The search for tacrine derivatives, as potential Alzheimer´s disease treatment, is still being at the forefront of scientific efforts. 7-MEOTA was found to be a potent, centrally active acetylcholinesterase inhibitor free of the serious side effects observed for tacrine. Unfortunately, a relevant argumentation about pharmacokinetics and potential toxicity is incomplete; information about tacrine derivatives absorption and especially CNS penetration are still rare as well as detailed toxicological profile in vivo. Although the structural changes between these compounds are not so distinctive, differences in plasma profile and CNS targeting were found. The maximum plasma concentration were attained at 18th min (tacrine; 38.20 ± 3.91 ng/ml and 7-MEOTA; 88.22 ± 15.19 ng/ml) after i.m. application in rats. Although the brain profiles seem to be similar; tacrine achieved 19.34 ± 0.71 ng/ml in 27 min and 7-MEOTA 15.80 ± 1.13 ng/ml in 22 min; the tacrine Kp (AUCbrain/AUCplasma) fit 1.20 and was significantly higher than 7-MEOTA Kp 0.10. Administration of tacrine and 7-MEOTA showed only mild elevation of some biochemical markers following single p.o. application in 24 hours and 7 days. Also histopathology revealed only mild-to-moderate changes following repeated p.o. administration for 14 days. It seems that small change in tacrine molecule leads to lower ability to penetrate through the biological barriers. The explanation that lower p.o. acute toxicity of 7-MEOTA depends only on differences in metabolic pathways may be now revised to newly described differences in pharmacokinetic and toxicological profiles.
- MeSH
- časové faktory MeSH
- cholinesterasové inhibitory aplikace a dávkování farmakokinetika toxicita MeSH
- krysa rodu rattus MeSH
- mozek metabolismus MeSH
- plocha pod křivkou MeSH
- potkani Wistar MeSH
- takrin aplikace a dávkování analogy a deriváty farmakokinetika toxicita MeSH
- tkáňová distribuce MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The formation and accumulation of amyloid aggregates are the phenomena that accompany amyloidoses, which are currently untreatable and include Alzheimer's and Parkinson's diseases, diabetes mellitus, non-neuropathic lysozyme systemic amyloidosis, and others. One of the very promising therapeutic approaches seems to be an inhibition of amyloid formation and/or clearance of amyloid aggregates. Small molecules have a great potential to interfere with amyloid fibrillation of peptides and polypeptides, which can be improved by connection of cyclic structures into single multicyclic molecules and their dimerization. In our study, we focused on heterodimers consisting of 7-methoxytacrine (7-MEOTA) and 2-aminobenzothiazole (BTZ) parent molecules connected by an aliphatic linker. Using in vitro and in silico methods, we investigated the ability of studied compounds to inhibit the amyloid aggregation of hen egg white lysozyme. Heterodimerization led to significant improvement of inhibitory activity compared to that of the parent molecules. The efficiency of the heterodimers varied; the most effective inhibitor contained the longest linker, eight carbons long. We suggest that binding of a heterodimer to a lysozyme blocks the interaction between the β-domain and C-helix region essential for the formation of amyloid cross-β structure. Elongation of the linker ultimately enhances the compound's ability to prevent this interaction by allowing the BTZ part of the heterodimer to bind more effectively, increasing the compound's binding affinity, and also by greater steric obstruction. This study represents an important contribution to the recent rational design of potential lead small molecules with anti-amyloid properties, and the heterodimers studied are prospective candidates for the treatment of systemic lysozyme amyloidosis and other amyloid-related diseases.
- MeSH
- amyloid * MeSH
- amyloidogenní proteiny MeSH
- amyloidóza * MeSH
- lidé MeSH
- prospektivní studie MeSH
- takrin analogy a deriváty MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Based on the prevalence studies, the number of people suffering from dementia will almost double every 20 years, to 65.7 million in 2030 and 115.4 million in 2050, assuming no changes in mortality, effective preventative measures, definitive diagnostic guidelines or curative treatment. From the abovementioned epidemiological data, it is obvious that dementia constitutes a major public health problem not only at present, but unfortunately also in the future. OBJECTIVES AND METHODS: Several N-alkylated tacrine (THA) derivatives have already been synthesized by Pomponi et al., in 1997. However, these compounds were tested for their anti-AChE activity using enzyme isolated from Electrophorus electricus. For this reason, we have decided to extend the previously reported series of THA derivatives and consequently test them in the battery of experiments, the results of which have served to more relevant evaluation of these compounds from the perspective of Alzeimer´s disease compared to that published by Pomponi. RESULTS AND CONCLUSION: In summary, all compounds of interest effectively inhibited ChEs in vitro. One of the most promising derivatives 8 bearing an N-octyl chain showed 2.5-fold higher AChE inhibitory activity in relation to tacrine. With respect to blood-brain barrier (BBB) penetration, it can be claimed that synthesized analogues are presumably able to cross the BBB. From the point of view of hepatotoxicity, selected Nalkylated tacrine derivatives exerted worse results compared to tacrine. However, in vitro results are only illustrative, therefore, only in vivo experiments could determine the real value of selected N-alkylated THA derivatives.
BACKGROUND: Alzheimer's disease (AD) is the most common form of dementia in the elderly. It is characterized as a multi-factorial disorder with a prevalent genetic component. Due to the unknown etiology, current treatment based on acetylcholinesterase (AChE) inhibitors and N-methyl-D-aspartate receptors (NMDAR) antagonist is effective only temporary. It seems that curative treatment will necessarily be complex due to the multifactorial nature of the disease. In this context, the so-called "multi-targeting" approach has been established. OBJECTIVES: The aim of this study was to develop a multi-target-directed ligand (MTDL) combining the support for the cholinergic system by inhibition of AChE and at the same time ameliorating the burden caused by glutamate excitotoxicity mediated by the NMDAR receptors. METHODS: We have applied common approaches of organic chemistry to prepare a hybrid of 6-chlorotacrine and memantine. Then, we investigated its blocking ability towards AChE and NMDRS in vitro, as well as its neuroprotective efficacy in vivo in the model of NMDA-induced lessions. We also studied cytotoxic potential of the compound and predicted the ability to cross the blood-brain barrier. RESULTS: A novel molecule formed by combination of 6-chlorotacrine and memantine proved to be a promising multipotent hybrid capable of blocking the action of AChE as well as NMDARs. The presented hybrid surpassed the AChE inhibitory activity of the parent compound 6-Cl-THA twofold. According to results it has been revealed that our novel hybrid blocks NMDARs in the same manner as memantine, potently inhibits AChE and is predicted to cross the blood-brain barrier via passive diffusion. Finally, the MTDL design strategy was indicated by in vivo results which showed that the novel 6-Cl-THA-memantine hybrid displayed a quantitatively better neuroprotective effect than the parent compound memantine. CONCLUSION: We conclude that the combination of two pharmacophores with a synergistic mechanism of action into a single molecule offers great potential for the treatment of CNS disorders associated with cognitive decline and/or excitotoxicity mediated by NMDARs.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- Alzheimerova nemoc farmakoterapie metabolismus MeSH
- CHO buňky MeSH
- cholinesterasové inhibitory chemická syntéza farmakologie MeSH
- Cricetulus MeSH
- HEK293 buňky MeSH
- hematoencefalická bariéra účinky léků metabolismus MeSH
- kapilární permeabilita MeSH
- kyselina glutamová metabolismus MeSH
- lidé MeSH
- ligandy MeSH
- memantin chemická syntéza farmakologie MeSH
- neuroprotektivní látky chemická syntéza farmakologie MeSH
- potkani Wistar MeSH
- receptory N-methyl-D-aspartátu antagonisté a inhibitory metabolismus MeSH
- simulace molekulového dockingu MeSH
- takrin analogy a deriváty chemická syntéza farmakologie MeSH
- techniky tkáňových kultur MeSH
- viabilita buněk účinky léků MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Being among the top five causes of death in the developed world, Alzheimer's disease represents a major socio-economic issue. We administered a single intramuscular dose of two new hybrid anti-Alzheimer's compounds, with 7-methoxytacrine (7-MEOTA; acetylcholinesterase inhibitor) and tryptophan (inhibitor of amyloid accumulation) in their structure, to rats. Using validated ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) methods, we uncovered their inability to enter the site of action - the brain. We discuss four possible explanations: i) physico-chemical properties, ii) lack of active/facilitated transport, iii) effective efflux and/or iv) extensive metabolism. High-resolution mass spectrometric analyses proved that the compounds are easily hydrolysed at amide bond between tryptophan and the linker both in vitro and in vivo. Contrary to the parent compounds these metabolites - analogues of 7-MEOTA - can enter the brain in significant amounts.
- MeSH
- Alzheimerova nemoc MeSH
- cholinesterasové inhibitory farmakokinetika MeSH
- hematoencefalická bariéra MeSH
- hydrolýza MeSH
- krysa rodu rattus MeSH
- mozek metabolismus MeSH
- potkani Wistar MeSH
- takrin analogy a deriváty farmakokinetika MeSH
- tandemová hmotnostní spektrometrie MeSH
- tryptofan farmakokinetika MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The novel prophylactic agent 7-methoxytacrine-4-pyridinealdoxime is a hybrid compound formerly designed to keep acetylcholinesterase resistant to organophosphates by reactivating it in case of intoxication by such inhibitors. In rational design, a 5-carbon length-spacer hybrid compound was synthesized to evaluate its inhibitory and reactivation capabilities. In this work, theoretical results were achieved through molecular modelling techniques, taking for granted the enzymatic reactivation reaction through nucleophilic substitution. Based on the near attack conformation approach, docking studies were performed to assess the spacer-length from 1 to 10 carbons long of a series of analogues of 7-methoxytacrine-4-pyridinealdoxime. Consequently, the hybrids with length-spacer of 4 and 5 carbons long were the best assessed and subsequently subjected to further molecular dynamics simulations, complemented by Poisson-Boltzmann surface area calculations. As a result, intermolecular interactions with the different binding sites inside human acetylcholinesterase were elucidated. Besides, thermodynamics and kinetics concepts pointed to the 4-carbon linker as optimum for enzymatic reactivation. Further studies, based on quantum mechanics in conjunction with molecular mechanics, were recommended to the presented near attack conformations to achieve more thermodynamics results between the hybrids with 4- and 5-carbon linkers, like values of activation energy for the reactivation reaction. All of those in silico evaluations could be considered as a set of tools for theoretically investigate novel enzymatic reactivators with different shape of spacers.
- MeSH
- acetylcholinesterasa chemie metabolismus MeSH
- cholinesterasové inhibitory chemie metabolismus MeSH
- lidé MeSH
- ligandy MeSH
- organothiofosforové sloučeniny chemie metabolismus MeSH
- oximy chemie MeSH
- simulace molekulového dockingu MeSH
- takrin analogy a deriváty chemie metabolismus MeSH
- terciární struktura proteinů MeSH
- termodynamika MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The objective of this study was to elucidate the pharmacokinetics and metabolite formation of newly developed non-selective AChE/BChE 7-MEOTA-donepezil-like inhibitors for potential therapeutic use in Alzheimer's disease (AD) patients. The chemical structures of metabolites were defined during incubation with human liver microsomes, and subsequently, the metabolization was verified in in vivo study. In vitro metabolic profiling revealed the formation of nine major metabolites in the case of PC-37 and eight metabolites of PC-48. Hydroxylation and the enzymatic hydrolysis of bonds close to the piperazine ring appeared to be the principal metabolic pathways in vitro. Of these metabolites, M1-M7 of PC-37 and M1-M6 of PC-48 were confirmed under in vivo conditions. Pilot pharmacokinetic experiments in rats were focused on the absorption, distribution and elimination of these compounds. Absorption after i.m. application was relatively fast; the bioavailability expressed as AUCtotal was 28179 ± 4691 min.ng/mL for PC-37 and 23374 ± 4045 min.ng/mL for PC-48. Both compounds showed ability to target the central nervous system, with brain concentrations exceeding those in plasma. The maximal brain concentrations are approximately two times higher than the plasma concentrations. The relatively high brain concentrations persisted throughout the experiment until 24 hr after application. Elimination via the kidneys (urine) significantly exceeded elimination via the liver (bile). All these characteristics are crucial for new candidates intended for AD treatment. The principle metabolic pathways that were verified in the in vivo study do not show any evidence for formation of extremely toxic metabolites, but this needs to be confirmed by further studies.
- MeSH
- Alzheimerova nemoc farmakoterapie MeSH
- biologická dostupnost MeSH
- cholinesterasové inhibitory chemická syntéza metabolismus farmakokinetika terapeutické užití MeSH
- hydrolýza MeSH
- hydroxylace MeSH
- jaterní mikrozomy metabolismus MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- metabolické sítě a dráhy MeSH
- mozek účinky léků MeSH
- pilotní projekty MeSH
- piperaziny chemická syntéza metabolismus farmakokinetika terapeutické užití MeSH
- potkani Wistar MeSH
- takrin analogy a deriváty chemická syntéza metabolismus farmakokinetika terapeutické užití MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: 6-chlorotacrine is a cholinesterase inhibitor showing good inhibitory potential, even better than parent compound tacrine, in vitro. Despite tacrine scaffold is broadly used for design and synthesis of novel compounds with anti-Alzheimer's potential, no in vivo effects have been investigated so far. Thus, basic toxicological and behavioural evaluation has been carried out throughout this study. METHODS: Maximum tolerated dose (MTD) and median lethal dose (LD50) were assessed in BALB/c mice and Wistar rats. Behavioural effects were observed in rats performing the multiple T-maze test, the water maze test and the step-through passive avoidance test. All outcomes were compared with the effects of parent compound - tacrine. RESULTS: The toxicity of 6-chlorotacrine was increased compared to tacrine with MTD 6.0/5.0 mg.kg-1 (i.m., male/female mice), 6.0/5.0 mg.kg-1 (i.p., male/female rats) and LD50 9.0 mg.kg-1 (male rats). At MTD doses, no histopathological changes and blood biochemistry abnormalities were observed except decreased plasma creatinine levels. 6-chlorotacrine showed good effects in the reversal of quinuclidinyl benzilate-induced amnesia. Best results were achieved at the dose of 1.8 mg.kg-1 (20% LD50) in the water maze test; the pro-cognitive effect was stronger than that of tacrine (5.2 mg.kg-1, 20% LD50). Other doses tested (0.9 mg.kg-1 and 2.7 mg.kg-1) showed similar effects as tacrine in the water maze, multiple T-maze and passive avoidance test. CONCLUSION: Observed effects predetermined 6-chlorotacrine as a potent parent compound for the synthesis of novel multifactorial drugs intended to the treatment of Alzheimer's disease. Even though 6- chlorotacrine showed in vivo beneficial effect with no signs of toxicity, further tests on the field of biochemistry and pharmacology are essential to disclose the exact mechanism of action, safety evaluation and the metabolic fate of the compound after the repeated administration.
- MeSH
- bludiště - učení účinky léků MeSH
- cholinesterasové inhibitory chemie farmakologie toxicita MeSH
- myši inbrední BALB C MeSH
- nootropní látky chemie farmakologie toxicita MeSH
- potkani Wistar MeSH
- preklinické hodnocení léčiv MeSH
- takrin analogy a deriváty chemie farmakologie toxicita MeSH
- učení vyhýbat se účinky léků MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
N-methyl-d-aspartate receptors (NMDARs) are ionotropic glutamate receptors that mediate excitatory neurotransmission in the mammalian central nervous system (CNS), and their dysregulation results in the aetiology of many CNS syndromes. Several NMDAR modulators have been used successfully in clinical trials (including memantine) and NMDARs remain a promising pharmacological target for the treatment of CNS syndromes. 1,2,3,4-Tetrahydro-9-aminoacridine (tacrine; THA) was the first approved drug for Alzheimer's disease (AD) treatment. 7-methoxyderivative of THA (7-MEOTA) is less toxic and showed promising results in patients with tardive dyskinesia. We employed electrophysiological recordings in HEK293 cells and rat neurones to examine the mechanism of action of THA and 7-MEOTA at the NMDAR. We showed that both THA and 7-MEOTA are "foot-in-the-door" open-channel blockers of GluN1/GluN2 receptors and that 7-MEOTA is a more potent but slower blocker than THA. We found that the IC50 values for THA and 7-MEOTA exhibited the GluN1/GluN2A < GluN1/GluN2B < GluN1/GluN2C = GluN1/GluN2D relationship and that 7-MEOTA effectively inhibits human GluN1/GluN2A-M817V receptors that carry a pathogenic mutation. We also showed that 7-MEOTA is a "foot-in-the-door" open-channel blocker of GluN1/GluN3 receptors, although these receptors were not inhibited by memantine. In addition, the inhibitory potency of 7-MEOTA at synaptic and extrasynaptic hippocampal NMDARs was similar, and 7-MEOTA exhibited better neuroprotective activity when compared with THA and memantine in rats with NMDA-induced lesions of the hippocampus. Finally, intraperitoneal administration of 7-MEOTA attenuated MK-801-induced hyperlocomotion and pre-pulse inhibition deficit in rats. We conclude that 7-MEOTA may be considered for the treatment of diseases associated with the dysfunction of NMDARs.
- MeSH
- dizocilpinmaleát antagonisté a inhibitory farmakologie MeSH
- hipokampus účinky léků MeSH
- krysa rodu rattus MeSH
- kultivované buňky MeSH
- lidé MeSH
- lokomoce účinky léků MeSH
- memantin farmakologie MeSH
- mutace MeSH
- neurony účinky léků fyziologie MeSH
- neuroprotektivní látky farmakologie MeSH
- prepulsní inhibice účinky léků MeSH
- receptory N-methyl-D-aspartátu antagonisté a inhibitory genetika MeSH
- takrin analogy a deriváty farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Na základě poznatků získaných z krystalografie acetylcholinesterasy (AChE) byly koncipovány nové homo- i heterodimerní molekuly, které jsou schopné vázat se do obou anionických míst enzymu a tím nejen zvýšit svůj inhibiční potenciál, ale i současně ovlivňovat další patologické mechanismy AD. Průkopnickou molekulou se v tomto ohledu stal bis(7)-takrin, který vznikl zdvojením takrinu přes alifatický můstek o délce sedmi uhlíkových atomů. Bis(7)-takrin je zajímavou multipotentní sloučeninou, která je schopna ovlivňovat řadu receptorových i enzymových systémů za podmínek in vitro i in vivo. Stal se rovněž předlohovou strukturou pro celou řadu nových sloučenin s dalšími pozitivními vlastnostmi, které jsou relevantní pro terapii AD.
The acetylcholinesterase (AChE) structure elucidation has significantly contributed to the development of both novel homo- and heterodimer molecules that are capable of simultaneous binding to both anionic sites of the enzyme. This mostly resulted into improved AChE inhibition potency concurrently affecting other pathological hallmarks of the disease. In this regard, bis(7)-tacrine can be considered as the pioneering molecule. It consists of two tacrine moieties connected via alkylene tether of seven carbon atoms. In in vitro and in vivo, bis(7)-tacrine revealed interesting multipotent profile capable to affect several enzymes and receptors which are implicated in the pathogenesis of AD. It also became a key structural template in the development of other more potent compounds intended for the therapy of neurodegenerative disorders.
- MeSH
- acetylcholinesterasa aplikace a dávkování škodlivé účinky terapeutické užití MeSH
- Alzheimerova nemoc * farmakoterapie prevence a kontrola terapie MeSH
- behaviorální výzkum metody trendy MeSH
- experimenty na zvířatech MeSH
- hodnotící studie jako téma MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- neurodegenerativní nemoci * farmakoterapie prevence a kontrola terapie MeSH
- skopolamin MeSH
- takrin * analogy a deriváty terapeutické užití MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
