Central Nervous System Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Central Nervous System Agents) - Online First

Epilepsy is a common disorder of the Central Nervous System (CNS). The rational design of small-molecule drugs for disorders of the CNS is a difficult process because the majority of small molecules are unable to cross the Blood-Brain-Barrier. An efficient method for the design of inhibitors that have high permeability through the Blood-Brain-Barrier has the potential for application in drug design for CNS disorders such as Addiction, Alzheimer’s disease, Bipolar disorder, Depression, Epilepsy, Gliomas, and Tuberculous meningitis.

Supervised learning was used to model the Blood-Brain-Barrier permeability of drugs like small organic molecules. This information was utilized to guide an evolutionary algorithm for the design of inhibitors with increased affinity for the target as well as higher Blood-Brain-Barrier permeability.

The ligands designed with guided evolution were predicted to have higher binding affinity for the target as well as higher permeability across the Blood-Brain-Barrier compared to an evolutionary algorithm without the guidance. The guided evolutionary method was applied to design a set of drug-like ligands that were predicted to bind to GABA-T with high affinity, to be BBB permeable, and to be chemically synthesizable.

Despite the availability of several drugs that are approved for the treatment of epilepsy, there are many cases that do not respond to available drugs or experience adverse effects. The novel ligands designed as part of this work have the potential to address the limitations of available drugs.

Guided evolution is an efficient computational approach for the design of CNS drugs. The de novo design of drugs by application of the guided evolution algorithm, developed as part of this work, has resulted in the generation of ligands that are potential drugs for the cure of epilepsy. However, the effectiveness of these drugs for the cure of epilepsy has to be validated experimentally.

Epilepsy is a common and frequently devastating disorder affecting millions of people. According to a recent survey, 1-2% of the Indian population suffers from major mental disorders and 5% suffers from minor mental disorders. Epilepsy is among those mental disorders that affect 30 million people worldwide. Currently, the treatment of epilepsy involves agents which modulate sodium-ion channels, enhance GABAergic transmission, and agents with multiple modes of action. Various classes of synthetic drugs are used to treat epilepsy, but these drugs are often challenged due to their unwanted side effects. Medicinal plants have been a part of human society which combating diseases from the dawn of civilization. The plant Cyanthillium cinereum (L.) H. Rob. is mainly found in the Himalayas from Kashmir to Nepal at an altitude of 8000 m. Decoction of this plant is traditionally used as an anti-cancer, anti-malarial, anti-epileptic, and in neurosis and skin diseases.

The present study investigated the anti-epileptic activity of Cyanthillium cinereum leaves against pentylenetetrazole (PTZ)-induced epileptic model in mice.

Plant extracts were prepared using solvents in increasing polarity viz., petroleum ether, chloroform, ethanol, and water, using a Soxhlet apparatus. The bio-active extract was characterized using FTIR and GC techniques. In vivo antioxidants like GSH and SOD level, oxidative stress markers- MDA and hemoglobin and platelet count were also estimated in the animal brain.

Amongst all extracts tested, only ethanol extract of Cyanthillium cinereum significantly (p<0.05) inhibited generalized tonic-clonic seizures in PTZ-induced epilepsy in mice in a dose (100 or 200 mg/kg., p.o.) dependent manner. The dose of 200 mg/kg of extract exhibited the most significant effect. It is also found that treatment with ethanol extract on PTZ-induced epilepsy in mice significantly (p<0.05) reduces the duration of convulsion and delays the onset of clonic convulsion.

The present findings suggest that the high amounts of phenols and flavonoids in the ethanol extract could be responsible for the anti-epileptic effect. Moreover, the ethanol extract also restored GSH, SOD and hemoglobin and platelet level and decreased oxidative marker- MDA content in the mice brain.

In stroke, reperfusion of blood to the cerebral ischemic area following sustained ischemia further exacerbates tissue damage, identified as cerebral ischemia and reperfusion (I/R) insult. Ischemic post-conditioning (IPoC) appears to offer benefits against I/R injury. The cascade of androgen receptors (ARs) has a vital role in cerebral stroke; however, its neurodefensive function in IPoC is unclear. This investigation aimed to explore the involvement of ARs in IPoC in cerebral I/R insult in rats.

Global cerebral ischemia/reperfusion (GCI/R) insult in experimental animals was provoked by 10 minutes of obstruction of the bilateral carotid arteries after reperfusion for 24 hours. IPoC was carried out by providing a triad of I/R insults with a gap of 10 minutes of GCI after 24 hours of reperfusion. Lateral push, inclined beam, rota rod, hanging wire, and Morris-water maze experimentations were conducted on animals to determine motor control and cognitive functions (learning and memory). Cerebral oxidative damage markers (raised lipid peroxidation and reduced glutathione levels), acetylcholinesterase (AChE) activity, inflammatory indicators (interleukin-6, interleukin-10, tumor necrosis factor-α, and myeloperoxidase), infarction, and histopathological alterations were also assessed.

Animals with I/R exhibited reduced motor function and memory along with raised cerebral oxidative damage, AChE activity, inflammation, infarction, and histopathological alterations. IPoC after ischemic events recuperated the damaging outcomes of I/R insult. 60 minutes before cerebral ischemia, pretreatment with testosterone mimicked the neurodefensive outcomes of IPoC. However, neuroprotective outcomes developed by IPoC were diminished by flutamide (ARs antagonist) pretreatment.

IPoC may offer neuroprotective outcomes in I/R insult by modulation of AR-mediated pathway.

Major Depressive Disorder (MDD) is a psychiatric disorder that has a tight connection to stressful experiences, decreased levels of endogenous antioxidants and enhanced levels of oxidative stress. We drafted this research to define the results of combining agmatine and melatonin on stress-induced depression in mice.

Experimental groups included the non-stressed group treated with vehicle (ethanol at a concentration of 0.0005%), stressed vehicle (ethanol at a concentration of 0.0005%)-treated group, group treated with fluoxetine (10 mg/kg/day), group treated with melatonin (10 mg/kg/day), group treated with agmatine (1 mg/kg/day), group receiving a combination of melatonin (10 mg/kg/day) and agmatine (1 mg/kg/day). The animals were subjected to restraint stress for two hours daily for a duration of one week, concurrently with the daily oral administration of agents through drinking water. Open field test and forced swimming test were operated on the 8th day. The oxidative stress markers were measured in the mice hippocampus.

Stress led to the elevation of immobility time. The combination group showed a significant effect in comparison to the agmatine and melatonin groups. The combination of melatonin and agmatine was successful in the elevation of hippocampus catalase activity; and this effect was comparable in the fluoxetine group. We observed enhancement of superoxide dismutase activity in treatment groups and reduction in malondialdehyde levels in melatonin, agmatine and combination groups.

A combination of agmatine and melatonin improves stress-induced depression more effectively than each alone, which may result from suppressing oxidative stress.

This study aims to investigate the antidepressant properties of Hispidulin, a flavonoid present in Scutellaria barbata D. Don. The selection of Hispidulin stems from its notable inhibitory activity against Xanthine Oxidase (XO), a parameter in the pathophysiology of depression.

Mice were subjected to a rigorous evaluation using a murine model of Chronic Unpredictable Mild Stress (CUMS) to induce depression for 21 days and antidepressant properties were rigorously assessed using the Tail Suspension Test (TST), Forced Swim Test (FST), and Open Field Test (OFT). Imipramine and fluoxetine were used as standard drugs. Additionally, neurochemical analyses were conducted to quantify serotonin (5-HT), norepinephrine (NE), and dopamine (DA) levels in the cortex, hippocampus, and hypothalamus. Further mechanistic insights were sought through the estimation of monoamine oxidase (MAO) activity and assessment of antioxidant enzyme levels in the brain. Plasma nitrite and corticosterone levels were also measured to delineate the underlying mechanism of action.

Hispidulin demonstrated significant antidepressant effects, as evidenced by reduced immobility time in TST and FST and increased exploratory behavior in OFT. Neurochemical analysis revealed restoration of 5-HT, NE, and DA levels in key brain regions. Furthermore, Hispidulin modulated MAO activity and enhanced antioxidant enzyme levels in the brain. Plasma nitrite levels were elevated, indicating enhanced nitric oxide synthesis, while corticosterone levels were reduced.

Our findings indicate that Hispidulin exerts potent antidepressant effects, potentially mediated through its influence on monoaminergic neurotransmitters, MAO activity, and antioxidant defenses. These results provide valuable mechanistic insights into the antidepressant action of Hispidulin, supporting its potential therapeutic application in depressive disorders.

Epilepsy is a critically deep-rooted CNS disorder affecting above 50 million people all over the world. Thus, a safe and effective treatment that proves its worth in this ailment is urgently needed. Thiazolidine-4-ones possess the molecules to be used as anticonvulsants. The thiazolidinedione is a cyclic analogue of thiosemicarbazides and thioureas as well as a (bio)isostere of hydantoin (imidazolidine-2,4-dione), which are recognized as novel anticonvulsant designs.

This study aimed to develop and evaluate a novel thiazolidine-4-one derivative by three-component condensation in one pot reaction method.

A novel thiazolidine-4-one derivative was formulated by three-component condensation. The selected OH (Alcohol) derivatives were found to be more potent; hence, a molecular docking study against a selected target LGI1 LRR domain was performed. Various analytical tests like FTIR and H¹ NMR were accomplished. The FTIR was used to validate the existence of multiple functional moieties like C-S, O-H, C=O, C-N, N=O, C-NH, C-O in the wave region from 3075 cm^-1 – 1236 cm^-1 and H¹ NMR was employed to ascertain if the synthesized analogues had the complete set of protons. Then, the anti-seizure activity of the selected compound was examined using PTZ models in mice at three successive doses, i.e., 25, 50, and 100mg/kg, and compared with standard ethosuximide.

The docking simulations were initiated using PyMOL after the binding site was determined and the receptor and ligand were suitably prepared. It showed higher binding frequency in comparison to the standard marketed drug Ethosuximide. FTIR and H¹ NMR spectroscopy were used to characterize the chemical components. Numerous functional groups, including O-H (alcohol), C=O (ketones), N=O, C-NH, C-N, C-S, and C-O bending stretching, were visible in the synthesized molecule accordingly. The synthesized compound was effective in inhibiting the convulsions at the concentration of 100 mg/kg.

The novel thiazolidine-4-one derivative showed promising activity and could be considered for further investigation and dosage form preparation.

Nattokinase (NK), a protease enzyme present in traditional fermented Japanese food, has shown fibrinolytic properties in vitro as well as in cardiac ischemia. In the present study, the Neuroprotective effect of standardized NK was evaluated in the thrombolytic focal cerebral ischemic model.

The parameters of behavioural assessment, cerebral blood flow, inflammatory mediators, excitatory amino acids, and immunohistochemistry were measured to support the NK effect. NK was administered at 150 and 300 mg/kg, and its effects were compared with streptokinase (STK) (100µl/rat). Each mg of NK contains 5.5 Units of the enzyme, which can cause lysis of the fibrin.

The results indicate that 7 days of treatment of 300 mg NK restored the cerebral blood flow and prevented the release of cytokine and excitatory amino acids. Similarly, neurological scores were reduced, and grip strength increased significantly with NK treatment. The GFAP and synaptophysin staining of the hippocampus (CA1) and cerebrum have shown recovery of neurons from ischemic damage in comparison to vehicle-treated ischemic-reperfused rats. The NK (300 mg/kg) fibrinolytic effect is comparable to STK treatment.

To conclude, NK, a serine protease, protects the brain from ischemic degeneration in thrombolytic cerebral ischemia. Consumption of this Japanese food might exhibit prophylactic activity.