Central Nervous System Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Central Nervous System Agents) - Volume 24, Issue 3, 2024

One essential component of the neurovascular system is known as the blood-brain barrier (BBB). This highly effective biological barrier plays a pivotal role in regulating the brain's internal microenvironment and carefully controlling the passage of various chemicals into and out of the brain. Notably, it serves as a safeguard for the brain, particularly when it comes to the selective transportation of drugs like opioids and non-steroidal anti-inflammatory medications (NSAIDs), which are commonly used in the management of chronic pain. It's important to note that during the development of chronic pain, the activation of microglia and astrocytes can potentially disrupt or damage the integrity of the BBB. In this comprehensive review, we aim to delve into the intricate interplay between the blood-brain barrier and the transportation of pain-relieving drugs, shedding light on the challenges and mechanisms involved in this process.

Resveratrol is a biologically active natural phenolic plant product. It has several properties which make them useful to treat the disease. In this review, we have highlighted the neuroprotective effects of resveratrol. Several available animal models have been proven to help understand the disease pathway and mechanism of action by resveratrol. In this review, we have highlighted the neuroprotective activity of resveratrol in AD, which effectively counter the neurodegenerative disease by decreasing the formation of plaques. Resveratrol is a natural plant product that is easily available, cost-effective, and possesses neuroprotective activity, which is useful for treating neurodegenerative diseases. Resveratrol presents a promising avenue for AD treatment due to its diverse neuroprotective mechanisms. Given the ongoing global challenge in treating AD, researchers have increasingly focused on exploring the therapeutic potential of resveratrol.

One of the most crippling effects of diabetes mellitus is diabetic neuropathy, which can cause discomfort, loss of movement, and even amputation. Diabetic neuropathy manifests in a variety of ways, ranging from pain to death. Diagnosing diabetic neuropathy can be challenging since it often goes unnoticed for many years following the onset of diabetes. In addition to oxidative stress in neurons, hyperglycemia activates a number of metabolic pathways that are important sources of damage and possible targets for treatment in diabetic neuropathy. Downstream metabolic cascades caused by prolonged hyperglycemia include activation of protein kinase C, increased production of advanced glycation end products, excessive release of cytokines, increased oxidative stress, and injury to peripheral nerves. Despite the fact that these metabolic anomalies are considered the main cause of diabetes-related microvascular issues, the diverse mechanistic processes of neuropathy are characterized by organ-specific histological and biochemical features. Although the symptoms of diabetic neuropathy can be treated, there are few options to correct the underlying problem. Diabetic neuropathy exerts a tremendous financial, psychological, and physical burden on society, emphasizing the need for efficient and focused treatment. The major goal of this review is to shed light on the multiple mechanisms and pathways that contribute to the onset of diabetic neuropathy and to provide readers with a comprehensive understanding of emerging therapeutic strategies to postpone or reverse various forms of diabetic neuropathy. The article discusses available medications and provides the latest guidelines for the treatment of pain and distal symmetric polyneuropathy, including diabetic autonomic neuropathy, which may help the patients control pain well and assess alternatives for treatment that might be more successful in preventing or delaying the course of a disease.

Alzheimer's disease (AD) is a form of brain degeneration that gradually impairs a person's memory and cognitive skills, eventually making it harder for them to perform everyday activities. Its pathophysiology has been attributed to the deposition of amyloid β (Aβ), neurofibrillary tangles (NFT), and α-synuclein (A-s) in some cases. Presently, 4 drugs have been approved for the treatment. They are Donepezil, Rivastigmine, Galantamine and Memantine. The first three are acetylcholinesterase inhibitors, while memantine is an NMDA receptor antagonist. Even though these medications are successful in treating mild to moderate Alzheimer's disease, they have not been able to reverse the disease or even slow its progression completely. Hence, natural products are gaining more popularity due to the advantage of the multitarget intervention effect. The most investigated spice, Curcuma longa's bioactive component, curcumin, has demonstrated anti-amyloid, anti-NFT, and anti-Lewy body properties and substantial antiinflammatory, antioxidant, and antiapoptotic properties. However, its proven neuroprotective activity is hampered by many factors, such as poor water solubility and bioavailability. Therefore, many novel formulations have been designed to improve its bioavailability with methods such as 1) Micellar Solubilization, 2) Cyclodextrin Complexation, 3) Crystal Modification, and 4) Particle Size Reduction, etc. The current chapter aims to summarize various novel formulations of curcumin and their effectiveness in treating AD.

Central nervous system disorders are prevalent, profoundly debilitating, and poorly managed. Developing innovative treatments for these conditions, including Alzheimer's disease, could significantly improve patients' quality of life and reduce the future economic burden on healthcare systems. However, groundbreaking drugs for central nervous system disorders have been scarce in recent years, highlighting the pressing need for advancements in this field. One significant challenge in the realm of nanotherapeutics is ensuring the precise delivery of drugs to their intended targets due to the complex nature of Alzheimer's disease. Although numerous therapeutic approaches for Alzheimer's have been explored, most drug candidates targeting amyloid-β have failed in clinical trials. Recent research has revealed that tau pathology can occur independently of amyloid-β and is closely correlated with the clinical progression of Alzheimer's symptoms. This discovery suggests that tau could be a promising therapeutic target. One viable approach to managing central nervous system disorders is the administration of nanoparticles to neurons, intending to inhibit tau aggregation by directly targeting p-tau. In Alzheimer's disease, beta-amyloid plaques and neurofibrillary tau tangles hinder neuron transmission and function. The disease also triggers persistent inflammation, compromises the blood-brain barrier, leads to brain shrinkage, and causes neuronal loss. While current medications primarily manage symptoms and slow cognitive decline, there is no cure for Alzheimer's.

Background: Parkinson’s disease is defined by the loss of dopaminergic neurons in the midbrain of substantia nigra associated with Lewy bodies. The precise mechanism is not yet entirely understood. Objective: The study aims to determine whether ocimene has antiparkinsonian activity by reducing α-Synuclein aggregation levels in the brains of rotenone-induced rat models. Methods: 36 male rats were used for six groups, with six animals in each group. Vehicle, control (rotenone, 2.5 mg/kg, i.p), standard (L-Dopa, 10 mg/kg, i.p), Test drug of low dose (66.66 mg/kg, i.p), medium dose (100 mg/kg, i.p), and high dose (200 mg/kg, i.p) were administered to the rats. The open field, actophotometer, hanging wire, and catalepsy tests were used to assess the rat’s motor performance. The expressions of biomarkers such as AchE, D2 Receptor, and α- Synuclein were evaluated, and their level of expression in the brain samples was checked using ELISA. Histopathological analysis was also carried out to determine the degree of neuron degeneration in the brain samples. Results: The open field test showed significant anxiety levels, whereas test groups showed fewer anxiety levels but increased motor activity. The biochemical tests revealed that rotenonetreated rats had higher levels of AchE, but ocimene-treated rats had a significant decrease in AchE levels. The test drug-treated rats also expressed high levels of D2 receptors. In ocimenetreated rats, α-Synuclein aggregation was reduced, however, in rotenone-treated rats' brain samples, higher clumps of α-Synuclein were observed. Conclusion: Ocimene has neuroprotective properties. As a result, this essential oil might be helpful as a therapeutic treatment for Parkinson's disease.

Background: Overactivation of receptors that respond to excitatory neurotransmitters can result in various harmful outcomes, such as the inability to properly modulate calcium levels, generation of free radicals, initiation of the mitochondrial permeability transition, and subsequent secondary damage caused by excitotoxicity. A non-proteinogenic amino acid of tea, L-theanine, is structurally related to glutamate, the major stimulatory neurotransmitter in the brain. Previous reports have emphasised its ability to bind with glutamate receptors. Objective: An in-depth understanding of the binding compatibility between ionotropic glutamate receptors and L-theanine is a compelling necessity. Methods: In this molecular docking study, the antagonistic effect of L-theanine and its possible therapeutic benefit in GluR5 kainate receptor inhibition has been evaluated and compared to the familiar AMPA and kainite receptor antagonists, cyanoquinoxaline (CNQX) and dinitroquinoxaline (DNQX), using Molegro Virtual Docker 7.0.0. Results: The capacity of L-theanine to cohere with the GluR5 receptor was revealed to be higher than that of glutamate, although it could not surpass the high binding tendency of competitive antagonists CNQX and DNQX. Nonetheless, the drug-likeness score and the blood-brain barrier traversing potential of L-theanine were higher than CNQX and DNQX. Conclusion: The study provides an inference to the advantage of L-theanine, which can be a safe and effective alternative natural therapy for rescuing neuronal death due to excitotoxicity.