[Pharmacological properties of donepezil hydrochloride (Aricept), a drug for Alzheimer's disease]

Evaluation of neuroprotective effects of Canna indica L against aluminium chloride induced memory impairment in rats

Memory disorders are the progressive neurological disorder, mainly causing dementia, memory loss and cognitive dysfunctions. The current study is aimed to experimentally validate the crude extract of Canna indica aerial parts (CIA) and root (CIR) against aluminium chloride induced altered memory in rats. Initially, methanolic extract of CIA, hydroalcoholic extract of CIR, and their combination of CIA + CIR were screened for Invitro antioxidant activity via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) assays, acetylcholinesterase (AChE) inhibitory assay and were also screened for their memory enhancing activity by in-vivo models such as elevated plus maze (EPM), morris water maze (MWM), cooks pole climb (CPC), Actophotometer, novel object recognition (NOR), and T-maze. Aluminium chloride (AlCl₃) (17 mg/kg/day p.o.) for 21 days, was used as an Alzheimer’s disease inducing agent and Donepezil (AChE inhibitor) as a standard treatment agent. The AChE, butyrylcholinesterase (BChE) activity and malondialdehyde (MDA) level were significantly increased, and glutathione (GSH), total protein (TP), catalase (CAT), and Dopamine were decreased only in AlCl₃ treated rats and treatment with CIA 200 mg/kg and CIA + CIR 200 mg/kg significantly reversed these mechanisms.Histopathology of cortex and hippocampus was examined at 40× magnification, indicating maintain of integrity and architecture of CA1 and CA3 neuronal cells compared to control and standard groups. The in vivo studies of interospective and exteroceptive behavior models (EPM), MWM, CPC, Actophotometer, NOR, T-maze revealed that AlCl₃ administration enhanced transfer latency (TL), escape latency time (ELT) and decreases locomotion, discriminatory index, and percentage alternation respectively. However, treatment with CIA and CIA + CIR 200 mg/kg highly significantly reversed the pathological changes of disease, extracts of Canna indica of both root and aerial parts phyto constituents are rich in flavonoids, phlobatannins, anthocyanin pigments, saponins, alkaloids, steroids, terpenoids etc. Which will decipher the acetylcholinestrase inhibitory, antioxidant and anti-inflammatory activity, will ameliorate the pathological state of Alzheimer disease.

Identification of ovalbumin-derived peptides as multi-target inhibitors of AChE, BChE, and BACE1

BACKGROUND

Alzheimer's disease (AD) is a kind of progressive neurodegenerative disease that affects the elderly. There is no ideal treatment for AD. Thus, the purpose of this study is to identify anti-AD peptides from ovalbumin.

RESULTS

The potential tripeptides IEK, LYR, and CIK were selected for molecular docking. The '-CDOCKER_Energy' values of the best docking positions of the tripeptide IEK, LYR, and CIK interacting with acetylcholinesterase (AChE) were 93.8119, 86.9556 and 73.6370 kcal mol^-1 , respectively. The '-CDOCKER_Energy' values for interaction with butyrylcholinesterase (BChE) were 96.6386, 80.8392, and 87.4341 kcal mol^-1 , respectively. Most importantly, the '-CDOCKER_Energy' values for interaction with β-site amyloid precursor protein cleavage enzyme1 (BACE1) were 85.5903, 71.3342, and 68.4290 kcal mol^-1 , respectively. Overall, in vitro assay results demonstrated that the peptide CIK exhibited impressive inhibitory activities against AChE, BChE, and BACE1, with half maximal inhibitory concentration (IC₅₀ ) values of 6.76, 7.72, and 34.48 μmol L^-1 , respectively. In particular, CIK can be joined with some peripheral anion sites (PAS) and catalytic sites on AChE, BChE, and BACE1.

CONCLUSION

Tripeptide CIK can effectively inhibit the activities of AChE, BChE, and BACE1. Tripeptide CIK therefore has the potential to treat AD effectively. © 2020 Society of Chemical Industry.

Jiao-Tai-Wan Improves Cognitive Dysfunctions through Cholinergic Pathway in Scopolamine-Treated Mice

Cognitive dysfunction is characterized as the gradual loss of learning ability and cognitive function, as well as memory impairment. Jiao-tai-wan (JTW), a Chinese medicine prescription including Coptis chinensis and cinnamon, is mainly used for the treatment of insomnia, while the effect of JTW in improving cognitive function has not been reported. In this study, we employed a scopolamine- (SCOP-) treated learning and memory deficit model to explore whether JTW could alleviate cognitive dysfunction. In behavioral experiments, Morris water maze, Y-maze, fearing condition test, and novel object discrimination test were conducted. Results showed that oral administration of JTW (2.1 g/kg, 4.2 g/kg, and 8.4 g/kg) can effectively promote the ability of spatial recognition, learning and memory, and the memory ability of fresh things of SCOP-treated mice. In addition, the activity of acetylcholinesterase (AChE) was effectively decreased; the activity of choline acetyltransferase (ChAT) and concentration of acetylcholine (Ach) were improved after JTW treatment in both hippocampus and cortex of SCOP-treated mice. JTW effectively ameliorated oxidative stress because of decreased the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) and increased the activities of superoxide dismutase (SOD) and catalase (CAT) in hippocampus and cortex. Furthermore, JTW promotes the expressions of neurotrophic factors including postsynaptic density protein 95 (PSD95) and synaptophysin (SYN) and brain-derived neurotrophic factor (BDNF) in both hippocampus and cortex. Nissl's staining shows that the neuroprotective effect of JTW was very effective. To sum up, JTW might be a promising candidate for the treatment of cognitive dysfunction.

An in vitro AChE inhibition assay combined with UF-HPLC-ESI-Q-TOF/MS approach for screening and characterizing of AChE inhibitors from roots of Coptis chinensis Franch

In this study, an in vitro acetylcholinesterase (AChE) inhibition assay based on microplate reader combined with ultrafiltration high performance liquid chromatography-electrospray quadrupole time of flight mass (UF-HPLC-ESI-Q-TOF/MS) was developed for the rapid screening and identification of acetylcholinesterase inhibitors (AChEI) from roots of Coptis chinensis Franch. Incubation conditions such as enzyme concentration, incubation time, incubation temperature and co-solvent was optimized so as to get better screening results. Five alkaloids including columbamine, jatrorrhizine, coptisine, palmatine and berberine were found with AChE inhibition activity in the 80% ethanol extract of C. chinensis Franch. The screened compounds were identified by HPLC-DAD-ESI-Q-TOF/MS compared with the reference stands and literatures. The screened results were verified by in vitro AChE inhibition assays, palmatine showed the best AChE inhibitory activities with IC50 values of 36.6μM among the five compounds. Results of the present study indicated that the combinative method using in vitro AChE inhibition assay and UF-HPLC-ESI-Q-TOF/MS could be widely applied for rapid screening and identification of AChEI from complex TCM extract.

FK962 and donepezil act synergistically to improve cognition in rats: potential as an add-on therapy for Alzheimer's disease

FK962 is a member of a novel class of compounds that promote somatostatin production in the brain, and is being developed as a treatment for patients with Alzheimer's disease. As acetylcholinesterase inhibitors such as Aricept© (donepezil) are widely used to treat these patients, it is important to confirm that potential new medicines in this disease area can be co-administered with drugs such as Aricept. To study the effect of FK962 in combination with donepezil, touchscreen methodology was used to measure the effect on cognition in rats. Doses of FK962 and donepezil were identified that resulted in minimal cognition enhancement when given separately. There was strong evidence (p=0.002) of a treatment difference between the combination of FK962/donepezil and FK962 alone: the estimated treatment difference is 5.47 (95% CI: 2.19-8.75). There was also evidence (p=0.017) of a treatment difference between the combination of FK962/donepezil and donepezil alone: the estimated treatment difference is 4.01 (95% CI: 0.77-7.26). Therefore, a combination of low doses of FK962 and donepezil showed a significantly greater effect on cognition than low doses of either compound alone. This is the first time that FK962 has shown activity in a reward-based model of cognition. In addition, these data suggest that this compound could beneficially be given in addition to Aricept to treat Alzheimer's disease patients.

Enzyme inhibitor screening by electrospray mass spectrometry with immobilized enzyme on magnetic silica microspheres

In this study, a novel technique for screening inhibitors by electrospray mass spectrometry (ESI-MS) with immobilized enzyme on magnetic microspheres has been demonstrated. First, the model enzyme acetylcholinesterase (AChE) is immobilized onto the 3-glycidoxypropyltrimethoxysilane (GLYMO)-modified magnetic silica microspheres. AChE activity was monitored by biochemical assay that is based on mixing of AChE immobilized microspheres and model substrate acetylcholine, separating and detecting the product through ESI-MS. Stability of the enzyme-immobilized microspheres was investigated. No apparent loss of enzyme activity was observed after fivefold reuse of AChE-immobilized microspheres. The enzyme-immobilized bioassay was used to effectively identify AChE inhibitors among two standard samples, huperzine A and huperzine B, and their source herbal Huperzia serrata, all of which were spiked into the substrate. The inhibition was determined by measuring a decrease of product formation using ESI-MS.

Preparative isolation of huperzines A and B from Huperzia serrata by displacement centrifugal partition chromatography

The pH-zone refining centrifugal partition chromatography technique was used to separate the two acetylcholinesterase inhibitors huperzines A and B from a crude alkaloid extract of the club moss Huperzia serrata. Complete co-elution of huperzines A and B was initially observed with the well-known methyl tert-butyl ether-acetonitrile-water (4:1:5, v/v/v) solvent system with triethylamine (8mM) as the displacer and methane sulfonic acid (6mM) as the retainer. An efficient biphasic system was designed on the basis of solvent association that provided selectivity in the elution mode: n-heptane/ethyl acetate/n-propanol/water (5:15:35:45, v/v/v/v). Lowering the bridge solvent content (n-propanol) of this system increased the polarity difference between the two phases thus adapting it to the pH-zone refining mode. Thus, the purification of these compounds was achieved using the biphasic system n-heptane/ethyl acetate/n-propanol/water (10:30:15:45, v/v/v/v) with triethylamine (8mM) as the displacer and methane sulfonic acid (6mM) as the retainer.