Pejchal J

References (23)

Title : Phenoxytacrine derivatives: Low-toxicity neuroprotectants exerting affinity to ifenprodil-binding site and cholinesterase inhibition - Misiachna_2024_Eur.J.Med.Chem_266_116130
Author(s) : Misiachna A , Svobodova B , Netolicky J , Chvojkova M , Kleteckova L , Prchal L , Novak M , Hrabinova M , Kucera T , Muckova L , Moravcova Z , Karasova JZ , Pejchal J , Blazek F , Malinak D , Hakenova K , Krausova BH , Kolcheva M , Ladislav M , Korabecny J , Pahnke J , Vales K , Horak M , Soukup O
Ref : Eur Journal of Medicinal Chemistry , 266 :116130 , 2024
Abstract : Tacrine (THA), a long withdrawn drug, is still a popular scaffold used in medicinal chemistry, mainly for its good reactivity and multi-targeted effect. However, THA-associated hepatotoxicity is still an issue and must be considered in drug discovery based on the THA scaffold. Following our previously identified hit compound 7-phenoxytacrine (7-PhO-THA), we systematically explored the chemical space with 30 novel derivatives, with a focus on low hepatotoxicity, anticholinesterase action, and antagonism at the GluN1/GluN2B subtype of the NMDA receptor. Applying the down-selection process based on in vitro and in vivo pharmacokinetic data, two candidates, I-52 and II-52, selective GluN1/GluN2B inhibitors thanks to the interaction with the ifenprodil-binding site, have entered in vivo pharmacodynamic studies. Finally, compound I-52, showing only minor affinity to AChE, was identified as a lead candidate with favorable behavioral and neuroprotective effects using open-field and prepulse inhibition tests, along with scopolamine-based behavioral and NMDA-induced hippocampal lesion models. Our data show that compound I-52 exhibits low toxicity often associated with NMDA receptor ligands, and low hepatotoxicity, often related to THA-based compounds.
ESTHER : Misiachna_2024_Eur.J.Med.Chem_266_116130
PubMedSearch : Misiachna_2024_Eur.J.Med.Chem_266_116130
PubMedID: 38218127

Title : A-series agent A-234: initial in vitro and in vivo characterization - Hrabinova_2024_Arch.Toxicol__
Author(s) : Hrabinova M , Pejchal J , Hepnarova V , Muckova L , Junova L , Opravil J , Zdarova Karasova J , Rozsypal T , Dlabkova A , Rehulkova H , Kucera T , Vecera Z , Caisberger F , Schmidt M , Soukup O , Jun D
Ref : Archives of Toxicology , : , 2024
Abstract : A-series agent A-234 belongs to a new generation of nerve agents. The poisoning of a former Russian spy Sergei Skripal and his daughter in Salisbury, England, in March 2018 led to the inclusion of A-234 and other A-series agents into the Chemical Weapons Convention. Even though five years have already passed, there is still very little information on its chemical properties, biological activities, and treatment options with established antidotes. In this article, we first assessed A-234 stability in neutral pH for subsequent experiments. Then, we determined its inhibitory potential towards human recombinant acetylcholinesterase (HssAChE; EC 3.1.1.7) and butyrylcholinesterase (HssBChE; EC 3.1.1.8), the ability of HI-6, obidoxime, pralidoxime, methoxime, and trimedoxime to reactivate inhibited cholinesterases (ChEs), its toxicity in rats and therapeutic effects of different antidotal approaches. Finally, we utilized molecular dynamics to explain our findings. The results of spontaneous A-234 hydrolysis showed a slow process with a reaction rate displaying a triphasic course during the first 72 h (the residual concentration 86.2%). A-234 was found to be a potent inhibitor of both human ChEs (HssAChE IC(50) = 0.101 +/- 0.003 microM and HssBChE IC(50) = 0.036 +/- 0.002 microM), whereas the five marketed oximes have negligible reactivation ability toward A-234-inhibited HssAChE and HssBChE. The acute toxicity of A-234 is comparable to that of VX and in the context of therapy, atropine and diazepam effectively mitigate A-234 lethality. Even though oxime administration may induce minor improvements, selected oximes (HI-6 and methoxime) do not reactivate ChEs in vivo. Molecular dynamics implies that all marketed oximes are weak nucleophiles, which may explain the failure to reactivate the A-234 phosphorus-serine oxygen bond characterized by low partial charge, in particular, HI-6 and trimedoxime oxime oxygen may not be able to effectively approach the A-234 phosphorus, while pralidoxime displayed low interaction energy. This study is the first to provide essential experimental preclinical data on the A-234 compound.
ESTHER : Hrabinova_2024_Arch.Toxicol__
PubMedSearch : Hrabinova_2024_Arch.Toxicol__
PubMedID: 38446233

Title : A-agents, misleadingly known as Novichoks: a narrative review - Opravil_2023_Arch.Toxicol__
Author(s) : Opravil J , Pejchal J , Finger V , Korabecny J , Rozsypal T , Hrabinova M , Muckova L , Hepnarova V , Konecny J , Soukup O , Jun D
Ref : Archives of Toxicology , : , 2023
Abstract : "Novichok" refers to a new group of nerve agents called the A-series agents. Their existence came to light in 2018 after incidents in the UK and again in 2020 in Russia. They are unique organophosphorus-based compounds developed during the Cold War in a program called Foliant in the USSR. This review is based on original chemical entities from Mirzayanov's memoirs published in 2008. Due to classified research, a considerable debate arose about their structures, and hence, various structural moieties were speculated. For this reason, the scientific literature is highly incomplete and, in some cases, contradictory. This review critically assesses the information published to date on this class of compounds. The scope of this work is to summarize all the available and relevant information, including the physicochemical properties, chemical synthesis, mechanism of action, toxicity, pharmacokinetics, and medical countermeasures used to date. The environmental stability of A-series agents, the lack of environmentally safe decontamination, their high toxicity, and the scarcity of information on post-contamination treatment pose a challenge for managing possible incidents.
ESTHER : Opravil_2023_Arch.Toxicol__
PubMedSearch : Opravil_2023_Arch.Toxicol__
PubMedID: 37612377

Title : The measured CSF\/plasma donepezil concentration ratio but not individually measured CSF and plasma concentrations significantly increase over 24h after donepezil treatment in patients with Alzheimer's disease - Valis_2023_Biomed.Pharmacother_159_114223
Author(s) : Valis M , Dlabkova A , Hort J , Angelucci F , Pejchal J , Kuca K , Pavelek Z , Karasova JZ , Novotny M
Ref : Biomed Pharmacother , 159 :114223 , 2023
Abstract : BACKGROUND: The acetylcholinesterase inhibitor donepezil is administered as a treatment for Alzheimer's disease (AD). However, the appropriate donepezil dosage is still a matter of debate. METHODS: Forty AD patients receiving 10smg/day of donepezil were randomly divided into four groups based on the time of plasma and cerebrospinal fluid (CSF) sampling: 6sh (n = 5), 12sh (n = 12), 18sh (n = 6) and 24sh (n = 17) after donepezil administration. High-performance liquid chromatography measured the donepezil concentration in plasma samples and CSF samples collected at 4-time points. RESULTS: Plasma and CSF levels among the groups were not significantly different. Conversely, the CSF/plasma donepezil concentration ratio considerably increased in the 24sh group compared to the 6sh (ps<s0.005) and 12sh (ps<s0.05) groups. CONCLUSION: The measurement of the CSF/plasma donepezil concentration ratio could be used to better evaluate the optimal dose of donepezil.
ESTHER : Valis_2023_Biomed.Pharmacother_159_114223
PubMedSearch : Valis_2023_Biomed.Pharmacother_159_114223
PubMedID: 36630846

Title : Neurotoxicity evoked by organophosphates and available countermeasures - Pulkrabkova_2022_Arch.Toxicol__
Author(s) : Pulkrabkova L , Svobodova B , Konecny J , Kobrlova T , Muckova L , Janousek J , Pejchal J , Korabecny J , Soukup O
Ref : Archives of Toxicology , : , 2022
Abstract : Organophosphorus compounds (OP) are a constant problem, both in the military and in the civilian field, not only in the form of acute poisoning but also for their long-lasting consequences. No antidote has been found that satisfactorily protects against the toxic effects of organophosphates. Likewise, there is no universal cure to avert damage after poisoning. The key mechanism of organophosphate toxicity is the inhibition of acetylcholinesterase. The overstimulation of nicotinic or muscarinic receptors by accumulated acetylcholine on a synaptic cleft leads to activation of the glutamatergic system and the development of seizures. Further consequences include generation of reactive oxygen species (ROS), neuroinflammation, and the formation of various other neuropathologists. In this review, we present neuroprotection strategies which can slow down the secondary nerve cell damage and alleviate neurological and neuropsychiatric disturbance. In our opinion, there is no unequivocal approach to ensure neuroprotection, however, sooner the neurotoxicity pathway is targeted, the better the results which can be expected. It seems crucial to target the key propagation pathways, i.e., to block cholinergic and, foremostly, glutamatergic cascades. Currently, the privileged approach oriented to stimulating GABA(A)R by benzodiazepines is of limited efficacy, so that antagonizing the hyperactivity of the glutamatergic system could provide an even more efficacious approach for terminating OP-induced seizures and protecting the brain from permanent damage. Encouraging results have been reported for tezampanel, an antagonist of GluK1 kainate and AMPA receptors, especially in combination with caramiphen, an anticholinergic and anti-glutamatergic agent. On the other hand, targeting ROS by antioxidants cannot or already developed neuroinflammation does not seem to be very productive as other processes are also involved.
ESTHER : Pulkrabkova_2022_Arch.Toxicol__
PubMedSearch : Pulkrabkova_2022_Arch.Toxicol__
PubMedID: 36335468

Title : Non-covalent acetylcholinesterase inhibitors: In vitro screening and molecular modeling for novel selective insecticides - Hepnarova_2022_Toxicol.In.Vitro__105463
Author(s) : Hepnarova V , Hrabinova M , Muckova L , Kucera T , Schmidt M , Dolezal R , Gorecki L , Hrabcova V , Korabecny J , Mezeiova E , Jun D , Pejchal J
Ref : Toxicol In Vitro , :105463 , 2022
Abstract : Insecticides represent the most crucial element in the integrated management approach to malaria and other vector-borne diseases. The evolution of insect resistance to long-used substances and the toxicity of organophosphates (OPs) and carbamates are the main factors contributing to the development of new, environmentally safe pesticides. In our work, fourteen compounds of 7-methoxytacrine-tacrine heterodimers were tested for their insecticidal effect. Compounds were evaluated in vitro on insect acetylcholinesterase from Anopheles gambiae (AgAChE) and Musca domestica (MdAChE). The evaluation was executed in parallel with testing on human erythrocyte acetylcholinesterase (HssAChE) and human butyrylcholinesterase (HssBChE) using a modified Ellman's method. Compound efficacy was determined as IC(50) values for the respective enzymes and selectivity indexes were expressed to compare the interspecies selectivity. Docking studies were performed to predict the binding modes of selected compounds. K1328 and K1329 provided high HssAChE/AgAChE selectivity outperforming standard pesticides (carbofuran and bendiocarb), and thus can be considered as suitable lead structure for novel anticholinesterase insecticides.
ESTHER : Hepnarova_2022_Toxicol.In.Vitro__105463
PubMedSearch : Hepnarova_2022_Toxicol.In.Vitro__105463
PubMedID: 36041654

Title : Toxicity, pharmacokinetics, and effectiveness of the ortho-chlorinated bispyridinium oxime, K870 - Karasova_2022_Food.Chem.Toxicol__113236
Author(s) : Karasova JZ , Kassa J , Hepnarova V , Pejchal J , Junova L , Andrys R , Malinak D , Bzonek P , Kohoutova Z , Musilek K
Ref : Food & Chemical Toxicology , :113236 , 2022
Abstract : Oxime reactivators are causal antidotes for organophosphate intoxication. Herein, the toxicity, pharmacokinetics, and reactivation effectiveness of o-chlorinated bispyridinium oxime K870 are reported. Oxime K870 was found to have a safe profile at a dose of 30 mg/kg in rats. It exhibited rapid absorption and renal clearance similar to those of other charged oximes after intramuscular administration. Its isoxazole-pyridinium degradation product was identified in vivo. Although it showed some improvement in brain targeting, it was nevertheless rapidly effluxed from the central nervous system. Its reactivation effectiveness was evaluated in rats and mice intoxicated with sarin, tabun, VX, and paraoxon and compared with pralidoxime and asoxime. K870 was found to be less effective in reversing tabun poisoning compared to its parent unchlorinated oxime K203. However, K870 efficiently reactivated blood acetylcholinesterase for all tested organophosphates in rats. In addition, K870 significantly protected against intoxication by all tested organophosphates in mice. For these reasons, oxime K870 seems to have a broader reactivation spectrum against multiple organophosphates. It seems important to properly modulate the oximate forming properties (pK(a)) to obtain more versatile oxime reactivators.
ESTHER : Karasova_2022_Food.Chem.Toxicol__113236
PubMedSearch : Karasova_2022_Food.Chem.Toxicol__113236
PubMedID: 35738326

Title : UHPLC-HRMS study of pharmacokinetics of a novel hybrid cholinesterase inhibitor K1234: A comparison between in silico, in vitro and in vivo data - Mzik_2022_J.Pharm.Biomed.Anal_219_114898
Author(s) : Mzik M , Sestak V , Mezeiova E , Korabecny J , Hroch M , Pejchal J , Karasova-Zdarova J
Ref : J Pharm Biomed Anal , 219 :114898 , 2022
Abstract : Alzheimer's disease (AD) is one of the most common forms of dementia. Current anti-AD therapeutics exploit the cholinergic hypothesis of its pathophysiology; they aim to inhibit cerebral cholinesterases. K1234 is a novel hybrid molecule derived from Huperzine A and 7-MEOTA-huperzine which shows increased potency in acetylcholinesterase inhibition in vitro compared to the compounds themselves. The study focused on description of the pharmacokinetic behaviour of K1234, blood-brain barrier penetration, identification of the main in vitro and in vivo metabolites. K1234 is relatively non-toxic compound, that is rapidly absorbed after i.p. administration reaching C(max) within minutes, with extensive distribution into tissues and fast metabolism in mice. The dominant metabolic pathway appears to be glucuronidation of the parent molecule and its phase-I metabolites. The passage of K1234 across the blood-brain-barrier in mice appears to be limited, as it reached only approximately one third of the AUC of plasma.
ESTHER : Mzik_2022_J.Pharm.Biomed.Anal_219_114898
PubMedSearch : Mzik_2022_J.Pharm.Biomed.Anal_219_114898
PubMedID: 35779353

Title : Determination of K869, a novel oxime reactivator of acetylcholinesterase, in rat body fluids and tissues by liquid-chromatography methods: Pharmacokinetic study - Vanova_2021_J.Pharm.Sci__
Author(s) : Vanova N , Hojna A , Pejchal J , Herman D , Malinak D , Prchalova E , Musilek K , Karasova JZ
Ref : J Pharm Sci , : , 2021
Abstract : Oxime reactivators of acetylcholinesterase (AChE) represent an integral part of standard antidote treatment of organophosphate poisoning. Oxime K869 is a novel bisquaternary non-symmetric pyridinium aldoxime with two pyridinium rings connected by a tetramethylene bridge where two chlorines modify the pyridinium ring bearing the oxime moiety. Based on in vitro assays, K869 is a potent AChE and butyrylcholinesterase (BChE) reactivator. For the investigation of the basic pharmacokinetic properties of K869 after its intramuscular application, new HPLC-UV and LC-MS/MS methods were developed and validated for its determination in rat body fluids and tissues. In this study, the SPE procedure for sample pretreatment was optimized as an alternative to routine protein precipitation widely used in oxime pharmacokinetics studies. K869 oxime is quickly absorbed into the central compartment reaching its maximum in plasma (39 +/- 4 microg/mL) between 15 and 20 minutes. The majority of K869 was eliminated by kidneys via urine when compared with biliary excretion. However, only a limited amount of K869 (65 +/- 4 ng/g of brain tissue) was found in the brain 30 minutes after oxime administration. Regarding the brain/plasma ratio calculated (less than 1%), the penetration of K869 into the brain did not exceed conventionally used oximes.
ESTHER : Vanova_2021_J.Pharm.Sci__
PubMedSearch : Vanova_2021_J.Pharm.Sci__
PubMedID: 33545185

Title : A Comparison of the Neuroprotective and Reactivating Efficacy of a Novel Bispyridinium Oxime K870 with Commonly Used Pralidoxime and the Oxime HI-6 in Tabun-Poisoned Rats - Kassa_2021_Acta.Medica.(Hradec.Kralove)_64_145
Author(s) : Kassa J , Hatlapatkova J , Karasova JZ , Hepnarova V , Caisberger F , Pejchal J
Ref : Acta Medica (Hradec Kralove) , 64 :145 , 2021
Abstract : AIM: The comparison of neuroprotective and central reactivating effects of the oxime K870 in combination with atropine with the efficacy of standard antidotal treatment in tabun-poisoned rats. METHODS: The neuroprotective effects of antidotal treatment were determined in rats poisoned with tabun at a sublethal dose using a functional observational battery 2 h and 24 h after tabun administration, the tabun-induced brain damage was investigated by the histopathological evaluation and central reactivating effects of oximes was evaluated by the determination of acetylcholinesterase activity in the brain using a standard spectrophotometric method. RESULTS: The central reactivating efficacy of a newly developed oxime K870 roughly corresponds to the central reactivating efficacy of pralidoxime while the ability of the oxime HI-6 to reactivate tabun-inhibited acetylcholinesterase in the brain was negligible. The ability of the oxime K870 to decrease tabun-induced acute neurotoxicity was slightly higher than that of pralidoxime and similar to the oxime HI-6. These results roughly correspond to the histopathological evaluation of tabun-induced brain damage. CONCLUSION: The newly synthesized oxime K870 is not a suitable replacement for commonly used oximes in the antidotal treatment of acute tabun poisonings because its neuroprotective efficacy is only slightly higher or similar compared to studied currently used oximes.
ESTHER : Kassa_2021_Acta.Medica.(Hradec.Kralove)_64_145
PubMedSearch : Kassa_2021_Acta.Medica.(Hradec.Kralove)_64_145
PubMedID: 34779379

Title : Phenothiazine-Tacrine Heterodimers: Pursuing Multitarget Directed Approach in Alzheimer's Disease - Gorecki_2021_ACS.Chem.Neurosci__
Author(s) : Gorecki L , Uliassi E , Bartolini M , Janockova J , Hrabinova M , Hepnarova V , Prchal L , Muckova L , Pejchal J , Karasova JZ , Mezeiova E , Benkova M , Kobrlova T , Soukup O , Petralla S , Monti B , Korabecny J , Bolognesi ML
Ref : ACS Chem Neurosci , : , 2021
Abstract : Since 2002, no clinical candidate against Alzheimer's disease has reached the market; hence, an effective therapy is urgently needed. We followed the so-called "multitarget directed ligand" approach and designed 36 novel tacrine-phenothiazine heterodimers which were in vitro evaluated for their anticholinesterase properties. The assessment of the structure-activity relationships of such derivatives highlighted compound 1dC as a potent and selective acetylcholinesterase inhibitor with IC(50) = 8 nM and 1aA as a potent butyrylcholinesterase inhibitor with IC(50) = 15 nM. Selected hybrids, namely, 1aC, 1bC, 1cC, 1dC, and 2dC, showed a significant inhibitory activity toward tau((306-336)) peptide aggregation with percent inhibition ranging from 50.5 to 62.1%. Likewise, 1dC and 2dC exerted a remarkable ability to inhibit self-induced Abeta(1-42) aggregation. Notwithstanding, in vitro studies displayed cytotoxicity toward HepG2 cells and cerebellar granule neurons; no pathophysiological abnormality was observed when 1dC was administered to mice at 14 mg/kg (i.p.). 1dC was also able to permeate to the CNS as shown by in vitro and in vivo models. The maximum brain concentration was close to the IC(50) value for acetylcholinesterase inhibition with a relatively slow elimination half-time. 1dC showed an acceptable safety and good pharmacokinetic properties and a multifunctional biological profile.
ESTHER : Gorecki_2021_ACS.Chem.Neurosci__
PubMedSearch : Gorecki_2021_ACS.Chem.Neurosci__
PubMedID: 33852284

Title : Encapsulation of oxime K027 into cucurbit[7]uril: In vivo evaluation of safety, absorption, brain distribution and reactivation effectiveness - Karasova_2020_Toxicol.Lett_320_64
Author(s) : Karasova JZ , Hepnarova V , Andrys R , Lisa M , Jost P , Muckova L , Pejchal J , Herman D , Jun D , Kassa J , Kuca K
Ref : Toxicol Lett , 320 :64 , 2020
Abstract : Oxime-based acetylcholinesterase reactivators (briefly oximes) regenerate organophosphate-inactivated acetylcholinesterase and restore its function. Poor blood-brain-barrier passage and fast elimination from blood limit their actual use in treatment of patients exposed to organophosphates. Previous in vitro results implicated further testing of cucurbit[7]uril as a delivery vehicle for bisquaternary oximes. The present paper focuses on cell toxicity, in vivo safety and influence of cucurbit[7]uril on oxime pharmacokinetics and pharmacodynamics. Neither the K027 nor the complex caused any cell toxicity, changes in blood biochemistry or hepato- or nephrotoxicity in tested concentrations. The encapsulation of K027 increased and accelerated the blood-brain-barrier penetration. The peripheral oxime exposure also increased, supporting the suggestion that cucurbit[7]uril protects the circulating oxime from rapid renal clearance. Contrary to the comparable in vitro reactivation power of K027 and the encapsulated K027, we failed to confirm this in vivo. In theory, this might result from the non-specific binding of molecules to the cucurbit[7]uril or the interaction of K027 with cucurbit[7]uril being too strong for acetylcholinesterase reactivation. Precise explanation requires additional in silico, in vitro and also in vivo experiments.
ESTHER : Karasova_2020_Toxicol.Lett_320_64
PubMedSearch : Karasova_2020_Toxicol.Lett_320_64
PubMedID: 31794810

Title : Pharmacological and toxicological in vitro and in vivo effect of higher doses of oxime reactivators - Hepnarova_2019_Toxicol.Appl.Pharmacol__114776
Author(s) : Hepnarova V , Muckova L , Ring A , Pejchal J , Herman D , Misik J , Hrabinova M , Jun D , Soukup O
Ref : Toxicol Appl Pharmacol , :114776 , 2019
Abstract : The major function of compounds with an oxime moiety attached to a quarternary nitrogen pyridinium ring is to reactivate acetylcholinesterase inhibited by organophosphorus agent (OP). However, other oxime mechanisms (e.g. modulation of cholinergic or glutamatergic receptor) may be involved in the recovery. The main disadvantage of positively charged reactivators is their low ability to penetrate into the brain although crossing the blood brain barrier could be supported via increasing the dose of administered oxime. Thus, this study presents maximal tolerated doses (MTD) for marketed oximes (TMB-4, MMB-4, LuH-6, HI-6, 2-PAM) and the most promising K-oximes (K027, K048, K203) which can be used in OP therapy in the future. No signs of sarin intoxication were observed in mice treated with 100% MTD of HI-6 in contrast to those treated with atropine and only 5% LD50 of HI-6. 100% MTD of HI-6 resulted in levels of 500muM and 12muM in plasma and brain, respectively. This concentration is by a far margin safe with respect to direct effects on neuronal cell viability and, on the other hand, does not have any effects on central NMDA receptors or central nACh receptors. However, a weak antimuscarinic activity in case of LuH-6 and a weak peripheral antinicotinic action in case of TMB-4 and 2-PAM could be observed at their respective 100% MTD dose. These high doses, represented by MTD, are, however, irrelevant to clinical practice since they led to mild to moderate toxic side effects. Therefore, we conclude that clinically used doses of marketed oxime reactivators have no significant direct pharmacological effect on the tested receptors.
ESTHER : Hepnarova_2019_Toxicol.Appl.Pharmacol__114776
PubMedSearch : Hepnarova_2019_Toxicol.Appl.Pharmacol__114776
PubMedID: 31629733

Title : Oxidative stress induced by oxime reactivators of acetylcholinesterase in vitro - Muckova_2019_Toxicol.In.Vitro_56_110
Author(s) : Muckova L , Vanova N , Misik J , Herman D , Pejchal J , Jun D
Ref : Toxicol In Vitro , 56 :110 , 2019
Abstract : In this study, we determined the effect of methoxime (MMB-4), asoxime (HI-6), obidoxime (LuH-6), trimedoxime (TMB-4), and pralidoxime (2-PAM) on redox homeostasis in vitro. Cultured human hepatoma cells (HepG2) were exposed to oximes at concentrations equivalent to their IC50 (assessed using MTT assay) and evaluated 1, 4 and 24h after incubation. Additionally, intact, early and late apoptotic and necrotic cells were quantified by microcapillary flow cytometry. Intracellular levels of oxygen/nitrogen species were determined using two fluorescent probes (2',7'-dichlorodihydrofluorescein diacetate and dihydroethidium). Malondialdehyde and 3-nitrotyrosine were measured by LC-MS/MS. Non-protein thiols and non-protein disulfides were evaluated using HPLC-UV to reflect antioxidant capacity. Oxidative and nitrosative stress was induced by LuH-6, TMB-4 and MMB-4, whereas 2-PAM and HI-6 appeared as weak oxidative stressors with no activity towards nitrosative stress in HepG2 cells. Based on these results, bisquartenary oxime reactivators containing two functional oxime groups at the position 4 of pyridinium ring appear as more intense oxidative and nitrosative inducers. Activation of apoptosis and necrosis do not seem to correlate with generation of RONS. On the other hand, both processes rather reflect MDA concentrations, i.e. the damage of biomolecules.
ESTHER : Muckova_2019_Toxicol.In.Vitro_56_110
PubMedSearch : Muckova_2019_Toxicol.In.Vitro_56_110
PubMedID: 30682493

Title : Novel tacrine-tryptophan hybrids: Multi-target directed ligands as potential treatment for Alzheimer's disease - Chalupova_2019_Eur.J.Med.Chem_168_491
Author(s) : Chalupova K , Korabecny J , Bartolini M , Monti B , Lamba D , Caliandro R , Pesaresi A , Brazzolotto X , Gastellier AJ , Nachon F , Pejchal J , Jarosova M , Hepnarova V , Jun D , Hrabinova M , Dolezal R , Karasova JZ , Mzik M , Kristofikova Z , Misik J , Muckova L , Jost P , Soukup O , Benkova M , Setnicka V , Habartova L , Chvojkova M , Kleteckova L , Vales K , Mezeiova E , Uliassi E , Valis M , Nepovimova E , Bolognesi ML , Kuca K
Ref : Eur Journal of Medicinal Chemistry , 168 :491 , 2019
Abstract : A combination of tacrine and tryptophan led to the development of a new family of heterodimers as multi-target agents with potential to treat Alzheimer's disease. Based on the in vitro biological profile, compound S-K1035 was found to be the most potent inhibitor of human acetylcholinesterase (hAChE) and human butyrylcholinesterase (hBChE), demonstrating balanced IC50 values of 6.3 and 9.1nM, respectively. For all the tacrine-tryptophan heterodimers, favorable inhibitory effect on hAChE as well as on hBChE was coined to the optimal spacer length ranging from five to eight carbon atoms between these two pharmacophores. S-K1035 also showed good ability to inhibit Abeta42 self-aggregation (58.6+/-5.1% at 50muM) as well as hAChE-induced Abeta40 aggregation (48.3+/-6.3% at 100muM). The X-ray crystallographic analysis of TcAChE in complex with S-K1035 pinpointed the utility of the hybridization strategy applied and the structures determined with the two K1035 enantiomers in complex with hBChE could explain the higher inhibition potency of S-K1035. Other in vitro evaluations predicted the ability of S-K1035 to cross blood-brain barrier and to exert a moderate inhibition potency against neuronal nitric oxide synthase. Based on the initial promising biochemical data and a safer in vivo toxicity compared to tacrine, S-K1035 was administered to scopolamine-treated rats being able to dose-dependently revert amnesia.
ESTHER : Chalupova_2019_Eur.J.Med.Chem_168_491
PubMedSearch : Chalupova_2019_Eur.J.Med.Chem_168_491
PubMedID: 30851693
Gene_locus related to this paper: torca-ACHE

Title : Cholinesterase inhibitor 6-chlorotacrine - in vivo toxicological profile and behavioural effects - Misik_2018_Curr.Alzheimer.Res_15_552
Author(s) : Misik J , Nepovimova E , Pejchal J , Kassa J , Korabecny J , Soukup O
Ref : Curr Alzheimer Res , 15 :552 , 2018
Abstract : 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 predetermine 6-chlorotacrine as a potent parent compound for synthesis of novel multifactorial drugs intended to 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 exact mechanism of action, safety evaluation and the metabolic fate of the compound after the repeated administration.
ESTHER : Misik_2018_Curr.Alzheimer.Res_15_552
PubMedSearch : Misik_2018_Curr.Alzheimer.Res_15_552
PubMedID: 29231138

Title : Oxidative stress in organophosphate poisoning: role of standard antidotal therapy - Vanova_2018_J.Appl.Toxicol_38_1058
Author(s) : Vanova N , Pejchal J , Herman D , Dlabkova A , Jun D
Ref : J Appl Toxicol , 38 :1058 , 2018
Abstract : Despite the main mechanism of organophosphate (OP) toxicity through inhibition of acetylcholinesterase (AChE) being well known over the years, some chronic adverse health effects indicate the involvement of additional pathways. Oxidative stress is among the most intensively studied. Overstimulation of cholinergic and glutamatergic nervous system is followed by intensified generation of reactive species and oxidative damage in many tissues. In this review, the role of oxidative stress in pathophysiology of OP poisoning and the influence of commonly used medical interventions on its levels are discussed. Current standardized therapy of OP intoxications comprises live-saving administration of the anticholinergic drug atropine accompanied by oxime AChE reactivator and diazepam. The capability of these antidotes to ameliorate OP-induced oxidative stress varies between both therapeutic groups and individual medications within the drug class. Regarding oxidative stress, atropine does not seem to have a significant effect on oxidative stress parameters in OP poisoning. In a case of AChE reactivators, pro-oxidative and antioxidative properties could be found. It is assumed that the ability of oximes to trigger oxidative stress is rather associated with their chemical structure than reactivation efficacy. The data indicating the potency of diazepam in preventing OP-induced oxidative stress are not available. Based on current knowledge on the mechanism of OP-mediated oxidative stress, alternative approaches (including antioxidants or multifunctional drugs) in therapy of OP poisoning are under consideration.
ESTHER : Vanova_2018_J.Appl.Toxicol_38_1058
PubMedSearch : Vanova_2018_J.Appl.Toxicol_38_1058
PubMedID: 29516527

Title : Development of small bisquaternary cholinesterase inhibitors as drugs for pre-treatment of nerve agent poisonings - Kuca_2018_Drug.Des.Devel.Ther_12_505
Author(s) : Kuca K , Karasova JZ , Soukup O , Kassa J , Novotna E , Sepsova V , Horova A , Pejchal J , Hrabinova M , Vodakova E , Jun D , Nepovimova E , Valis M , Musilek K
Ref : Drug Des Devel Ther , 12 :505 , 2018
Abstract : Background: Intoxication by nerve agents could be prevented by using small acetylcholinesterase inhibitors (eg, pyridostigmine) for potentially exposed personnel. However, the serious side effects of currently used drugs led to research of novel potent molecules for prophylaxis of organophosphorus intoxication. Methods: The molecular design, molecular docking, chemical synthesis, in vitro methods (enzyme inhibition, cytotoxicity, and nicotinic receptors modulation), and in vivo methods (acute toxicity and prophylactic effect) were used to study bispyridinium, bisquinolinium, bisisoquinolinium, and pyridinium-quinolinium/isoquinolinium molecules presented in this study. Results: The studied molecules showed non-competitive inhibitory ability towards human acetylcholinesterase in vitro that was further confirmed by molecular modelling studies. Several compounds were selected for further studies. First, their cytotoxicity, nicotinic receptors modulation, and acute toxicity (lethal dose for 50% of laboratory animals [LD50]; mice and rats) were tested to evaluate their safety with promising results. Furthermore, their blood levels were measured to select the appropriate time for prophylactic administration. Finally, the protective ratio of selected compounds against soman-induced toxicity was determined when selected compounds were found similarly potent or only slightly better to standard pyridostigmine. Conclusion: The presented small bisquaternary molecules did not show overall benefit in prophylaxis of soman-induced in vivo toxicity.
ESTHER : Kuca_2018_Drug.Des.Devel.Ther_12_505
PubMedSearch : Kuca_2018_Drug.Des.Devel.Ther_12_505
PubMedID: 29563775

Title : Cytotoxicity of acetylcholinesterase reactivators evaluated in vitro and its relation to their structure - Muckova_2018_Drug.Chem.Toxicol__1
Author(s) : Muckova L , Pejchal J , Jost P , Vanova N , Herman D , Jun D
Ref : Drug & Chemical Toxicology , :1 , 2018
Abstract : The development of acetylcholinesterase reactivators, i.e., antidotes against organophosphorus poisoning, is an important goal of defense research. The aim of this study was to compare cytotoxicity and chemical structure of five currently available oximes (pralidoxime, trimedoxime, obidoxime, methoxime, and asoxime) together with four perspective oximes from K-series (K027, K074, K075, and K203). The cytotoxicity of tested substances was measured using two methods - colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay and impedance based real-time cytotoxicity assay - in three different cell lines (HepG2, ACHN, and NHLF). Toxicity was subsequently expressed as toxicological index IC50. The tested compounds showed different cytotoxicity ranging from 0.92 to 40.06 mM. In HepG2 cells, K027 was the least and asoxime was the most toxic reactivator. In ACHN and NHLF cell lines, trimedoxime was the compound with the lowest adverse effects, whereas the highest toxicity was found in methoxime-treated cells. The results show that at least five structural features affect the reactivators' toxicity such as the number of oxime groups in the molecule, their position on pyridinium ring, the length of carbon linker, and the oxygen substitution or insertion of the double bond into the connection chain. Newly synthetized oximes with IC50 >/= 1 mM evaluated in this three cell lines model might appear suitable for further testing.
ESTHER : Muckova_2018_Drug.Chem.Toxicol__1
PubMedSearch : Muckova_2018_Drug.Chem.Toxicol__1
PubMedID: 29421945

Title : The Evaluation of the Reactivating and Neuroprotective Efficacy of Two Newly Prepared Bispyridinium Oximes (K305, K307) in Tabun-Poisoned Rats-A Comparison with Trimedoxime and the Oxime K203 - Kassa_2017_Molecules_22_
Author(s) : Kassa J , Misik J , Hatlapatkova J , Karasova JZ , Sepsova V , Caisberger F , Pejchal J
Ref : Molecules , 22 : , 2017
Abstract : The ability of two newly developed oximes (K305, K307) to protect tabun-poisoned rats from tabun-induced inhibition of brain acetylcholinesterase, acute neurotoxic signs and symptoms and brain damage was compared with that of the oxime K203 and trimedoxime. The reactivating and neuroprotective effects of the oximes studied combined with atropine on rats poisoned with tabun at a sublethal dose were evaluated. The reactivating efficacy of a newly developed oxime K305 is lower compared to the reactivating efficacy of the oxime K203 and trimedoxime while the ability of the oxime K307 to reactivate tabun-inhibited acetylcholinesterase (AChE) in the brain roughly corresponds to the reactivating efficacy of the oxime K203 and it is slightly lower compared to trimedoxime. In addition, only one newly developed oxime (K307) combined with atropine was able to markedly decrease tabun-induced neurotoxicity although it did not eliminate all tabun-induced acute neurotoxic signs and symptoms. These results correspond to the histopathological evaluation of tabun-induced brain damage. Therefore, the newly developed oximes are not suitable for the replacement of commonly used oximes (especially trimedoxime) in the treatment of acute tabun poisonings.
ESTHER : Kassa_2017_Molecules_22_
PubMedSearch : Kassa_2017_Molecules_22_
PubMedID: 28696367

Title : HI-6 treatment does not reactivate sarin inhibited acetylcholinesterase activity in dog brain when administered in human therapeutical dose 30 minutes after the poisoning - Caisberger_2016_Mil.Med.Sci.Lett_85_2
Author(s) : Caisberger F , Novotny L , Hajek P , Misik J , Kassa J , Pejchal J
Ref : Military Medical Science Letters , 85 :2 , 2016
Abstract : Purpose: The aim of our study was to determine and compare the activity of acetylcholinesterase (AChE) in different parts of dog brain after the exposure to nerve agent sarin with or without HI-6 oxime treatment. Material and methods: Before intoxication, beagle dogs were intravenously anaesthetized and premedicated with atropine sulphate (0.01 mg/kg). Three experimental groups were established - control, sarin (0.03 mg/kg, intramuscularly, 5 min after anaesthesia onset), and sarin + HI-6 dichloride (11.4 mg/kg, intramuscularly, 30 min after sarin poisoning). Brain (amygdaloid body, head of caudate nucleus, somatosensory cortex, Amon's horn of hippocampus, hypothalamus, brain stem ventral respiratory group, and medial nuclei of thalamus) samples were taken 4 h after sarin administration. AChE activity was detected by histochemistry using the Karnovsky-Roots method and computer image analysis. Results: Sarin poisoning decreased AChE activity in all selected brain areas. HI-6 did not affect this outcome. Conclusion: HI-6 does not reactivate brain AChE in dogs when administered 30 min after sarin poisoning.
ESTHER : Caisberger_2016_Mil.Med.Sci.Lett_85_2
PubMedSearch : Caisberger_2016_Mil.Med.Sci.Lett_85_2
PubMedID:

Title : Structure-activity relationship for the reactivators of acetylcholinesterase inhibited by nerve agent VX - Kuca_2013_Med.Chem_9_689
Author(s) : Kuca K , Musilek K , Jun D , Karasova J , Soukup O , Pejchal J , Hrabinova M
Ref : Med Chem , 9 :689 , 2013
Abstract : Nerve agents such as sarin, VX and tabun are organophosphorus compounds able to inhibit an enzyme acetylcholinesterase (AChE). AChE reactivators and anticholinergics are generally used as antidotes in the case of intoxication with these agents. None from the known AChE reactivators is able to reactivate AChE inhibited by all kinds of nerve agents. In this work, reactivation potency of seventeen structurally different AChE reactivators was tested in vitro and subsequently, relationship between their chemical structure and biological activity was outlined. VX was chosen as appropriate member of the nerve agent family.
ESTHER : Kuca_2013_Med.Chem_9_689
PubMedSearch : Kuca_2013_Med.Chem_9_689
PubMedID: 22779796

Title : Modulation of ionising radiation generated oxidative stress by HI-6 (asoxime) in a laboratory rat model - Pohanka_2010_Neuro.Endocrinol.Lett_31 Suppl 2_62
Author(s) : Pohanka M , Pejchal J , Horackova S , Kuca K , Bandouchova H , Damkova V , Pikula J
Ref : Neuro Endocrinol Lett , 31 Suppl 2 :62 , 2010
Abstract : OBJECTIVES: HI-6 is an antidotum suitable for treatment of intoxication by nerve agents. The recent investigation appointed its modulation of inflammatory response as well as vegetative nervous system activity. However, the present experiments were carried out in order to assess the antioxidant effect of HI-6 in irradiated animals. METHODS: male Wistar rats were irradiated by ionizing radiation (7.5 Gy, LD50/30). Animals were divided into four groups: i.e. controls (A), irradiated (B), treated with HI-6 (C), and both irradiated and treated with HI-6 (D). Ferric reducing antioxidant power (FRAP), thiobarbituric acid reactive substances (TBARS) and glutathione reductase activity were assayed in liver, spleen, plasma, and whole blood. Clinical biochemistry markers were determined in plasma samples. RESULTS: We found significantly increased FRAP levels in liver, while its levels decreased in the spleen of B group animals. Ionising radiation (B group) also significantly elevated TBARS values in spleen. HI-6 reversed FRAP and TBARS values to control levels. Glutathione reductase activity was significantly elevated in spleen and liver of animals exposed to HI-6 (C and D groups). Clinical biochemistry markers were shifted only slightly. The in vitro test confirmed the inhibitory effect of HI-6 towards acetylcholinesterase. CONCLUSIONS: In conclusion, HI-6 is potent in suppressing oxidative stress and might be a promising drug in the field of radiation protection.
ESTHER : Pohanka_2010_Neuro.Endocrinol.Lett_31 Suppl 2_62
PubMedSearch : Pohanka_2010_Neuro.Endocrinol.Lett_31 Suppl 2_62
PubMedID: 21187825