Ferulic Acid Esters and Withanolides: In Search of Withania somnifera GABAA Receptor Modulators

Investigating the Impact of Ashwagandha and Meditation on Stress Induced Obesogenic Eating Behaviours

Obesity has been identified as a rapidly rising pandemic within the developed world, potentially increasing the risks of type 2 diabetes and cardiovascular disease. Various studies have identified a positive association between stress, elevated cortisol levels and obesity. Mechanisms of the stress response lead to hyperpalatable food preference and increased appetite through the activation of the HPA axis, elevated cortisol and the resulting interactions with the dopaminergic system, neuropeptide Y, ghrelin, leptin and insulin. The methodology of this review involved a Systematic Search of the Literature with a Critical Appraisal of papers considering ashwagandha, mediation and mindfulness in relation to mechanisms of the stress response. It incorporated 12 searches yielding 330 hits. A total of 51 studies met the inclusion criteria and were critically appraised with ARRIVE, SIGN50 and Strobe checklists. Data from the 51 studies was extracted, coded into key themes and summarized in a narrative analysis. Thematic analysis identified 4 key themes related to ashwagandha and 2 key themes related to meditation. Results provide an overview of evidence assessing the efficacy of ashwagandha and meditation in relation to weight loss interventions by supporting the stress response and the pathways highlighted. Results of Clinical studies indicate that ashwagandha supports weight loss through reduced stress, cortisol and food cravings. Pre-clinical studies also suggest that ashwagandha possesses the capacity to regulate food intake by improving leptin and insulin sensitivity and reducing addictive behaviors through dopamine regulation. Clinical studies on meditation indicate it may enhance a weight loss protocol by reducing the stress response, cortisol release and blood glucose and improving eating behaviors.

Functional Food Nutrients, Redox Resilience Signaling and Neurosteroids for Brain Health

The interplay between functional food nutrients and neurosteroids has garnered significant attention for its potential to enhance stress resilience in health and/or disease. Several bioactive nutrients, including medicinal herbs, flavonoids, and bioavailable polyphenol-combined nanoparticles, as well as probiotics, vitamin D and omega-3 fatty acids, have been shown to improve blood-brain barrier (BBB) dysfunction, endogenous neurosteroid homeostasis and brain function. These nutrients can inhibit oxidative stress and neuroinflammation, which are linked to the pathogenesis of various neurological disorders. Interestingly, flavonoids exhibit dose-dependent effects, activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway at the physiological/low dose (neurohormesis). This leads to the upregulation of antioxidant phase II genes and proteins such as heme oxygenase-1 (HO-1) and sirtuin-1 (Sirt1), which are activated by curcumin and resveratrol, respectively. These adaptive neuronal response mechanisms help protect against reactive oxygen species (ROS) and neurotoxicity. Impaired Nrf2 and neurosteroid hormone signaling in the brain can exacerbate selective vulnerability to neuroinflammatory conditions, contributing to the onset and progression of neurodegenerative and psychiatric disorders, including Alzheimer's disease, anxiety and depression and other neurological disorders, due to the vulnerability of neurons to stress. This review focuses on functional food nutrients targeting Nrf2 antioxidant pathway and redox resilience genes to regulate the neurosteroid homeostasis and BBB damage associated with altered GABAergic neurotransmission. By exploring the underlying molecular mechanisms using innovative technologies, we aim to develop promising neuroprotective strategies and personalized nutritional and neuroregenerative therapies to prevent or attenuate oxidative stress and neuroinflammation, ultimately promoting brain health.

The benefits of ashwagandha (Withania somnifera) supplements on brain function and sports performance

Ashwagandha or Withania somnifera is an herbal plant belonging to the Solanaceae family. Because of its wide range of phytochemicals, ashwagandha root extract has been used in numerous research studies, either alone or in conjunction with other natural plants, for various biomedical applications, which include its anti-microbial, anti-inflammatory, anti-stress, anti-tumor, cardioprotective, and neuroprotective properties. Additionally, it improves endothelial function, lowers reactive oxygen species, controls apoptosis, and improves mitochondrial function. These properties make it a useful treatment for a variety of conditions, including age-related symptoms, anxiety, neurodegenerative diseases, diabetes, stress, arthritis, fatigue, and cognitive/memory impairment. Despite the numerous benefits of ashwagandha supplementation, there have been just four meta-analyses on the herb's effectiveness in treating anxiety, neurobehavioral disorders, impotence, and infertility. Moreover, no reviews exist that examine how ashwagandha affects antioxidant response and physical sports performance. Consequently, the goal of this study was to analyze the scientific literature regarding the effects of ashwagandha consumption on antioxidant response and athletic performance.

In silico evaluation of pharmacokinetics properties of withanolides and simulation of their biological activities against Alzheimer's disease

The withanolides are naturally occurring steroidal lactones found mainly in plants of the Solanaceae family. The subtribe Withaninae includes species like Withania sominifera, which are a source of many bioactive withanolides. In this work, we selected and evaluate the ADMET-related properties of 91 withanolides found in species of the subtribe Withaninae computationally, to predict the relationship between their structures and their pharmacokinetic profiles. We also evaluated the interaction of these withanolides with known targets of Alzheimer's disease (AD) through molecular docking and molecular dynamics. Withanolides presented favorable pharmacokinetic properties, like high gastrointestinal absorption, lipophilicity (logP ≤ 5), good distribution and excretion parameters, and a favorable toxicity profile. The specie Withania aristata stood out as an interesting source of the promising withanolides classified as 5-ene with 16-ene or 17-ene. These withanolides presented a favourable pharmacokinetic profile and were also highlighted as the best candidates for inhibition of AD-related targets. Our results also suggest that withanolides are likely to act as cholinesterase inhibitors by interacting with the catalytic pocket in an energy favorable and stable way.Communicated by Ramaswamy H. Sarma.

Natural Products for the Treatment of Drug Addiction: Narrative Review

Drug addiction is considered a chronic disorder affecting the individual's life, his/her family and society. Up till now the treatment of drug addiction is considered a problematic issue. Synthetic drugs available for the treatment of drug addiction are few, of limited efficacy and associated with serious side effects. Therefore, there is a continuous search for better therapeutic agents for drug addiction. Natural products represent a promising source for drug addiction treatment. This review summaries drug addiction definition, its mechanism of action, its types, its diagnosis, factors affecting its development and different available approaches for its treatment especially the use of natural products. Six plants were discussed thoroughly in this review, including, Tabernanthe iboga Baill., Mitragyna speciosa Korth., Pueraria montana var. lobata (Willd.) Sanjappa & Pradeep, Hypericum perforatum L., Panax ginseng C.A. Mey., and Withania somnifera (L.) Dunal.

Recent Research Progress: Discovery of Anti-Plant Virus Agents Based on Natural Scaffold

Plant virus diseases, also known as “plant cancers”, cause serious harm to the agriculture of the world and huge economic losses every year. Antiviral agents are one of the most effective ways to control plant virus diseases. Ningnanmycin is currently the most successful anti-plant virus agent, but its field control effect is not ideal due to its instability. In recent years, great progress has been made in the research and development of antiviral agents, the mainstream research direction is to obtain antiviral agents or lead compounds based on structural modification of natural products. However, no antiviral agent has been able to completely inhibit plant viruses. Therefore, the development of highly effective antiviral agents still faces enormous challenges. Therefore, we reviewed the recent research progress of anti-plant virus agents based on natural products in the past decade, and discussed their structure-activity relationship (SAR) and mechanism of action. It is hoped that this review can provide new inspiration for the discovery and mechanism of action of novel antiviral agents.

The Genus Alternanthera: Phytochemical and Ethnopharmacological Perspectives

Ethnopharmacological relevance: The genus Alternanthera (Amaranthaceae) comprises 139 species including 14 species used traditionally for the treatment of various ailments such as hypertension, pain, inflammation, diabetes, cancer, microbial and mental disorders.

Aim of the review: To search research gaps through critical assessment of pharmacological activities not performed to validate traditional claims of various species of Alternanthera. This review will aid natural product researchers in identifying Alternanthera species with therapeutic potential for future investigation.

Materials and methods: Scattered raw data on ethnopharmacological, morphological, phytochemical, pharmacological, toxicological, and clinical studies of various species of the genus Alternanthera have been compiled utilizing search engines like SciFinder, Google Scholar, PubMed, Science Direct, and Open J-Gate for 100 years up to April 2021.

Results: Few species of Alternanthera genus have been exhaustively investigated phytochemically, and about 129 chemical constituents related to different classes such as flavonoids, steroids, saponins, alkaloids, triterpenoids, glycosides, and phenolic compounds have been isolated from 9 species. Anticancer, antioxidant, antibacterial, CNS depressive, antidiabetic, analgesic, anti-inflammatory, and immunomodulator effects have been explored in the twelve species of the genus. A toxicity study has been conducted on 3 species and a clinical study on 2 species.

Conclusions: The available literature on pharmacological studies of Alternanthera species reveals that few species have been selected based on ethnobotanical surveys for scientific validation of their traditional claims. But most of these studies have been conducted on uncharacterized and non-standardized crude extracts. A roadmap of research needs to be developed for the isolation of new bioactive compounds from Alternanthera species, which can emerge out as clinically potential medicines.

Effects of docosanyl ferulate, a constituent of Withania somnifera, on ethanol- and morphine-elicited conditioned place preference and ERK phosphorylation in the accumbens shell of CD1 mice

BACKGROUND

Docosanyl ferulate (DF) is a behaviourally active GABA_A receptor complex (GABA_AR) agonist, recently isolated from the standardized methanolic extract of Withania somnifera Dunal (WSE) root. Previous studies have shown that WSE prevents both ethanol- and morphine-dependent acquisition and expression of conditioned place preference (CPP) and stimulation of dopamine release in the nucleus accumbens shell (AcbSh).

AIMS

The study aimed at determining (a) whether DF contributes to WSE's ability to affect the acquisition and expression of ethanol- and morphine-elicited CPP and, given that phosphorylation of extracellular signal-regulated kinase (pERK) in the AcbSh is involved in associative learning and motivated behaviours, (b) whether WSE and DF may affect ethanol- and morphine-induced ERKs phosphorylation in the AcbSh.

METHODS

In adult male CD1 mice, DF's effects on the acquisition and expression of ethanol- and morphine-elicited CPP were evaluated by a classical place conditioning paradigm, whereas the effects of WSE and DF on ethanol- and morphine-elicited pERK in the AcbSh were evaluated by immunohistochemistry.

RESULTS AND CONCLUSIONS

The study shows that DF, differently from WSE, affects only the acquisition but not the expression of ethanol- and morphine-induced CPP. Moreover, the study shows that both WSE and DF can prevent ethanol- and morphine-elicited pERK expression in the AcbSh. Overall, these results highlight subtle but critical differences for the role of GABA_ARs in the mechanism by which WSE affects these ethanol- and morphine-dependent behavioural and molecular/cellular responses and support the suggestion of WSE and DF for the control of different components of drug addiction.

Natural withanolides, an update

Covering: March 2010 to December 2020. Previous review: Nat. Prod. Rep., 2011, 28, 705This review summarizes the latest progress and perspectives on the structural classification, biological activities and mechanisms, metabolism and pharmacokinetic investigations, biosynthesis, chemical synthesis and structural modifications, as well as future research directions of the promising natural withanolides. The literature from March 2010 to December 2020 is reviewed, and 287 references are cited.

A new diphenylheptanoid from the rhizomes of Curcuma zedoaria

A phytochemical investigation of the rhizomes of Curcuma zedoaria was carried out, leading to the isolation of a new diphenylheptanoid, zedoaroxane A (1), together with four known compounds (2-5). Their structures were elucidated based on NMR spectroscopic data. All isolated compounds possessed α-glucosidase inhibitory activity, with the IC₅₀ values ranging from 35.2 to 89.0 µM, more potent than that of the positive control acarbose (IC₅₀, 214.5 µM).

The biologically active compound of Withania somnifera (L.) Dunal, docosanyl ferulate, is endowed with potent anxiolytic properties but devoid of typical benzodiazepine-like side effects

BACKGROUND

Clinical and experimental studies support the therapeutic potential of Withania somnifera (WS) (L.) Dunal on anxiety disorders. This potential is attributable to components present in different plant extracts; however, the individual compound(s) endowed with specific anxiolytic effects and potential modulatory activity of the GABAA receptor complex (GABAAR) have remained unidentified until the recent isolation from a WS methanolic root extract of some GABAAR-active compounds, including the long alkyl-chain ferulic acid ester, docosanyl ferulate (DF).

AIMS

This study was designed to assess whether DF (0.05, 0.25 and 2 mg/kg), similarly to diazepam (2 mg/kg), may exert anxiolytic effects, whether these effects may be significantly blocked by the benzodiazepine antagonist flumazenil (10 mg/kg) and whether DF may lack some of the benzodiazepines' typical motor, cognitive and motivational side effects.

METHODS

The behavioural paradigms Elevated Plus Maze, Static Rods, Novel Object Recognition, Place Conditioning and potentiation of ethanol-induced Loss of Righting Reflex were applied on male CD-1 mice.

RESULTS

Similarly to diazepam, DF exerts anxiolytic effects that are blocked by flumazenil. Moreover, at the full anxiolytic dose of 2 mg/kg, DF lacks typical benzodiazepine-like side effects on motor and cognitive performances and on place conditioning. Moreover, DF fails to potentiate ethanol's (3 g/kg) depressant activity at the ethanol-induced Loss of Righting Reflex paradigm.

CONCLUSIONS

These data point to DF as an effective benzodiazepine-like anxiolytic compound that, in light of its lack of motor, mnemonic and motivational side effects, could be a suitable candidate for the treatment of anxiety disorders.

Rosmarinic Acid, a Bioactive Phenolic Compound, Inhibits Glutamate Release from Rat Cerebrocortical Synaptosomes through GABAA Receptor Activation

Rosmarinic acid, a major component of rosemary, is a polyphenolic compound with potential neuroprotective effects. Asreducing the synaptic release of glutamate is crucial to achieving neuroprotectant's pharmacotherapeutic effects, the effect of rosmarinic acid on glutamate release was investigated in rat cerebrocortical nerve terminals (synaptosomes). Rosmarinic acid depressed the 4-aminopyridine (4-AP)-induced glutamate release in a concentration-dependent manner. The removal of extracellular calcium and the blockade of vesicular transporters prevented the inhibition of glutamate release by rosmarinic acid. Rosmarinic acid reduced 4-AP-induced intrasynaptosomal Ca2+ elevation. The inhibition of N-, P/Q-type Ca2+ channels and the calcium/calmodulin-dependent kinase II (CaMKII) prevented rosmarinic acid from having effects on glutamate release. Rosmarinic acid also reduced the 4-AP-induced activation of CaMKII and the subsequent phosphorylation of synapsin I, the main presynaptic target of CaMKII. In addition, immunocytochemistry confirmed the presence of GABAA receptors. GABAA receptor agonist and antagonist blocked the inhibitory effect of rosmarinic acid on 4-AP-evoked glutamate release. Docking data also revealed that rosmarinic acid formed a hydrogen bond with the amino acid residues of GABAA receptor. These results suggested that rosmarinic acid activates GABAA receptors in cerebrocortical synaptosomes to decrease Ca2+ influx and CaMKII/synapsin I pathway to inhibit the evoked glutamate release.

Effects of Withania somnifera (Ashwagandha) on Stress and the Stress- Related Neuropsychiatric Disorders Anxiety, Depression, and Insomnia

BACKGROUND

Withania somnifera (WS), also known as Ashwagandha, is commonly used in Ayurveda and other traditional medicine systems. WS has seen an increase in worldwide usage due to its reputation as an adaptogen. This popularity has elicited increased scientific study of its biological effects, including a potential application for neuropsychiatric and neurodegenerative disorders.

OBJECTIVE

This review aims to provide a comprehensive summary of preclinical and clinical studies examining the neuropsychiatric effects of WS, specifically its application in stress, anxiety, depression, and insomnia.

METHODS

Reports of human trials and animal studies of WS were collected primarily from the PubMed, Scopus, and Google Scholar databases.

RESULTS

WS root and leaf extracts exhibited noteworthy anti-stress and anti-anxiety activity in animal and human studies. WS also improved symptoms of depression and insomnia, though fewer studies investigated these applications. WS may alleviate these conditions predominantly through modulation of the hypothalamic-pituitary-adrenal and sympathetic-adrenal-medullary axes, as well as through GABAergic and serotonergic pathways. While some studies link specific withanolide components to its neuropsychiatric benefits, there is evidence for the presence of additional, as yet unidentified, active compounds in WS.

CONCLUSION

While benefits were seen in the reviewed studies, significant variability in the WS extracts examined prevents a consensus on the optimum WS preparation or dosage for treating neuropsychiatric conditions. WS generally appears safe for human use; however, it will be important to investigate potential herb-drug interactions involving WS if used alongside pharmaceutical interventions. Further elucidation of active compounds of WS is also needed.

Withania somnifera L.: Insights into the phytochemical profile, therapeutic potential, clinical trials, and future prospective

Withania somnifera L. is a multipurpose medicinal plant of family Solanaceae occurring abundantly in sub-tropical regions of the world. The folk healers used the plant to treat several diseases such as fever, cancer, asthma, diabetes, ulcer, hepatitis, eyesores, arthritis, heart problems, and hemorrhoids. The plant is famous for the anti-cancerous activity, low back pain treatment, and muscle strengthening, which may be attributed to the withanolide alkaloids. W. somnifera is also rich in numerous valued secondary metabolites such as steroids, alkaloids, flavonoids, phenolics, saponins, and glycosides. A wide range of preclinical trials such as cardioprotective, anticancer, antioxidant, antibacterial, antifungal, anti-inflammatory, hepatoprotective, anti-depressant, and hypoglycemic have been attributed to various parts of the plant. Different parts of the plant have also been evaluated for the clinical trials such as male infertility, obsessive-compulsive disorder, antianxiety, bone and muscle strengthening potential, hypolipidemic, and antidiabetic. This review focuses on folk medicinal uses, phytochemistry, pharmacological, and nutrapharmaceutical potential of the versatile plant.

Inhibition of Morphine- and Ethanol-Mediated Stimulation of Mesolimbic Dopamine Neurons by Withania somnifera

Morphine- and ethanol-induced stimulation of neuronal firing of ventral tegmental area (VTA) dopaminergic neurons and of dopamine (DA) transmission in the shell of the nucleus accumbens (AcbSh) represents a crucial electrophysiological and neurochemical response underlying the ability of these compounds to elicit motivated behaviors and trigger a cascade of plasticity-related biochemical events. Previous studies indicate that the standardized methanolic extract of Withania somnifera roots (WSE) prevents morphine- and ethanol-elicited conditioned place preference and oral ethanol self-administration. Aim of the present research was to investigate whether WSE may also interfere with the ability of morphine and ethanol to stimulate VTA dopaminergic neurons and thus AcbSh DA transmission as assessed in male Sprague-Dawley rats by means of patch-clamp recordings in mesencephalic slices and in vivo brain microdialysis, respectively. Morphine and ethanol significantly stimulated spontaneous firing rate of VTA neurons and DA transmission in the AcbSh. WSE, at concentrations (200-400 μg/ml) that significantly reduce spontaneous neuronal firing of VTA DA neurons via a GABA_A- but not GABA_B-mediated mechanism, suppressed the stimulatory actions of both morphine and ethanol. Moreover, in vivo administration of WSE at a dose (75 mg/kg) that fails to affect basal DA transmission, significantly prevented both morphine- and ethanol-elicited increases of DA in the AcbSh. Overall, these results highlight the ability of WSE to interfere with morphine- and ethanol-mediated central effects and suggest a mechanistic interpretation of the efficacy of this extract to prevent the motivational properties of these compounds.