The deleterious effects of nerve agents over the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) turned these compounds into the most dangerous chemical weapons known. Among the antidotes in use today against these agents, oximes in combination with other drugs are the only treatment with any action. HI-6 and 2-PAM are cationic oximes proved to be effective for the reactivation of AChE inhibited by the nerve agents VX and sarin (GB). However, when it comes to reactivation of AChE inside the central or peripheral nervous systems, charged molecules present low diffusion due to low penetration through the blood-brain barrier. Uncharged oximes appear as an interesting alternative to solve this problem, but the development and enhancement of more efficient uncharged oximes capable of reactivating human AChE is still necessary. Given the limitations for in vivo and in vitro experimental studies with nerve agents, modeling is an important tool that can contribute to a better understanding of factors that may affect the efficiency of uncharged oximes. In order to investigate the interaction and behavior of cationic and uncharged oximes, we performed here molecular docking, molecular dynamics simulations, and binding energies calculations of the known cationic oximes HI-6 and 2-PAM plus four uncharged oximes found in the literature, complexed with human AChE (HssACHE) conjugated with the nerve agents VX and GB. The uncharged oximes showed different behaviors, especially RS194B, which presented stability inside AChE-VX, but presented free binding energy lower than cationic oximes, suggesting that structural alterations could favor its interactions with these complexes. In contrast, HI-6 and 2-PAM showed higher affinities with more negative binding energy values and larger contribution of the amino acid Asp74, demonstrating the importance of the quaternary nitrogen to the affinity and interaction of oximes with AChE-GB and AChE-VX conjugates.

• Publikační typ
• časopisecké články MeSH

Acknowledging the importance of studies toward the development of measures against terrorism and bioterrorism, this study aims to contribute to the design of new prototypes of potential drugs against smallpox. Based on a former study, nine synthetic feasible prototypes of selective inhibitors for thymidylate kinase from Variola virus (VarTMPK) were designed and submitted to molecular docking, molecular dynamics simulations and binding energy calculations. The compounds are simplifications of two more complex scaffolds, with a guanine connected to an amide or alcohol through a spacer containing ether and/or amide groups, formerly suggested as promising for the design of selective inhibitors of VarTMPK. Our study showed that, despite the structural simplifications, the compounds presented effective energy values in interactions with VarTMPK and HssTMPK and that the guanine could be replaced by a simpler imidazole ring linked to a -NH2 group, without compromising the affinity for VarTMPK. It was also observed that a positive charge in the imidazole ring is important for the selectivity toward VarTMPK and that an amide group in the spacer does not contribute to selectivity. Finally, prototype 3 was pointed as the most promising to be synthesized and experimentally evaluated. Communicated by Ramaswamy H. Sarma.

• Klíčová slova
• Drug design, Variola virus, docking, molecular dynamics simulations, smallpox, thymidylate kinase,
• MeSH
• inhibitory enzymů chemie   farmakologie   terapeutické užití   MeSH
• lidé MeSH
• ligandy MeSH
• nukleosidmonofosfátkinasa antagonisté a inhibitory   chemie   MeSH
• pravé neštovice farmakoterapie   MeSH
• racionální návrh léčiv * MeSH
• simulace molekulární dynamiky MeSH
• simulace molekulového dockingu MeSH
• termodynamika MeSH
• virus varioly enzymologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dTMP kinase MeSH Prohlížeč
• inhibitory enzymů MeSH
• ligandy MeSH
• nukleosidmonofosfátkinasa MeSH

The present work aimed to compare the small, neutral and monoaromatic oxime, isatin-3-oxime (isatin-O), to the commercial ones, pralidoxime (2-PAM) and obidoxime, in a search for a new potential reactivator for acetylcholinesterase (AChE) inhibited by the pesticide paraoxon (AChE/POX) as well as a novel potential scaffold for further synthetic modifications. The multicriteria decision methods (MCDM) allowed the identification of the best docking poses of those molecules inside AChE/POX for further molecular dynamic (MD) studies, while Ellman's modified method enabled in vitro inhibition and reactivation assays. In corroboration with the theoretical studies, our experimental results showed that isatin-O have a reactivation potential capable of overcoming 2-PAM at the initial moments of the assay. Despite not achieving better results than obidoxime, this molecule is promising for being an active neutral oxime with capacity of crossing the blood⁻brain barrier (BBB), to reactivate AChE/POX inside the central and peripheral nervous systems. Moreover, the fact that isatin-O can also act as anticonvulsant makes this molecule a possible multipotent reactivator. Besides, the MCDM method showed to be an accurate method for the selection of the best docking poses generated in the docking studies.

• Klíčová slova
• Ellman’s method, TOPSIS-AHP, acetylcholinesterase, molecular modeling, multicriteria decision making, neutral oxime,
• MeSH
• cholinesterasové inhibitory farmakologie   MeSH
• erytrocyty účinky léků   enzymologie   MeSH
• molekulární modely * MeSH
• molekulární struktura MeSH
• oximy chemie   farmakologie   MeSH
• paraoxon chemie   farmakologie   MeSH
• reaktivátory cholinesterázy chemie   farmakologie   MeSH
• simulace molekulární dynamiky MeSH
• simulace molekulového dockingu MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cholinesterasové inhibitory MeSH
• oximy MeSH
• paraoxon MeSH
• reaktivátory cholinesterázy MeSH

The most common type of aflatoxin (AFT) found in nature is aflatoxin B1 (AFB1). This micotoxin is extremely hepatotoxic and carcinogenic to mammals, with acute and chronic effects. It is believed that this could be related to the capacity of AFB1 and its metabolites in inhibiting the enzyme acetylcholinesterase (AChE). In a previous work, we performed an inedited theoretical investigation on the binding modes of these molecules on the peripheral anionic site (PAS) of human AChE (HssAChE), revealing that the metabolites can also bind in the PAS in the same way as AFB1. Here, we investigated the binding modes of these compounds on the catalytic anionic site (CAS) of HssAChE to compare the affinity of the metabolites for both binding sites as well as verify which is the preferential one. Our results corroborated with experimental studies pointing to AFB1 and its metabolites as mixed-type inhibitors, and pointed to the residues relevant for the stabilization of these compounds on the CAS of HssAChE.

• Klíčová slova
• acetylcholinesterase, aflatoxin B1, catalytic anionic site, metabolites,
• MeSH
• acetylcholinesterasa chemie   metabolismus   MeSH
• aflatoxin B1 chemie   metabolismus   MeSH
• cholinesterasové inhibitory chemie   metabolismus   MeSH
• hydrofobní a hydrofilní interakce MeSH
• katalytická doména MeSH
• lidé MeSH
• molekulární modely * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• aflatoxin B1 MeSH
• cholinesterasové inhibitory MeSH

Nerve agents and oxon forms of organophosphorus pesticides act as strong irreversible inhibitors of two cholinesterases in the human body: acetylcholinesterase (AChE; EC 3.1.1.7) and butyrylcholinesterase (BChE; EC 3.1.1.8), and are therefore highly toxic compounds. For the recovery of inhibited AChE, antidotes from the group of pyridinium or bispyridinium aldoxime reactivators (pralidoxime, obidoxime, HI-6) are used in combination with anticholinergics and anticonvulsives. Therapeutic efficacy of reactivators (called “oximes”) depends on their chemical structure and also the type of organophosphorus inhibitor. Three novel oximes (K131, K142, K153) with an oxime group in position four of the pyridinium ring were designed and then tested for their potency to reactivate human (Homo sapiens sapiens) AChE (HssACHE) and BChE (HssBChE) inhibited by the pesticide paraoxon (diethyl 4-nitrophenyl phosphate). According to the obtained results, none of the prepared oximes were able to satisfactorily reactivate paraoxon-inhibited cholinesterases. On the contrary, extraordinary activity of obidoxime in the case of paraoxon-inhibited HssAChE reactivation was confirmed. Additional docking studies pointed to possible explanations for these results.

• Klíčová slova
• acetylcholinesterase, antidote, butyrylcholinesterase, organophosphate, oxime, paraoxon,
• MeSH
• acetylcholinesterasa chemie   MeSH
• antidota chemická syntéza   farmakologie   MeSH
• butyrylcholinesterasa chemie   MeSH
• cholinesterasové inhibitory chemie   MeSH
• enzymatické testy MeSH
• erytrocyty účinky léků   enzymologie   MeSH
• insekticidy antagonisté a inhibitory   chemie   toxicita   MeSH
• interakční proteinové domény a motivy MeSH
• lidé MeSH
• obidoxim chlorid chemie   farmakologie   MeSH
• oximy chemická syntéza   farmakologie   MeSH
• paraoxon antagonisté a inhibitory   chemie   toxicita   MeSH
• reaktivátory cholinesterázy chemická syntéza   farmakologie   MeSH
• sekundární struktura proteinů MeSH
• simulace molekulového dockingu MeSH
• termodynamika MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• antidota MeSH
• butyrylcholinesterasa MeSH
• cholinesterasové inhibitory MeSH
• insekticidy MeSH
• obidoxim chlorid MeSH
• oximy MeSH
• paraoxon MeSH
• reaktivátory cholinesterázy MeSH