Protective effects of Gastrodia elata Blume on MPP+-induced cytotoxicity in human dopaminergic SH-SY5Y cells

The neuroprotective effect of traditional Chinese medicinal plants-A critical review

Neurodegenerative and neuropsychiatric diseases are increasingly affecting individuals' quality of life, thus increasing their cost to social and health systems. These diseases have overlapping mechanisms, such as oxidative stress, protein aggregation, neuroinflammation, neurotransmission impairment, mitochondrial dysfunction, and excitotoxicity. Currently, there is no cure for neurodegenerative diseases, and the available therapies have adverse effects and low efficacy. For neuropsychiatric disorders, such as depression, the current therapies are not adequate to one-third of the patients, the so-called treatment-resistant patients. So, searching for new treatments is fundamental. Medicinal plants appear as a strong alternative and complement towards new treatment protocols, as they have been used for health purposes for thousands of years. Thus, the main goal of this review is to revisit the neuroprotective potential of some of the most predominant medicinal plants (and one fungus) used in traditional Chinese medicine (TCM), focusing on their proven mechanisms of action and their chemical compositions, to give clues on how they can be useful against neurodegeneration progression.

Bioactivity Profiling and Quantification of Gastrodin in Gastrodia elata Cultivated in the Field versus Facility via Hyphenated High-Performance Thin-Layer Chromatography

Gastrodia elata (Orchidaceae) is native to mountainous areas of Asia and is a plant species used in traditional medicine for more than two thousand years. The species was reported to have many biological activities, such as neuroprotective, antioxidant, and anti-inflammatory activity. After many years of extensive exploitation from the wild, the plant was added to lists of endangered species. Since its desired cultivation is considered difficult, innovative cultivation methods that can reduce the costs of using new soil in each cycle and at the same time avoid contamination with pathogens and chemicals are urgently needed on large scale. In this work, five G. elata samples cultivated in a facility utilizing electron beam-treated soil were compared to two samples grown in the field concerning their chemical composition and bioactivity. Using hyphenated high-performance thin-layer chromatography (HPTLC) and multi-imaging (UV/Vis/FLD, also after derivatization), the chemical marker compound gastrodin was quantified in the seven G. elata rhizome/tuber samples, which showed differences in their contents between facility and field samples and between samples collected during different seasons. Parishin E was also found to be present. Combining HPTLC with on-surface (bio)assays, the antioxidant activity and inhibition of acetylcholinesterase as well as the absence of cytotoxicity against human cells were demonstrated and compared between samples.

The processing methods, phytochemistry and pharmacology of Gastrodia elata Bl.: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Bl. (GE) is one of the rare Chinese medicinal materials with a long history of medicine and cooking. It consists of a variety of chemical components, including aromatic compounds, organic acids and esters, steroids, saccharides and their glycosides, etc., which has medicinal and edible value, and is widely used in various diseases, such as infantile convulsions, epilepsy, tetanus, headache, dizziness, limb numbness, rheumatism and arthralgia. It is also commonly used in health care products and cosmetics. Thus, its chemical composition and pharmacological activity have attracted more and more attention from the scientific community.

AIM

In this review, the processing methods, phytochemistry and pharmacological activities of GE were comprehensively and systematically summarized, which provides a valuable reference for researchers the rational of GE.

MATERIALS AND METHODS

A comprehensive search of published literature and classic books from 1958 to 2023 was conducted using online bibliographic databases PubMed, Google Scholar, ACS, Science Direct Database, CNKI and others to identify original research related to GE, its processing methods, active ingredients and pharmacological activities.

RESULTS

GE is traditionally used to treat infantile convulsion, epilepsy, tetanus, headache, dizziness, limb numbness, rheumatism and arthralgia. To date, more than 435 chemical constituents were identified from GE including 276 chemical constituents, 72 volatile components and 87 synthetic compounds, which are the primary bioactive compounds. In addition, there are other biological components, such as organic acids and esters, steroids and adenosines. These extracts have nervous system and cardiovascular and cerebrovascular system activities such as sedative-hypnotic, anticonvulsant, antiepileptic, neuron protection and regeneration, analgesia, antidepressant, antihypertensive, antidiabetic, antiplatelet aggregation, anti-inflammatory, etc. CONCLUSION: This review summarizes the processing methods, chemical composition, pharmacological activities, and molecular mechanism of GE over the last 66 years, which provides a valuable reference for researchers to understand its research status and applications.

The effects of bioactive components from the rhizome of gastrodia elata blume (Tianma) on the characteristics of Parkinson's disease

Parkinson's disease (PD) is an age-related chronic neurodegenerative disease caused by the death and degeneration of dopaminergic neurons in the substantia nigra of the midbrain. The decrease of the neurotransmitter dopamine in the patient's brain leads to various motor symptoms. PD drugs mainly enhance dopamine levels but cannot prevent or slow down the loss of dopaminergic neurons. In addition, they exhibit significant side effects and addiction issues during long-term use. Therefore, it is particularly urgent to develop novel drugs that have fewer side effects, can improve PD symptoms, and prevent the death of dopaminergic neurons. The rhizome of Gastrodia elata Blume (Tianma) is a well-known medicinal herb and has long been used as a treatment of nervous system-related diseases in China. Several clinical studies showed that formula comprising Tianma could be used as an add-on therapy for PD patients. Pharmacological studies indicated that Tianma and its bioactive components can reduce the death of dopaminergic neurons, α-synuclein accumulation, and neuroinflammation in various PD models. In this review, we briefly summarize studies regarding the effects of Tianma and its bioactive components' effects on major PD features and explore the potential use of Tianma components for the treatment of PD.

A review: traditional herbs and remedies impacting pathogenesis of Parkinson's disease

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons, leading to misbalance and loss of coordination. Current therapies are claimed only for symptomatic relief, on long-term use, which causes alteration in basal ganglia, and give rise to various adverse effects like dyskinesia and extra pyramidal side effects, which is reversed and proved to be attenuated with the help of various herbal approaches. Therefore, in order to attenuate the dopaminergic complications, focus of current research has been shifted from dopaminergic to non-dopaminergic strategies. Herbs and herbal remedies seems to be a better option to overcome the complications associated with current dopaminergic therapies. In recent years, various herbs and herbal remedies based on Ayurveda, traditional Chinese and Korean remedies, have become the target of various researches. These herbs and their bioactive compound are being extensively used to treat PD in India, China, Japan, and Korea. The major focus of this current review is to analyze preclinical studies with reference to various herbs, bioactive compounds, and traditional remedies for the management of Parkinson disorder, which will give an insight towards clinical trials.

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.

Characterization of the antiapoptotic effect of copper sulfate on striatal and midbrain damage induced by MPP+ in rats

1-Methyl-4-phenylpyridinium ion (MPP⁺)-induced neurotoxicity produces cellular damage resembling that encountered in Parkinson's disease. The mechanisms of cellular death after MPP⁺ include the participation of oxidative stress in the loss of dopaminergic neurons. Among the mechanisms of defense against oxidative stress, several copper-dependent proteins have been implicated: Cu/Zn-SOD, ceruloplasmin, and metallothionein. Another important mechanism of damage, is MPP + interference with mitochondrial respiration. Both, oxidative stress and inhibition of mitochondrial respiration may trigger apoptosis in the neurons after MPP⁺. The aim of the present study was to characterize the time-course of apoptosis induced by MPP⁺ to determine if copper sulfate pretreatment is able to prevent the activation of caspases and decreased the neuronal apoptosis. MPP⁺ was microinjected into rat striatum using a stereotactic frame. The results showed increased activities of caspases 8, 9 and 3, between 72-120 hours after administration of MPP⁺, both in striatum and midbrain. After this study, we tested the effect of CuSO₄ on MPP⁺ neurotoxicity, showing a diminution of the apoptotic damage induced by MPP⁺, decreased levels of enzymatic activity of caspases: 8 (-34 and -25 %), 9 (-25 and -42 %) and 3 (-40 and -29 %) in striatum and midbrain, respectively. Finally, we performed an immunohistochemical analysis, evidencing a decreased number of apoptotic cells in the groups pretreated with copper sulfate pretreatment compared to the control group. With these findings, it is concluded that pretreatment with copper sulfate may be a good alternative to prevent MPP⁺-induced apoptosis.

Probiotic Properties and Neuroprotective Effects of Lactobacillus buchneri KU200793 Isolated from Korean Fermented Foods

The purpose of this study was to evaluate the probiotic characteristics and neuroprotective effects of bacteria isolated from Korean fermented foods. Three bacterial strains (Lactobacillus fermentum KU200060, Lactobacillus delbrueckii KU200171, and Lactobacillus buchneri KU200793) showed potential probiotic properties, such as high tolerance against artificial gastric juice and bile salts, sensitivity to antibiotics, nonproduction of carcinogenic enzymes, and high adhesion to intestinal cells. Heat-killed L. fermentum KU200060 and L. buchneri KU200793 showed higher antioxidant activity than heat-killed L. delbrueckii KU200171. The conditioned medium (CM) was used to evaluate the reaction between HT-29 cells and each heat-killed strain. All CMs protected SH-SY5Y cells from 1-methyl-4-phenylpyridinium (MPP⁺)-induced toxicity. The expression of brain-derived neurotropic factor (BDNF) mRNA in HT-29 cells treated with CM containing heat-killed L. buchneri KU200793 was the highest. The CM significantly reduced the Bax/Bcl-2 ratio and increased BDNF mRNA expression in SH-SY5Y cells treated with MPP⁺. These results indicate that L. buchneri KU200793 can be used as a prophylactic functional food, having probiotic potential and neuroprotective effects.

Four New Depsides Isolated from Salvia miltiorrhiza and Their Significant Nerve-Protective Activities

By investigating of the roots of Salvia miltiorrhiza, which is one of the most widely used Chinese herbs, we used phytochemical methods successfully to obtain twelve depsides: four depsides (1⁻4) that were previously undescribed, along with eight known ones (5⁻12). Their structure characteristics were assessed by HR-ESIMS, CD, NMR (¹H, ¹³C, HSQC, HMBC) data analyses. These four newly isolated compounds (1⁻4), as well as the other eight compounds (5⁻12), show extraordinary protective effects on hydrogen peroxide-induced apoptosis in HS-SY5Y cells. Among them, depside 4 and depside 6 displayed more obviously protective effects than others.

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.

Mitigation Effects of a Novel Herbal Medicine, Hepad, on Neuroinflammation, Neuroapoptosis, and Neuro-Oxidation

Parkinson’s disease (PD), a common adult-onset neurodegenerative disorder with complex pathological mechanisms, is characterized by the degeneration of dopaminergic nigrostriatal neurons. The present study demonstrated that the herbal medicines Hepad 1 and 2 protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neurotoxicity in C57BL/6 mice and SH-SY5Y cells. Hepad 1 and 2 remarkably alleviated the enhanced expression of pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-6, inducible nitric oxide synthase, cyclooxygenase-2, macrophage-1, and phosphorylated iκB-α) and apoptotic signals (Bcl-2-associated X protein, caspase-3, and poly [ADP-ribose] polymerase-1). Additionally, Hepad reduced MPTP-induced oxidative damage by increasing the expression of anti-oxidant defense enzymes (superoxide dismutase and glutathione S-transferase) and downregulating the levels of nicotinamide adenine dinucleotide phosphate oxidase 4. This study also showed that the neuroprotective effects of Hepad include anti-inflammatory, anti-apoptotic, and anti-oxidative properties, in addition to activation of the protein kinase B, extracellular-signal-regulated kinase, and c-Jun N-terminal kinase signaling pathways. Furthermore, oral administration of Hepad 1 and 2 attenuated the death of tyrosine hydroxylase-positive substantia nigra neurons that was induced by 20 mg/kg MPTP. Therefore, our results suggest that Hepad 1 and 2 are useful for treating PD and other disorders associated with neuro-inflammatory, neuro-apoptotic, and neuro-oxidative damage.

Cellular phenotypes as inflammatory mediators in Parkinson's disease: Interventional targets and role of natural products

Pathogenesis of Parkinson's disease (PD) is undoubtedly a multifactorial phenomenon, with diverse etiological agents. Pro-inflammatory mediators act as a skew that directs disease progression during neurodegenerative diseases. Understanding the dynamics of inflammation and inflammatory mediators in preventing or reducing disease progression has recently gained much attention. Inflammatory neuro-degeneration is regulated via cytokines, chemokines, lipid mediators and immune cell subsets; however, individual cellular phenotypes in the Central Nervous System (CNS) acts in diverse ways whose persistent activation leads to unresolving inflammation often causing unfavorable outcomes in neurodegenerative disease like PD. Specifically, activation of cellular phenotypes like astrocytes, microglia, activation of peripheral immune cells requires different activation signals and agents like (cytokines, misfolded protein aggregates, infectious agents, pesticides like organophosphates, etc.,). However, what is unknown is how the different cellular phenotypes respond uniquely and the role of the factors they secrete alters the signal cascades in the complex neuron-microglial connections in the CNS. Hence, understanding the role of cellular phenotypes and the inflammatory mediators, the cross talk among the signals and their receptors can help us to identify the potential therapeutic target using natural products. In this review we have tried to put together the role of cellular phenotypes as a skew that favors PD progression and we have also discussed how the lack of experimental approaches and challenges that affects understanding the cellular targets that can be used against natural derivatives in alleviating PD pathophysiology. Together, this review will provide the better insights into the role of cellular phenotypes of neuroinflammation, inflammatory mediators and the orchestrating factors of inflammation and how they can be targeted in a more specific way that can be used in the clinical management of PD.

Gastrodia elata alleviates mutant huntingtin aggregation through mitochondrial function and biogenesis mediation

BACKGROUND

According to the Compendium of Materia Medica, Gastrodia elata (GE) Blume is a top-grade herbal medicine frequently used to treat dizziness, headaches, tetanus, and epilepsy, suggesting that it affects neurological functions. Although studies have supported its effects in preventing diverse neurodegenerations such as Huntington's disease (HD), its mechanisms require further investigation.

PURPOSE

To investigate the ability of the molecular mechanism of GE to prevent mutant huntingtin (mHTT) protein aggregation by focusing on mitochondrial function and biogenesis, which have been proposed as the therapeutic targets of HD.

STUDY DESIGN/METHODS

mHtt overexpression in pheochromocytoma (PC12) cells was used as an in vitro cell model of HD. A retardation assay was applied to measure protein aggregation during Htt expression. Cotransfection with transcriptional genes was used to test their relationships with HTT aggregates by monitoring with a confocal laser scanning microscope. Western blot analysis was used to estimate protein expression under different drug treatments or when cotransfected with other related genes.

RESULTS

Mutant, abnormal Htt overexpression resulted in significant protein aggregation in PC12 cells. GE dose-dependently attenuated mHTT aggregates and increased cyclic-AMP response element-binding protein (CREB) phosphorylation. Adenosine A_2A-R receptor (A_2A-R) antagonist counteracted these phenomena. CREB overexpression significantly attenuated mHTT aggregation. GE increased the promoter activity and expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). Furthermore, wild-type PGC-1α but not mutant PGC-1α overexpression attenuated mHTT aggregates.

CONCLUSION

GE attenuated mHtt aggregation by mediating mitochondrial function and biogenesis through the A_2A-R/PKA/CREB/PGC-1α-dependent pathway.

Neuroprotective effect of polysaccharides from Gastrodia elata blume against corticosterone‑induced apoptosis in PC12 cells via inhibition of the endoplasmic reticulum stress‑mediated pathway

Depression is a common mental health disorder and is the leading cause of disability worldwide. Gastrodia elata (G. elata) was demonstrated to exhibit a neuroprotective effect in the authors' previous study. The present study investigated the effect of polysaccharides from G. elata (GEP) on PC12 cell apoptosis induced by corticosterone (CORT) and its possible underlying mechanisms. PC12 cells were treated with 200 µM CORT in the absence or presence of different concentrations of GEP for 48 h. Then, cell viability was measured by CCK‑8 assay. The lactate dehydrogenase (LDH) leakage was quantified using an LDH assay kit. The apoptosis degree of the PC12 cells and the morphology was measured by DAPI staining. Subsequently, intracellular ROS level was detected by using DCFH‑DA method, the morphology staining of the endoplasmic reticulum in PC12 cells was determined using the cationic probe, and levels of five proteins involved in apoptosis, i.e., glucose‑regulated protein, 78k Da (GRP78), X‑box binding protein 1 (XBP‑1), growth arrest‑ and DNA damage‑inducible gene 153 (GADD153), caspase 9 and caspase 12 were determined by western blotting. The results demonstrated that treatment with 1,000 µg/ml GEP prior to 200 µM CORT exposure significantly protected the PC12 cells from CORT‑induced cell apoptosis, and reduced levels of LDH leakage and intracellular reactive oxygen species. In addition, pretreatment with GEP inhibited the activation of GRP78, X‑BP‑1, GADD153, caspase 9 and caspase 12. These findings suggested that GEP exhibited a neuroprotective effect against CORT‑induced apoptosis in PC12 cells, and the underlying molecular mechanisms were dependent on inhibition of the endoplasmic reticulum stress‑mediated pathway. This provides novel insight into the effect of GEP when used for the treatment of diseases of the nervous system.

Gastrodin causes vasodilation by activating KATP channels in vascular smooth muscles via PKA-dependent signaling pathway

Gastrodin, one of the major components extracted from the Chinese herb Gastrodia elata Bl., has been widely used as an anticonvulsant, sedative, analgesic and hypotensive. In our study, we aimed to investigate the effects and possible mechanisms of gastrodin on vascular K_ATP channels. Tension experiments were used on rat mesenteric artery rings without an endothelium. Patch clamp experiments were executed to investigate the influences of gastrodin on the membrane current in mesenteric artery smooth muscle cells. Gastrodin induced vasorelaxation in a concentration dependent manner when rat mesenteric artery rings were pre-contracted with Phenylephrine. The vasorelaxation effect was partially diminished by pre-treating with a K_ATP channel inhibitor, or a PKA inhibitor. With whole-cell patch-clamp recording techniques, we found that gastrodin is a activator of K_ATP in rat mesenteric artery smooth muscle cells, and this effect was eliminate by pre-treating with H89or PKI, PKA inhibitor. In addition, when rat vascular smooth muscle cells were treated with 100 μM gastrodin for 24 h, maximum K_ATP current density increased by 28.1%. The results indicate that gastrodin exerts vasorelaxation effect through activation of PKA and subsequent opening of smooth muscle K_ATP channels.

Plants-Derived Neuroprotective Agents: Cutting the Cycle of Cell Death through Multiple Mechanisms

Neuroprotection is the preservation of the structure and function of neurons from insults arising from cellular injuries induced by a variety of agents or neurodegenerative diseases (NDs). The various NDs including Alzheimer's, Parkinson's, and Huntington's diseases as well as amyotropic lateral sclerosis affect millions of people around the world with the main risk factor being advancing age. Each of these diseases affects specific neurons and/or regions in the brain and involves characteristic pathological and molecular features. Hence, several in vitro and in vivo study models specific to each disease have been employed to study NDs with the aim of understanding their underlying mechanisms and identifying new therapeutic strategies. Of the most prevalent drug development efforts employed in the past few decades, mechanisms implicated in the accumulation of protein-based deposits, oxidative stress, neuroinflammation, and certain neurotransmitter deficits such as acetylcholine and dopamine have been scrutinized in great detail. In this review, we presented classical examples of plant-derived neuroprotective agents by highlighting their structural class and specific mechanisms of action. Many of these natural products that have shown therapeutic efficacies appear to be working through the above-mentioned key multiple mechanisms of action.

Acetagastrodin effects on retinal oscillatory potentials in patients during the early stages of diabetes

AIMS

To investigate the protective effect of acetagastrodin on visual electrophysiology in patients with early-stage diabetes.

METHODS

A prospective, randomized, controlled, double-blind trial was conducted. Subjects who were randomly assigned to either the treatment group or the control group were orally administered acetagastrodin or placebo, respectively, for 6 months. The quantity, mean amplitude and mean latency of oscillatory potentials (OPs) wavelets at baseline and 6 months were measured on electroretinogram (ERG), in all subjects.

RESULTS

A total of 92 right eyes in 92 patients with type 2 diabetes, who were diagnosed for the first time, were enrolled. Each group consisted of 46 cases (46 eyes). There was no significant difference in baseline characteristic between treatment and control groups at baseline, but quantity in treatment group was more than that in control group at 6 months (P = 0.001). The mean amplitude of OPs was reduced in the control group 6 months later compared with treatment group (P = 0.001). As to mean latency of OPs, statistical difference was also detectable between the treatment group and control group 6 months later (P < 0.001). No statistical differences were found in hemoglobin between both groups at 6 months (P > 0.05).

CONCLUSIONS

Electrophysiological changes would go on worsening even hemoglobin was under control during the initial stage of diabetes. Acetagastrodin treatment may be an effective treatment to protect retinal neurons against such functional impairment during the early stages of diabetes.

Neuroprotective mechanisms of plant extracts against MPTP induced neurotoxicity: Future applications in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease, affecting about seven to 10 million patients worldwide. The major pathological features of PD are loss of dopaminergic neurons in the nigrostriatal pathway and accumulation of alpha-synuclein molecules, forming Lewy bodies. Until now, there is no effective cure for PD, and investigators are searching for neuroprotective strategies to stop or slow the disease progression. The MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) induced neurotoxicity of the nigrostriatal pathway has been used to initiate PD in animal models. Multiple experimental studies showed the ability of several plant extracts to protect against MPTP induced neurotoxicity through activation of catalase, superoxide dismutase, and glutathione reductase enzymes, which reduce the cellular concentration of free radicals, preventing intracellular Ca⁺⁺ release and subsequent apoptosis signaling. Other neuroprotective mechanisms of plant extracts include promoting autophagy of alpha-synuclein molecules and exerting an antiapoptotic activity via inhibition of proteolytic poly (ADP-ribose) polymerase and preventing caspase cleavage. The variety of neuroprotective mechanisms of natural plant extracts may allow researchers to target PD progression in different pathological stages and may be through multiple pathways. Further investigations are required to translate these neuroprotective mechanisms into safe and effective treatments for PD.

Gastrodia elata Blume Extract Modulates Antioxidant Activity and Ultraviolet A-Irradiated Skin Aging in Human Dermal Fibroblast Cells

Gastrodia elata Blume (GEB), a traditional herbal medicine, has been used to treat a wide range of neurological disorders (e.g., paralysis and stroke) and skin problems (e.g., atopic dermatitis and eczema) in oriental medicine. This study was designed to investigate the antioxidant ability of GEB and its antiaging effect on human dermal fibroblast cells (HDF). The total phenolic and flavonoid contents of GEB were 21.8 and 0.43 mg/g dry weight (DW), respectively. The ergothioneine content of GEB was 0.41 mg/mL DW. The DPPH and ABTS radical scavenging activities of GEB at 5 and 10 mg/mL approximately ranged between 31% and 44%. The superoxide dismutase activity of GEB at 10 and 25 mg/mL was 57% and 76%, respectively. GEB increased procollagen type 1 (PC1) production and inhibited matrix metalloproteinase-1 (MMP-1) production and elastase-1 activity in UVA-irradiated HDF. PC1 messenger RNA (mRNA) levels decreased upon UVA irradiation, but recovered in response to high doses of GEB in HDF. On the contrary, GEB significantly decreased MMP-1 and elastase-1 mRNA levels, which were markedly induced in UVA-irradiated HDF. Collectively, these results suggest that GEB has sufficient antioxidant ability to prevent the signs of skin aging in UVA-irradiated human skin cells, suggesting its potential as a natural antiaging product.

Gastrodia elata and epilepsy: Rationale and therapeutic potential

BACKGROUND

Gastrodia elata Blume (G. elata) is a traditional Chinese herb used for centuries in folk medicine. Due to the claimed anticonvulsant properties of G. elata, it is expected that this herb continues to be a target of research, aiming to deepen the available knowledge on its biological activity and safety.

PURPOSE

The current review aims to discuss the most recent advances on the elucidation of the phytochemical composition and anticonvulsant potential of G. elata.

METHODS

Available literature was reviewed from PubMed, ISI Web of Knowledge and Science Direct, using combinations of the following keywords: Gastrodia elata, tianma, epilepsy, anticonvulsant and pharmacokinetics. Abstracts and full texts were evaluated for their clarity and scientific merit.

RESULTS

G. elata rhizome, as well as specific phenolic compounds isolated from this herb, have demonstrated anticonvulsant potential in a variety of in vitro and in vivo models. The pharmacological mechanisms potentially involved in the anticonvulsant activity have been extensively studied, being similar to the known mechanisms claimed for the available antiepileptic drugs. In addition, the pharmacokinetics of the main bioactive component of G. elata (gastrodin) has also been studied.

CONCLUSION

Due to its recognised therapeutic properties, G. elata has gained an increasing interest within the scientific community and, therefore, new medicinal preparations containing G. elata rhizome itself or its bioactive components are expected to be developed in the coming years. Moreover, specific phytochemical constituents isolated from G. elata may also be considered to integrate programs of discovery and development of new anticonvulsant drug candidates.

PROTECTIVE EFFECTS OF ETHYL ACETATE EXTRACTION FROM GASTRODIA ELATA BLUME ON BLOOD-BRAIN BARRIER IN FOCAL CEREBRAL ISCHEMIA REPERFUSION

Background:

Damage of the blood brain barrier (BBB) during the process of cerebral ischemic injury is a key factor which influences the therapeutic efficacy to the cerebral ischemic injury. The present study was designed to verify the mechanisms underlying the protective effects of the ethyl acetate (EtOAc) extraction from Gastrodia elata Blume (GEB) on the BBB by developing a model of cerebral ischemia-reperfusion in rats.

Material and methods:

MCAO/R model in rats was developed through a thread embolism method. The neurological scales, the moisture and the evans blue (EB) contents of brains were detected. Meanwhile, the release of nitric oxide (NO) and activities of NO synthase (NOS) in brain tissues were measured. Western blotting analyses were also performed to assess the protein expressions of AQP-4, Occludin and Claudin-5 in brain tissue.

Results:

After rats were pretreated with different concentrations of EtOAc extractions from GEB, the neurologic scores, the EB contents in the brain tissues and the moisture of the brains were significantly decreased. Meanwhile, the release of NO, the activities of nNOS and iNOS were notably inhibited. Furthemore, the protein expression of AQP-4 was markedly decreased, but the protein expressions of -5 and Occludin were significantly increased.

Conclusion:

the EtOAc extracts of GEB may decrease the permeability of BBB when focal cerebral ischemia occurs. The inhibition of the NOS pathways, the attenuation of the protein expression of AQP-4 and the enhancement of the expressions of the tight junction proteins may contribute to the protective effects of the EtOAc extracts from GEB on BBB.

Anti-depressant effects of Gastrodia elata Blume and its compounds gastrodin and 4-hydroxybenzyl alcohol, via the monoaminergic system and neuronal cytoskeletal remodeling

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume is a highly valuable traditional Chinese medicine used in the treatment of depression. However, compounds with antidepressant effects in water extracts of G. elata Bl. (WGE) have not been identified. The aims of this study were to determine the major antidepressant compound in WGE and to evaluate the antidepressant effects of WGE and its active compounds which involved the monoaminergic system and neuronal cytoskeletal remodeling.

MATERIALS AND METHODS

Gastrodin (GAS) and 4-hydroxybenzyl alcohol (HBA) in WGE, were analyzed with high-performance liquid chromatography (HPLC)-ultraviolet detection. The forced swimming test (FST) was used to induce depression-like symptoms in 9 weeks old male Sprague-Dawley rats. The open field test (OFT) was used to measure anxiety after WGE, GAS, and HBA treatments. The levels of monoamine such as serotonin (5-HT), dopamine (DA), and their metabolites 5-hydroxyindoleacetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) were measured using HPLC-electrochemical detection. Western blotting was used to examine the 5-HT1A receptor and the neuronal cytoskeleton remodeling-related proteins, Slit, dihydropyrimidinase-related protein 2 (DPYSL2, also called CRMP2), Ras homologous member A (RhoA), and profilin 1 (PFN1) in vivo. Slit1 expression was evaluated in Hs683 cell line after treated with WGE (0.5mg/mL), GAS (50, 100 and 100μM), and HBA (50, 100 and 100μM).

RESULTS

Oral administration of WGE (500mg/kg bw), GAS (100mg/kg bw), and HBA (100mg/kg bw) exhibited the anti-depressant effect by significantly reducing the immobility time in FST, monoamine metabolism including the 5-HT to 5-HIAA in the hippocampus and DA to DOPAC and HVA ratios in the frontal cortex, amygdala, and hippocampus. In the hippocampus, the expression of the neuronal cytoskeleton remodeling-related negative regulators Slit1 and RhoA were significantly down-regulated. In addition, the positive regulators CRMP2 and PFN1 were significantly up-regulated following GAS, HBA, and WGE treatments. Moreover, WGE, GAS, and HBA were directly down-regulated Slit1 expression in Hs683 cells.

CONCLUSION

WGE, GAS, and HBA exhibited potential anti-depressant effects in rats by decreasing monoamine metabolism and modulated cytoskeleton remodeling-related protein expression in the Slit-Robo pathway. These results suggest that WGE can be used as agent for depressive prevention.

A Potential Alternative against Neurodegenerative Diseases: Phytodrugs

Neurodegenerative diseases (ND) primarily affect the neurons in the human brain secondary to oxidative stress and neuroinflammation. ND are more common and have a disproportionate impact on countries with longer life expectancies and represent the fourth highest source of overall disease burden in the high-income countries. A large majority of the medicinal plant compounds, such as polyphenols, alkaloids, and terpenes, have therapeutic properties. Polyphenols are the most common active compounds in herbs and vegetables consumed by man. The biological bioactivity of polyphenols against neurodegeneration is mainly due to its antioxidant, anti-inflammatory, and antiamyloidogenic effects. Multiple scientific studies support the use of herbal medicine in the treatment of ND; however, relevant aspects are still pending to explore such as metabolic analysis, pharmacokinetics, and brain bioavailability.

Plant-Derived Natural Products for Parkinson's Disease Therapy

Plant-derived natural products have made their own niche in the treatment of neurological diseases since time immemorial. Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, has no cure and the treatment available currently is symptomatic. This chapter thoughtfully and objectively assesses the scientific basis that supports the increasing use of these plant-derived natural products for the treatment of this chronic and progressive disorder. Proper considerations are made on the chemical nature, sources, preclinical tests and their validity, and mechanisms of behavioural or biochemical recovery observed following treatment with various plants derived natural products relevant to PD therapy. The scientific basis underlying the neuroprotective effect of 6 Ayurvedic herbs/formulations, 12 Chinese medicinal herbs/formulations, 33 other plants, and 5 plant-derived molecules have been judiciously examined emphasizing behavioral, cellular, or biochemical aspects of neuroprotection observed in the cellular or animal models of the disease. The molecular mechanisms triggered by these natural products to promote cell survivability and to reduce the risk of cellular degeneration have also been brought to light in this study. The study helped to reveal certain limitations in the scenario: lack of preclinical studies in all cases barring two; heavy dependence on in vitro test systems; singular animal or cellular model to establish any therapeutic potential of drugs. This strongly warrants further studies so as to reproduce and confirm these reported effects. However, the current literature offers scientific credence to traditionally used plant-derived natural products for the treatment of PD.

Neuropharmacological Potential of Gastrodia elata Blume and Its Components

Research has been conducted in various fields in an attempt to develop new therapeutic agents for incurable neurodegenerative diseases. Gastrodia elata Blume (GE), a traditional herbal medicine, has been used in neurological disorders as an anticonvulsant, analgesic, and sedative medication. Several neurodegenerative models are characterized by oxidative stress and inflammation in the brain, which lead to cell death via multiple extracellular and intracellular signaling pathways. The blockade of certain signaling cascades may represent a compensatory therapy for injured brain tissue. Antioxidative and anti-inflammatory compounds isolated from natural resources have been investigated, as have various synthetic chemicals. Specifically, GE rhizome extract and its components have been shown to protect neuronal cells and recover brain function in various preclinical brain injury models by inhibiting oxidative stress and inflammatory responses. The present review discusses the neuroprotective potential of GE and its components and the related mechanisms; we also provide possible preventive and therapeutic strategies for neurodegenerative disorders using herbal resources.

Anti-neuroinflammatory effects of DPTP, a novel synthetic clovamide derivative in in vitro and in vivo model of neuroinflammation

Neuroinflammation is one of the critical pathological mechanisms influencing various neurodegenerative disorders. Most of the neurodegenerative diseases involve over-activation of microglial cells contributing to the demise of neurons. The objective of the current study is to evaluate the anti-inflammatory effect of novel synthetic clovamide derivative on the suppression of microglial activation in an in vitro and in vivo model of neuroinflammation. We have used lipopolysaccharide (LPS) to induce an inflammatory response in murine BV-2 microglial cells. Molecular tools like immunocytochemistry and immunoblotting were used to study the activity of novel synthetic clovamide derivative to inhibit inflammation induced by LPS in microglial cells. In in vivo experiments, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxicated mouse model of neuroinflammation was developed to investigate the anti-neuroinflammatory effects of DPTP [3-(3,4-Dihydroxy-phenyl)-2-[4-(3-trifluoromethylphenyl)-but-2-enoylamino]-propionic acid methyl ester]. DPTP was observed to reduce the proinflammatory response in BV-2 cells induced by LPS. Further investigation revealed that DPTP attenuated phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), which was accompanied by a decrease in nuclear translocation of nuclear factor-κB (NF-κB) in LPS-treated BV2 microglia. Moreover, prophylactic treatment with DPTP (20mg/kg) for 7 days suppressed MPTP induced glial activation and behavioral impairment. Overall, our findings suggested that, DPTP exerts anti-neuroinflammatory effects against activated microglia in an in vitro and in vivo model and hence might be a promising therapeutic agent for alleviating the evolvement of neurodegenerative diseases associated with microglial activation.

EOP, a newly synthesized ethyl pyruvate derivative, attenuates the production of inflammatory mediators via p38, ERK and NF-κB pathways in lipopolysaccharide-activated BV-2 microglial cells

Microglia-induced neuroinflammation is an important pathological mechanism influencing various neurodegenerative disorders. Excess activation of microglia produces a myriad of proinflammatory mediators that decimate neurons. Hence, therapeutic strategies aimed to suppress the activation of microglia might lead to advancements in the treatment of neurodegenerative diseases. In this study, we synthesized a novel ethyl pyruvate derivative, named EOP (S-ethyl 2-oxopropanethioate) and studied its effects on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in rat primary microglia and mouse BV-2 microglia. EOP significantly decreased the production of NO, inducible nitric oxide synthase, cyclooxygenase and other proinflammatory cytokines, such as interleukin (IL)-6, IL-1β and tumor necrosis factor-α, in LPS-stimulated BV-2 microglia. The phosphorylation levels of extracellular regulated kinase, p38 mitogen-activated protein kinase, and nuclear translocation of NF-κB were also inhibited by EOP in LPS-activated BV-2 microglial cells. Overall, our observations indicate that EOP might be a promising therapeutic agent to diminish the development of neurodegenerative diseases associated with microglia activation.

Gastrodiae Rhizoma (tiān má): a review of biological activity and antidepressant mechanisms

Gastrodiae Rhizoma, also called chì jiàn (赤箭), guǐ dū yóu (鬼督郵), or tiān má (天麻) in Chinese, is considered a top grade (上品 shàng pǐn) medicine described to enter liver channel (肝經 gān jīng) in classic literatures of traditional Chinese medicine and has been used for centuries. Many studies investigating its various bioactivities and active compounds have been conducted worldwide. This article reviews these biological activities and details the antidepressant pharmacology of Gastrodiae Rhizoma. Gastrodiae Rhizoma treatment exerts an effective inhibition of diverse diseases and disorders, including convulsion, oxidative stress, mental disorders, amnesia, cardio-cerebral-vascular diseases, and inflammation, among others. The antidepressant effect of Gastrodiae Rhizoma was evaluated in animal models and several mechanisms of activity were found, including the modulation and regulation of monoamine oxidase activity, monoamine concentration and turnover, antioxidatant activity, GABAergic system induction, BDNF induction, neuroprotection and anti-inflammatory activity.

Gastrodia elata Blume alleviates L-DOPA-induced dyskinesia by normalizing FosB and ERK activation in a 6-OHDA-lesioned Parkinson's disease mouse model

Background

Gastrodia elata Blume (GEB), commonly used medicinal herb, has been reported as a promising candidate for neurodegenerative diseases such as Parkinson’s disease. The dopamine precursor, L-3,4-dihydroxyphenylalanine (L-DOPA), is the gold-standard drug for Parkinson’s disease, but long-term treatment results in the L-dopa-induced dyskinesia (LID). This study was undertaken to examine the beneficial effects of GEB on L-DOPA induced dyskinesia in 6-hydroxydopamine (6-OHDA)-induced experimental Parkinsonism.

Methods

We tested the effects of GEB on LID in 6-hydroxydopamine hydrochloride-hemiparkinsonian mice. To analyze the dyskinetic anomalies, we measured abnormal involuntary movement (AIM). Immunohistological analyses of pERK and FosB expressions in the striatum are performed to explore the mechanism of GEB on LID.

Results

The finding of this study demonstrated that GEB (200, 400 and 800 mg/kg) alleviated L-dopa induced AIMs in a dose-dependent manner. In each integrative AIM subtype analysis, we also found that the GEB (400 and 800 mg/kg) treatment decreased L-DOPA-induced axial, limb, orolingual, and locomotive AIMs compared to the LID group. In addition, GEB normalized the abnormal LID-induced increase of pERK1/2 and FosB, the immediate early genes of LID in the striatum.

Conclusions

In conclusion, our results provide a novel insight into the pharmacological actions of GEB that could have a benefit for PD patients through the reduction of LID.

A novel synthetic HTB derivative, BECT inhibits lipopolysaccharide-mediated inflammatory response by suppressing the p38 MAPK/JNK and NF-κB activation pathways

Activated microglia cells are well recognized as mediators of neuroinflammation, as they release nitric oxide and pro-inflammatory cytokines in various neuroinflammatory diseases. Thus, suppressing microglial activation may alleviate neuroinflammatory and neurodegenerative processes. In the present study, we synthesized and investigated the anti-neuroinflammatory effect of a novel HTB (2-hydroxy-4-trifuoromethylbenzoic acid) derivative in lipopolysaccharide (LPS)-stimulated microglial cells. Among the synthesized derivatives, the BECT [But-2-enedioic acid bis-(2-carboxy-5-trifluoromethyl-phenyl) ester] significantly decreased production of nitric oxide and other pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interleukin-6 in microglial cells. BECT also mitigated the expression of inducible nitric oxide synthase and cyclooxygenase-2 at both the mRNA and protein levels. Further mechanistic studies demonstrated that the HTB derivative inhibited phosphorylation of JNK and p38 mitogen-activated protein kinase and nuclear translocation of nuclear factor kappa-B in LPS-stimulated BV-2 microglial cells. Thus BECT, our novel synthesized compound have anti-inflammatory activity in microglial cells, and may have therapeutic potential for treating neuroinflammatory diseases.

Herbal medicines for treating tic disorders: a systematic review of randomised controlled trials

Background

It was reported that 64% of tic disorder patients used complementary and alternative medicine. This review aims to evaluate the efficacy of herbal medicines in treating tic disorders.

Methods

We searched eight databases including MEDLINE and CINAHL from their respective inceptions up to September 2013. The search terms were related to the concept of “herbal medicine” AND “tic disorder OR Tourette’s syndrome”. We included randomised controlled trials (RCTs) of any type of herbal medicines. We assessed the methodological quality of the trials according to the Cochrane risk of bias criteria.

Results

Sixty one studies were identified, and four RCTs met the inclusion criteria. Two types of herbal medicines, Qufeng Zhidong Recipe (QZR) decoction and Ningdong (ND) granules, were used in the included RCTs. All four RCTs had a high risk of bias. Two RCTs tested the effects of QZR on the Yale Global Tic Severity Scale (YGTSS) score and response rate compared with conventional medicine. The meta-analysis showed significant effects of QZR on the YGTSS score with high statistical heterogeneity (n = 142; weighted mean difference: −18.34; 95% confidence interval (CI): −23.07 to −13.60; I² = 97%) and the response rate (n = 142; risk ratio: 1.69; 95% CI: 1.39 to 2.06; I² = 0%). One RCT compared ND granules with placebo and showed significant effects on the YGTSS score and response rate. The other RCT show significant effects of ND granules plus conventional medicine on the response rate compared with conventional medicine only.

Conclusion

This systematic review provided first piece of limited meta-analytic evidence for the effectiveness of herbal medicines in improving the symptoms of tic disorders.

Pinocembrin protects SH-SY5Y cells against MPP+-induced neurotoxicity through the mitochondrial apoptotic pathway

Pinocembrin (PB), the most abundant flavonoid in propolis, has been proven to have neuroprotective property against neurotoxicity in vivo and in vitro. Our recent study demonstrated the neuroprotective effect of PB against Aβ25-35-induced SH-SY5Y neurotoxicity. However, the mechanism as how PB can induce neuroprotection is not known. In the present study, we demonstrate here that PB abrogates the effects of the neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)) which mimics Parkinson's disease (PD) with elevation of intracellular reactive oxygen species (ROS) level and apoptotic death. We found that pretreatment of SH-SY5Y cells with PB significantly reduced the MPP(+)-induced loss of cell viability, the generation of intracellular ROS, apoptotic rate, and the cleavage of caspase-3. PB strikingly inhibited MPP(+)-induced mitochondrial dysfunctions, including lowered membrane potential, decreased Bcl-2/Bax ratio, and the release of cytochrome c. Overall, these results suggest that PB is intimately involved in inhibiting MPP(+)-induced loss of mitochondrial function and induction of apoptosis that contributes toward neuronal survival. These data indicated that PB might provide a valuable therapeutic strategy for the treatment of PD.

Neuroprotective effects of Gua Lou Gui Zhi decoction against glutamate-induced apoptosis in BV-2 cells

Gua Lou Gui Zhi decoction (GLGZD), a traditional Chinese medicine consisting of different herbal medicines, has been used for centuries in the treatment of muscular spasticity following stroke, epilepsy or spinal cord injury. However, the precise mechanisms involved remain poorly understood. In the present study, we investigated the neuroprotective effects of GLGZD on glutamate-induced apoptosis in cultured BV-2 cells, as well as the underlying mechanisms. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was applied to assess the viability of the cells. An Annexin V/propidium iodide (PI) assay was utilized to analyze cellular apoptosis. Mitochondrial membrane potential (MMP) was evaluated by flow cytometry and laser scanning confocal microscopy. The gene and protein expression of the apoptosis-related genes, Bcl-2 and Bax, was analyzed by RT-PCR and western blot analysis, respectively. Furthermore, the expression of cleaved caspase-3 protein was detected by immunofluorescence. Glutamate treatment induced the loss of BV-2 cell viability, which was associated with an increase in the apoptotic rate, as well as an increase in the Bax/Bcl-2 ratio and the extracellular levels of cleaved caspase-3. Treatment with GLGZD significantly reversed these phenotypes, with its maximum protective effects observed at the concentration of 1,000 µg/ml. These results indicate that GLGZD protects BV-2 cells from glutamate-induced cytotoxicity. These protective effects may be ascribed to its anti-apoptotic activities, in part, associated with the decrease in the Bax/Bcl-2 ratio and caspase-3 expression, as well as with the stability of high mitochondrial membrane potential.

The Aqueous Extract of Rhizome of Gastrodia elata Protected Drosophila and PC12 Cells against Beta-Amyloid-Induced Neurotoxicity

This study aims to investigate the neuroprotective effect of the rhizome of Gastrodia elata (GE) aqueous extract on beta-amyloid(Aβ)-induced toxicity in vivo and in vitro. Transgenic Drosophila mutants with Aβ-induced neurodegeneration in pan-neuron and ommatidia were used to determine the efficacy of GE. The antiapoptotic and antioxidative mechanisms of GE were also studied in Aβ-treated pheochromocytoma (PC12) cells. In vivo studies demonstrated that GE (5 mg/g Drosophila media)-treated Drosophila possessed a longer lifespan, better locomotor function, and less-degenerated ommatidia when compared with the Aβ-expressing control (all P < 0.05). In vitro studies illustrated that GE increased the cell viability of Aβ-treated PC12 cells in dose-dependent manner, probably through attenuation of Aβ-induced oxidative and apoptotic stress. GE also significantly upregulated the enzymatic activities of catalase, superoxide dismutase, and glutathione peroxidase, leading to the decrease of reactive oxidation species production and apoptotic marker caspase-3 activity. In conclusion, our current data presented the first evidence that the aqueous extract of GE was capable of reducing the Aβ-induced neurodegeneration in Drosophila, possibly through inhibition of apoptosis and reduction of oxidative stress. GE aqueous extract could be developed as a promising herbal agent for neuroprotection and novel adjuvant therapies for Alzheimer's disease.

Advances in neuroprotective ingredients of medicinal herbs by using cellular and animal models of Parkinson's disease

Parkinson's disease (PD) is a multifactorial disorder, which is neuropathologically identified by age-dependent neurodegeneration of dopaminergic neurons in the substantia nigra. Development of symptomatic treatments has been partly successful for PD research, but there remain a number of inadequacies in therapeutic strategies for the disease. The pathogenesis of PD remains intricate, and the present anti-PD treatments appears to be clinically insufficient. Comprehensive research on discovery of novel drug candidates has demonstrated that natural products, such as medicinal herbs, plant extracts, and their secondary metabolites, have great potential as therapeutics with neuroprotective activity in PD. Recent preclinical studies suggest that a number of herbal medicines and their bioactive ingredients can be developed into optimum pharmaceuticals for treating PD. In many countries, traditional herbal medicines are used to prevent or treat neurodegenerative disorders, and some have been developed as nutraceuticals or functional foods. Here we focus on recent advances of the evidence-linked neuroprotective activity of bioactive ingredients of herbal origin in cellular and animal models of PD research.

Two new neuroprotective phenolic compounds from Gastrodia elata

Two new phenolic compounds 4-(4'-hydroxybenzyl) phenyl glucoside (gastrodin B, 1) and 1'-hydroxymethyl-phenyl 4-hydroxy-3-(4″-hydroxybenzyl) benzyl ether (gastrol B, 2) were isolated from the rhizomes of Gastrodia elata. Their structures were elucidated on the basis of spectroscopic data and chemical reaction. All compounds exhibited potent neuroprotective activity against H2O2-induced PC12 cell damage.

Differential Effects of Methyl-4-Phenylpyridinium Ion, Rotenone, and Paraquat on Differentiated SH-SY5Y Cells

Paraquat (PQ), a cationic nonselective bipyridyl herbicide, has been used as neurotoxicant to modulate Parkinson's disease in laboratory settings. Other compounds like rotenone (ROT), a pesticide, and 1-methyl-4-phenylpyridinium ion (MPP(+)) have been widely used as neurotoxicants. We compared the toxicity of these three neurotoxicants using differentiated dopaminergic SH-SY5Y human cells, aiming to elucidate their differential effects. PQ-induced neurotoxicity was shown to be concentration and time dependent, being mitochondrial dysfunction followed by neuronal death. On the other hand, cells exposure to MPP(+) induced mitochondrial dysfunction, but not cellular lyses. Meanwhile, ROT promoted both mitochondrial dysfunction and neuronal death, revealing a biphasic pattern. To further elucidate PQ neurotoxic mechanism, several protective agents were used. SH-SY5Y cells pretreatment with tiron (TIR) and 2-hydroxybenzoic acid sodium salt (NaSAL), both antioxidants, and N ω -nitro-L-arginine methyl ester hydrochloride (L-NAME), a nitric oxide synthase inhibitor, partially protected against PQ-induced cell injury. Additionally, 1-(2-[bis(4-fluorophenyl)methoxy]ethyl)-4-(3-phenyl-propyl)piperazine (GBR 12909), a dopamine transporter inhibitor, and cycloheximide (CHX), a protein synthesis inhibitor, also partially protected against PQ-induced cell injury. In conclusion, we demonstrated that PQ, MPP(+), and ROT exerted differential toxic effects on dopaminergic cells. PQ neurotoxicity occurred through exacerbated oxidative stress, with involvement of uptake through the dopamine transporter and protein synthesis.

Recent updates in redox regulation and free radical scavenging effects by herbal products in experimental models of Parkinson's disease

Parkinson’s disease (PD) is a complex multifactorial disease marked by extensive neuropathology in the brain with selective yet prominent and progressive loss of mid-brain dopaminergic neurons. The etiological factors involved in the development of PD are still elusive, but oxidative stress arising when reactive oxygen species (ROS) exceed amounts required for normal redox signaling is considered one of the major factors. ROS cause oxidative damage to proteins, lipids, and DNA and are one of the most prominent factors related to neurodegeneration. Pre-clinical and clinical studies clearly demonstrate the effectiveness of oxidative stress in the pathogenesis of PD. Therefore, regulation of redox signaling and inhibiting excess ROS would contribute greatly not only to extend longevity but also to ameliorate the progression of dopaminergic cell death seen in patients with PD. Several herbal products are beneficial for maintaining nerve cell function and for treating various neurodegenerative disorders by reducing oxidative stress. Here, we summarize the recent knowledge concerning promising herbs that have shown significant beneficial effects based on regulation of redox status and ROS inhibition in toxin-induced PD models.

New insights into the brain protein metabolism of Gastrodia elata-treated rats by quantitative proteomics

Gastrodia elata (tianma) is a traditional Chinese herbal medicine (TCM) often used for the treatment of cerebrovascular diseases. In this study, we investigated the effects of tianma on the brain protein metabolism by quantitative proteomics to gain evidence for a direct relationship between tianma treatment and brain functions. One-year-old rats were treated with tianma (~2.5 g/kg/day) for 3months and the brain tissue proteome was analyzed by using the iTRAQ (isobaric tag for relative and absolute quantification) technology. According to our results, the long-term treatment with tianma could modulate the brain protein metabolism at the proteome level by down-regulating the expressions of various proteins, such as Gnao1 and Dctn2, which are related to neuronal growth cone control and synaptic activities. In addition, tianma treatment also induced the up-regulation of molecular chaperons and proteins related to the misfolded protein response, like Anxa5, and also other proteins involved in Huntington's disease (HD) (e.g. Pacsin1 and Arf3). Concluding, tianma could eventually contribute to activities related to synaptic plasticity and neuro-restorative processes and thus might be a novel candidate agent for the treatment of neurodegenerative diseases by regulating the brain proteome.

Anti-Parkinsonian drug discovery from herbal medicines: what have we got from neurotoxic models?

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal medicines are used to treat Parkinson's disease (PD) in ancient medical systems in Asian countries such as India, China, Japan and Korea based on their own anecdotal or experience-based theories.

AIM OF THE REVIEW

To systematically summarize and analyze the anti-Parkinsonian activities of herbal preparations (including active compounds, herbal extracts and formulations) investigated in the neurotoxic models of PD and provide future references for basic and clinical investigations.

MATERIALS AND METHODS

All the herbal materials tested on in vitro and in vivo neurotoxic models of PD were retrieved from PubMed database by using pre-set searching strings. The relevant compounds and herbal extracts with anti-Parkinsonian activities were included and analyzed according to their chemical classifications or biological activities.

RESULTS

A total of 51 herbal medicines were analyzed. A diversity of compounds isolated from herbal materials were reported to be effective on neurotoxic models of PD by modulating multiple key events or signaling pathways implicated in the pathogenesis of PD. The main structure types of these compounds belong to catechols, stilbenoids, flavonoids, phenylpropanoids and lignans, phenylethanoid glycosides and terpenes. Although some herbal extracts and formulations have shown positive results on PD animal models, the relative compounds accounting for the effects and the underlying mechanisms remain to be further investigated.

CONCLUSIONS

Herbal medicines can be an alternative and valuable source for anti-Parkinsonian drug discovery. Compounds classified into stilbenoids, flavonoids, catechols and terpenes may be the most promising candidates for further investigation. Some well-studies compounds such as baicalein, puerarin, resveratrol, curcumin and ginsenosides deserve further consideration in clinical trials. In-depth experimental studies are still needed to evaluate the efficacy of herbal extracts and formulations in PD models.

Modulation of LPS-stimulated neuroinflammation in BV-2 microglia by Gastrodia elata: 4-hydroxybenzyl alcohol is the bioactive candidate

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Blume (Orchidaceae, GE) a traditional plant in Oriental countries is known for its enormous benefits to treat headaches, dizziness, vertigo and convulsive illnesses. In the present study, the ethnopharmacological role of GE in neuroinflammation mediated by activated microglia and the mechanisms underlying were reported.

MATERIALS AND METHODS

BV-2 microglia activated by lipopolysaccharide (LPS) was employed and the effects of GE on corresponding neuroinflammatory parameters were assessed.

RESULTS

GE extract inhibited LPS-stimulated production of inflammatory cytokines and down regulated the c-Jun NH(2)-Terminal Kinase (JNK) and nuclear factor-kappa B (NF-κB) signaling pathways, which are known to be involved in neuroinflammation. Further, inhibition of NO and iNOS by 4-hydroxybenzyl alcohol (4-HBA), one of the active constituent of GE in LPS-stimulated BV-2 cells suggest that 4-HBA might be the bioactive candidate.

CONCLUSION

GE extract and its active constituent 4-HBA could be further exploited to mitigate microglial activation and may be developed as a new therapeutic remedy in treating various neuroinflammatory diseases.