Effect of Several New and Currently Available Oxime Cholinesterase Reactivators on Tabun-intoxicated Rats

The therapeutical efficacies of eleven oxime-based acetylcholinesterase reactivators were compared in an in vivo (rat model) study of treatment of intoxication caused by tabun. In this group there were some currently available oximes (obidoxime, trimedoxime and HI-6) and the rest were newly synthesized compounds. The best reactivation efficacy for acetylcholinesterase in blood (expressed as percent of reactivation) among the currently available oximes was observed after administration of trimedoxime (16%) and of the newly synthesized K127 (22432) (25%). The reactivation of butyrylcholinesterase in plasma was also studied; the best reactivators were trimedoxime, K117 (22435), and K127 (22432), with overall reactivation efficacies of approximately 30%. Partial protection of brain ChE against tabun inhibition was observed after administration of trimedoxime (acetylcholinesterase 20%; butyrylcholinesterase 30%) and obidoxime (acetylcholinesterase 12%; butyrylcholinesterase 16%)

Effects of Oxime K203 and Oxidative Stress in Plasma of Tabun Poisoned Rats

The highly toxic nature of tabun has been known for many years, but there are still serious limitations to antidotal therapy. In this study, we used rats as an experimental model to evaluate the efficiency of bispyridinium para-oxime K203 as therapy against tabun poisoning as well as to examine if induction of oxidative stress is linked to organophosphate toxicity. K203 showed high potency in counteracting tabun poisoning. Either alone or in combination with atropine, this oxime significantly increased cholinesterase activity at 0.5 and 1 h compared to untreated rats poisoned with tabun. Simultaneous measurements of markers of oxidative stress (lipid peroxidation and superoxide dismutase) showed that tabun poisoning, but also therapy (oxime alone or oxime plus atropine) applied immediately after tabun poisoning, could generate free radical species that may cause oxidative stress in rats. (doi: 10.5562/cca1811

Molecular modeling studies on the multistep reactivation process of organophosphate-inhibited acetylcholinesterase and butyrylcholinesterase

Poisoning with organophosphorus compounds used as pesticides or misused as chemical weapons remains a serious threat to human health and life. Their toxic effects result from irreversible blockade of the enzymes acetylcholinesterase and butyrylcholinesterase, which causes overstimulation of the cholinergic system and often leads to serious injury or death. Treatment of organophosphorus poisoning involves, among other strategies, the administration of oxime compounds. Oximes reactivate cholinesterases by breaking the covalent bond between the serine residue from the enzyme active site and the phosphorus atom of the organophosphorus compound. Although the general mechanism of reactivation has been known for years, the exact molecular aspects determining the efficiency and selectivity of individual oximes are still not clear. This hinders the development of new active compounds. In our research, using relatively simple and widely available molecular docking methods, we investigated the reactivation of acetyl- and butyrylcholinesterase blocked by sarin and tabun. For the selected oximes, their binding modes at each step of the reactivation process were identified. Amino acids essential for effective reactivation and those responsible for the selectivity of individual oximes against inhibited acetyl- and butyrylcholinesterase were identified. This research broadens the knowledge about cholinesterase reactivation and demonstrates the usefulness of molecular docking in the study of this process. The presented observations and methods can be used in the future to support the search for new effective reactivators

Effect of Seven Newly Synthesized and Currently Available Oxime Cholinesterase Reactivators on Cyclosarin-Intoxicated Rats

Seven new oxime-based acetylcholinesterase reactivators were compared with three currently available ones (obidoxime, trimedoxime, HI-6) for their ability to lessen cholinesterase inhibition in blood and brain of cyclosarin-treated rats. Oximes were given at doses of 5% their LD50 along with 21 mg/kg atropine five min before the LD50 of cyclosarin (120 ug/kg) was administered. Blood and brain samples were collected 30 minutes later. The greatest difference between acetylcholinesterase inhibition in blood of cyclosarin-treated rats was found after administration of HI-6 (40%), compared to 22% for trimedoxime and 6% for obidoxime. Only two of the seven newly synthesized oximes had any effect (K203 at 7%, K156 at 5%). Effective oximes against cyclosarin-inhibited plasma butyrylcholinesterase were HI-6 (42%), trimedoxime (11%), and K156 (4%). The oximes were less effective in brain than in blood, with reactivation values for HI-6 30% against acetylcholinesterase and 10% against butyrylcholinesterase. Values for newly synthesized oximes were less than 10% for K206, K269 and K203

Usporedno određivanje učinkovitosti bispiridinijevih oksima pri trovanju paraoksonom

The inability of standard therapy to provide adequate protection against poisoning by organophosphorus compounds (pesticides and nerve agents) motivated us to search for new, more effective oximes. We investigated the pharmacotoxicological properties of six experimental K-oximes (K027, K033, K048, K074, K075, and K203) in vivo. The therapeutic efficacy of K-oximes (at doses of 5 or 25 % of their LD50) combined with atropine was assessed in paraoxon-poisoned mice and compared with conventionally used oximes HI-6 and TMB-4. The bisoxime K074 was the most toxic (LD50=21.4 mg kg-1) to mice, while monoxime K027 was the least toxic (LD50=672.8 mg kg-1). With the exception of K033, all of the tested K-oximes showed better therapeutic efficiency than HI-6 and TMB-4. K027 and K048 stood out by demonstrating low acute toxicities and ensuring protective indices ranging from 60.0 to 100.0 LD50 of paraoxon. Taking into account that these two oximes showed a similar therapeutic efficacy regardless of the applied doses, our results suggest that K027 and K048 could be antidotes for paraoxon intoxication.Činjenica da standardna terapija ne omogućuje dovoljnu zaštitu pri otrovanju organofosfornim spojevima (pesticidima i živčanim bojnim otrovima) potaknula nas je na istraživanje novih, učinkovitijih oksima. U uvjetima in vivo ispitali smo farmakotoksikološka svojstva šest eksperimentalnih K-oksima (K027, K033, K048, K074, K075 i K203). Terapijski učinak kombinacije K-oksima (primjenjenih u dozi 5 ili 25 % njihove LD50) i atropina testiran je na miševima otrovanim paraoksonom i uspoređen s konvencionalnim oksimima HI-6 i TMB-4. Bisoksim K074 je bio najtoksičniji (LD50=21.4 mg kg-1) za miševe, dok je monooksim K027 bio najmanje toksičan (LD50=672.8 mg kg-1). Osim K033, svi K-oksimi pokazali su bolji terapijski učinak u miševa trovanih paraoksonom u odnosu na HI-6 i TMB-4. Iz skupine testiranih oksima istaknuli su se K027 i K048 koji su pokazali nisku akutnu toksičnost i osigurali protektivne indekse u rasponu od 60.0 do 100.0 LD50 paraoksona. Uzmemo li u obzir da su ta dva oksima pokazala sličan terapijski učinak bez obzira na primjenjenu dozu, prikazani rezultati upućuju na K027 i K048 kao perspektivne antidote u terapiji trovanja paraoksonom

Posebnosti bogoslužja na spomendane

This work was supported by the Ministry of Education, Youth and Sports CZ (no. LD14009, no. SV/FVZ201201, no. SVV260062), COST CM1103, MH CZ - DRO (UHHK, 00179906), The Alzheimer’s Society, The Barcopel Foundation and the MSD Scottish Life Sciences fund.The amyloid-β peptide (Aβ) has been associated with Alzheimer’s disease (AD) for decades. The original amyloid cascade hypothesis declared that the insoluble extracellular plaques were responsible for Aβ toxicity. Later, this hypothesis has been updated and soluble intracellular Aβ forms and their effects within the cell have come into focus. Mitochondrial dysfunction plays an important role in the pathophysiology of AD. Aβ was detected inside mitochondria and several mitochondrial proteins were found to interact directly with Aβ. Such interactions can affect a protein’s function and cause damage to the mitochondria and finally to the whole cell. This review summarizes the current knowledge of mitochondrial proteins directly interacting with Aβ and discusses their significance for the development of therapeutics in the treatment of AD.PostprintPeer reviewe

1-(Benzo[d]thiazol-2-yl)-3-phenylureas as dual inhibitors of casein kinase 1 and ABAD enzymes for treatment of neurodegenerative disorders

This work was supported by the Ministry of Health of the Czech Republic [no. NV15-28967 A], Specific Research Project of Faculty of Science, University of Hradec Kralove [no. 2103-2017], National Institute of Mental Health [NIMH CZ; no. ED2.1.00/03.0078] from the European Regional Development Fund, COST CA15135, The Alzheimer’s Society (specifically The Barcopel Foundation), The Rosetrees trust and The Biotechnology and Biological Sciences Research Council (BBSRC) [no. BB/J01446X/1]. Funding from Ministry of Economy and competitiveness, Spain [no. SAF2012-37979-C03-01] is also acknowledged.Several neurodegenerative disorders including Alzheimer’s disease (AD) have been connected with deregulation of casein kinase 1 (CK1) activity. Inhibition of CK1 therefore presents a potential therapeutic strategy against such pathologies. Recently, novel class of CK1-specific inhibitors with N-(benzo[d]thiazol-2-yl)-2-phenylacetamide structural scaffold has been discovered. 1-(benzo[d]thiazol-2-yl)-3-phenylureas, on the other hand, are known inhibitors amyloid-beta binding alcohol dehydrogenase (ABAD), an enzyme also involved in pathophysiology of AD. Based on their tight structural similarity, we decided to evaluate series of previously published benzothiazolylphenylureas, originally designed as ABAD inhibitors, for their inhibitory activity towards CK1. Several compounds were found to be submicromolar CK1 inhibitors. Moreover, two compounds were found to inhibit both, ABAD and CK1. Such dual-activity could be of advantage for AD treatment, as it would simultaneously target two distinct pathological processes involved in disease’s progression. Based on PAMPA testing both compounds were suggested to permeate the blood-brain barrier, which makes them, together with their unique dual activity, interesting lead compounds for further development.Publisher PDFPeer reviewe

6-benzothiazolyl ureas, thioureas and guanidines are potent inhibitors of ABAD/17β-HSD10 and potential drugs for Alzheimer's disease treatment : design, synthesis and in vitro evaluation

Background : The mitochondrial enzyme amyloid beta-binding alcohol dehydrogenase (ABAD) also known as 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10) has been connected with the pathogenesis of Alzheimer’s disease (AD). ABAD/ 17β-HSD10 is a binding site for the amyloid-beta peptide (Aβ) inside the mitochondrial matrix where it exacerbates Aβ toxicity. Interaction between these two proteins triggers a series of events leading to mitochondrial dysfunction as seen in AD. Methods : As ABAD’s enzymatic activity is required for mediating Aβ toxicity, its inhibition presents a promising strategy for AD treatment. In this study, a series of new benzothiazolylurea analogues have been prepared and evaluated in vitro for their potency to inhibit ABAD/ 17β-HSD10 enzymatic activity. The most potent compounds have also been tested for their cytotoxic properties and their ability to permeate through blood-brain barrier has been predicted. To explain the structure-activity relationship QSAR and pharmacophore studies have been performed. Results and Conclusions : Compound 12 was identified being the most promising hit compound with good inhibitory activity (IC50 = 3.06 ± 0.40µM) and acceptable cytotoxicity profile comparable to the parent compound of frentizole. The satisfactory physical-chemical properties suggesting its capability to permeate through BBB make compound 12 a novel lead structure for further development and biological assessment.PostprintPeer reviewe