Emetine and Indirubin- 3- monoxime interaction with human brain acetylcholinesterase: A computational and statistical analysis

Alzheimer's disease is a chronic neurodegenerative ailment and the most familiar type of dementia in the older population with no effective cure to date. It is characterized by a decrease in memory, associated with the mutilation of cholinergic neurotransmission. Presently, acetylcholinesterase inhibitors have emerged as the most endorsed pharmacological medications for the symptomatic treatment of mild to moderate Alzheimer's disease. This study aimed to research the molecular enzymatic inhibition of human brain acetylcholinesterase by a natural compound emetine and I3M. Molecular docking studies were used to identify superior interaction between enzyme acetylcholinesterase and ligands. Furthermore, the docked acetylcholinesterase-emetine complex was validated statistically using an analysis of variance in all tested conformers. In this interaction, H-bond, hydrophobic interaction, pi-pi, and Cation-pi interactions played a vital function in predicting the accurate conformation of the ligand that binds with the active site of acetylcholinesterase. The conformer with the lowest free energy of binding was further analyzed. The binding energy for acetylcholinesterase complex with emetine and I3M was -9.72kcal/mol and -7.09kcal/mol, respectively. In the current study, the prediction was studied to establish a relationship between binding energy and intermolecular energy (coefficient of determination [R2 linear = 0.999), and intermolecular energy and Van der wall forces (R2 linear = 0.994). These results would be useful in gaining structural insight for designing novel lead compounds against acetylcholinesterase for the effective management of Alzheimer's disease.

Effects of Perinatal Cardamom Exposure on Social Behavior, Anxiety, Locomotor Activity, Blood Biochemical Parameters and Brain Acetylcholinesterase of Mice Offspring

Background: Cardamom is the flavouring spices mainly cultivated all over the world. Apart from being used as the spice, it has many medicinal values. Therefore, the present study aimed to investigate the potential use of cardamom and its effects on the ability of learning, developmental, and various biochemical factors of Swiss-Webster mice offspring at different stages. Methods: In this method, Swiss-Webster mice offspring at different stages were used for the analysis of biochemical factors. After the administration of cardamom orally, the pups were subjected to various tests for determining social and defense behaviors of males and females, anxiety behavior; locomotor and neuromuscular activities, haemotological parameters, and hormonal factors of males and females. Results: The present findings indicate that the cardamom induced reduction in the social and defense behaviors of males and females, respectively, and also anxiety behavior. Interestingly, locomotor and neuromuscular activities decreased significantly. Discussion: In addition, the packed cell volume, red blood count, hemoglobin content, AChE in forebrain, the testosterone in males and progesterone in females were observed to increase significantly, whereas the blood platelets and total white blood count decreased non-significantly. Through perinatal exposure, cardamom can pass through the placenta or/and lactation and reaches the fetus. Care must be taken when using cardamom and especially during pregnancy and lactation. Conclusion: The administration of cardamom enhances the ability of social, developmental, and various biochemical factors of Swiss-Webster mice offspring at different stages.

An acetylcholinesterase inhibitor, donepezil, increases anxiety and cortisol levels in adult zebrafish

Background: A potent acetylcholinesterase inhibitor, donepezil is a cognitive enhancer clinically used to treat neurodegenerative diseases. However, its complete pharmacological profile beyond cognition remains unclear. The zebrafish ( Danio rerio) is rapidly becoming a powerful novel model organism in neuroscience and central nervous system drug screening. Aim: Here, we characterize the effects of 24-h donepezil administration on anxiety-like behavioral and endocrine responses in adult zebrafish. Methods: We evaluated zebrafish anxiety-like behaviors in the novel tank, the light-dark and the shoaling tests, paralleled by assessing brain acetylcholinesterase activity and whole-body cortisol levels. Results: Overall, donepezil dose-dependently decreased zebrafish locomotor activity in the novel tank test and reduced time in light in the light-dark test, likely representing hypolocomotion and anxiety-like behaviors. Donepezil predictably decreased brain acetylcholinesterase activity, also increasing whole-body cortisol levels, thus further linking acetylcholinesterase inhibition to anxiety-like behavioral and endocrine responses. Conclusion: Collectively, these findings suggest negative modulation of zebrafish affective behavior by donepezil, support the key role of cholinergic mechanisms in behavioral regulation in zebrafish, and reinforce the growing utility of zebrafish models for studying complex behavioral processess and their neuroendocrine and neurochemical regulation.

Kinetic characterization of rat brain acetylcholinesterase modulated by lead and cartap: the ameliorative effect of Citrus limon fruit juice

ObjectivesHuman exposure to heavy metals and pesticides is a worldwide major health problem. These environmental pollutants have been considered as the most neurotoxic agents and responsible to causing neurological toxicity. Plant-based therapeutic supplement may be used in the event of toxicity. Citrus limon contains several useful bioactive ingredients including flavonoids, dietary fiber, carotenoids, vitamins, pectin, minerals, and essential oils, which are responsible for its therapeutic potential. In the present investigation, we have studied the toxicity of heavy metals such as lead (Pb) and a carbamate pesticide such as cartap (Cp) on rat brain acetylcholinesterase (AChE).MethodsThe chemical characterization of C. limon involved determination of total antioxidants and 2,2-diphenyl-1-picryl-hydrazyl-hydrate free radical scavenging activity using known methods. The AChE activity and its kinetic characterization were performed by assaying the enzyme activity at varying substrate concentrations, pH, temperature, and time of reaction. Its different kinetic parameters such as Ki, Vmax, Km, Kcat, and Kcat/Km were determined by using standard procedures. The amelioration potential of the extract was evaluated on the neurotransmission system of rat brain AChE treated with Pb, Cp, and their combination (Pb–Cp), considering their 50% inhibitory concentration (IC50) values.ResultsThe optimal activity of rat brain AChE was recorded at 25 µg of protein, pH of 7.4, substrate concentration [S] of 0.5 mM, and temperature of 37.4–40°C. The enzyme was stable for 10 min when incubated at 37.4 °C in vitro. The enzyme displayed 70% of its activity remaining even after 160 min of incubation in this condition. It may be stable up to 1 month when stored at −20°C. The IC50 values for Pb, Cp, and Pb–Cp were found to be 75, 2.9, and 5 mM, respectively. Pb, Cp, and Pb–Cp inhibited the activity of rat brain AChE in the noncompetitive, mixed, and uncompetitive manners, respectively, with their respective Ki values to be 675, 2.37, and 22.72 mM.ConclusionsThe results indicated that the Pb and Cp were able to cause significant alterations in the level and properties of AChE. However, the introduction of lemon juice on Pb- and Cp-treated AChE indicated protection of its activity from their adverse effects. The results may be useful in prospective therapeutic applications of lemon juice or as a food supplement to protect mammalian systems from adverse effects of these toxicants.

MODELING AND STRUCTURAL ANALYSIS OF ACETYLCHOLINESTERASE ENZYME OF FISHES

Objective: Computational studies on fish brain acetylcholinesterase were conducted, expanding our views and for a deeper understanding of the activity of the fish acetylcholinesterase enzyme. Methods: Physico-chemical properties of the fish acetylcholinesterase enzyme were studied. Homology model of the acetylcholinesterase enzyme was predicted, validated its quality and active sites were predicted. The amino acid frequency in the active sites was also compared. Similarly, the secondary structure of the sequences was predicted and compared. Phylogenetic analysis was performed by the neighbour joining tree method. Results: Among the selected fish species stability of acetylcholinesterase was found in fish species namely Esox lucius. The negative GRAVY score value of enzyme in all the fish species ensured better interaction and activity in the aqueous phase. It was found that the molecular weight of the acetylcholinesterase enzyme ranged between 9113 and 15991 Da. Iso-electric (pI) of acetylcholinesterase was found to be acidic in nature. GOR IV was used to predict the secondary structure of acetylcholinesterase, which showed that random coil was dominated. Neighbor joining tree of the enzyme showed that fish species named Amphiprion ocellaris as the most divergent species, while the species Oreochromis niloticus is the most primitive one. Conclusion: Acetlycholinesterase enzyme of Esox lucius was found to be the best compared to the other species, which possess a high number of active sites with Ile, Set and Glu rich active sites.