Natural products and derivatives affecting neurotransmission relevant to Alzheimer's and Parkinson's disease

Novel LC-MS/MS Method for Simultaneous Determination of Monoamine Neurotransmitters and Metabolites in Human Samples

For the simultaneous determination of monoamine neurotransmitters (NTs) like dopamine, serotonin, noradrenaline, and epinephrine, and their metabolites (metanephrine, normetanephrine, 3-methoxytyramine, vanillylmandelic acid, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid), a robust liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) was introduced as the analytical method. This analytical method proved to be accurate for the simultaneous measurement of the amounts of 11 NTs and their metabolites in biological samples. The method proved to be more efficient and better than the previously reported method in terms of precision, recovery, sample requirement, and extraction procedure. The reported method requires only 100 μL of blood and 200 μL of urine, and the extraction procedure requires acetonitrile precipitation, filtration, drying, and reconstitution in water. The separation of all analytes was performed on an C18 column (4.6 mm × 150 mm and 1.8 μm). A 10 min gradient elution program with a mobile phase consisting of phase A (0.2% formic acid in water) and phase B (methanol) was used. The positive ionization mode was used for the detection of all analytes in multiple reaction monitoring (MRM). The proposed method was validated with an internal standard and yielded lower limits of detection and quantification ranges of 0.0182-0.0797 ng/mL and 0.0553-0.2415 ng/mL, respectively, with a good linearity (R2) between 0.9959 and 0.9994. The recoveries ranged from 73.37% to 116.63% in blood and from 80.9% to 115.33% in urine. For the NTs and metabolites, the intra- and interday % CV were 0.24-9.36 and 0.85-9.67, respectively. The developed LC-MS/MS method was successfully used for the determination of trace amounts of endogenous compounds in human blood and urine samples.

Epiberberine induced p53/p21-dependent G2/M cell cycle arrest and cell apoptosis in gastric cancer cells by activating γ-aminobutyric acid receptor- β3

BACKGROUND AND PURPOSE

Epiberberine (EPI) is one of the most important bioalkaloid found in the rhizome of Coptis chinensis, which has been observed to exhibit pharmaceutical effects against gastric cancer (GC). Nevertheless, the potential mechanism of EPI against GC cells still remains unclear. This study aimed to identify the core receptor on GC cells through which EPI inhibited the growth of GC cells and to explore the underlying inhibitory mechanisms.

METHODS

To identify hub receptor targets that respond to EPI treatment, RNA sequencing (RNA-Seq) data from a tumor-bearing mouse model were analyzed using bioinformatics method and molecular docking. The binding interaction between EPI and GABRB3 was validated through western blotting based-cellular thermal shift assay (WB-CETSA). To further verify the binding region between EPI and GABRB3 through circular dichroism (CD) chromatography, fragments of the extracellular and transmembrane domains of the GABRB3 protein were expressed and purified in vitro. Stable cell lines with the overexpression or knockdown of GABRB3 were established using the recombinant lentivirus system. MTT ((3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide)) assay, colony formation assay, invasion and migration experiments, and flow cytometry were conducted to validate the inhibitory effect of EPI on the GC cells via GABRB3. Additionally, western blotting was utilized to explore the potential inhibitory mechanisms.

RESULTS

Through the combination of multiple bioinformatics methods and molecular docking, we found that the γ-aminobutyric acid type A receptor subunit -β3 (GABRB3) might be the critical receptor target in response to EPI treatment. The results of WB-CETSA analysis indicated that EPI significantly promoted the thermostability of the GABRB3 protein. Importantly, EPI could directly bind to GABRB3 and alter the secondary structure of GABRB3 fragments similar to the natural agonist, γ-aminobutyric acid (GABA). The EPI-induced suppression of the malignant phenotype of GC cells was dependent on the presence of GABRB3. GABRB3 expression was positively correlated with TP53 in patients with GC. The binding of EPI to GABRB3 stimulated p53 accumulation in GC cells. This activated the p21/CDK1/cyclinB1 pathway, resulting in G2/M cell cycle arrest, and induced the Bcl-2/BAX/Caspase axis-dependent cell apoptosis.

CONCLUSION

This study revealed the target receptor for EPI in GC cells and provided new insights into its anticancer mechanisms.

Phytomolecules from conventional to nano form: Next-generation approach for Parkinson's disease

The incidence of neurodegenerative diseases is increasing exponentially worldwide. Parkinson's disease (PD) is a neurodegenerative disease caused by factors like oxidative stress, gene mutation, mitochondrial dysfunction, neurotoxins, activation of microglial inflammatory mediators, deposition of Lewy's bodies, and α- synuclein proteins in the neurons leading to neuroinflammation and neurodegeneration in the substantia nigra. Hence the development of efficacious neuro-therapy is in demand which can prevent neurodegeneration and protect the nigrostriatal pathway. One of the approaches for managing PD is reducing oxidative stress due to aging and other co-morbid diseased conditions. The phytomolecules are reported as safe and efficacious antioxidants as they contain different secondary metabolites. However, the limitations of low solubility restricted permeability through the blood-brain barrier, and low bioavailability limits their clinical evaluation and application. This review discusses the therapeutic efficacy of phytomolecules in PD and different nanotechnological approaches to improve their brain permeability.

Computational Studies to Understand the Neuroprotective Mechanism of Action Basil Compounds

Neurodegenerative diseases, such as Alzheimer's and Parkinson's, pose a significant global health challenge, emphasizing the need for novel neuroprotective agents. Basil (Ocimum spp.) has been recognized for its therapeutic potential, and numerous studies have reported neuroprotective effects. In this manuscript, we present a computational protocol to extricate the underlying mechanism of action of basil compounds in neuroprotective effects. Molecular docking-based investigation of the chemical interactions between selected bioactive compounds from basil and key neuroprotective targets, including AChE, GSK3β, γ-secretase, and sirtuin2. Our results demonstrate that basil compound myricerone caffeoyl ester possesses a high affinity of -10.01 and -8.85 kcal/mol against GSK3β and γ-secretase, respectively, indicating their potential in modulating various neurobiological processes. Additionally, molecular dynamics simulations were performed to explore the protein-ligand complexes' stability and to analyze the bound basil compounds' dynamic behavior. This comprehensive computational investigation enlightens the putative mechanistic basis for the neuroprotective effects of basil compounds, providing a rationale for their therapeutic use in neurodegenerative disorders after further experimental validation.

Neuroprotective Effects of Sparassis crispa Ethanol Extract through the AKT/NRF2 and ERK/CREB Pathway in Mouse Hippocampal Cells

Sparassis crispa, known as the "Cauliflower mushroom", is an edible medicinal fungus found in Asia, Europe, and North America. Its fruiting bodies contain active biological and pharmacological ingredients with antitumor and anti-inflammatory properties. In this study, we investigated the neuroprotective effect of various Sparassis crispa extract against glutamate-induced toxicity and oxidative stress in hippocampal HT22 cells. Cell viability and reactive oxygen species (ROS) analyses served to evaluate the neuroprotective effects of Sparassis crispa ethanol extract (SCE) and their fractions partitioned with ethyl acetate (EtOAc; SCE-E) and water (SCE-W) in HT22 cells. SCE and SCE-E treatment reduced glutamate-induced cell death and ROS generation. SCE-E reduced apoptosis and ROS levels by regulating anti-apoptotic proteins. Under glutamate treatment, SCE-E activated nuclear factor erythroid-derived 2-related factor 2 (Nrf2) and regulated extracellular signal-regulated kinase (ERK) and AKT signals at late stages. SCE-E increased the protein expression of cAMP response element binding (CREB), brain-derived neurotrophic factor (BDNF), and Kelch-like ECH-associated protein 1 (Keap1), and decreased the Nrf2 protein expression. Moreover, co-treatment of SCE-E and wortmannin did not activate Nrf2 expression. Thus, the neuroprotective effect of SCE-E is likely due to Nrf2 and CREB activation through AKT and ERK phosphorylation, which effectively suppress glutamate-induced oxidative stress in HT22 cells. Accordingly, a daily supplement of SCE-E could become a potential treatment for oxidative-stress-related neurological diseases.

A proton-inhibited DEG/ENaC ion channel maintains neuronal ionstasis and promotes neuronal survival under stress

The nervous system participates in the initiation and modulation of systemic stress. Ionstasis is of utmost importance for neuronal function. Imbalance in neuronal sodium homeostasis is associated with pathologies of the nervous system. However, the effects of stress on neuronal Na⁺ homeostasis, excitability, and survival remain unclear. We report that the DEG/ENaC family member DEL-4 assembles into a proton-inactivated sodium channel. DEL-4 operates at the neuronal membrane and synapse to modulate Caenorhabditis elegans locomotion. Heat stress and starvation alter DEL-4 expression, which in turn alters the expression and activity of key stress-response transcription factors and triggers appropriate motor adaptations. Similar to heat stress and starvation, DEL-4 deficiency causes hyperpolarization of dopaminergic neurons and affects neurotransmission. Using humanized models of neurodegenerative diseases in C. elegans, we showed that DEL-4 promotes neuronal survival. Our findings provide insights into the molecular mechanisms by which sodium channels promote neuronal function and adaptation under stress.

Stem Cells and Natural Agents in the Management of Neurodegenerative Diseases: A New Approach

Neurodegenerative diseases refer to a group of neurological disorders as a consequence of various destructive illnesses, that predominantly impact neurons in the central nervous system, resulting in impairments in certain brain functions. Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, and other neurodegenerative disorders represent a major risk to human health. In order to optimize structural and functional recovery, reconstructive methods integrate many approaches now, to address the complex and multivariate pathophysiology of neurodegenerative disorders. Stem cells, with their unique property of regeneration, offer new possibilities in regenerative and reconstructive medicine. Concurrently, there is an important role for natural products in controlling many health sufferings and they can delay or even prevent the onset of various diseases. In addition, due to their therapeutic properties, they have been used as neuroprotective agents to treat neurodegenerative disorders. After decades of intensive research, scientists made advances in treating these disorders so far, but current therapies are still not capable of preventing the illnesses from progressing. Therefore, in this review, we focused on a new perspective combining stem cells and natural products as an innovative therapy option in the management of neurodegenerative diseases.

Actaea racemosa L. Rhizome Protect against MPTP-Induced Neurotoxicity in Mice by Modulating Oxidative Stress and Neuroinflammation

Parkinson's disease (PD) is a dopaminergic neuron-related neurodegenerative illness. Treatments exist that alleviate symptoms but have a variety of negative effects. Recent research has revealed that oxidative stress, along with neuroinflammation, is a major factor in the course of this disease. Therefore, the aim of our study was to observe for the first time the effects of a natural compound such as Actaea racemosa L. rhizome in an in vivo model of PD induced by neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). For the study, mice received four injections of MPTP (20 mg/kg) for the induction of PD. Starting 24 h after the first administration of MPTP we treated mice with Actaea racemosa L. rhizome (100 mg/kg) daily for seven days. Our findings clearly demonstrated that Actaea racemosa L. rhizome treatment decreases oxidative stress by activating redox balance enzymes such as Nrf2/HO-1. We also demonstrated that Actaea racemosa L. rhizome is capable of modulating inflammatory indicators involved in PD, such as IκB-α, NF-κB, GFAP and Iba1, thus reducing the degeneration of dopaminergic neurons and motor and non-motor alterations. To summarize, Actaea racemosa L. rhizome, which is subject to fewer regulations than traditional medications, could be used as a dietary supplement to improve patients' brain health and could be a promising nutraceutical choice to slow the course and symptoms of PD.

A comprehensive review on medicinal herbs and novel formulations for the prevention of Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases reported in the aging population across the globe. About 46.8 million people are reported to have dementia, and AD is mainly responsible for dementia in aged people. Alzheimer's disease (AD) is thought to occur due to the accumulation of β-amyloid (Aβ) in the neocortex portion of the brain, nitric oxide mediated dysfunctioning of blood-brain barrier, reduced activity of serine racemase enzyme, cell cycle disturbances, damage of N-methyl-D-aspartate (NMDA) receptors and glutamatergic neurotransmission. Modern treatment methods target the pathways responsible for the disease. To date, solely symptomatic treatments exist for this disease, all making an attempt to counterbalance the neurotransmitter disturbance. Treatments able to prevent or at least effectively modifying the course of AD, referred to as 'disease-modifying' drugs, are still under extensive research. Effective treatments entail a better indulgence of the herbal bioactives by novel drug delivery systems. The herbal bioactive administered by novel drug delivery systems have proved beneficial in treating this disease. This review provides detailed information about the role of medicinal plants and their formulations in treating Alzheimer disease which will be highly beneficial for the researchers working in this area.

The effect of Origanum majorana tea on motor and non-motor symptoms in patients with idiopathic Parkinson's disease: A randomized controlled pilot study

AIMS

The effect of Origanum majorana tea consumption on motor and non-motor symptoms was investigated in patients with idiopathic Parkinson's disease, measured by validated tools.

METHODS

Sixty patients with idiopathic Parkinson's disease and under conventional medication were enrolled voluntarily in the study. All participants were randomized on double-blind to placebo or Origanum majorana. Clinical assessment with validated tools (UPDRSIII, NMSS, and BDI) was done before Origanum majorana or placebo consumption (Day 0) and at the end of the experiment (Day 30).

RESULTS

The treatment groups were similar at baseline on demographic and clinical variables. During the course of study, nine participants withdrew for reasons of noncompliance and inability to follow-up. Fifty-one participants completed the study. Upon completion of 30 days of treatment, Origanum majorana tea consumption did not decrease the UPDRSIII score ([UPDRSIII^] D0 = 18.76 ± 8.58, D30 = 16.52 ± 7.96, p = 0.069) at the p value was 0.07. However, a statistically significant improvement was noted in NMSS and BDI scores (p < 0.0001 and p < 0.0001, respectively). Assessment of the UPDRSIII, NMSS and BDI scores of the patients did not reflect any improvement with placebo. No side effect was detected during the study^. CONCLUSION: These findings show improvement of depressive and non-motor signs in patients with Parkinson's disease in the group that consumed Origanum majorana tea in combination with conventional therapy. Improvement of motor signs may need an extended treatment period. However, more research with a large number of participants and lasting longer than 1 month is needed to argue these findings.

Natural Alkaloid Compounds as Inhibitors for Alpha-Synuclein Seeded Fibril Formation and Toxicity

The accumulation and aggregation of α-synuclein (α-syn) is the main pathologic event in Parkinson’s disease (PD), dementia with Lewy bodies, and multiple system atrophy. α-Syn-seeded fibril formation and its induced toxicity occupy a major role in PD pathogenesis. Thus, assessing compounds that inhibit this seeding process is considered a key towards the therapeutics of synucleinopathies. Using biophysical and biochemical techniques and seeding-dependent cell viability assays, we screened a total of nine natural compounds of alkaloid origin extracted from Chinese medicinal herbs. Of these compounds, synephrine, trigonelline, cytisine, harmine, koumine, peimisine, and hupehenine exhibited in vitro inhibition of α-syn-seeded fibril formation. Furthermore, using cell viability assays, six of these compounds inhibited α-syn-seeding-dependent toxicity. These six potent inhibitors of amyloid fibril formation and toxicity caused by the seeding process represent a promising therapeutic strategy for the treatment of PD and other synucleinopathies.

Role of Withaferin A and Its Derivatives in the Management of Alzheimer's Disease: Recent Trends and Future Perspectives

Globally, Alzheimer's disease (AD) is one of the most prevalent age-related neurodegenerative disorders associated with cognitive decline and memory deficits due to beta-amyloid deposition (Aβ) and tau protein hyperphosphorylation. To date, approximately 47 million people worldwide have AD. This figure will rise to an estimated 75.6 million by 2030 and 135.5 million by 2050. According to the literature, the efficacy of conventional medications for AD is statistically substantial, but clinical relevance is restricted to disease slowing rather than reversal. Withaferin A (WA) is a steroidal lactone glycowithanolides, a secondary metabolite with comprehensive biological effects. Biosynthetically, it is derived from Withania somnifera (Ashwagandha) and Acnistus breviflorus (Gallinero) through the mevalonate and non-mevalonate pathways. Mounting evidence shows that WA possesses inhibitory activities against developing a pathological marker of Alzheimer's diseases. Several cellular and animal models' particulates to AD have been conducted to assess the underlying protective effect of WA. In AD, the neuroprotective potential of WA is mediated by reduction of beta-amyloid plaque aggregation, tau protein accumulation, regulation of heat shock proteins, and inhibition of oxidative and inflammatory constituents. Despite the various preclinical studies on WA's therapeutic potentiality, less is known regarding its definite efficacy in humans for AD. Accordingly, the present study focuses on the biosynthesis of WA, the epidemiology and pathophysiology of AD, and finally the therapeutic potential of WA for the treatment and prevention of AD, highlighting the research and augmentation of new therapeutic approaches. Further clinical trials are necessary for evaluating the safety profile and confirming WA's neuroprotective potency against AD.

Herbal Resources to Combat a Progressive & Degenerative Nervous System Disorder- Parkinson's Disease

Parkinson's disease is one of the most common adult-onset, a chronic disorder involving neurodegeneration, which progressively leads to deprivation of dopaminergic neurons in substantia nigra, causing a subsequent reduction of dopamine levels in the striatum resulting in tremor, myotonia, and dyskinesia. Genetics and environmental factors are believed to be responsible for the onset of Parkinson's disease. The exact pathogenesis of Parkinson's disease is quite complicated and the present anti-Parkinson's disease treatments appear to be clinically insufficient. Comprehensive researches have demonstrated the use of natural products such as ginseng, curcumin, ashwagandha, baicalein, etc. for the symptomatic treatment of this disease. The neuroprotective effects exhibited by these natural products are mainly due to their ability to increase dopamine levels in the striatum, manage oxidative stress, mitochondrial dysfunction, glutathione levels, clear the aggregation of α- synuclein, induce autophagy and decrease the pro-inflammatory cytokines and lipid peroxidation. This paper reviews various natural product studies conducted by scientists to establish the role of natural products (both metabolite extracts as well as pure metabolites) as adjunctive neuroprotective agents.

Current Quest in Natural Bioactive Compounds for Alzheimer's Disease: Multi-Targeted-Designed-Ligand Based Approach with Preclinical and Clinical Based Evidence

Alzheimer's disease is a common and most chronic neurological disorder (NDs) associated with cognitive dysfunction. Pathologically, Alzheimer's disease (AD) is characterized by the presence of β-amyloid (Aβ) plaques, hyper-phosphorylated tau proteins, and neurofibrillary tangles, however, persistence oxidative-nitrative stress, endoplasmic reticulum stress, mitochondrial dysfunction, inflammatory cytokines, pro-apoptotic proteins along with altered neurotransmitters level are common etiological attributes in its pathogenesis. Rivastigmine, memantine, galantamine, and donepezil are FDA approved drugs for symptomatic management of AD, whereas tacrine has been withdrawn because of hepatotoxic profile. These approved drugs only exert symptomatic relief and exhibit poor patient compliance. In the current scenario, the number of published evidence shows the neuroprotective potential of naturally occurring bioactive molecules via their antioxidant, anti-inflammatory, antiapoptotic and neurotransmitter modulatory properties. Despite their potent therapeutic implications, concerns have arisen in context to their efficacy and probable clinical outcome. Thus, to overcome these glitches, many heterocyclic and cyclic hydrocarbon compounds inspired by natural sources have been synthesized and showed improved therapeutic activity. Computational studies (molecular docking) have been used to predict the binding affinity of these natural bioactive as well as synthetic compounds derived from natural sources for the acetylcholine esterase, α/β secretase Nuclear Factor kappa- light-chain-enhancer of activated B cells (NF-kB), Nuclear factor erythroid 2-related factor 2(Nrf2) and other neurological targets. Thus, in this review, we have discussed the molecular etiology of AD, focused on the pharmacotherapeutics of natural products, chemical and pharmacological aspects and multi-targeted designed ligands (MTDLs) of synthetic and semisynthetic molecules derived from the natural sources along with some important on-going clinical trials.

Protection by rhynchophylline against MPTP/MPP+-induced neurotoxicity via regulating PI3K/Akt pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Isolated from Uncaria rhynchophylla (U. rhynchophylla), rhynchophylline (Rhy) has been applied for treating diseases related to central nervous system such as Parkinson's disease. Nevertheless, the molecular mechanism of the neuroprotective effect has not been well interpreted.

AIM OF THE STUDY

To investigate the effects of Rhy on MPTP/MPP + -induced neurotoxicity in C57BL/6 mice or PC12 cells and study the mechanisms involved.

MATERIALS AND METHODS

The neuroprotective effect of Rhy on MPTP-induced neurotoxicity was evaluated by spontaneous motor activity test, as well as a test of rota-rod on a rat model of Parkinson's disease. The numbers of TH-positive neurons in the substantia nigra pars compacta (SNpc) was assessed by immunohistological. CCK-8, lactate dehydrogenase (LDH), reactive oxygen species (ROS), the concentration of intracellular calcium ([Ca²⁺]i) and flow cytometry analysis were performed to evaluate the pharmacological property of Rhy on 1-methyl-4-phenylpyridinium (MPP⁺) induced neurotoxicity in PC12 cells. Besides, LY294002, a PI3K inhibitor was employed to determine the underlying molecular signaling pathway revealing the effect of Rhy by western-blot analysis.

RESULTS

The results showed that Rhy exhibited a protective effect against the MPTP-induced decrease in tyrosine hydroxylase (TH)-positive fibers in the substantia nigra at 30 mg/kg, demonstrated by the immunohistological and behavioral outcomes. Furthermore, it has been indicated that cell viability was improved and the MPP⁺-induced apoptosis was inhibited after the treatment of Rhy at 20 μM, which were severally analyzed by the CCK-8 and the Annexin V/propidium iodide staining method. In addition, Rhy treatment attenuated MPP⁺-induced up-regulation of LDH, ([Ca²⁺]i), and the levels of ROS. Besides, it can be revealed from the Western blot assay that LY294002, as a selective Phosphatidylinositol 3-Kinase (PI3K) inhibitor, effectively inhibited the Akt phosphorylation caused by Rhy, which suggested that Rhy showed its protective property through the activated the PI3K/Akt signaling pathway. Moreover, the Rhy-induced decreases of Bax and caspase-3 as the proapoptotic markers and the increase of Bcl-2 as the antiapoptotic marker, were blocked by LY294002 in the MPP⁺-treated PC12 cells.

CONCLUSIONS

Rhy exerts a neuroprotective effect is partly mediated by activating the PI3K/Akt signaling pathway.

Nicotiflorin attenuates cell apoptosis in renal ischemia-reperfusion injury through activating transcription factor 3

INTRODUCTION

Nicotiflorin is the main characteristic component of Nymphaea candida, which is a natural product that reportedly ameliorates acute injury of the liver and cerebral cortex, but the effect of nicotiflorin on acute kidney injury (AKI) remains unknown. This study aimed to investigate the effects of nicotiflorin on ischaemia/reperfusion (I/R) AKI and the associated mechanisms.

METHODS

We performed both (a) in vivo experiments with C57BL/6 mice with bilateral renal pedicles clamped for 45 minutes and (b) in vitro experiments with human kidney epithelial cells (HK-2) exposed to hypoxia/reoxygenation to mimic I/R injury to study the role of nicotiflorin in AKI.

RESULTS

In vivo, nicotiflorin administration exerted protective effects on renal injury, as demonstrated by reductions in the levels of caspase3 and Bad (P < .05), the upregulation of Bcl-2 expression (P < .05) and improved renal histologic changes, which suggested that nicotiflorin can alleviate I/R injury and cell apoptosis. In vitro, nicotiflorin at a concentration of 75 μg/mL protected cells from hypoxia, which further confirmed that nicotiflorin exerts beneficial effects on hypoxia/reoxygenation. Through computational molecular docking, we found that activating transcription factor 3 (ATF3) exhibits a robust interaction with nicotiflorin with a simulated binding energy of -9.2°. We verified the interaction of nicotiflorin with ATF3 in HK-2 cells, and found that nicotiflorin reduced the apoptosis of HK-2 through ATF3.

CONCLUSION

Based on the above-described results, nicotiflorin appears to have a beneficial impact on deteriorated renal function, as demonstrated using an experimental I/R model. The underlying mechanisms of nicotiflorin might inhibit HK-2 cell apoptosis through ATF3.

Alkaloids extracted from Uncaria rhynchophylla demonstrate neuroprotective effects in MPTP-induced experimental parkinsonism by regulating the PI3K/Akt/mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Alkaloids isolated from Uncaria rhynchophylla (Miq.) Miq. ex Havil. (Rubiaceae), alkaloids (URA) have been used to treat diseases related to the central nervous system, such as Parkinson's disease. Nevertheless, the potential mechanisms underlying their neuroprotective effects are not well-understood.

AIM OF THE STUDY

We investigated the neuroprotective effects of URAs in a mouse model of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) and the possible involvement of a molecular signaling pathway.

MATERIALS AND METHODS

Two typical experiments for animal behavior despair, the spontaneous motor activity and the rotarod experiments, were employed to evaluate the efficacy of URAs in mice with PD symptoms. Dopamine (DA) neurons and their metabolism were evaluated using high-performance liquid chromatography-tandem mass spectrometry. The mechanism of action of the alkaloids was investigated by analyzing their effects on the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway using western blotting.

RESULTS

URA treatment effectively improved the behaviors of the mice during the "spontaneous motor activity and latency to fall off the rotarod test". Moreover, URAs demonstrated a protective role in dopaminergic neurons by increasing the expression of the dopamine transporter and tyrosine hydroxylase, which were supposed to be reduced by MPTP, inhibiting dopamine turnover, and changing dopamine and relevant metabolites. In addition to its association with the increase in the Bcl-2/Bad ratio, URA treatment also attenuated the cleaved caspase-3 level and enhanced the phosphorylation of Akt and mTOR.

CONCLUSION

These findings provide evidence that URA can effectively protect neurons from the neurotoxicity caused by MPTP in mouse models of PD by up-regulating the PI3K/Akt/mTOR signaling pathway.

Evaluation of Cholinesterase Inhibitory Potential of Different Genotypes of Ziziphus nummularia, Their HPLC-UV, and Molecular Docking Analysis

Ziziphus nummularia is an important source of valuable phytoconstituents, which are widely used in traditional medicine system of Indo-Pak sub-continent. In this study we investigated the distribution of phenolic compounds in the fruit pericarps of six different genotypes (ZNP01-06) of Z. nummularia growing in the unexplored hilly areas of Pakistan. The methanolic extracts of these genotypes were screened for total phenolic content (TPC), total flavonoid content (TFC), antioxidant, and cholinesterase inhibitory potentials. The observed biological potentials were explained in terms of the outcome of molecular docking and HPLC analyses. Among them, genotype ZNP02 displayed high TPC (88.50 ± 1.23 μg/mL) and showed potent scavenging activity against DPPH (67.03 ± 1.04 μg/mL) and ABTS (65.3 ± 1.74 μg/mL) in comparison to ascorbic acid (68.7 ± 0.47 μg/mL). Moreover, genotypes ZNP01, ZNP02, and ZNP04 displayed potent inhibition against acetyl and butyryl cholinesterases (AChE and BChE) with IC50 values of 21.2, 20.5, and 23.7 μg/mL (AChE) and 22.7, 24.4, and 33.1 μg/mL (BChE), respectively. Furthermore, the individual compounds in the most potent species ZNP01 responsible for potent enzyme inhibition (identified through HPLC-UV analysis), were computed via docking simulation software to the enzyme structures. Among these compounds rutin exhibited significant binding affinity with value of -9.20 kcal/mol. The differences amongst the phytochemical compositions of the selected genotypes highlighted the genotypic variations in them. Based on our results it was concluded that the selected plant can be used as remedy of oxidative stress and neurodegenerative diseases. However, further studies are needed to isolate responsible compounds and test the observed potential in vivo, along with toxicological evaluations in animal models.

In vitro Acetylcholinesterase inhibitory activity of polyphenolic compounds identified from Matricaria recutita

Acetylcholinesterase (AChE) is a key enzyme enhancing the cognitive disorder, leading to Alzheimer’s disease, and AChE inhibition is a crucial therapeutic mechanism against it. Matricaria recutita (MR) is widely used as a herbal medicine due to its phytotherapeutic properties. For this reason, MR flower was evaluated to identify polyphenolic compounds (PC), and then each PC is examined for AChE inhibitory activity. The ultra-performance liquid chromatography-electrospray tandem mass spectrometry UPLC-ESI-MS/MS was used to detect PC, and molecular docking was performed to insight potential inhibitory activity of PC against AChE. A series of 13 PC compounds were identified in the fractions of MR plant. Docking studies revealed that the inhibitory free energy and the position of the docked compounds in the active site are favored for the active compounds complex formed between AChE and the identified PC compounds. The accurate analysis of the docking result demonstrates that Kaempferol-3-O-rutinoside (KR) and Luteolin-8-C-glucoside (orientin) (LG) are the most significant inhibitory compounds against AChE. It can be concluded that MR is a significant source of PC compounds, and KR and LG are the most promising compounds that have high-affinity binding to AChE, based on docking outcome. Further experiments are recommended to explore in vivo enzyme compound interaction and toxicity models to establish the maximum suggested dose.

Phenolic lipids as unique bioactive compounds: a comprehensive review on their multifunctional activity toward the prevention of Alzheimer's disease

Phenolic lipids are multifunctional compounds which play an important biological role in the body. Their unique biologic functionality stems from their strong amphiphilic character which allows them to be incorporated in erythrocytes. Through membrane incorporation, these compounds exert their biological effects on neurons which are not modulated by hydrophilic compounds. These bioactive compounds are present in nature as secondary plant metabolites, and consequently their availability is limited, for dietary and medical purposes. In this review, the pathways and mechanisms associated with the pathogenesis of Alzheimer's disease will be described. In addition, the modulatory effects of phenolic lipids on these pathways and a list of several synthetic, semi synthetic and natural sources of phenolic lipids will be examined as having the potential to prevent or combat Alzheimer's disease.

An Upcoming Approach to Alzheimer's Disease: Ethnopharmacological Potential of Plant Bioactive Molecules

BACKGROUND

Neurodegenerative disorders have achieved epidemic levels in the last decades; not only the elderly but also adult individuals have been increasingly affected. Among them, Alzheimer's disease is one of the most prevalent and crippling diseases, associated with high rates of multi-morbidities and dependency. Despite the existence of a wide variety of drugs used as the symptomatic treatment, they have some side effects and toxicity, apart from their limited effectiveness. Botanical preparations have a secular use, being widely recommended for a multitude of purposes, such as for the improvement of brain health.

OBJECTIVE

The aim of the present report is to systematize the knowledge on plant-food derived bioactive molecules with promising in vitro enzymatic inhibitory activities.

RESULTS

Alkaloids, phenolic compounds and terpenes are the most studied phytochemicals, both derived from natural and commercial sources. In spite of their efficient activity as enzymatic inhibitors, the number of in vivo studies and even clinical trials have confirmed that their real bioactive potential remains scarce.

CONCLUSION

Thus, it is of the utmost importance to deepen knowledge in this area, once those relevant and informative tools can significantly contribute to the promising advances in the field of Alzheimer's disease treatment.

Solanum vegetable-based diets improve impairments in memory, redox imbalance, and altered critical enzyme activities in Drosophila melanogaster model of neurodegeneration

The effects of two Solanum vegetables, S. macrocarpon L. (African eggplant), and S. nigrum L. (black nightshade) on aluminum model of neurodegeneration in Drosophila melanogaster was investigated. Flies were treated with AlCl₃ alone or in combination with the leaves from both samples in their diets for 7 days. Thereafter, locomotor performance and aversive phototaxic suppression test for learning and memory were carried out. This was followed by assay for reactive oxygen species, antioxidant properties, and enzyme (monoamine oxidase and cholinesterase) activities. Also, the in vitro antioxidant properties and chromatographic phenolic and alkaloid characterization of the samples were determined. Results showed that impaired behavioral physiology, antioxidant status, and enzyme activities observed in Al-treated flies were ameliorated in flies treated with both samples. In addition, both samples exhibited in vitro antioxidant effects. The protective effects from these samples against Al-induced toxicity can be associated with their antioxidant, antimonoaminergic, and anticholinergic properties. PRACTICAL APPLICATIONS: In the quest for a holistic prevention/management approach to neurodegenerative diseases, functional foods are becoming prominent. The use of Drosophila melanogaster to study human diseases is gaining huge recognition due to the high homologue between disease-causing genes between the two organisms. Consequently, this study presents African eggplant and black nightshade leafy vegetables as sources of polyphenols and alkaloids which are able to ameliorate impaired learning and memory, redox status, and enzyme activities in Al-induced D. melanogaster model of neurodegeneration.

Stress-Induced Neurodegeneration: The Potential for Coping as Neuroprotective Therapy

Stress responses are essential for survival, but become detrimental to health and cognition with chronic activation. Chronic hypothalamic-pituitary-adrenal axis release of glucocorticoids induces hypothalamic-pituitary-adrenal axis dysfunction and neuronal loss, decreases learning and memory, and modifies glucocorticoid receptor/mineralocorticoid receptor expression. Elderly who report increased stress are nearly 3 times more likely to develop Alzheimer's disease, have decreased global cognition and faster cognitive decline than those reporting no stress. Patients with mild cognitive impairment are more sensitive to stress compared to healthy elderly and those with Alzheimer's disease. Stress may also transduce neurodegeneration via the gut microbiome. Coping styles determine hippocampal mineralocorticoid receptor expression in mice, indicating that coping modifies cortisol's effect on the brain. Identifying neuroprotective coping strategies that lessen the burden of stress may prevent or slow cognitive decline. Treatments and education designed to reduce stress should be recognized as neuroprotective.

An In Vitro and In Vivo Cholinesterase Inhibitory Activity of Pistacia khinjuk and Allium sativum Essential Oils

Objectives

Alzheimer’s disease (AD), an overwhelming neurodegenerative disease, has deleterious effects on the brain that consequently causes memory loss and language impairment. This study was intended to investigate the neuroprotective activity of the two essential oils (EOs) from Iranian Pistacia khinjuk (PK) leaves and Allium sativum (AS) cloves against β-Amyloid 25–35 (Aβ25-35) induced elevation of cholinesterase enzymes in AD.

Methods

The EOs of PK (PKEO) and AS (ASEO) were prepared and analyzed in terms of extraction yield, phenolic content, and cholinergic markers in vitro. Moreover, both were administered orally to adult male Wistar rats at concentrations of 1, 2, and 3%. The inhibitory potential of PKEO and ASEO was compared with Donepezil (0.75 mg/kg) against the high activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes.

Results

PKEO reached an inhibition rate of 83.6% and 81.4% against AChE and BChE, respectively. ASEO had lower anti-cholinesterase activity (65.4% and 31.5% for the inhibition AChE and BChE). PKEO was found to have more phenolic content than ASEO. A significantly positive correlation was observed between the total phenolics and anti-cholinesterase potential. In rats, both EOs decreased the enzyme activity in a concentration-dependent manner. As compared with Donepezil, the significant difference in the AChE and BChE inhibition occurred as rats were treated with PKEO 3% (p < 0.05).

Conclusion

It could be concluded that PKEO and ASEO are potent inhibitors of AChE and BChE in rats that hold promise to be used for the treatment of AD.

Total glucosides of paeony (TGP) extracted from Radix Paeoniae Alba exerts neuroprotective effects in MPTP-induced experimental parkinsonism by regulating the cAMP/PKA/CREB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The totally-amounted glucosides of paeony (TGP), which are made up of paeoniflorin, albiflorin, oxypaeoniflorin as well as benzoylpaeoniflorin, constitute the Baishao' actively-working component extracted from Radix Paeonia alba employed in conventional oriental medicine aiming to treat cerebrovascular disorders, such as Parkinson's disease. However, its pharmacologic mechanism is not clear.

AIM OF THE STUDY

The initial investigation was made on TGP's neuroprotective effects on PD of the mouse model based on 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) as well as the identification of potential involvement of a molecular signaling pathway.

MATERIALS AND METHODS

The evaluation of the behavioral damage as well as neurotoxicity in mice was made through MPTP. Spontaneous motor activity test, as well as a test of Rota-rod on mice was employed for the measurement of bradykinesia symptom. Additionally, liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) works as the determiner of the main monoamine neurotransmitters dopamine (DA) along with its metabolites 3, 4-dihydroxyphenylacetic acid (DOPAC) as well as homovanillic acid (HVA) based on mouse hippocampus connected with the anti-Parkinson's disease like effect of TGP. Besides, the measurement of the effects of TGP treatment on the expressions level of TH, DAT, a-synuclein, p-CREBS¹³³ as well as apoptosis influence was made with the help of western-blot assay with apoptosis-related markers such as Bax and Bcl-2.

RESULTS

The results showed that TGP treatment lessened the behavior-based loss shown "in the spontaneous motor activity as well as the potential of falling to rotarod test". In addition, we found that pretreatment with TGP markedly improved motor coordination, striatal dopamine and its metabolite levels. Furthermore, pretreatment of TGP conducted the protection for dopaminergic neurons with the prevented MPTP-induced reductions within the tyrosine hydroxylase (TH), substantia nigra dopaminergic transporter (DAT), as well as increasing α-synuclein protein levels with transformed dopamine catabolism as well as inhibited dopamine turnover. Besides, TGP treatment helped reversed apoptosis signaling molecules Bcl-2/Bax' reduction; meanwhile improving p-CREBS¹³³ the factor of growth signaling in the substantia nigra' decrease.

CONCLUSION

These results suggested that TGP can enhance dopaminergic neuron's cell survival in the SNpc in virtue of the activated cAMP/PKA/CREB factor of growth on inhibiting the pathway of second messenger apoptosis as well. In conclusion, the current findings indicate TGP is expected to be a new cure for PD.

Neuroprotective effects of myristargenol A against glutamate-induced apoptotic HT22 cell death

Glutamate is an important neurotransmitter in the central nervous system; however, at high concentrations, it causes excitotoxicity and many neurological disorders. Excitotoxicity induces cell death by apoptosis. Thus, factors that can inhibit the apoptotic pathways are a target of drug development for the treatment and prevention of neurodegenerative diseases. Herein, the antioxidative and neuroprotective effects of myristargenol A were examined in glutamate-induced mouse hippocampal neuronal HT22 cells. When the HT22 cells were stressed with glutamate, cell viability decreased to 44.4 ± 5.6% when compared with the case of the control cells (100 ± 4.8%); however, when these cells were treated with myristargenol A (10 μM), the cell viability was increased by 113.6 ± 2.3%. The protective effect of myristargenol A against the apoptosis of glutamate-induced HT22 cells was also confirmed using FITC-annexin V/propidium iodide double staining. In addition, myristargenol A protected the mitochondrial membrane potential (ΔΨ m). Subsequently, the expression levels of proteins in the caspase pathway related with the induction of apoptosis were decreased. Moreover, the expression levels of mitochondrial-related proteins, such as Bcl-2 and Bax, were examined, and it was found that the expression ratio of Bax/Bcl-2 decreased. In addition, myristargenol A inhibited the activity of mitogen-activated protein kinases, including p38 and c-Jun N-terminal kinase, for an oxidative stress protection effect but increased the activity of the extracellular signal-regulated kinases 1 and 2 for cell proliferation. These results reveal that myristargenol A possesses a neuroprotective effect against the neuronal cell damage caused by glutamate.

Effects of MDMA on neuroplasticity, amyloid burden and phospho-tau expression in APPswe/PS1dE9 mice

BACKGROUND

3,4-Methylenedioxymethamphetamine (MDMA) is still one of the most consumed drugs by adolescents. Its abuse is related with cognitive impairment, which seems due to maladaptive plasticity and neural stress. In turn, new hypotheses suggest that Alzheimer's disease (AD) may be promoted by neural stressors.

AIMS AND METHODS

To test if there is an increase in vulnerability to AD after chronic MDMA consumption, we investigated the effects of this drug on recognition memory and its neurotoxic and neuroplastic effects in a transgenic mouse model of presymptomatic familiar AD (APP/PS1 dE9, Tg).

RESULTS

MDMA-treated animals showed recognition memory deficits, regardless of genotype, which were accompanied by changes in plasticity markers. Tg mice showed an impaired expression of Arc compared with wild-type animals, but exposure to MDMA induced an increase in the expression of this factor of the same percentage in both genotypes. However, the expression of c-fos, BDNF and p-CREB was not significantly altered by MDMA treatment in Tg mice. Although Tg mice had higher free choline levels than wild-type mice (about 123%), MDMA did not modify these levels in any case, ruling out any specific effect of this drug on the acetylcholine pathway. MDMA treatment significantly increased the presence of cortical amyloid plaques, as well as Aβ40, Aβ42 and secreted APPβ levels in Tg mice. These plaques were accompanied by increased tau phosphorylation (S199), which does not seem to occur via the canonic pathway involving AKT, CDK5 or GSK3β.

CONCLUSIONS

The present results support previous evidences that MDMA can contribute to the amyloid cascade.

Comprehensive review on the interaction between natural compounds and brain receptors: Benefits and toxicity

Given their therapeutic activity, natural products have been used in traditional medicines throughout the centuries. The growing interest of the scientific community in phytopharmaceuticals, and more recently in marine products, has resulted in a significant number of research efforts towards understanding their effect in the treatment of neurodegenerative diseases, such as Alzheimer's (AD), Parkinson (PD) and Huntington (HD). Several studies have shown that many of the primary and secondary metabolites of plants, marine organisms and others, have high affinities for various brain receptors and may play a crucial role in the treatment of diseases affecting the central nervous system (CNS) in mammalians. Actually, such compounds may act on the brain receptors either by agonism, antagonism, allosteric modulation or other type of activity aimed at enhancing a certain effect. The current manuscript comprehensively reviews the state of the art on the interactions between natural compounds and brain receptors. This information is of foremost importance when it is intended to investigate and develop cutting-edge drugs, more effective and with alternative mechanisms of action to the conventional drugs presently used for the treatment of neurodegenerative diseases. Thus, we reviewed the effect of 173 natural products on neurotransmitter receptors, diabetes related receptors, neurotrophic factor related receptors, immune system related receptors, oxidative stress related receptors, transcription factors regulating gene expression related receptors and blood-brain barrier receptors.

Natural cholinesterase inhibitors from marine organisms

Covering: Published between 1974 up to 2018Inhibition of cholinesterases is a common approach for the management of several disease states. Most notably, cholinesterase inhibitors are used to alleviate the symptoms of neurological disorders like dementia and Alzheimer's disease and treat myasthenia gravis and glaucoma. Historically, most drugs of natural origin have been isolated from terrestrial sources and inhibitors of cholinesterases are no exception. However, the last 50 years have seen a rise in the quantity of marine natural products with close to 25 000 reported in the scientific literature. A number of marine natural products with potent cholinesterase inhibitory properties have also been reported; isolated from a variety of marine sources from algae to ascidians. Representing a diverse range of structural classes, these compounds provide inspirational leads that could aid the development of therapeutics. The current paper aims to, for the first time, comprehensively summarize the literature pertaining to cholinesterase inhibitors derived from marine sources, including the first papers published in 1974 up to 2018. The review does not report bioactive extracts, only isolated compounds, and a specific focus lies on compounds with reported dose-response data. In vivo and mechanistic data is included for compounds where this is reported. In total 185 marine cholinesterase inhibitors and selected analogs have been identified and reported and some of the compounds display inhibitory activities comparable or superior to cholinesterase inhibitors in clinical use.

Ulmosides A: Flavonoid 6-C-glycosides from Ulmus wallichiana attenuates lipopolysacchride induced oxidative stress, apoptosis and neuronal death

Extract of Ulmus wallichiana is being used as traditional medicine used for the treatment of fractured bones however the effect of its individual flavonols is not known. The present study was conducted to investigate the effect of its novel flavonol, (2S, 3S)-(+)-30, 40, 5, 7-tetrahydroxydihydroflavonol-6-C-b-d-glucopyranoside named as Ulmoside A (UA), on lipopolysaccharides (LPS) treated neurons. LPS treatment to neuronal cells caused significant cytotoxicity, reactive oxygen species generation, depletion in glutathione and mitochondrial impairment which were significantly inhibited with UA treatment. LPS treatment also caused significant translocation of cytochrome-c, decreased level of Bcl2, increased level of Bax and cleaved caspase-3 in neuronal cells reflecting the involvement of intrinsic apoptotic pathway in neuronal death which was attenuated with UA treatment. Since LPS is a well known pro-inflammatory agent it also offered the significant increase in proinflammatory cytokines (tumor necrosis factors-α & interleukin 1-beta) however, UA treatment did not exhibit significant inhibition against LPS induced inflammatory response. LPS also caused the augmented level of inducible nitric oxide synthase (iNOS) which was also not inhibited with co treatment of UA. We have also observed the significant DNA fragmentation and augmented level of cleaved Poly (ADP-Ribose) polymerase 1 after LPS treatment which was significantly reverted with UA treatment. Findings suggested that UA acts through mitochondria and exhibited its anti-oxidative and anti-apoptotic activities in neuronal cells while no significant anti-inflammatory activity and effect on iNOS were observed.

The Protective Effects of PSM-04 Against Beta Amyloid-Induced Neurotoxicity in Primary Cortical Neurons and an Animal Model of Alzheimer's Disease

Polygala tenuifolia Willdenow is a herb known for its therapeutic effects in insomnia, depression, disorientation, and memory impairment. In Alzheimer's disease (AD) animal model, there has been no report on the effects of memory and cognitive impairment. PSM-04, an extract from the root of P. tenuifolia Willdenow, was developed with improved bioabsorption. The present study aimed to investigate the neuroprotective effects of PSM-04 on AD and reveal the possible molecular mechanism. The neuroprotective effect of PSM-04 in primary cortical neurons treated with L-glutamate, oligomeric Aβ, or H2O2. PSM-04 exhibited significant neuroprotective effects against neurotoxicity induced by L-glutamate or oligomeric Aβ was studied. PSM-04 exhibited significant neuroprotective effects against neurotoxicity induced by L-glutamate or oligomeric Aβ. Oxidative stress induced by ROS was monitored using the DCF-DA assay, and apoptosis was assessed using the TUNEL assay in primary cortical neurons treated with H2O2 or oligomeric Aβ. PSM-04 also decreased oxidative stress induced by H2O2 and apoptotic cell death induced by oligomeric Aβ. We evaluated the therapeutic effect of PSM-04 in 5xFAD (Tg) mice, an animal model for AD. PSM-04 was orally administered to 4-month-old 5xFAD mice for 2 months. To confirm the degree of cognitive impairment, a novel object recognition task was performed. The treatment with PSM-04 significantly alleviated cognitive impairments in Tg mice. In addition, amyloid plaques and gliosis decreased significantly in the brains of PSM-04-administered Tg mice compared with Tg-vehicle mice. Furthermore, the administration of PSM-04 increased the superoxide dismutase-2 (SOD-2) protein level in hippocampal brain tissues. Our results indicated that PSM-04 showed therapeutic effects by alleviating cognitive impairment and decreasing amyloid plaque deposition in Tg mice. Therefore, PSM-04 was considered as a potential pharmacological agent for neuroprotective effects in neurodegenerative diseases, including AD.

Neuroprotective Effects of Gagam-Sipjeondaebo-Tang, a Novel Herbal Formula, against MPTP-Induced Parkinsonian Mice and MPP+-Induced Cell Death in SH-SY5Y Cells

Parkinson's disease is a neurodegenerative disease characterized by progressive cell death of dopaminergic neuron and following neurological disorders. Gagam-Sipjeondaebo-Tang (GST) is a novel herbal formula made of twelve medicinal herbs derived from Sipjeondaebo-Tang, which has been broadly used in a traditional herbal medicine. In the present study, we investigated the effects of GST against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor abnormalities in mice and 1-methyl-4-phenylpyridinium (MPP⁺)-induced neurotoxicity in SH-SY5Y cell. First, we found that GST alleviated motor dysfunction induced by MPTP, and the result showed dopaminergic neurons recovery in substantia nigra. In the cell experiment, pretreatment with GST increased the cell viability and attenuated apoptotic cell death in MPP⁺-treated SH-SY5Y cells. GST also inhibited reactive oxygen species production and restored the mitochondrial membrane potential loss, which were induced by MPP⁺. Furthermore, GST extract significantly activated ERK and Akt, cell survival-related proteins, in SH-SY5Y cells. The effect of GST preventing mitochondrial dysfunction was antagonized by pretreatment of PD98059 and LY294002, selective inhibitors of ERK and Akt, respectively. Taken together, GST alleviated abnormal motor functions and recovered neuronal cell death, mitochondrial dysfunction, possibly via ERK and Akt activation. Therefore, we suggest that GST may be a candidate for the treatment and prevention of Parkinson's disease.

Ukgansan protects dopaminergic neurons from 6-hydroxydopamine neurotoxicity via activation of the nuclear factor (erythroid-derived 2)-like 2 factor signaling pathway

The sustenance of redox homeostasis in brain is the crucial factor to treat Parkinson's disease (PD). Nuclear factor (erythroid-derived 2)-like 2 factor (Nrf2)-mediated antioxidant response is well known for the main cellular endogenous defense mechanisms against oxidative stress. This study investigated for the first time the effects and possible mechanisms of action of Ukgansan on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in both in vitro and in vivo models of PD. We investigated the protective effect of Ukgansan against 6-OHDA with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. In addition, we demonstrated that Ukgansan significantly increased the expression of antioxidant response elements (ARE) and pro-survival protein as Bcl2 and suppressed the expression of pro-apoptotic factors, such as Bax, cytochrome c, and caspase-3 using immunoblotting. For the in vivo study, we used a mouse model of PD involving stereotaxic injection of 6-OHDA into the striatum (ST). Ukgansan alleviated motor dysfunctions induced by 6-OHDA followed by pole, open-field, and rotation tests. Dopaminergic neuronal loss and Nrf2 activation were evaluated by immunohistochemistry in the mouse ST and substantia nigra pars compacta (SNpc) regions. Ukgansan significantly protected dopaminergic neurons from 6-OHDA toxicity in mouse ST and SNpc by activating Nrf2. These results indicate that Ukgansan inhibited 6-OHDA-induced dopaminergic neuronal cell damage via activation of Nrf2 and its related factors in 6-OHDA-induced dopaminergic loss in vitro and in vivo. Thus, Ukgansan might delay the progression of PD via maintenance of redox homeostasis.

Lavandula stoechas (L) a Very Potent Antioxidant Attenuates Dementia in Scopolamine Induced Memory Deficit Mice

The objective of the current project was to explore the pharmacotherapeutic role of Lavandula stoechas (L) for the management of dementia. Dementia is considered a global challenge of current century seeking special attention of pharmacologists to explore its best remedies. Methanolic extract of aerial parts of L. stoechas was tested for phytochemical analysis along with free radical scavenging activity. Behavioral studies were performed on scopolamine induced amnesic mice by using elevated plus maze (EPM), light and dark test and hole board paradigms. Biochemical investigations were made after decapitating the mice. Their brains were isolated for biochemical estimation of acetylcholinesterase (AChE), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). Phytochemical study ensured the presence of total phenolic contents (285.91 ± 0.75 mg of GAE/g of extract), total flavonoids (134.06 ± 0.63 mg of RE/g of extract), total tannins (149.60 ± 0.93 mg of TAE/g of extract) and free radical scavenging activity (IC₅₀ value = 76.73 μg/ml found by DPPH method). Behavioral studies indicated that animals of GVII showed higher inflexion ratio (0.40 ± 0.03) for EPM, spent most of time (227.17 ± 2.13 s) in dark area of light dark test and had many hole pockings (39.83 ± 1.88) for hole board paradigm. Moreover, biochemical studies revealed that methanolic extract of L. stoechas (800 mg/kg/p.o.) significantly (P < 0.001) reduced brain AChE and MDA levels while improved SOD, CAT, and GSH levels. Thus the findings suggest that L. stoechas stabilizes memory by enhancing cholinergic neurotransmission and by providing defense against oxidative stress in mice brain.

Phytochemical and Pharmacological Role of Liquiritigenin and Isoliquiritigenin From Radix Glycyrrhizae in Human Health and Disease Models

The increasing lifespan in developed countries results in age-associated chronic diseases. Biological aging is a complex process associated with accumulated cellular damage by environmental or genetic factors with increasing age. Aging results in marked changes in brain structure and function. Age-related neurodegenerative diseases and disorders (NDDs) represent an ever-growing socioeconomic challenge and lead to an overall reduction in quality of life around the world. Alzheimer’s disease (AD) and Parkinson’s disease (PD) are most common degenerative neurological disorders of the central nervous system (CNS) in aging process. The low levels of acetylcholine and dopamine are major neuropathological feature of NDDs in addition to oxidative stress, intracellular calcium ion imbalance, mitochondrial dysfunction, ubiquitin-proteasome system impairment and endoplasmic reticulum stress. Current treatments minimally influence these diseases and are ineffective in curing the multifunctional pathological mechanisms. Synthetic neuroprotective agents sometimes have negative reactions as an adverse effect in humans. Recently, numerous ethnobotanical studies have reported that herbal medicines for the treatment or prevention of NDDs are significantly better than synthetic drug treatment. Medicinal herbs have traditionally been used around the world for centuries. Radix Glycyrrhizae (RG) is the dried roots and rhizomes of Glycyrrhiza uralensis or G. glabra or G. inflata from the Leguminosae/Fabaceae family. It has been used for centuries in traditional medicine as a life enhancer, for the treatment of coughs and influenza, and for detoxification. Diverse chemical constituents from RG have reported including flavanones, chalcones, triterpenoid saponins, coumarines, and other glycosides. Among them, flavanone liquiritigenin (LG) and its precursor and isomer chalcone isoliquiritigenin (ILG) are the main bioactive constituents of RG. In the present review, we summarize evidence in the literature on the structure and phytochemical properties and pharmacological applications of LG and ILG in age-related diseases to establish new therapeutics to improve human health and lifespan.

The Confrontation between Ethnopharmacology and Pharmacological Tests of Medicinal Plants Associated with Mental and Neurological Disorders

For neurological disorders, pharmacological tests have shown promising results in the reduction of side effects when using plants with known therapeutic effects in the treatment of some types of dementia. Therefore, the goals of this study are to gather data about the major medicinal plants used in the nervous system as described in ethnopharmacological surveys from South America and Brazil and to compare this data with the results from pharmacological tests on the active principles of those same plants found in the scientific literature. After collecting the data about each plant, their respective popular indication was compared with the results found through pharmacological tests. The discrepancy rate between the effects observed by ethnopharmacological and pharmacological methods in this study is greater than 50%. In conclusion, despite the importance of ethnopharmacological data, it is important to make comparisons with pharmacological tests for the same plants, since the pharmacological studies, although few, have shown a high rate of discrepancy in the results.

Identification of Natural Compounds against Neurodegenerative Diseases Using In Silico Techniques

The aim of this study was to identify new potentially active compounds for three protein targets, tropomyosin receptor kinase A (TrkA), N-methyl-d-aspartate (NMDA) receptor, and leucine-rich repeat kinase 2 (LRRK2), that are related to various neurodegenerative diseases such as Alzheimer's, Parkinson's, and neuropathic pain. We used a combination of machine learning methods including artificial neural networks and advanced multilinear techniques to develop quantitative structure⁻activity relationship (QSAR) models for all target proteins. The models were applied to screen more than 13,000 natural compounds from a public database to identify active molecules. The best candidate compounds were further confirmed by docking analysis and molecular dynamics simulations using the crystal structures of the proteins. Several compounds with novel scaffolds were predicted that could be used as the basis for development of novel drug inhibitors related to each target.

Features and outcomes of drugs for combination therapy as multi-targets strategy to combat Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD), a deleterious neurodegenerative disorder that impairs memory, cognitive functions and may lead to dementia in late stage of life. The pathogenic cause of AD remains incompletely understood and FDA approved drugs are partial inhibitors rather than curative. Most of drugs are synthetic or natural products as galanthamine is an alkaloid obtained from Galanthus spp. Huperzine A, an alkaloid found in Huperzia spp., gingkolides a diterpenoids from Gingko biloba and many ethnobotanicals like Withania somnifera (L.) Dunal., Physostigma venenosum Balf., Bacopa monnieri (L.) Wettst., Centella asiatica (L.) Urb. have been used by traditional Indian, Chinese, and European system of medicines in AD. Clinical significance opioid alkaloid in Papaver somniferum has shown another dimension to this study. Over exploitation of medicinal plants with limited bioactive principles has provided templates to design synthetic drugs in AD e.g. rivastigmine, phenserine, eptastigmine based on chemical structure of physostigmine of Physostigma venenosum Balf. Even ZT-1 a prodrug of Hup A and memogain a prodrug of galantamine has achieved new direction in drug development in AD. All these first-line cholinesterase-inhibitors are used as symptomatic treatments in AD. Single modality of "One-molecule-one-target" strategy for treating AD has failed and so future therapies on "Combination-drugs-multi-targets" strategy (CDMT) will need to address multiple aspects to block the progression of pathogenesis of AD. Besides, cholinergic and amyloid drugs, in this article we summarize proteinopathy-based drugs as AD therapeutics from a variety of biological sources. In this review, an attempt has been made to elucidate the molecular mode of action of various plant products, and synthetic drugs investigated in various preclinical and clinical tests in AD. It also discusses current attempts to formulate a comprehensive CDMT strategy to counter complex pathogenesis in AD.

MATERIALS AND METHODS

Information were collected from classical books on medicinal plants, pharmacopoeias and scientific databases like PubMed, Scopus, GoogleScholar, Web of Science and electronic searches were performed using Cochrane Library, Medline and EMBASE. Also published scientific literatures from Elsevier, Taylor and Francis, Springer, ACS, Wiley publishers and reports by government bodies and documentations were assessed.

RESULTS

60 no. of natural and synthetic drugs have been studied with their significant bioactivities. A decision matrix designed for evaluation of drugs for considering to the hypothetic "CDMT" strategy in AD. We have introduced the scoring pattern of individual drugs and based on scoring pattern, drugs that fall within the scoring range of 18-25 are considered in the proposed CDMT. It also highlights the importance of available natural products and in future those drugs may be considered in CDMT along with the qualified synthetic drugs.

CONCLUSION

A successful validation of the CDMT strategy may open up a debate on health care reform to explore other possibilities of combination therapy. In doing so, it should focus on clinical and molecular relationships between AD and CDMT. A better understanding of these relationships could inform and impact future development of AD-directed treatment strategies. This strategy also involves in reducing costs in treatment phases which will be affordable to a common man suffering from AD.

Estrogen: The necessary evil for human health, and ways to tame it

Estrogen is a pivotal enzyme for survival and health in both genders, though their quantum, tropism, tissue-specific distribution, and receptor affinity varies with different phases of life. Converted from androgen via aromatase enzyme, this hormone is indispensable to glucose homeostasis, immune robustness, bone health, cardiovascular health, fertility, and neural functions. However, estrogen is at the center of almost all human pathologies as well-infectious, autoimmune, metabolic to degenerative. Both hypo and hyper level of estrogen has been linked to chronic and acute diseases. While normal aging is supposed to lower its level, leading to tissue degeneration (bone, muscle, neural etc.), and metabolite imbalance (glucose, lipid etc.), the increment in inflammatory agents in day-to-day life are enhancing the estrogen (or estrogen mimic) level, fueling 'estrogen dominance'. The resultant excess estrogen is inducing an overexpression of estrogen receptors (ERα and ERβ), harming tissues, leading to autoimmune diseases, and neoplasms. The unprecedented escalation in the polycystic ovary syndrome, infertility, breast cancer, ovary cancer, and gynecomastia cases are indicating that this sensitive hormone is getting exacerbated. This critical review is an effort to analyze the dual, and opposing facets of estrogen, via understanding its crosstalk with other hormones, enzymes, metabolites, and drugs. Why estrogen level correction is no trivial task, and how it can be restored to normalcy by a disciplined lifestyle with wise dietary and selective chemical usage choices has been discussed. Overall, our current state of knowledge does not disclose the full picture of estrogen's pleiotropic importance. Hence, this review should be a resource for general public as well as researchers to work in that direction.