Computational evidence to inhibition of human acetyl cholinesterase by withanolide a for Alzheimer treatment

Neuroprotection by Polyherbal Medicine Divya-Medha-Vati Against Scopolamine-Induced Cognitive Impairment Through Modulation of Oxidative Stress, Acetylcholine Activity, and Cell Signaling

Alzheimer disease is associated with cognitive impairments and neuronal damages. In this study, Scopolamine, a model drug used for the generation of Alzheimer-like symptoms induced cognitive dysfunction in C57BL/6 mice. It also elevated acetylcholine esterase (AcHE) activity, and reduced antioxidant (superoxide dismutase and catalase) activity in cortex tissue. Scop reduced neuronal density and increased pyknotic neurons in hippocampus tissue. In mouse neuroblastoma (Neuro2a) cells, Scop triggered a dose-dependent loss of cell viability and neurite outgrowth reduction. Scop-treated Neuro2a cells showed oxidative stress and reduction in mRNA expression for brain-derived neurotrophic factor (BDNF), nerve growth factor-1 (NGF-1), and Synapsin-1 (SYN-1) genes. Mice treated with Divya-Medha-Vati (DMV), an Ayurvedic polyherbal medicine showed protection against Scop-induced cognitive impairment (Morris Water Maze Escape Latency, and Elevated Plus Maze Transfer Latency). DMV protected against Scop-induced AcHE activity, and loss of antioxidant activities in the mice brain cortex while sustaining neuronal density in the hippocampus region. In the Neuro2a cells, DMV reduced Scop-induced loss of cell viability and neurite outgrowth loss. DMV protected the cells against induction of oxidative stress and promoted mRNA expression of BDNF, NGF-1, and SYN-1 genes. Phytochemical profiling of DMV showed the presence of Withanolide A, Withanolide B, Bacopaside II, Jujubogenin, Apigenin, Gallic acid, Caffeic acid, and Quercetin that are associated with antioxidant and neurostimulatory activities. In conclusion, the study showed that Divya-Medha-Vati was capable of promoting neuronal health and inhibiting Alzheimer-like cognitive dysfunction through enhanced antioxidant activities and modulation of neuronal activities.

Revisiting the Multifaceted Therapeutic Potential of Withaferin A (WA), a Novel Steroidal Lactone, W-ferinAmax Ashwagandha, from Withania Somnifera (L) Dunal

Withania somnifera (L.) Dunal, abundant in the Indian subcontinent as Ashwagandha or winter cherry, is a herb of unprecedented therapeutic value. The number of ailments for which crude Ashwagandha extract can be used as a preventive or curative is practically limitless; and this explains why its use has been in vogue in ancient Ayurveda since at-least about four thousand years. The therapeutic potential of Ashwagandha mainly owes from its reservoir of alkaloids (isopelletierine, anaferine), steroidal lactones (withanolides) and saponins with an extra acyl group (sitoindoside VII and VIII). Withaferin A is an exceptionally potent withanolide which is found in high concentrations in W. somnifera plant extracts. The high reactivity of Withaferin A owes to the presence of a C-28 ergostane network with multiple sites of unsaturation and differential oxygenation. It interacts with the effectors of multiple signaling pathways involved in inflammatory response, oxidative stress response, cell cycle regulation and synaptic transmission and has been found to be significantly effective in inducing programmed cell death in cancer cells, restoring cognitive health, managing diabetes, alleviating metabolic disorders, and rejuvenating the overall body homeostasis. Additionally, recent studies suggest that Withaferin A (WA) has the potential to prevent viral endocytosis by sequestering TMPRSS2, the host transmembrane protease, without altering ACE-2 expression. The scope of performing subtle structural modifications in this multi-ring compound is believed to further expand its pharmacotherapeutic horizon. Very recently, a novel, heavy metal and pesticide free formulation of Ashwagandha whole herb extract, with a significant amount of WA, termed W-ferinAmax Ashwagandha, has been developed. The present review attempts to fathom the present and future of this wonder molecule with comprehensive discussion on its therapeutic potential, safety and toxicity.Key teaching pointsWithania somnifera (L.) Dunal is a medicinal plant with versatile therapeutic values.The therapeutic potential of the plant owes to the presence of withanolides such as Withaferin A.Withaferin A is a C-28 ergostane based triterpenoid with multiple reactive sites of therapeutic potential.It is effective against a broad spectrum of ailments including neurodegenerative disorders, cancer, inflammatory and oxidative stress disorders and it also promotes cardiovascular and sexual health.W-ferinAmax Ashwagandha, is a heavy metal and pesticide free Ashwagandha whole herb extract based formulation with significant amount of Withaferin A.

Screening of Multitarget-Directed Natural Compounds as Drug Candidates for Alzheimer's Disease Using In Silico Techniques: Their Extraction and In Vitro Validation

Alzheimer's disease (AD) is a neurodegenerative disorder that impairs neurocognitive function. Acetylcholinesterase (AChE) and β-site APP cleaving enzyme 1 (BACE1) are the two main proteins implicated in AD. Indeed, the major available commercial drugs (donepezil, rivastigmine, and galantamine) against Alzheimer's are AChE inhibitors. However, none of these drugs are known to reverse or reduce the pathophysiological condition of the disease since there are multiple contributing factors to AD. Therefore, there is a need to develop a multitarget-directed ligand approach for its treatment. In the present study, plant bioactive compounds were screened for their AChE and BACE1 inhibition potential by conducting molecular docking studies. Considering their docking score and pharmacokinetic properties, limonin, peimisine, serratanine B, and withanolide A were selected as the lead compounds. Molecular dynamics simulations of these protein-ligand complexes confirmed the conformational and energetically stabilized enzyme-inhibitor complexes. The inhibition potential of the lead compounds was validated by in vitro enzyme assay. Withanolide A inhibited AChE (IC50 value of 107 μM) and showed mixed-type inhibition. At this concentration, it inhibited BACE1 activity by 57.10% and was stated as most effective. Both the compounds, as well as their crude extracts, were found to have no cytotoxic effect on the SH-SY5Y cell line.

Current trends in natural products for the treatment and management of dementia: Computational to clinical studies

The number of preclinical and clinical studies evaluating natural products-based management of dementia has gradually increased, with an exponential rise in 2020 and 2021. Keeping this in mind, we examined current trends from 2016 to 2021 in order to assess the growth potential of natural products in the treatment of dementia. Publicly available literature was collected from various databases like PubMed and Google Scholar. Oxidative stress-related targets, NF-κB pathway, anti-tau aggregation, anti-AChE, and A-β aggregation were found to be common targets and pathways. A retrospective analysis of 33 antidementia natural compounds identified 125 sustainable resources distributed among 65 families, 39 orders, and 7 classes. We found that families such as Berberidaceae, Zingiberaceae, and Fabaceae, as well as orders such as Lamiales, Sapindales, and Myrtales, appear to be important and should be researched further for antidementia compounds. Moreover, some natural products, such as quercetin, curcumin, icariside II, berberine, and resveratrol, have a wide range of applications. Clinical studies and patents support the importance of dietary supplements and natural products, which we will also discuss. Finally, we conclude with the broad scope, future challenges, and opportunities for field researchers.

An updated review on phytochemistry and molecular targets of Withania somnifera (L.) Dunal (Ashwagandha)

Withania somnifera (L.) Dunal belongs to the nightshade family Solanaceae and is commonly known as Ashwagandha. It is pharmacologically a significant medicinal plant of the Indian sub-continent, used in Ayurvedic and indigenous systems of medicine for more than 3,000 years. It is a rich reservoir of pharmaceutically bioactive constituents known as withanolides (a group of 300 naturally occurring C-28 steroidal lactones with an ergostane-based skeleton). Most of the biological activities of W. somnifera have been attributed to two key withanolides, namely, withaferin-A and withanolide-D. In addition, bioactive constituents such as withanosides, sitoindosides, steroidal lactones, and alkaloids are also present with a broad spectrum of therapeutic potential. Several research groups worldwide have discovered various molecular targets of W. somnifera, such as inhibiting the activation of nuclear factor kappa-B and promoting apoptosis of cancer cells. It also enhances dopaminergic D2 receptor activity (relief in Parkinson’s disease). The active principles such as sitoindosides VII-X and withaferin-A possess free radical properties. Withanolide-D increases the radio sensitivity of human cancer cells via inhibiting deoxyribonucleic acid (DNA) damage to non-homologous end-joining repair (NHEJ) pathways. Withanolide-V may serve as a potential inhibitor against the main protease (Mpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to combat COVID. The molecular docking studies revealed that the withanolide-A inhibits acetyl-cholinesterase in the brain, which could be a potential drug to treat Alzheimer’s disease. Besides, withanolide-A reduces the expression of the N-methyl-D-aspartate (NMDA) receptor, which is responsible for memory loss in epileptic rats. This review demonstrates that W. somnifera is a rich source of withanolides and other bioactive constituents, which can be used as a safe drug for various chronic diseases due to the minimal side effects in various pre-clinical studies. These results are interesting and signify that more clinical trials should be conducted to prove the efficacy and other potential therapeutic effects in human settings.

Current Naturopathy to Combat Alzheimer's Disease

Neurodegeneration is the progressive loss of structure or function of neurons, which may ultimately involve cell death. The most common neurodegenerative disorder in the brain happens with Alzheimer's disease (AD), the most common cause of dementia. It ultimately leads to neuronal death, thereby impairing the normal functionality of the central or peripheral nervous system. The onset and prevalence of AD involve heterogeneous etiology, either in terms of genetic predisposition, neurometabolomic malfunctioning, or lifestyle. The worldwide relevancies are estimated to be over 45 million people. The rapid increase in AD has led to a concomitant increase in the research work directed towards discovering a lucrative cure for AD. The neuropathology of AD comprises the deficiency in the availability of neurotransmitters and important neurotrophic factors in the brain, extracellular betaamyloid plaque depositions, and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. Current pharmaceutical interventions utilizing synthetic drugs have manifested resistance and toxicity problems. This has led to the quest for new pharmacotherapeutic candidates naturally prevalent in phytochemicals. This review aims to provide an elaborative description of promising Phyto component entities having activities against various potential AD targets. Therefore, naturopathy may combine with synthetic chemotherapeutics to longer the survival of the patients.

Withania somnifera (L.) Dunal (Ashwagandha); current understanding and future prospect as a potential drug candidate

Cancer and Neurodegenerative diseases are one of the most dreadful diseases to cure and chemotherapy has found a prime place in cancerous treatments while as different strategies have been tested in neurodegenerative diseases as well. However, due to adverse shortcomings like the resistance of cancerous cells and inefficiency in neurodegenerative disease, plant sources have always found a prime importance in medicinal use for decades, Withania somnifera (L.) Dunal (W. somnifera) is a well-known plant with medicinal use reported for centuries. It is commonly known as winter cherry or ashwagandha and is a prime source of pharmaceutically active compounds withanolides. In recent years research is being carried in understanding the extensive role of W. somnifera in cancer and neurological disorders. W. somnifera has been reported to be beneficial in DNA repair mechanisms; it is known for its cellular repairing properties and helps to prevent the apoptosis of normal cells. This review summarizes the potential properties and medicinal benefits of W. somnifera especially in cancer and neurodegenerative diseases. Available data suggest that W. somnifera is effective in controlling disease progressions and could be a potential therapeutic target benefiting human health status. The current review also discusses the traditional medicinal applications of W. somnifera, the experimental evidence supporting its therapeutical potential as well as obstacles that necessitate being overcome for W. somnifera to be evaluated as a curative agent in humans.

Integrated System Pharmacology and In Silico Analysis Elucidating Neuropharmacological Actions of Withania somnifera in the Treatment of Alzheimer's Disease

BACKGROUND

Withania somnifera (WS), also referred to as Medhya Rasayana (nootropic or rejuvenating), has traditionally been prescribed for various neurological ailments, including dementia. Despite substantial evidence, pharmacological roles of WS, neither as nootropic nor as an antidementia agent, are well-understood at the cellular and molecular levels.

OBJECTIVES

We aimed at elucidating the pharmacological action mechanisms of WS root constituents against Alzheimer's Disease (AD) pathology.

METHODS

Various bioinformatics tools and resources, including DAVID, Cytoscape, NetworkAnalyst and KEGG pathway database were employed to analyze the interaction of WS root bioactive molecules with the protein targets of AD-associated cellular processes. We also used a molecular simulation approach to validate the interaction of compounds with selected protein targets.

RESULTS

Network analysis revealed that β-sitosterol, withaferin A, stigmasterol, withanolide A, and withanolide D are the major constituents of WS root that primarily target the cellular pathways such as PI3K/Akt signaling, neurotrophin signaling and toll-like receptor signaling and proteins such as Tropomyosin receptor Kinase B (TrkB), Glycogen Synthase Kinase-3β (GSK-3β), Toll-Like Receptor 2/4 (TLR2/4), and β-secretase (BACE-1). Also, the in silico analysis further validated the interaction patterns and binding affinity of the major WS compounds, particularly stigmasterol, withanolide A, withanolide D and β-sitosterol with TrkB, GSK-3β, TLR2/4, and BACE-1.

CONCLUSION

The present findings demonstrate that stigmasterol, withanolide A, withanolide D and β-sitosterol are the major metabolites that are responsible for the neuropharmacological action of WS root against AD-associated pathobiology, and TrkB, GSK-3β, TLR2/4, and BACE-1 could be the potential druggable targets.

Ashwagandha in brain disorders: A review of recent developments

ETHNOPHARMACOLOGICAL RELEVANCE

Withania somnifera (Family: Solanaceae), commonly known as Ashwagandha or Indian ginseng is distributed widely in India, Nepal, China and Yemen. The roots of plant consist of active phytoconstituents mainly withanolides, alkaloids and sitoindosides and are conventionally used for the treatment of multiple brain disorders.

AIM OF THE REVIEW

This review aims to critically assess and summarize the current state and implication of Ashwagandha in brain disorders. We have mainly focussed on the reported neuroactive phytoconstituents, available marketed products, pharmacological studies, mechanism of action and recent patents published related to neuroprotective effects of Ashwagandha in brain disorders.

MATERIALS AND METHODS

All the information and data was collected on Ashwagandha using keywords "Ashwagandha" along with "Phytoconstituents", "Ayurvedic, Unani and Homeopathy marketed formulation", "Brain disorders", "Mechanism" and "Patents". Following sources were searched for data collection: electronic scientific databases such as Science Direct, Google Scholar, Elsevier, PubMed, Wiley On-line Library, Taylor and Francis, Springer; books such as AYUSH Pharmacopoeia; authentic textbooks and formularies.

RESULTS

Identified neuroprotective phytoconstituents of Ashwagandha are sitoindosides VII-X, withaferin A, withanosides IV, withanols, withanolide A, withanolide B, anaferine, beta-sitosterol, withanolide D with key pharmacological effects in brain disorders mainly anxiety, Alzheimer's, Parkinson's, Schizophrenia, Huntington's disease, dyslexia, depression, autism, addiction, amyotrophic lateral sclerosis, attention deficit hyperactivity disorder and bipolar disorders. The literature survey does not highlight any toxic effects of Ashwagandha. Further, multiple available marketed products and patents recognized its beneficial role in various brain disorders; however, very few data is available on mechanistic pathway and clinical studies of Ashwagandha for various brain disorders is scarce and not promising.

CONCLUSION

The review concludes the results of recent studies on Ashwagandha suggesting its extensive potential as neuroprotective in various brain disorders as supported by preclinical studies, clinical trials and published patents. However vague understanding of the mechanistic pathways involved in imparting the neuroprotective effect of Ashwagandha warrants further study to promote it as a promising drug candidate.

GJ-4 alleviates Aβ25-35-induced memory dysfunction in mice through protecting the neurovascular unit

Alzheimer's disease (AD) is the most common neurodegenerative disease. AD has become an important social health problem but there are few therapeutic drugs. Many researchers devote to the development of drugs for the treatment of AD. GJ-4 is crocin enrichments from Gardenia jasminoides J. Ellis, and our previous studies have shown GJ-4 had potent neuroprotective effects on several AD animal models. However, the underlying mechanisms have not been fully elucidated. The aim of the present study was to explore the mechanism of GJ-4 on a Aβ_25-35-intoxicated mouse model. The results demonstrated that GJ-4 treatment significantly improved spatial learning and memory abilities of the AD mice challenged by Aβ_25-35. Mechanistic study indicated that GJ-4 could alleviate endothelial dysfunction, as GJ-4 markedly reduced endothelial cell edema, as well as improved tight junction structures by up-regulating Zonula occludens-1 (ZO-1), Claudin-5 and Occludin expressions. Moreover, GJ-4 markedly reduced receptor for advanced glycation end products (RAGE) expression and increased low-density lipoprotein receptor-related protein-1 (LRP-1) expression, suggesting endothelial transduction and clearance of toxic species capabilities improved by GJ-4 treatment. The results also indicated that GJ-4 significantly decreased IL-6 and IL-1β mRNA expressions, as well as intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) expressions, implying the inhibition of glial activation and vascular inflammation by GJ-4 treatment. Furthermore, GJ-4 treatment inhibited glial activation mediated neuroinflammation through inhibiting high-mobility group box protein 1(HMGB-1)/RAGE/NF-κB signaling pathway, which might confer to the neuroprotection. In conclusion, our present study proved GJ-4 could protect the neurovascular unit (NVU), through attenuating endothelial cell damage, enhancing tight junction function, inhibiting of glial activation and protecting of neurons. This study provided evidence that the beneficial effects of GJ-4 on AD might be owing to its protection on NVU.

Pharmacological evaluation of Ashwagandha highlighting its healthcare claims, safety, and toxicity aspects

Withania somnifera, commonly known as "Ashwagandha" or "Indian ginseng" is an essential therapeutic plant of Indian subcontinent regions. It is regularly used, alone or in combination with other plants for the treatment of various illnesses in Indian Systems of Medicine over the period of 3,000 years. Ashwagandha (W. somnifera) belongs to the genus Withania and family Solanaceae. It comprises a broad spectrum of phytochemicals having wide range of biological effects. W. somnifera has demonstrated various biological actions such as anti-cancer, anti-inflammatory, anti-diabetic, anti-microbial, anti-arthritic, anti-stress/adaptogenic, neuro-protective, cardio-protective, hepato-protective, immunomodulatory properties. Furthermore, W. somnifera has revealed the capability to decrease reactive oxygen species and inflammation, modulation of mitochondrial function, apoptosis regulation and improve endothelial function. Withaferin-A is an important phytoconstituents of W. somnifera belonging to the category of withanolides been used in the traditional system of medicine for the treatment of various disorders. In this review, we have summarized the active phytoconstituents, pharmacologic activities (preclinical and clinical), mechanisms of action, potential beneficial applications, marketed formulations and safety and toxicity profile of W. somnifera.

The Effects of Probiotic Lactobacillus and Bifidobacterium Strains on Memory and Learning Behavior, Long-Term Potentiation (LTP), and Some Biochemical Parameters in β-Amyloid-Induced Rat's Model of Alzheimer's Disease

This study assessed the effects of probiotic supplementation on spatial learning and memory, long-term potentiation (LTP), paired-pulse facilitation (PPF) ratios, nitric oxide (NO) concentrations, and lipid profiles in a rat model of amyloid beta (Aβ)(1–42)-induced Alzheimer’s disease (AD). Forty rats were randomly divided into 4 groups. The sham (control and prevention) group received intracerebroventricular (ICV) injections of artificial cerebrospinal fluid, the Alzheimer group received ICV injection of Aβ(1–42), and the probiotic+Alzheimer group received 500 mg probiotics daily (15×10⁹ colony-forming unit) by gavage for 4 weeks before and 2 weeks after injection of Aβ(1–42). The Morris water maze test was performed for evaluation of spatial learning and memory. LTP and PPF ratios were measured to evaluate longterm synaptic plasticity and pre-synaptic mechanisms, respectively. The results showed that probiotic supplementation significantly improved learning, but not memory impairment, and increased PPF ratios compared to those in the Alzheimer group. Both Aβ(1–42) injection and probiotic supplementation alone did not significantly effect plasma level of NO. Probiotic supplementation of rats in the probiotic (6 weeks)+Alzheimer group decreased serum levels of total cholesterol, triglyceride, and very low-density lipoprotein-cholesterol significantly compared to the Alzheimer group. The results of this study suggest that probiotic supplementation may positively impact learning capacity and LTP in rats with AD, most likely via the release of neurotransmitters via presynaptic mechanisms or via a protective effect on serum lipid profiles.

Effect of hydroalcoholic Echium amoenum extract on scopolamine-induced learning and memory impairment in rats

CONTEXT

Scopolamine, a muscarinic receptor antagonist, causes memory loss that resembles Alzheimer's disease (AD). Echium amoenum L. (Boraginaceae) is a famous medicinal plant of Iran that is traditionally used as a sedative and mood enhancer.

OBJECTIVE

This study evaluates the effect of hydroalcoholic extract of E. amoenum flowers on scopolamine-induced memory impairment in rats.

MATERIALS AND METHODS

Fifty male Wistar rats were randomly divided into five groups. Control group received normal saline, model group received scopolamine (0.7 mg/kg, IP, daily for 21 days), and test groups received E. amoenum extract (50, 75, and 100 mg/kg, IP, daily for 21 days) 30 min before each scopolamine injection. The elevated plus maze (EPM), shuttle box, novel object and rotarod tests were performed after treatment. Brain levels of malondialdehyde (MDA) and total antioxidant capacity (TCA) were also determined.

RESULTS

Scopolamine-treated rats spent more time exploring the novel object compared to the control, and E. amoenum extract at all three doses significantly decreased the time spent exploring the novel object (p < 0.05). E. amoenum extract (75 and 100 mg/kg) significantly elongated the secondary latency in rats receiving scopolamine in the shuttle box test (p < 0.05). In addition, treatment with 75 and 100 mg/kg doses of E. amoenum extract significantly ameliorated scopolamine-induced motor in coordination in rotarod test (p < 0.05). It also significantly increased the time spent in the open arms and reduced the time spent in the closed arms of EPM (p < 0.05). Treatment of scopolamine-exposed rats with E. amoenum extract significantly increased TCA and reduced MDA level of brain (p < 0.05).

DISCUSSION AND CONCLUSIONS

E. amoenum extract shows protective effect against scopolamine-induced impairment and is suggested to be tested in clinical trials to evaluate the efficacy on AD.

Natural Withanolides in the Treatment of Chronic Diseases

Withanolides, and in particular extracts from Withania somnifera, have been used for over 3,000 years in traditional Ayurvedic and Unani Indian medical systems as well as within several other Asian countries. Traditionally, the extracts were ascribed a wide range of pharmacologic properties with corresponding medical uses, including adaptogenic, diuretic, anti-inflammatory, sedative/anxiolytic, cytotoxic, antitussive, and immunomodulatory. Since the discovery of the archetype withaferin A in 1965, approximately 900 of these naturally occurring, polyoxygenated steroidal lactones with 28-carbon ergostane skeletons have been discovered across 24 diverse structural types. Subsequently, extensive pharmacologic research has identified multiple mechanisms of action across key inflammatory pathways. In this chapter we identify and describe the major withanolides with anti-inflammatory properties, illustrate their role within essential and supportive inflammatory pathways (including NF-κB, JAK/STAT, AP-1, PPARγ, Hsp90 Nrf2, and HIF-1), and then discuss the clinical application of these withanolides in inflammation-mediated chronic diseases (including arthritis, autoimmune, cancer, neurodegenerative, and neurobehavioral). These naturally derived compounds exhibit remarkable biologic activity across these complex disease processes, while showing minimal adverse effects. As novel compounds and analogs continue to be discovered, characterized, and clinically evaluated, the interest in withanolides as a novel therapeutic only continues to grow.

Identification of molecular descriptors for design of novel Isoalloxazine derivatives as potential Acetylcholinesterase inhibitors against Alzheimer's disease

In Alzheimer's disease (AD), the level of Acetylcholine (ACh) neurotransmitter is reduced. Since Acetylcholinesterase (AChE) cleaves ACh, inhibitors of AChE are very much sought after for AD treatment. The side effects of current inhibitors necessitate development of newer AChE inhibitors. Isoalloxazine derivatives have proved to be promising (AChE) inhibitors. However, their structure-activity relationship studies have not been reported till date. In the present work, various quantitative structure-activity relationship (QSAR) building methods such as multiple linear regression (MLR), partial least squares ,and principal component regression were employed to derive 3D-QSAR models using steric and electrostatic field descriptors. Statistically significant model was obtained using MLR coupled with stepwise selection method having r² = .9405, cross validated r² (q²) = .6683, and a high predictability (pred_r² = .6206 and standard error, pred_r²se = .2491). Steric and electrostatic contribution plot revealed three electrostatic fields E_496, E_386 and E_577 and one steric field S_60 contributing towards biological activity. A ligand-based 3D-pharmacophore model was generated consisting of eight pharmacophore features. Isoalloxazine derivatives were docked against human AChE, which revealed critical residues implicated in hydrogen bonds as well as hydrophobic interactions. The binding modes of docked complexes (AChE_IA1 and AChE_IA14) were validated by molecular dynamics simulation which showed their stable trajectories in terms of root mean square deviation and molecular mechanics/Poisson-Boltzmann surface area binding free energy analysis revealed key residues contributing significantly to overall binding energy. The present study may be useful in the design of more potent Isoalloxazine derivatives as AChE inhibitors.

Pharmacologic overview of Withania somnifera, the Indian Ginseng

Withania somnifera, also called 'Indian ginseng', is an important medicinal plant of the Indian subcontinent. It is widely used, singly or in combination, with other herbs against many ailments in Indian Systems of Medicine since time immemorial. Withania somnifera contains a spectrum of diverse phytochemicals enabling it to have a broad range of biological implications. In preclinical studies, it has shown anti-microbial, anti-inflammatory, anti-tumor, anti-stress, neuroprotective, cardioprotective, and anti-diabetic properties. Additionally, it has demonstrated the ability to reduce reactive oxygen species, modulate mitochondrial function, regulate apoptosis, and reduce inflammation and enhance endothelial function. In view of these pharmacologic properties, W. somnifera is a potential drug candidate to treat various clinical conditions, particularly related to the nervous system. In this review, we summarize the pharmacologic characteristics and discuss the mechanisms of action and potential therapeutic applications of the plant and its active constituents.

Nootropic potential of Ashwagandha leaves: Beyond traditional root extracts

Rapidly increasing aging population and environmental stressors are the two main global concerns of the modern society. These have brought in light rapidly increasing incidence of a variety of pathological conditions including brain tumors, neurodegenerative & neuropsychiatric disorders, and new challenges for their treatment. The overlapping symptoms, complex etiology and lack of full understanding of the brain structure and function to-date further complicate these tasks. On the other hand, several herbal reagents with a long history of their use have been asserted to possess neurodifferentiation, neuroregenerative and neuroprotective potentials, and hence been recommended as supplement to enhance and maintain brain health and function. Although they have been claimed to function by holistic approach resulting in maintaining body homeostasis and brain health, there are not enough laboratory studies in support to these and mechanism(s) of such beneficial activities remain largely undefined. One such herb is Ashwagandha, also called "Queen of Ayurveda" for its popular use in Indian traditional home medicine because of its extensive benefits including anticancer, anti-stress and remedial potential for aging and neurodegenerative pathologies. However, active principles and underlying mechanism(s) of action remain largely unknown. Here we provide a review on the effects of Ashwagandha extracts and active principles, and underlying molecular mechanism(s) for brain pathologies. We highlight our findings on the nootropic potential of Ashwagandha leaves. The effects of Ashwagandha leaf extracts are multidimensional ranging from differentiation of neuroblastoma and glioma cells, reversal of Alzheimer and Parkinson's pathologies, protection against environmental neurotoxins and enhancement of memory.

Identification of potential herbal inhibitor of acetylcholinesterase associated Alzheimer's disorders using molecular docking and molecular dynamics simulation

Cholinesterase inhibitors (ChE-Is) are the standard for the therapy of AD associated disorders and are the only class of approved drugs by the Food and Drug Administration (FDA). Additionally, acetylcholinesterase (AChE) is the target for many Alzheimer's dementia drugs which block the function of AChE but have some side effects. Therefore, in this paper, an attempt was made to elucidate cholinesterase inhibition potential of secondary metabolite from Cannabis plant which has negligible or no side effect. Molecular docking of 500 herbal compounds, against AChE, was performed using Autodock 4.2 as per the standard protocols. Molecular dynamics simulations have also been carried out to check stability of binding complex in water for 1000 ps. Our molecular docking and simulation have predicted high binding affinity of secondary metabolite (C28H34N2O6) to AChE. Further, molecular dynamics simulations for 1000 ps suggest that ligand interaction with the residues Asp72, Tyr70-121-334, and Phe288 of AChE, all of which fall under active site/subsite or binding pocket, might be critical for the inhibitory activity of AChE. This approach might be helpful to understand the selectivity of the given drug molecule in the treatment of Alzheimer's disease. The study provides evidence for consideration of C28H34N2O6 as a valuable small ligand molecule in treatment and prevention of AD associated disorders and further in vitro and in vivo investigations may prove its therapeutic potential.

Inhibition of flavonoids on acetylcholine esterase: binding and structure–activity relationship

Hydroxyl groups on the aromatic rings of flavonoids are favorable for inhibiting AChE, and the hydroxylation increases the affinities for AChE. However, methoxylation may decrease or increase the activities depending on the class of flavonoids.

Nature: a substantial source of auspicious substances with acetylcholinesterase inhibitory action

Acetylcholinesterase (AChE) (EC 3.1.1.7) is an important enzyme that breaks down of acetylcholine in synaptic cleft in neuronal junctions. Inhibition of AChE is associated with treatment of several diseases such as Alzheimer's disease (AD), myasthenia gravis, and glaucoma as well as the mechanisms of insecticide and anthelmintic drugs. Several AChE inhibitors are available in clinical use currently for the treatment of AD; however, none of them has ability, yet, to seize progress of the disease. Consequently, an extensive research has been going on finding new AChE inhibitors. In this sense, natural inhibitors have gained great attention due to their encouraging effects toward AChE. In this review, promising candidate molecules with marked AChE inhibition from both plant and animal sources will be underlined.

De novo assembly, functional annotation and comparative analysis of Withania somnifera leaf and root transcriptomes to identify putative genes involved in the withanolides biosynthesis

Withania somnifera is one of the most valuable medicinal plants used in Ayurvedic and other indigenous medicine systems due to bioactive molecules known as withanolides. As genomic information regarding this plant is very limited, little information is available about biosynthesis of withanolides. To facilitate the basic understanding about the withanolide biosynthesis pathways, we performed transcriptome sequencing for Withania leaf (101L) and root (101R) which specifically synthesize withaferin A and withanolide A, respectively. Pyrosequencing yielded 8,34,068 and 7,21,755 reads which got assembled into 89,548 and 1,14,814 unique sequences from 101L and 101R, respectively. A total of 47,885 (101L) and 54,123 (101R) could be annotated using TAIR10, NR, tomato and potato databases. Gene Ontology and KEGG analyses provided a detailed view of all the enzymes involved in withanolide backbone synthesis. Our analysis identified members of cytochrome P450, glycosyltransferase and methyltransferase gene families with unique presence or differential expression in leaf and root and might be involved in synthesis of tissue-specific withanolides. We also detected simple sequence repeats (SSRs) in transcriptome data for use in future genetic studies. Comprehensive sequence resource developed for Withania, in this study, will help to elucidate biosynthetic pathway for tissue-specific synthesis of secondary plant products in non-model plant organisms as well as will be helpful in developing strategies for enhanced biosynthesis of withanolides through biotechnological approaches.

Traditional Chinese medicine: a promising candidate for the treatment of Alzheimer's disease

Alzheimer’s disease (AD) is an age-related neurodegenerative disorder, characterized clinically by insidious onset of memory and cognition impairment, emergence of psychiatric symptoms and behavioral disorder, and impairment of activities of daily living (ADL). Traditional Chinese medicine (TCM) is practiced in the Chinese health care system for more than 2,000 years. In recent years, scientists have isolated many novel compounds from herbs, some of which improve dementia with fewer side effects than conventional drugs and are regarded as potential anti-AD drugs. In this review, we summarize the latest research progress on TCM showing their possible role of treatment of AD and other demented diseases and possible pharmacological actions.

Blocking protein kinase C signaling pathway: mechanistic insights into the anti-leishmanial activity of prospective herbal drugs from Withania somnifera

BACKGROUND

Leishmaniasis is caused by several species of leishmania protozoan and is one of the major vector-born diseases after malaria and sleeping sickness. Toxicity of available drugs and drug resistance development by protozoa in recent years has made Leishmaniasis cure difficult and challenging. This urges the need to discover new antileishmanial-drug targets and antileishmanial-drug development.

RESULTS

Tertiary structure of leishmanial protein kinase C was predicted and found stable with a RMSD of 5.8Å during MD simulations. Natural compound withaferin A inhibited the predicted protein at its active site with -28.47 kcal/mol binding free energy. Withanone was also found to inhibit LPKC with good binding affinity of -22.57 kcal/mol. Both withaferin A and withanone were found stable within the binding pocket of predicted protein when MD simulations of ligand-bound protein complexes were carried out to examine the consistency of interactions between the two.

CONCLUSIONS

Leishmanial protein kinase C (LPKC) has been identified as a potential target to develop drugs against Leishmaniasis. We modelled and refined the tertiary structure of LPKC using computational methods such as homology modelling and molecular dynamics simulations. This structure of LPKC was used to reveal mode of inhibition of two previous experimentally reported natural compounds from Withania somnifera - withaferin A and withanone.

Homology modeling and docking studies of FabH (β-ketoacyl-ACP synthase III) enzyme involved in type II fatty acid biosynthesis of Chlorella variabilis: a potential algal feedstock for biofuel production

The concept of using microalgae as an alternative renewable source of biofuel has gained much importance in recent years. However, its commercial feasibility is still an area of concern for researchers. Unraveling the fatty acid metabolic pathway and understanding structural features of various key enzymes regulating the process will provide valuable insights to target microalgae for augmented oil content. FabH (β-ketoacyl-acyl carrier protein synthase; KAS III) is a condensing enzyme catalyzing the initial elongation step of type II fatty acid biosynthetic process and acyl carrier protein (ACP) facilitates the shuttling of the fatty acyl intermediates to the active site of the respective enzymes in the pathway. In the present study, a reliable three-dimensional structure of FabH from Chlorella variabilis, an oleaginous green microalga was modeled and subsequently the key residues involved in substrate binding were determined by employing protein-protein docking and molecular dynamics (MD) simulation protocols. The FabH-ACP complex having the lowest docking energy score showed the binding of ACP to the electropositive FabH surface with strong hydrogen bond interactions. The MD simulation results indicated that the substrate-complexed FabH adopted a more stable conformation than the free enzyme. Further, the FabH structure retained its stability throughout the simulation although noticeable displacements were observed in the loop regions. Molecular simulation studies suggested the importance of crucial hydrogen bonding of the conserved Arg(91) of FabH with Glu(53) and Asp(56) of ACP for exhibiting high affinity between the enzyme and substrate. The molecular modeling results are consistent with available experimental results on the flexibility of FabH and the present study provides first in silico insights into the structural and dynamical aspect of catalytic mechanism of FabH, which could be used for further site-specific mutagenic experiments to develop engineered high oil-yielding microalgal strains for biofuel production.