental poses of known ligands (RMSD<1.5 A). GOLD fitness values of known ligands were also in good agreement with their activities. In the present GOLD docking protocol, (-)-MEP seemed to bind with the enzyme catalytic site in an open-gate conformation through strong hydrophobic interactions and a hydrogen bond. Virtual screening of a potential candidate compound library suggested that the most promising 15 bis-MEP derivatives on the list were mainly derived from (-)-MEP with conformations of (S,S) and (SR,RS) and with a 2- to 7-carbon linkage. Although there are still no biological results to confirm the predictive power of this method, the current study could provide an alternate tool for structural optimization of (-)-MEP as new AChE inhibitors. [Figure: see text].