The cholinergic system, relying on the neurotransmitter acetylcholine (ACh), plays a significant role in muscle contraction, cognition, and autonomic nervous system regulation. The enzymes ...acetylcholinesterase, AChE, and butyrylcholinesterase, BChE, responsible for hydrolyzing ACh, can fine-tune the cholinergic system's activity and are, therefore, excellent pharmacological targets to address a range of medical conditions. We designed, synthesized, and profiled 14
-alkyl quaternary quinuclidines as inhibitors of human AChE and BChE and analyzed their impact on cell viability to assess their safety in the context of application as potential therapeutics. Our results showed that all of the 14 tested quinuclidines inhibited both AChE and BChE in the micromolar range (
= 0.26 - 156.2 μM). The highest inhibition potency was observed for two bisquaternary derivatives,
(1,1'-(decano)bis(3-hydroxyquinuclidinium bromide)) and
(1,1'-(decano)bis(3-hydroxyiminoquinuclidinium bromide)). The cytotoxic effect within 7-200 μM was observed only for monoquaternary quinuclidine derivatives, especially those with the C12-C16 alkyl chain. Further analysis revealed a time-independent mechanism of action, significant LDH release, and a decrease in the cells' mitochondrial membrane potential. Taking all results into consideration, we can confirm that a quinuclidine core presents a good scaffold for cholinesterase binding and that two bisquaternary quinuclidine derivatives could be considered as candidates worth further investigations as drugs acting in the cholinergic system. On the other hand, specific cell-related effects probably triggered by the free long alkyl chain in monoquaternary quinuclidine derivatives should not be neglected in future
-alkyl quaternary quinuclidine derivative structure refinements. Such an effect and their potential to interact with other specific targets, as indicated by a pharmacophore model, open up a new perspective for future investigations of these compounds' scaffold in the treatment of specific conditions and diseases other than cholinergic system-linked disorders.
This study investigated the levels and distribution of polychlorinated biphenyls (PCBs) and organochlorine pesticides in three tissue types of farmed Bluefin tuna (Thunnus thynnus): muscle, liver and ...branchiae. Seven adult species were caught in 2015 at a tuna farm in the Croatian Adriatic. The organochlorine compound levels decreased in the following order: liver > muscle > branchiae while contaminant distribution in all three tissues followed the same order: ΣPCB ≫ ΣDDT > ΣHCH ~ HCB. The found POP levels indicated moderate pollution of farmed tuna and were below all limits set by current laws. Furthermore, no cytotoxic effect of the POP mixture extracted from tuna liver samples on human neuroblastoma cells was observed.
•POPs were quantified in tissues of farmed Bluefin tuna from the Adriatic Sea.•PCBs were the dominant contaminant group•The detected POP levels do not pose risk for human health.•There were no observed citotoxic effects.
For the last six decades, researchers have been focused on finding efficient reactivators of organophosphorus compound (OP)-inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). In ...this study, we have focused our research on a new oxime scaffold based on the Cinchona structure since it was proven to fit the cholinesterases active site and reversibly inhibit their activity. Three Cinchona oximes (C1, C2, and C3), derivatives of the 9-oxocinchonidine, were synthesized and investigated in reactivation of various OP-inhibited AChE and BChE. As the results showed, the tested oximes were more efficient in the reactivation of BChE and they reactivated enzyme activity to up to 70% with reactivation rates similar to known pyridinium oximes used as antidotes in medical practice today. Furthermore, the oximes showed selectivity towards binding to the BChE active site and the determined enzyme-oxime dissociation constants supported work on the future development of inhibitors in other targeted studies (e.g., in treatment of neurodegenerative disease). Also, we monitored the cytotoxic effect of Cinchona oximes on two cell lines Hep G2 and SH-SY5Y to determine the possible limits for in vivo application. The cytotoxicity results support future studies of these compounds as long as their biological activity is targeted in the lower micromolar range.
Current research has shown that several imidazolium and chlorinated bispyridinium oximes are cytotoxic and activate different mechanisms or types of cell death. To investigate this further, we ...analysed interactions between these oximes and acetylcholine receptors (AChRs) and how they affect several signalling pathways to find a relation between the observed toxicities and their effects on these specific targets. Chlorinated bispyridinium oximes caused time-dependent cytotoxicity by inhibiting the phosphorylation of STAT3 and AMPK without decreasing ATP and activated ERK1/2 and p38 MAPK signal cascades. Imidazolium oximes induced a time-independent and significant decrease in ATP and inhibition of the ERK1/2 signalling pathway along with phosphorylation of p38 MAPK, AMPK, and ACC. These pathways are usually triggered by a change in cellular energy status or by external signals, which suggests that oximes interact with some membrane receptors. Interestingly,
analysis also indicated that the highest probability of interaction for all of our oximes is with the family of G-coupled membrane receptors (GPCR). Furthermore, our experimental results showed that the tested oximes acted as acetylcholine antagonists for membrane AChRs. Even though oxime interactions with membrane receptors need further research and clarification, our findings suggest that these oximes make promising candidates for the development of specific therapies not only in the field of cholinesterase research but in other fields too, such as anticancer therapy via altering the Ca
flux involved in cancer progression.
Seven pyridoxal dioxime quaternary salts (1–7) were synthesized with the aim of studying their interactions with human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The synthesis was ...achieved by the quaternization of pyridoxal monooxime with substituted 2-bromoacetophenone oximes (phenacyl bromide oximes). All compounds, prepared in good yields (43–76%) and characterized by 1D and 2D NMR spectroscopy, were evaluated as reversible inhibitors of cholinesterase and/or reactivators of enzymes inhibited by toxic organophosphorus compounds. Their potency was compared with that of their monooxime analogues and medically approved oxime HI-6. The obtained pyridoxal dioximes were relatively weak inhibitors for both enzymes (Ki = 100–400 µM). The second oxime group in the structure did not improve the binding compared to the monooxime analogues. The same was observed for reactivation of VX-, tabun-, and paraoxon-inhibited AChE and BChE, where no significant efficiency burst was noted. In silico analysis and molecular docking studies connected the kinetic data to the structural features of the tested compound, showing that the low binding affinity and reactivation efficacy may be a consequence of a bulk structure hindering important reactive groups. The tested dioximes were non-toxic to human neuroblastoma cells (SH-SY5Y) and human embryonal kidney cells (HEK293).
As butyrylcholinesterase (BChE) plays a role in the progression of symptoms and pathophysiology of Alzheimer’s disease (AD), selective inhibition of BChE over acetylcholinesterase (AChE) can ...represent a promising pathway in treating AD. The carbamate group was chosen as a pharmacophore because the carbamates currently or previously in use for the treatment of AD displayed significant positive effects on cognitive symptoms. Eighteen biscarbamates with different substituents at the carbamoyl and hydroxyaminoethyl chain were synthesized, and their inhibitory potential toward both cholinesterases and inhibition selectivity were determined. The ability of carbamates to cross the blood–brain barrier (BBB) by passive transport, their cytotoxic profile and their ability to chelate biometals were also evaluated. All biscarbamates displayed a time-dependent inhibition with inhibition rate constants within 10−3–10−6 M−1 min−1 range for both cholinesterases, with generally higher preference to BChE. For two biscarbamates, it was determined that they should be able to pass the BBB by passive transport, while for five biscarbamates, this ability was slightly limited. Fourteen biscarbamates did not exhibit a cytotoxic effect toward liver, kidney and neuronal cells. In conclusion, considering their high BChE selectivity, non-toxicity, ability to chelate biometals and pass the BBB, compounds 2 and 16 were pointed out as the most promising compounds for the treatment of middle and late stages of AD.
We evaluated the potential of nine vitamin B3 scaffold-based derivatives as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors, as a starting point for the development of novel ...drugs for treating disorders with cholinergic neurotransmission-linked pathology. As the results indicate, all compounds reversibly inhibited both enzymes in the micromolar range pointing to the preference of AChE over BChE for binding the tested derivatives. Molecular docking studies revealed the importance of interactions with AChE active site residues Tyr337 and Tyr124, which dictated most of the observed differences. The most potent inhibitor of both enzymes with
of 4 μM for AChE and 8 μM for BChE was the nicotinamide derivative 1-(4'-phenylphenacyl)-3-carbamoylpyridinium bromide. Such a result places it within the range of several currently studied novel cholinesterase inhibitors. Cytotoxicity profiling did not classify this compound as highly toxic, but the induced effects on cells should not be neglected in any future detailed studies and when considering this scaffold for drug development.
Ketamine is a dissociative anaesthetic used to induce general anaesthesia in humans and laboratory animals. Due to its hallucinogenic and dissociative effects, it is also used as a recreational drug. ...Anaesthetic agents can cause toxic effects at the cellular level and affect cell survival, induce DNA damage, and cause oxidant/antioxidant imbalance. The aim of this study was to explore these possible adverse effects of ketamine on hepatocellular HepG2 and neuroblastoma SH-SY5Y cells after 24-hour exposure to a concentration range covering concentrations used in analgesia, drug abuse, and anaesthesia (0.39, 1.56, and 6.25 µmol/L, respectively). At these concentrations ketamine had relatively low toxic outcomes, as it lowered HepG2 and SH-SY5Y cell viability up to 30 %, and low, potentially repairable DNA damage. Interestingly, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH) remained unchanged in both cell lines. On the other hand, oxidative stress markers superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) pointed to ketamine-induced oxidant/antioxidant imbalance.
The toxicity of eight polybrominated diphenyl ethers (PBDEs) congeners detected in environmental and biological samples (BDE-28, -47, -99, -100, -153, -154, -183, and -209) was evaluated on the ...epithelial lung cells. Exposure to these PBDEs increased membrane disruption and a release of lactate dehydrogenase, accompanied by oxidative stress in cells through the formation of reactive oxygen species (ROS) and a decrease in mitochondrial membrane potential. Interestingly, some of the tested PBDEs increased apoptotic markers as well. For several congeners, the observed toxicity was time dependent, meaning that even smaller concentrations of these compounds will have negative effects over time. Such time-dependent toxicity was also confirmed for cell treatment with a real house dust sample extract. This could be indicative with regard to the constant exposure to a mixture of PBDE congeners through different pathways in the organism and thereby presenting a risk for human health. As such, our findings point to the importance of further studies on the negative effects of PBDEs to understand their mechanism of action in detail.
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