Neuroprotective effect of aqueous extract of Selaginella delicatula as evidenced by abrogation of rotenone-induced motor deficits, oxidative dysfunctions, and neurotoxicity in mice

Neuroprotective potential of Mentha piperita extract prevents motor dysfunctions in mouse model of Parkinson's disease through anti-oxidant capacities

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world. Neurodegeneration of the substantia nigra (SN) and diminished release of dopamine are prominent causes of this progressive disease. The current study aims to evaluate the protective potential of ethanolic extract of Mentha piperita (EthMP) against rotenone-mediated PD features, dopaminergic neuronal degeneration, oxidative stress and neuronal survival in a mouse model. Swiss albino male mice were assigned to five groups: control (2.5% DMSO vehicle), PD (rotenone 2.5 mg/kg), EthMP and rotenone (200mg/kg and 2.5mg/kg, respectively), EthMP (200 mg/kg), and Sinemet, reference treatment containing levodopa and carbidopa (20 mg/kg and rotenone 2.5mg/kg). Behavioral tests for motor functional deficit analysis were performed. Anti-oxidant capacity was estimated using standard antioxidant markers. Histopathology of the mid-brain for neurodegeneration estimation was performed. HPLC based dopamine level analysis and modulation of gene expression using quantitative real-time polymerase chain reaction was performed for the selected genes. EthMP administration significantly prevented the rotenone-mediated motor dysfunctions compared to PD group as assessed through open field, beam walk, pole climb down, stepping, tail suspension, and stride length tests. EthMP administration modulated the lipid peroxidation (LPO), reduced glutathione (GSH), and superoxide dismutase (SOD) levels, as well as glutathione-s-transferase (GST) and catalase (CAT) activities in mouse brain. EthMP extract prevented neurodegeneration in the SN of mice and partially maintained dopamine levels. The expression of genes related to dopamine, anti-oxidant potential and synapses were modulated in M. piperita (MP) extract treated mice brains. Current data suggest therapeutic capacities of MP extract and neuroprotective capacities, possibly through antioxidant capacities. Therefore, it may have potential clinical applications for PD management.

NLRP3 mediates the neuroprotective effects of SVHRSP derived from scorpion venom in rotenone-induced experimental Parkinson's disease model

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, scorpion is used to treat diseases with symptoms such as trembling, convulsion and dementia. Our laboratory employs patented technology to extract and purify the active single component from scorpion venom. We then utilize mass spectrometry to determine the amino acid sequence of the polypeptide and synthesize it artificially to acquire the polypeptide with a purity of 99.3%, named SVHRSP (Scorpion Venom Heat-Resistant Peptide). SVHRSP has been demonstrated to display potent neuroprotective efficacy in Parkinson's disease.

AIM OF THE STUDY

To explore the molecular mechanisms and potential molecular targets of SVHRSP-afforded neuroprotection in PD mouse models, as well as to investigate the role of NLRP3 in SVHRSP-mediated neuroprotection.

MATERIALS AND METHODS

The PD mouse model was induced by rotenone and the neuroprotective role of SVHRSP on the PD mouse model was measured using the gait test, rotarod test, the number of dopaminergic neurons, and the activation of microglia. RNA sequencing and GSEA analysis were performed to find the differentially biological pathways regulated by SVHRSP. Primary mid-brain neuron-glial cultures and NLRP3-/- mice were applied to verify the role of NLRP3 by using qRT-PCR, western blotting, enzyme-linked immunosorbent assay (ELISA) and immunostaining.

RESULTS

SVHRSP-afforded dopaminergic neuroprotection was accompanied with inhibition of microglia-mediated neuroinflammatory pathways. Importantly, depletion of microglia markedly reduced the neuroprotective efficacy of SVHRSP against rotenone-induced dopaminergic neurotoxicity in vitro. SVHRSP inhibited microglial NOD-like receptor pathway, mRNA expression and protein level of NLRP3 in rotenone PD mice. SVHRSP also reduced rotenone-induced caspse-1 activation and IL-1β maturation, indicating that SVHRSP mitigated activation of NLRP3 inflammasome. Moreover, inactivation of NLRP3 inflammasome by MCC950 or genetic deletion of NLRP3 almost abolished SVHRSP-afforded anti-inflammatory, neuroprotective effects and improvement of motor performance in response to rotenone.

CONCLUSIONS

NLRP3 mediated the neuroprotective effects of SVHRSP in rotenone-induced experimental PD model, providing additional evidence for the mechanisms of SVHRSP-afforded anti-inflammatory and neuroprotective effects in PD.

Mitochondrial dysfunction-targeting therapeutics of natural products in Parkinson's disease

Parkinson's disease (PD), the second most common neurodegenerative disease worldwide, often occurs in middle-aged and elderly individuals. The pathogenesis of PD is complex and includes mitochondrial dysfunction, and oxidative stress. Recently, natural products with multiple structures and their bioactive components have become one of the most important resources for small molecule PD drug research targeting mitochondrial dysfunction. Multiple lines of studies have proven that natural products display ameliorative benefits in PD treatment by regulating mitochondrial dysfunction. Therefore, a comprehensive search of recent published articles between 2012 and 2022 in PubMed, Web of Science, Elesvier, Wliey and Springer was carried out, focusing on original publications related to natural products against PD by restoring mitochondrial dysfunction. This paper presented the mechanisms of various kinds of natural products on PD-related mitochondrial dysfunction regulation and provided evidence that natural products are promising to be developed as drugs for PD therapeutics.

Isocyanate induces cytotoxicity via activation of phosphorylated alpha synuclein protein, nitrosative stress, and apoptotic pathway in Parkinson's Disease model-SHSY-5Y cells

BACKGROUND

Neurotoxic disorders account for a significant portion of the diseases that influence the worldwide disease burden. Parkinson's disease is one such disease that is linked with environmental toxin exposure. Isocyanates are a highly reactive industrial intermediate used widely in manufacturing plastic products, paints, etc. This study aims to delineate the neurotoxic potential of isocyanate in Parkinson's cell model-SHSY-5Y cells.

METHODOLOGY

SHSY-5Y cells were treated with isocyanate analogue (N succinimidyl N methyl carbamate) in time and dose dependant manner. Different parameters were assessed like protein expression, nitrosative stress level, antioxidant enzymes level and apoptosis.

RESULTS

Our findings demonstrate that dose- and time-dependent isocyanate exposure increases reactive nitrogen species and decreases the glutathione, SOD, and catalase levels. Further, increased phosphorylated alpha-synuclein protein and activation of caspase 3 exert cytotoxicity in SHSY-5Y cells.

CONCLUSION

Our research reveals that widely used isocyanate induces cytotoxicity, apoptosis, nitrosative stress, and protein dysfunction, which might constitute a potential mechanism of neurodegeneration in Parkinsonism.

Medicinal pteridophytes: ethnopharmacological, phytochemical, and clinical attributes

Background

Almost from the very beginning of human existence, man has been interacting with plants. Throughout human history, plants have provided humans with basic needs such as sustenance, firewood, livestock feed, and wood. The world has approximately 3 million vascular plants. The treatment of primary health problems is provided primarily by traditional medicines by around 80% of the world's population. Compared to other vascular plants, pteridophytes remain underexplored in ethnobotanical aspects, despite being regarded as a valuable component of healthcare for centuries. As an alternative medicine, pteridophytes are being investigated for their pharmacological activity. Almost 2000 years ago, humans were exploring and using plant species from this lineage because of its beneficial properties since pteridophytes were the first vascular plants.

Main body of the abstract

All popular search engines such as PubMed, Google Scholar, ScienceDirect, and Scopus were searched to retrieve the relevant literature using various search strings relevant to the topic. Pteridophytes belonging to thirty different families have been documented as medicinal plants. For instance, Selaginella sp. has been demonstrated to have numerous therapeutic properties, including antioxidative, inflammation-reducing, anti-carcinogenic, diabetes-fighting, virucidal, antibacterial, and anti-senile dementia effects. In addition, clinical trials and studies performed on pteridophytes and derived compounds are also discussed in details.

Short conclusion

This review offers a compilation of therapeutically valuable pteridophytes utilized by local ethnic groups, as well as the public.

Graphical Abstract

A novel synthetic peptide SVHRSP attenuates dopaminergic neurodegeneration by inhibiting NADPH oxidase-mediated neuroinflammation in experimental models of Parkinson's disease

Current treatment of Parkinson's disease (PD) ameliorates symptoms but fails to block disease progression. This study was conducted to explore the protective effects of SVHRSP, a synthetic heat-resistant peptide derived from scorpion venom, against dopaminergic neurodegeneration in experimental models of PD. Results showed that SVHRSP dose-dependently reduced the loss of dopaminergic neuron in the nigrostriatal pathway and motor impairments in both rotenone and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/probenecid (MPTP/p)-induced mouse PD models. Microglial activation and imbalance of M1/M2 polarization were also abrogated by SVHRSP in both models. In rotenone-treated primary midbrain neuron-glial cultures, loss of dopaminergic neuron and microglial activation were mitigated by SVHRSP. Furthermore, lipopolysaccharide (LPS)-elicited microglial activation, M1 polarization and related dopaminergic neurodegeneration in primary cultures were also abrogated by SVHRSP, suggesting that inhibition of microglial activation contributed to SVHRSP-afforded neuroprotection. Mechanistic studies revealed that SVHRSP blocked both LPS- and rotenone-induced microglial NADPH oxidase (NOX2) activation by preventing membrane translocation of cytosolic subunit p47phox. NOX2 knockdown by siRNA markedly attenuated the inhibitory effects of SVHRSP against LPS- and rotenone-induced gene expressions of proinflammatory factors and related neurotoxicity. Altogether, SVHRSP protects dopaminergic neurons by blocking NOX2-mediated microglial activation in experimental PD models, providing experimental basis for the screening of clinical therapeutic drugs for PD.

Trehalose ameliorates prodromal non-motor deficits and aberrant protein accumulation in a rotenone-induced mouse model of Parkinson's disease

Trehalose has been recently revealed as an attractive candidate to prevent and modify Parkinson's disease (PD) progression by regulating autophagy; however, studies have only focused on the reduction of motor symptoms rather than the modulation of disease course from prodromal stage. This study aimed to evaluate whether trehalose has a disease-modifying effect at the prodromal stage before the onset of a motor deficit in 8-week-old male C57BL/6 mice exposed to rotenone. We found significant decrease in tyrosine hydroxylase immunoreactivity in the substantia nigra and motor dysfunction after 2 weeks rotenone treatment. Mice exposed to rotenone for a week showed an accumulation of protein aggregates in the brain and prodromal non-motor deficits, such as depression and olfactory dysfunction, prior to motor deficits. Trehalose significantly improved olfactory dysfunction and depressive-like behaviors and markedly reduced α-synuclein and p62 deposition in the brain. Trehalose further ameliorated motor impairment and loss of nigral tyrosine hydroxylase-positive cells in rotenone-treated mice. We demonstrated that prodromal non-motor signs in a rotenone-induced PD mouse model are associated with protein aggregate accumulation in the brain and that an autophagy inducer could be valuable to prevent PD progression from prodromal stage by regulating abnormal protein accumulation.

An overview on therapeutic and medicinal potential of poly-hydroxy flavone viz. Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone for management of Alzheimer's and Parkinson's diseases: a critical analysis on mechanistic insight

Neurodegenerative disorders occur when nerve cells in the brain or peripheral nervous system partial or complete fail in their functions and sometimes even die due to some injuries or aging. Neurodegenerative disorders such as Alzheimer's Disease (AD) and Parkinson's Disease (PD), have been majorly resulted due to degeneration of neurons and neuroinflammation progressively. There are many similarities that correlates both AD and PD on a cellular and sub-cellular level. Therefore, a hope for therapeutic advancement for simultaneous upgradation in both the diseases are directly depending on the discovery of common mechanism at molecular and cellular level. Recent and past evidences from scientific literature supporting the efficacy of plants flavonoids in treatment and protection of both AD and PD. Further, dietary flavones, specially Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone gains recently much more attention for producing many health beneficiary effects including neuroprotection. Despite of these evidence a detailed updated overview of neuroprotective effects against both AD and PD by Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone are still missing. In this context several published studies were assessed by using various online electronic search engines/databases to meet the objective from 1981 to 2021 (Approx. 224). Therefore, present review was designed to deliver the detailed description on these flavones including therapeutic benefits in AD, PD and other CNS complications with critical analysis on underlying mechanisms.

Using Rotenone to Model Parkinson's Disease in Mice: A Review of the Role of Pharmacokinetics

Rotenone is a naturally occurring toxin that inhibits complex I of the mitochondrial electron transport chain. Several epidemiological studies have shown an increased risk of Parkinson's disease (PD) in individuals exposed chronically to rotenone, and it has received great attention for its ability to reproduce many critical features of PD in animal models. Laboratory studies of rotenone have repeatedly shown that it induces in vivo substantia nigra dopaminergic cell loss, a hallmark of PD neuropathology. Additionally, rotenone induces in vivo aggregation of α-synuclein, the major component of Lewy bodies and Lewy neurites found in the brain of PD patients and another hallmark of PD neuropathology. Some in vivo rotenone models also reproduce peripheral signs of PD, such as reduced intestinal motility and peripheral α-synuclein aggregation, both of which are thought to precede classical signs of PD in humans, such as cogwheel rigidity, bradykinesia, and resting tremor. Nevertheless, variability has been noted in cohorts of animals exposed to the same rotenone exposure regimen and also between cohorts exposed to similar doses of rotenone. Low doses, administered chronically, may reproduce PD symptoms and neuropathology more faithfully than excessively high doses, but overlap between toxicity and parkinsonian motor phenotypes makes it difficult to separate if behavior is examined in isolation. Rotenone degrades when exposed to light or water, and choice of vehicle may affect outcome. Rotenone is metabolized extensively in vivo, and choice of route of exposure influences greatly the dose used. However, male rodents may be capable of greater metabolism of rotenone, which could therefore reduce their total body exposure when compared with female rodents. The pharmacokinetics of rotenone has been studied extensively, over many decades. Here, we review these pharmacokinetics and models of PD using this important piscicide.

Can Cranberry Juice Protect against Rotenone-Induced Toxicity in Rats?

The high polyphenols content of cranberry accounts for its strong antioxidant activity underlying the beneficial health effects of this fruit. Rotenone (ROT) is a specific inhibitor of mitochondrial complex I in the brain which leads to the generation of oxidative stress. To date, there are few data indicating that toxicity of ROT is not limited to the brain but can also affect other tissues. We aimed to examine whether ROT-induced oxidative stress could be counteracted by cranberry juice not only in the brain but also in the liver and kidney. Wistar rats were given the combined treatment with ROT and cranberry juice (CJ) for 35 days. Parameters of antioxidant status were determined in the organs. ROT enhanced lipid peroxidation solely in the brain. The increase in the DNA damage was noticed in all organs examined and in leukocytes. The beneficial effect of CJ on these parameters appeared only in the brain. Additionally, CJ decreased the activity of serum hepatic enzymes. The effect of CJ on antioxidant enzymes was not consistent, however, in some organs, CJ reversed changes evoked by ROT. Summing up, ROT can cause oxidative damage not only in the brain but also in other organs. CJ demonstrated a protective effect against ROT-induced toxicity.

Reversal effect of Solanum dasyphyllum against rotenone-induced neurotoxicity

We earlier reported the protective effect of Solanum dasyphyllum against cyanide neurotoxicity. In furtherance to this, we investigated the protective effect of S. dasyphyllum against rotenone, a chemical toxin that causes brain-related diseases. Mitochondria fraction obtained from the brain of male Wistar rats was incubated with various solvents (hexane, dichloromethane, ethylacetate, and methanol) extracts of S. dasyphyllum before rotenone exposure. Mitochondria respiratory enzymes (MRE) were evaluated along with markers of oxidative stress. The inhibition of MRE by rotenone was reversed by treatment with various fractions of S. dasyphyllum. The oxidative stress induced by rotenone was also reversed by fractions of S. dasyphyllum. In addition, the ethylacetate fraction of S. dasyphyllum was most potent against rotenone-induced neurotoxicity. In conclusion, S. dasyphyllum is rich in active phytochemicals that can prevent some neurotoxic effects of rotenone exposure. Further study can be done in an in vivo model to substantiate our results.

Comparison of Chemical Composition and Biological Activities of Eight Selaginella Species

Selaginella P. Beauv. is a group of vascular plants in the family Selaginellaceae Willk., found worldwide and numbering more than 700 species, with some used as foods and medicines. The aim of this paper was to compare methanolic (MeOH) and dichloromethane (DCM) extracts of eight Selaginella species on the basis of their composition and biological activities. Six of these Selaginella species are underinvestigated. Using ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) analysis, we identified a total of 193 compounds among the tested Selaginella species, with flavonoids predominating. MeOH extracts recovered more constituents that were detected, including selaginellins, the occurrence of which is only typical for this plant genus. Of all the tested species, Selaginella apoda contained the highest number of identified selaginellins. The majority of the compounds were identified in S. apoda, the fewest compounds in Selaginella cupressina. All the tested species demonstrated antioxidant activity using oxygen radical absorption capacity (ORAC) assay, which showed that MeOH extracts had higher antioxidant capacity, with the half maximal effective concentration (EC₅₀) ranging from 12 ± 1 (Selaginella myosuroides) to 124 ± 2 (Selaginella cupressina) mg/L. The antioxidant capacity was presumed to be correlated with the content of flavonoids, (neo)lignans, and selaginellins. Inhibition of acetylcholinesterase (AChE) was mostly discerned in DCM extracts and was only exhibited in S. myosuroides, S. cupressina, Selaginella biformis, and S. apoda extracts with the half maximal inhibitory concentration (IC₅₀) in the range of 19 ± 3 to 62 ± 1 mg/L. Substantial cytotoxicity against cancer cell lines was demonstrated by the MeOH extract of S. apoda, where the ratio of the IC₅₀ HEK (human embryonic kidney) to IC₅₀ HepG2 (hepatocellular carcinoma) was 7.9 ± 0.2. MeOH extracts inhibited the production of nitrate oxide and cytokines in a dose-dependent manner. Notably, S. biformis halved the production of NO, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 at the following concentrations: 105 ± 9, 11 ± 1, and 10 ± 1 mg/L, respectively. Our data confirmed that extracts from Selaginella species exhibited cytotoxicity against cancer cell lines and AChE inhibition. The activity observed in S. apoda was the most promising and is worth further exploration.

Seladelicatulasine A-G, C27 steroidal glycosides with cholinesterase inhibitory activities from Selaginella delicatula

Seven undescribed C₂₇ steroidal glycosides, Seladelicatulasine A-G, including six cholestanol glycosides and one spirostanol glycoside, were isolated from Selaginella delicatula. Their structures were elucidated by 1D/2D NMR spectra and HRESIMS analyses. The absolute configurations of the sugars were determined by enzymatic hydrolysis and GC/MS analyses. These cholestanol glycosides were isolated from the family Selaginellaceae for the first time. Seladelicatulasine F is characterized as a rare B-5,6-secosteroid. In addition, all the compounds were evaluated for their inhibitory activities against cholinesterase (AChE/BChE) and monoamine oxidase (MAO-A/MAO-B). These steroidal glycosides displayed selective inhibition activities on cholinesterase. Seladelicatulasine A, B and E inhibited the AChE activity with IC₅₀ values of 0.31, 0.09, and 0.04 μM, respectively. Seladelicatulasine A and F showed the strongest inhibition activity on BChE with IC₅₀ values of 0.37 and 0.65 μM, respectively.

Effect of Curcumin on Protein Damage Induced by Rotenone in Dopaminergic PC12 Cells

Oxidative stress is considered to be a key factor of the pathogenesis of Parkinson's disease, a multifactorial neurodegenerative disorder characterized by reduced dopaminergic neurons in the substantia nigra pars compacta and accumulated protein aggregates. Rotenone is a worldwide-used pesticide that induces the most common features of Parkinson's by direct inhibition of the mitochondrial complex I. Rotenone-induced Parkinson's models, as well as brain tissues from Parkinson's patients, are characterized by the presence of both lipid peroxidation and protein oxidation markers resulting from the increased level of free radical species. Oxidation introduces several modifications in protein structure, including carbonylation and nitrotyrosine formation, which severely compromise cell function. Due to the link existing between oxidative stress and Parkinson's disease, antioxidant molecules could represent possible therapeutic tools for this disease. In this study, we evaluated the effect of curcumin, a natural compound known for its antioxidant properties, in dopaminergic PC12 cells treated with rotenone, a cell model of Parkinsonism. Our results demonstrate that the treatment of PC12 cells with rotenone causes severe protein damage, with formation of both carbonylated and nitrotyrosine-derived proteins, whereas curcumin (10 µM) co-exposure exerts protective effects by reducing the levels of oxidized proteins. Curcumin also promotes proteasome activation, abolishing the inhibitory effect exerted by rotenone on this degradative system.

An Overview of Crucial Dietary Substances and Their Modes of Action for Prevention of Neurodegenerative Diseases

Neurodegenerative diseases, namely Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis are becoming one of the main health concerns due to the increasing aging of the world's population. These diseases often share the same biological mechanisms, including neuroinflammation, oxidative stress, and/or protein fibrillation. Recently, there have been many studies published pointing out the possibilities to reduce and postpone the clinical manifestation of these deadly diseases through lifelong consumption of some crucial dietary substances, among which phytochemicals (e.g., polyphenols) and endogenous substances (e.g., acetyl-L-carnitine, coenzyme Q10, n-3 poysaturated fatty acids) showed the most promising results. Another important issue that has been pointed out recently is the availability of these substances to the central nervous system, where they have to be present in high enough concentrations in order to exhibit their neuroprotective properties. As so, such the aim of this review is to summarize the recent findings regarding neuroprotective substances, their mechanisms of action, as well as to point out therapeutic considerations, including their bioavailability and safety for humans.

Effects of phytochemicals on cellular signaling: reviewing their recent usage approaches

Most of the previous studies in last three decades report evidence of interactions between the different phytochemicals and the proteins involved in signal transduction pathways using in silico, in vitro, ex vivo, and in vivo analyses. However, extrapolation of these findings for clinical purposes has not been that fruitful. The efficacy of the phytochemicals in vivo studies is limited by parameters such as solubility, metabolic degradation, excretion, etc. Various approaches have now been devised to circumvent these limitations. Recently, chemical modification of the phytochemicals are demonstrated to reduce some of the limitations and improve their efficacy. Similar to traditional medicines several combinatorial phytochemical formulations have shown to be more efficient. Further, phytochemicals have been reported to be even more efficient in the form of nanoparticles. However, systematic evaluation of their efficacy, mode of action in pathway modulation, usage and associated challenges is required to be done. The present review begins with basic understanding of how signaling cascades regulate cellular response and the consequences of their dysregulation further summarizing the developments and problems associated with the dietary phytochemicals and also discuss recent approaches in strengthening these compounds in pharmacological applications. Only context relevant studies have been reviewed. Considering the limitations and scope of the article, authors do not claim inclusion of all the early and recent studies.

Protein carbonylation in dopaminergic cells exposed to rotenone

Rotenone is an environmental neurotoxin that induces degeneration of dopaminergic neurons and the most common features of Parkinson's disease in animal models. It acts as a mitochondrial complex I inhibitor that impairs cellular respiration, with consequent increase of reactive oxygen species and oxidative stress. This study evaluates the rotenone-induced oxidative damage in PC12 cells, focusing particularly on protein oxidation. The identification of specific carbonylated proteins highlighted putative alterations of important cellular processes possibly associated with Parkinson's disease. Carbonylation of ATP synthase and of enzymes acting in pyruvate and glucose metabolism suggested a failure of mechanisms ensuring cellular energy supply. Concomitant oxidation of cytoskeletal proteins and of enzymes involved in the synthesis of neuroactive molecules indicated alterations of the neurotransmission system. Carbonylation of chaperon proteins as well as of proteins acting in the autophagy-lysosome pathway and the ubiquitin-proteasome system suggested the possible formation of cytosolic unfolded protein inclusions as result of defective processes assisting recovery/degradation of damaged molecules. In conclusion, this study originally evidences specific protein targets of rotenone-induced oxidative damage, suggesting some possible molecular mechanisms involved in rotenone toxicity.

New adenine analogues and a pyrrole alkaloid from Selaginella delicatula

Phytochemical study on the n-BuOH extract of Selaginella delicatula lead to the isolation, characterization and structure elucidation of two new adenine analogues, delicatulines A (1) and B (2), one new pyrrole alkaloid (4), and five known compounds (3, 5-8). These new substances all contain an aliphatic chain in their parent nucleus, which were unusual to find in plants. In the present study, they were identified from Selaginellaceae for the first time. The structures and absolute configurations of these new compounds were determined by a combination of NMR and CD spectroscopic analyses. Compounds 1, 3 and 4 were evaluated for their inhibitory activities on HBV surface antigen and HBV DNA in HepAD38 cells. The results showed that these compounds had only weak or no inhibitive effects on HBV.

The Role of Reactive Oxygen Species in the Pathogenesis of Alzheimer's Disease, Parkinson's Disease, and Huntington's Disease: A Mini Review

Neurodegenerative diseases affect not only the life quality of aging populations, but also their life spans. All forms of neurodegenerative diseases have a massive impact on the elderly. The major threat of these brain diseases includes progressive loss of memory, Alzheimer's disease (AD), impairments in the movement, Parkinson's disease (PD), and the inability to walk, talk, and think, Huntington's disease (HD). Oxidative stress and mitochondrial dysfunction are highlighted as a central feature of brain degenerative diseases. Oxidative stress, a condition that occurs due to imbalance in oxidant and antioxidant status, has been known to play a vital role in the pathophysiology of neurodegenerative diseases including AD, PD, and HD. A large number of studies have utilized oxidative stress biomarkers to investigate the severity of these neurodegenerative diseases and medications are available, but these only treat the symptoms. In traditional medicine, a large number of medicinal plants have been used to treat the symptoms of these neurodegenerative diseases. Extensive studies scientifically validated the beneficial effect of natural products against neurodegenerative diseases using suitable animal models. This short review focuses the role of oxidative stress in the pathogenesis of AD, PD, and HD and the protective efficacy of natural products against these diseases.

Neuroprotective effect of curcumin as evinced by abrogation of rotenone-induced motor deficits, oxidative and mitochondrial dysfunctions in mouse model of Parkinson's disease

Curcumin, a natural polyphenolic compound extracted from rhizomes of Curcuma longa (turmeric), a plant in the ginger family (Zingiberaceae) has been used worldwide and extensively in Southeast Asia. Curcumin exhibited numerous biological and pharmacological activities including potent antioxidant, cardiovascular disease, anticancer, anti-inflammatory effects and neurodegenerative disorders in cell cultures and animal models. Hence, the present study was designed in order to explore the possible neuroprotective role of curcumin against rotenone induced cognitive impairment, oxidative and mitochondrial dysfunction in mice. Chronic administration of rotenone (1mg/kg i.p.) for a period of three weeks significantly impaired cognitive function (actophotometer, rotarod and open field test), oxidative defense (increased lipid peroxidation, nitrite concentration and decreased activity of superoxide dismutase, catalase and reduced glutathione level) and mitochondrial complex (II and III) enzymes activities as compared to normal control group. Three weeks of curcumin (50, 100 and 200mg/kg, p.o.) treatment significantly improved behavioral alterations, oxidative damage and mitochondrial enzyme complex activities as compared to negative control (rotenone treated) group. Curcumin treated mice also mitigated enhanced acetylcholine esterase enzyme level as compared to negative control group. We found that curcumin restored motor deficits and enhanced the activities of antioxidant enzymes suggesting its antioxidant potential in vivo. The findings of the present study conclude neuroprotective role of curcumin against rotenone induced Parkinson's in mice and offer strong justification for the therapeutic prospective of this compound in the management of PD.

Neurorestorative effects of eugenol, a spice bioactive: Evidence in cell model and its efficacy as an intervention molecule to abrogate brain oxidative dysfunctions in the streptozotocin diabetic rat

Eugenol (EU), an active principle of cloves, is also widely distributed in various other plants (eg. basil, cinnamon, etc). While its antioxidant and anti-inflammatory properties are well established, biochemical insights related to its neuromodulatory potential in diabetic conditions are not clear. In the present study, initially we investigated its potential to modulate specific biochemical responses in SHSY5Y cells under experimentally -induced hyperglycemic condition. Co-exposure of cells with EU (5-10 μM) not only enhanced the cell viability, but significantly offset glucose -associated oxidative stress (as evidenced by diminished levels of reactive oxygen species and hydroperoxides). Further EU enhanced the reduced glutathione (GSH) levels and also ameliorated the levels of 3 - nitrotyrosine and expression of HSP70. We subsequently examined its efficacy to attenuate biochemical aberrations in brain regions of a streptozotocin (STZ) diabetic rat employing an intervention approach. Brain regions of EU treated (10 mg/kg bw/d, post 6 weeks of STZ) diabetic rats showed diminished levels of oxidative markers and protein carbonyls in both cytosolic and mitochondrial fractions. EU treatment caused enhanced activities of enzymic antioxidants and diminished both GSH and total thiols. Further, activities of complex I - III, succinate dehydrogenase and citrate synthase in brain regions were also significantly restored. Interestingly, EU treatment differentially attenuated the elevated activity of acetylcholinesterase and levels of calcium in brain regions. Collectively, based on the data obtained in in vitro and in vivo models, we hypothesize that EU may be employed as an adjuvant therapeutic molecule to alleviate complications under diabetic conditions.

An update on the rotenone models of Parkinson's disease: their ability to reproduce the features of clinical disease and model gene-environment interactions

Parkinson's disease (PD) is the second most common neurodegenerative disorder that is characterized by two major neuropathological hallmarks: the degeneration of dopaminergic neurons in the substantia nigra (SN) and the presence of Lewy bodies in the surviving SN neurons, as well as other regions of the central and peripheral nervous system. Animal models have been invaluable tools for investigating the underlying mechanisms of the pathogenesis of PD and testing new potential symptomatic, neuroprotective and neurorestorative therapies. However, the usefulness of these models is dependent on how precisely they replicate the features of clinical PD with some studies now employing combined gene-environment models to replicate more of the affected pathways. The rotenone model of PD has become of great interest following the seminal paper by the Greenamyre group in 2000 (Betarbet et al., 2000). This paper reported for the first time that systemic rotenone was able to reproduce the two pathological hallmarks of PD as well as certain parkinsonian motor deficits. Since 2000, many research groups have actively used the rotenone model worldwide. This paper will review rotenone models, focusing upon their ability to reproduce the two pathological hallmarks of PD, motor deficits, extranigral pathology and non-motor symptoms. We will also summarize the recent advances in neuroprotective therapies, focusing on those that investigated non-motor symptoms and review rotenone models used in combination with PD genetic models to investigate gene-environment interactions.

Neuroprotective effects of aldehyde dehydrogenase 2 activation in rotenone-induced cellular and animal models of parkinsonism

Many studies have shown that mitochondrial aldehyde dehydrogenase 2 (ALDH2) functions as a cellular protector against oxidative stress by detoxification of cytotoxic aldehydes. Within dopaminergic neurons, dopamine is metabolized by monoamine oxidase to yield 3,4-dihydroxyphenylacetaldehyde (DOPAL) then converts to a less toxic acid product by ALDH. The highly toxic and reactive DOPAL has been hypothesized to contribute to the selective neurodegeneration in Parkinson’s disease (PD). In this study, we investigated the neuroprotective mechanism and therapeutic effect of ALDH2 in rotenone models for parkinsonism. Overexpression of wild-type ALDH2 gene, but not the enzymatically deficient mutant ALDH2*2 (E504K), reduced rotenone-induced cell death. Application of a potent activator of ALDH2, Alda-1, was effective in protecting against rotenone-induced apoptotic cell death in both SH-SY5Y cells and primary cultured substantia nigra (SN) dopaminergic neurons. In addition, intraperitoneal administration of Alda-1 significantly reduced rotenone- or MPTP-induced death of SN tyrosine hydroxylase (TH)-positive dopaminergic neurons. The attenuation of rotenone-induced apoptosis by Alda-1 resulted from decreasing ROS accumulation, reversal of mitochondrial membrane potential depolarization, and inhibition of activation of proteins related to mitochondrial apoptotic pathway. The present study demonstrates that ALDH2 plays a crucial role in maintaining normal mitochondrial function to protect against neurotoxicity and that Alda-1 is effective in ameliorating mitochondrial dysfunction and inhibiting mitochondria-mediated apoptotic pathway. These results indicate that ALDH2 activation could be a neuroprotective therapy for PD.

Oral supplements of aqueous extract of tomato seeds alleviate motor abnormality, oxidative impairments and neurotoxicity induced by rotenone in mice: relevance to Parkinson's disease

Although tomato seeds (an industrial by-product) are known to contain several bioactive compounds, studies describing their health effects are limited. Previously, we evidenced that aqueous extract of tomato seeds (TSE) markedly attenuated rotenone (ROT)-induced oxidative stress and neurotoxicity in Drosophila system. This study investigated the neuroprotective effect of TSE in a chronic ROT model of neurotoxicity in mice. Initially, we assessed the potential of oral supplements of TSE to modulate the levels of endogenous markers of oxidative stress in brain regions of mice. Subsequently, employing a co-exposure paradigm, the propensity of TSE (100 mg/kg bw, 3 weeks) to attenuate ROT-induced behavioral phenotype (gait abnormalities, anxiety-like state), oxidative dysfunctions and neurotoxicity was examined. We found that mice provided with TSE supplements exhibited progressive improvement in gait pattern and exploratory behavior. TSE markedly offset ROT-induced oxidative impairments, restored reduced glutathione levels, antioxidant defenses (superoxide dismutase, glutathione peroxidase) and protein carbonyls content in brain regions. Specifically, TSE effectively diminished ROT induced elevation in the activity levels of acetylcholinesterase and restored the dopamine levels in striatum. Interestingly, in mitochondria, TSE was able to restore the activity of mitochondrial complexes and redox state. Collectively, our findings in the chronic ROT model demonstrate the ability of TSE to alleviate behavioral phenotype, oxidative stress, mitochondrial dysfunction and neurotoxicity. Further studies in dopaminergic cell models are necessary to understand the precise molecular mechanism/s by which tomato seed bioactives offer significant neuroprotection.