Propensity of Selaginella delicatula aqueous extract to offset rotenone-induced oxidative dysfunctions and neurotoxicity in Drosophila melanogaster: Implications for Parkinson's disease

Exploring the Efficient Natural Products for the Therapy of Parkinson's Disease via Drosophila Melanogaster (Fruit Fly) Models

Parkinson's disease (PD) is a severe neurodegenerative disorder, partly attributed to mutations, environmental toxins, oxidative stress, abnormal protein aggregation, and mitochondrial dysfunction. However, the precise pathogenesis of PD and its treatment strategy still require investigation. Fortunately, natural products have demonstrated potential as therapeutic agents for alleviating PD symptoms due to their neuroprotective properties. To identify promising lead compounds from herbal medicines' natural products for PD management and understand their modes of action, suitable animal models are necessary. Drosophila melanogaster (fruit fly) serves as an essential model for studying genetic and cellular pathways in complex biological processes. Diverse Drosophila PD models have been extensively utilized in PD research, particularly for discovering neuroprotective natural products. This review emphasizes the research progress of natural products in PD using the fruit fly PD model, offering valuable insights into utilizing invertebrate models for developing novel anti-PD drugs.

Kaempferol counteracts toxicity induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in D. melanogaster: An implication of its mitoprotective activity

The current study aimed to investigate whether kaempferol (KMP), the major bioactive component of green leafy vegetables, could counteract the toxicity elicited by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in Drosophila melanogaster or not. First, we performed a dose-response curve, where adult wild-type flies were fed on diet-containing different concentrations of KMP throughout their lifespan. Afterward, flies were fed on a diet containing MPTP (500 μM) and KMP (20 and 40 μM) for 7 days. The MPTP- fed flies presented a higher mortality rate, lower emergence rate, locomotor deficits, and disruption in circadian rhythm when compared to the control. MPTP exposure induced severe oxidative stress, which was marked by reduction in thiol content, overproduction of reactive species, lipid and protein oxidation, and disruption of enzymes of antioxidant and neurotransmission pathways. MPTP also compromised the mitochondrial dynamics and respiration of flies, affecting the electron transport chain, oxidative phosphorylation, and fusion/fission processes. Besides extending per se the lifespan of flies, KMP counteracted the toxic effects of MPTP on the circadian cycle, survival, climbing, and hatching rates. KMP was also effective in restoring the activities of acetylcholinesterase (AChE) and monoamine oxidase (MAO) enzymes, as well as in normalizing the levels of all oxidant/antioxidant markers disrupted in MPTP-fed flies. Indeed, KMP reestablished the mitochondrial functionality in MPTP- fed flies, restoring the electron transport system linked to mitochondrial complex I and II, and rescuing the mRNA transcription of genes associated with mitochondrial fusion and fission, namely OPA-1 (Optic atrophy 1) and DRP-1 (Dynamin related protein 1). Our results showed the efficacy of KMP in hindering the toxicity induced by MPTP in D. melanogaster and suggest that the mitoprotective action of flavonoid may be boosting its anti-parkinsonism activity in the model. Besides, the study showed that wild-type strains of D. melanogaster proved to be reproducible in vivo model to mimic parkinsonian phenotypes through exposure to the neurotoxin MPTP.

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

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.

Diet with Low Molecular Weight Chitosan exerts neuromodulation in Rotenone induced Drosophila model of Parkinson's disease

Rotenone (ROT) is well known pesticide been used in agriculture due to its low cost and rapid action. This has also been widely used to establish Parkinson's disease (PD) models in rodents. Here we have evaluated the role of well established potent molecule 'Low Molecular Weight Chitosan (LMWC)' against ROT induced neurotoxicity in Drosophila melanogaster. Male adult flies (8-10 days) were induced for neurotoxicity using ROT (500 μM) and treated with LMWC (5 & 10 mg/mL basal media) during 7 days experiment. Subsequently, neurodegenerative and behavioural parameters were assessed. As a result, flies exposed to ROT alone showed decreased locomotor behaviour in negative geotaxis and open-field studies and had a higher incidence of mortality compared to control group. These effects were accompanied by decrease in dopamine level, ETC complexes and increase in reactive oxygen species (ROS) production and cholinergic activities in head and body of the flies, suggesting ROT was able to induce oxidative stress. Co-exposure of LMWC reversed the ROT induced locomotor impairment, exploratory deficits and changes the biochemical parameters to normal level and increased the survival rate to 16 days. Thus, we suggested LMWC may be considered as better supplement in the prevention and management of Parkinson's disease.

Hesperidin modulates the rhythmic proteomic profiling in Drosophila melanogaster under oxidative stress

The circadian clock regulates vital aspects of physiology including protein synthesis and oxidative stress response. In this investigation, we performed a proteome-wide scrutiny of rhythmic protein accrual in Drosophila melanogaster on exposure to rotenone, rotenone + hesperidin and hesperidin in D. melanogaster. Total protein from fly samples collected at 6 h intervals over the 24 h period was subjected to two-dimensional gel electrophoresis and mass spectrometry. Bioinformatics tool, Protein ANalysis THrough Evolutionary Relationships classification system was used to the determine the biological processes of the proteins of altered abundance. Conspicuous variations in the proteome (151 proteins) of the flies exposed to oxidative stress (by rotenone treatment) and after alleviating oxidative stress (by hesperidin treatment) were observed during the 24 h cycle. Significantly altered levels of abundance of a wide variety of proteins under oxidative stress (rotenone treatment) and under alleviation of oxidative stress (rotenone + hesperidin treatment) and hesperidin (alone) treatment were observed. These proteins are involved in metabolism, muscle activity, heat shock response, redox homeostasis, protein synthesis/folding/degradation, development, ion-channel/cellular transport, and gustatory and olfactory function of the flies. Our data indicates that numerous cellular processes are involved in the temporal regulation of proteins and widespread modulations happen under rotenone treatment and, action of hesperidin could also be seen on these categories of proteins.

Modulation of dopamine metabolizing enzymes and antioxidant status by Capsicum annuum Lin in rotenone-intoxicated rat brain

Rotenone is a natural pesticide and environmental neurotoxin which mimics key aspects of Parkinson's disease. This study evaluated the effect of ethyl acetate extract of Capsicum annuum L. (C. annuum) in rotenone-intoxicated rats. Oral doses of C. annuum extract (50, 100 & 200 mg kg-1) and rotenone (2 mg kg-1 i.p.) were co-administered for 25 days during which rearing behavior was monitored. Biochemical alterations in the levels of tyrosine hydroxylase (TH), monoamine oxidase (MAO), superoxide dismutase (SOD) as well as reduced and oxidized glutathione (GSH) were estimated. Decrease in rearing behavior resulting from rotenone exposure was ameliorated by 200 mg kg-1 of C. annuum. Furthermore, rotenone exposure significantly (P < 0.05) decreased TH and increased MAO levels respectively. Impaired brain antioxidant capacity, typified by significantly (P < 0.05) decreased GSH redox status and SOD levels were also observed in rotenone-treated rats. However, co-administration of C. annuum ameliorated rotenone-induced derangements and potentiated the effect of levodopa. These results taken together suggests that C. annuum protects against rotenone-induced neurotoxicity by modulating dopamine metabolism and GSH redox status in rat brain.

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.

Phytochemicals from fern species: potential for medicine applications

Ferns are an important phytogenetic bridge between lower and higher plants. Historically they have been used in many ways by humans, including as ornamental plants, domestic utensils, foods, and in handicrafts. In addition, they have found uses as medicinal herbs. Ferns produce a wide array of secondary metabolites endowed with different bioactivities that could potentially be useful in the treatment of many diseases. However, there is currently relatively little information in the literature on the phytochemicals present in ferns and their pharmacological applications, and the most recent review of the literature on the occurrence, chemotaxonomy and physiological activity of fern secondary metabolites was published over 20 years ago, by Soeder (Bot Rev 51:442-536, 1985). Here, we provide an updated review of this field, covering recent findings concerning the bioactive phytochemicals and pharmacology of fern species.

Influence of Quercetin in the Temporal Regulation of Redox Homeostasis in Drosophila melanogaster

Numerous biological processes are governed by the biological clock. Studies using Drosophila melanogaster (L.) are valuable that could be of importance for their effective applications on rodent studies. In this study, the beneficial role of quercetin (a flavonoid) on H2O2 induced stress in D. melanogaster was investigated. D. melanogaster flies were divided into four groups (group I - control, group II - H2O2 (acute exposure), group III - quercetin, and group IV - quercetin + H2O2 treated). Negative geotaxis assay, oxidative stress indicators (protein carbonyls, thiobarbituric reactive substances [TBARS]), and antioxidants (superoxide dismutase [SOD], catalase [CAT], glutathione-S-transferase [GST], glutathione peroxidase, and reduced glutathione [GSH]) were measured at 4 h intervals over 24 h and temporal expression of heat shock protein-70 (Hsp70), Upd1 (homolog of IL-6 in Drosophila), and nitric oxide synthase (Nos) was analyzed by Western blotting. Groups II and IV showed altered biochemical rhythms (compared with controls). Decreased mesor values of negative geotaxis, SOD, CAT, GST, and GSH were noticed in H2O2, increased mesor of oxidative stress indicators (TBARS and protein carbonyl content) and a reversibility of the rhythmic characteristics were conspicuous after quercetin treatment. The expression levels of Hsp70, Upd1, and Nos were noticeably maximum at 04:00. Significant elevation of expression by H2O2 was nearly normalized by quercetin treatment. The possible mechanism by which quercetin modulates oxidant-antioxidant imbalance under oxidative stress could be ascribed to the modulation of the rhythmic properties. Our results will be helpful to understand the molecular interlink between circadian rhythm and oxidative stress mechanism.

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.

20C, a bibenzyl compound isolated from Gastrodia elata, protects PC12 cells against rotenone-induced apoptosis via activation of the Nrf2/ARE/HO-1 signaling pathway

AIM

Our preliminary study shows that a bibenzyl compound isolated from Gastrodia elata, 2-[4-hydroxy-3-(4-hydroxybenzyl)benzyl]-4-(4-hydroxybenzyl)phenol (designated 20C), protects PC12 cells against H2O2-induced injury. In this study we investigated whether 20C exerted neuroprotective action in a cell model of Parkinson's disease.

METHODS

A cell model of Parkinson's disease was established in PC12 cells by exposure to rotenone (4 μmol/L) for 48 h. Cell viability and apoptosis were assessed, and intracellular ROS level and the mitochondrial membrane potential (MMP) were detected. The expression of apoptosis-related proteins Bax, Bcl-2, cytochrome c, cleaved caspase-3, and oxidative stress-related proteins Nrf2, HO-1 and NQO1 were examined using Western blotting. The mRNA levels of HO-1 and NQO1 were determined with RT-PCR. The nuclear translocation of Nrf2 was observed with immunofluorescence staining.

RESULTS

Treatment with rotenone significantly increased the number of apoptotic cells, accompanied by marked increases in the Bax/Bcl-2 ratio, cytochrome c release and caspase-3 activation. Rotenone also increased ROS accumulation, reduced MMP, and increased the nuclear translocation of Nrf2 as well as the mRNA and protein levels of the Nrf2 downstream target genes HO-1 and NQO1 in PC12 cells. Co-treatment with 20C (0.01-1 μmol/L) dose-dependently attenuated rotenone-induced apoptosis and oxidative stress in PC12 cells. Nrf2 knockdown by siRNA partially reversed the protective effects of 20C in rotenone-treated PC12 cells.

CONCLUSION

The bibenzyl compound 20C protects PC12 cells from rotenone-induced apoptosis, at least in part, via activation of the Nrf2/ARE/HO-1 signaling pathway.

Aqueous extract of tomato seeds attenuates rotenone-induced oxidative stress and neurotoxicity in Drosophila melanogaster

BACKGROUND

Tomato seeds, a major by-product from the food processing industry, constitute a rich source of bioactives and a large population consumes tomato (either in raw or cooked form). In the present study, initially we assessed the antioxidant activity of aqueous extract of tomato seeds (TSE) in selected chemical systems and further explored the neuroprotective effects of TSE utilising the rotenone (ROT) model of neurotoxicity in Drosophila.

RESULTS

Adult male flies (Oregon K) were fed TSE-enriched medium (0.1-0.2%) with or without ROT (500 µmol L(-1)) for 7 days. The propensity of TSE to protect flies against ROT-induced lethality, locomotor phenotype, oxidative stress and neurotoxicity was investigated. TSE offered marked protection against ROT-induced mortality, while survivors exhibited improved locomotor phenotype. TSE significantly attenuated ROT-induced oxidative stress, mitochondrial dysfunctions, protein carbonyls content, restored the cholinergic function and dopamine levels.

CONCLUSION

We hypothesise that the efficacy of tomato seed extract to attenuate ROT-mediated neurotoxicity may be largely related to the combined antioxidant activity of bioactives resulting in abrogation of oxidative stress and mitochondrial dysfunction. More importantly, our approach provides an experimental paradigm to rapidly assess the potential neuroprotective effects of common dietary components employing Drosophila, since it corroborates previous evidence in a mouse model.

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.

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.

Ameliorative effects of ferulic Acid against lead acetate-induced oxidative stress, mitochondrial dysfunctions and toxicity in prepubertal rat brain

Epidemiological evidence has shown higher susceptibility of Children to the adverse effects of lead (Pb) exposure. However, experimental studies on Pb-induced neurotoxicity in prepubertal (PP) rats are limited. The present study aimed to examine the propensity of ferulic acid (FA), a commonly occurring phenolic acid in staple foods (fruits, vegetables, cereals, coffee etc.) to abrogate Pb-induced toxicity. Initially, we characterized Pb-induced adverse effects among PP rats exposed to Pb acetate (1,000-3,000 ppm in drinking water) for 5 weeks in terms of locomotor phenotype, activity of 5-aminolevulinic acid dehydratase (ALAD) in the blood, blood Pb levels and oxidative stress in brain regions. Further, the ameliorative effects of oral supplements of FA (25 mg/kg bw/day) were investigated in PP rats exposed to Pb (3,000 ppm). Pb intoxication increased the locomotor activity and FA supplements partially reversed the phenotype, while the reduced ALAD activity was also restored. FA significantly abrogated the enhanced oxidative stress in cerebellum (Cb) and hippocampus (Hc) as evidenced in terms of ROS generation, lipid peroxidation and protein carbonyls. Further, Pb-mediated perturbations in the glutathione levels and activity of enzymic antioxidants were also markedly restored. Furthermore, the protective effect of FA was discernible in striatum in terms of reduced oxidative stress, restored cholinergic activity and dopamine levels. Interestingly, reduced activity levels of mitochondrial complex I in Cb and enhanced levels in Hc among Pb-intoxicated rats were ameliorated by FA supplements. FA also decreased the number of damaged cells in cornu ammonis area CA1 and dentate gyrus as reflected by the histoarchitecture of Hc among Pb intoxicated rats. Collectively, our findings in the PP model allow us to hypothesize that ingestion of common phenolics such as FA may significantly alleviate the neurotoxic effects of Pb which may be largely attributed to its ability to abrogate oxidative stress.

Neuroprotective effect of geraniol and curcumin in an acrylamide model of neurotoxicity in Drosophila melanogaster: relevance to neuropathy

Chronic exposure of acrylamide (ACR) leads to neuronal damage in both experimental animals and humans. The primary focus of this study was to assess the ameliorative effect of geraniol, (a natural monoterpene) against ACR-induced oxidative stress, mitochondrial dysfunction and neurotoxicity in a Drosophila model and compare its efficacy to that of curcumin, a spice active principle with pleiotropic biological activity. Adult male flies (8-10 days) were exposed (7 days) to ACR (5 mM) with or without geraniol and curcumin (5-10 μM) in the medium. Both phytoconstituents significantly reduced the incidence of ACR-induced mortality, rescued the locomotor phenotype and alleviated the enhanced levels of oxidative stress markers in head/body regions. The levels of reduced glutathione (GSH) and total thiols (TSH) resulting from ACR exposure was also restored with concomitant elevation in the activities of detoxifying enzymes. Interestingly, ACR induced mitochondrial dysfunctions (MTT reduction, activities of SDH and citrate synthase enzymes) were alleviated by both phytoconstituents. While ACR elevated the activity of acetylcholinesterase in head/body regions, marked diminution in enzyme activity ensued with co-exposure to phytoconstituents suggesting their potency to mitigate cholinergic function. Furthermore, phytoconstituents also restored the dopamine levels in head/body regions. The neuroprotective effect of geraniol was comparable to curcumin in terms of phenotypic and biochemical markers. Based on our evidences in fly model we hypothesise that geraniol possess significant neuromodulatory propensity and may be exploited for therapeutic application in human pathophysiology associated with neuropathy. However, the precise mechanism/s by which geraniol offers neuroprotection needs to be investigated in appropriate neuronal cell models.

Standardized extract of Withania somnifera (Ashwagandha) markedly offsets rotenone-induced locomotor deficits, oxidative impairments and neurotoxicity in Drosophila melanogaster

Withania somnifera (Ashwagandha, WS) or Indian ginseng possesses multiple pharmacological properties which are mainly attributed to the active constituents, withanolides. Despite its extensive usage as a memory enhancer and a nerve tonic, few attempts have been made to ascertain its usage in the management of Parkinson's disease. In the present study, we investigated the neuroameliorative effects of WS in a rotenone (ROT) model of Drosophila melanogaster (Oregon-K). Initially, we ascertained the ability of WS-enriched diet (0-0.05 %) to protect against ROT induced lethality and locomotor phenotype in adult male flies. Further, employing a co-exposure paradigm, we investigated the propensity of WS to offset ROT-induced oxidative stress, mitochondrial dysfunctions and neurotoxicity. WS conferred significant protection against ROT-induced lethality, while the survivor flies exhibited improved locomotor phenotype. Biochemical investigations revealed that ROT-induced oxidative stress was significantly diminished by WS enrichment. WS caused significant elevation in the levels of reduced GSH/non-protein thiols. Furthermore, the altered activity levels of succinate dehydrogenase, MTT, membrane bound enzymes viz., NADH-cytochrome-c reductase and succinate-cytochrome-c reductase were markedly restored to normalcy. Interestingly, ROT-induced perturbations in cholinergic function and depletion in dopamine levels were normalized by WS. Taken together these data suggests that the neuromodulatory effect of WS against ROT- induced neurotoxicity is probably mediated via suppression of oxidative stress and its potential to attenuate mitochondrial dysfunctions. Our further studies aim to understand the underlying neuroprotective mechanisms of WS and withanolides employing neuronal cell models.

Neuroprotective effect of Decalepis hamiltonii in paraquat-induced neurotoxicity in Drosophila melanogaster: biochemical and behavioral evidences

In this paper, we have demonstrated for the first time, the antioxidant and neuroprotective effects of Decalepis hamiltonii (Dh) root extract against paraquat (PQ)-induced oxidative stress and neurotoxicity in Drosophila melanogaster. Exposure of adult D. melanogaster (Oregon K) to PQ induced oxidative stress as evidenced by glutathione depletion, lipid peroxidation and enhanced activities of antioxidant enzymes such as catalase, superoxide dismutase as well as elevated levels of acetylcholine esterase. Pretreatment of flies by feeding with Dh extract (0.1, 0.5 %) for 14 days boosted the activities of antioxidant enzymes and prevented the PQ-induced oxidative stress. Dietary feeding of Dh extract prior to PQ exposure showed a lower incidence of mortality and enhanced motor activities of flies in a negative geotaxis assay; both suggesting the neuroprotective potential of Dh. Based on the results, we contemplate that the roots of Dh might prevent and ameliorate the human diseases caused by oxidative stress. The neuroprotective action of Dh can be attributed to the antioxidant constituents while the precise mechanism of its action needs further investigations.

Ameliorative effect of Sida cordifolia in rotenone induced oxidative stress model of Parkinson's disease

Present study focused on the evaluation of aqueous extract of Sida cordifolia (AESC), and its different fractions; hexane (HFSC), chloroform (CFSC) and aqueous (AFSC), against rotenone induced biochemical, neurochemical, histopathological and behavioral alterations in a rat model of Parkinson's disease (PD). An estimation of the level of thiobarbituric acid reactive substances (TBARS), glutathione (GSH) and catalase (CAT) along with superoxide anion generation (SAG) in different brain regions (cortex, midbrain and cerebellum) was carried out to assess biochemical changes. Behavioral evaluation tests (catalepsy, rearing behavior and posture instability) and neurochemical estimations (norepinephrine, dopamine and serotonin level) along with histopathological evaluations of different brain regions were also performed. The varying doses (50, 100, 250mg/kg; p.o.) of different test treatments (AESC, HFSC, CFSC and AFSC) were co-administered along with rotenone (2mg/kg; s.c.), for a period of 35 days to rats of various groups and compared with rotenone per se (negative control) and l-deprenyl (positive control; 10mg/kg; p.o.) treated groups for the above mentioned parameters. The increase in catalepsy and posture instability along with decrease in rearing behavior observed due to rotenone treatment was significantly attenuated by co-treatment with varying doses of AESC and AFSC. Results of the histopathological studies of different brain regions of rats showed eosinophilic lesions in the mid brain region due to rotenone treatment. The eosinophilic lesions were significantly attenuated in co-treated groups of AESC-100mg/kg and AFSC-100mg/kg. Rotenone induced oxidative damage, revealed by increased level of TBARS, SAG and decreased level of GSH and CAT in mid brain region of rats, was attenuated by the co-treatment of AESC and AFSC. The rotenone induced decrease of dopamine level in the midbrain region of rats was also attenuated by co-treatment of AESC-100mg/kg and AFSC-100mg/kg. The maximum effect in all the above activities was observed in AFSC (100mg/kg) treated group, which was comparable to l-deprenyl treated group. The HFSC and CFSC co-treatment failed to show significant attenuation of rotenone induced damage. These results indicate the possible therapeutic potential of most polar fraction of AESC i.e. AFSC in PD by virtue of its antioxidative actions.

p38(MAPK)/p53-Mediated Bax induction contributes to neurons degeneration in rotenone-induced cellular and rat models of Parkinson's disease

Rotenone is an environmental neurotoxin that induces degeneration of dopaminergic (DA) neurons in substantia nigra pars compacta (SNpc), which ultimately results in parkinsonism, but the molecular mechanisms of selective degeneration of nigral DA neurons are not fully understood. In the present study, we investigated the induction of p38(MAPK)/p53 and Bax in SNpc of Lewis rats after chronic treatment with rotenone and the contribution of Bax to rotenone-induced apoptotic commitment of differentiated PC12 cells. Lewis rats were subcutaneously treated with rotenone (1.5mg/kg) twice a day for 50days and the loss of tyrosine hydroxylase (THase), motor function impairment, and expression of p38(MAPK), P-p38(MAPK), p53, and Bax were assessed. After differentiated PC cells were treated with rotenone (500nM) for 6-36h, protein levels of p38(MAPK) and P-p38(MAPK), p53 nuclear translocation, Bax induction and cell death were measured. The results showed that rotenone administration significantly reduced motor activity and caused a loss of THase immunoreactivity in SNpc of Lewis rats. The degeneration of nigral DA neurons was accompanied by the increases in p38(MAPK), P-p38(MAPK), p53, and Bax protein levels. In cultured PC12 cells, rotenone also induced an upregulation of p38(MAPK), P-p38(MAPK), p53 and Bax. Pharmacological inhibition of p38(MAPK) with SB203580 (25μM) blunted rotenone-induced cell apoptosis. Treatment with SB203580 prevented the p53 nuclear translocation and upregulation of Bax. Inhibition of p53 with pifthrin-alpha or Bax with siRNAs significantly reduced rotenone-induced Bax induction and apoptotic cell death. These results suggest that the p38(MAPK)/p53-dependent induction of Bax contributes to rotenone's neurotoxicity in PD models.

Neuroprotective efficacy of eugenol and isoeugenol in acrylamide-induced neuropathy in rats: behavioral and biochemical evidence

The primary objective of this investigation was to assess the neuroprotective efficacy of spice active principles namely Eugenol (Eug) and isoeugenol (IE) in an acrylamide (ACR) neuropathy model in rats. In the present study, ACR administration (50 mg/kg bw, i.p. 3 times/week) for 5 weeks to growing rats caused typical symptoms of neuropathy. We found that treatment of ACR rats with spice active principles (10 mg/kg bw, for 5 weeks) caused marked improvement in gait score and responses in a battery of behavioral tests. Terminally, both spice active principles markedly attenuated ACR-induced markers of oxidative stress viz., reactive oxygen species (ROS), malondialdehyde (MDA) and nitric oxide (NO) in sciatic nerve (SN) as well as brain regions (cortex Ct, cerebellum Cb). Treatment with Eug restored the reduced glutathione levels in SN and brain regions. Interestingly, both spice active principles effectively diminished ACR-induced elevation in cytosolic calcium levels and acetylcholinesterase activity in SN and Ct. Further, the diminished activity of ATPase among ACR rats was enhanced in SN and restored in brain regions. Furthermore, Eug treatment significantly offset ACR-induced depletion in dopamine levels in brain regions. Collectively our findings suggest the propensity of these spice active principles to attenuate ACR-induced neuropathy. Further studies are necessary to understand the precise molecular mechanism/s by which these spice active principles attenuate neuropathy. Nevertheless, our data clearly demonstrate the beneficial effects of spice active principles in ACR-induced neuropathy in rats and suggest their possible therapeutic usage as an adjuvant in the management of other forms of neuropathy in humans.

Evidence of acrylamide induced oxidative stress and neurotoxicity in Drosophila melanogaster - its amelioration with spice active enrichment: relevance to neuropathy

Acrylamide (ACR) intoxication in its monomeric form leads to neuronal damage in both experimental animals and humans. Oxidative stress is one of the principle mechanisms related to the neurotoxicity of ACR exposure. Hence, the present study aimed to recapitulate the potential of ACR to cause oxidative stress and neurotoxic effects in Drosophila melanogaster. Exposure of adult male flies (Oregon K strain) to ACR (1-10 mM, 7 d) in the diet resulted in a concentration and time dependent mortality, while the survivors exhibited significant locomotor deficits. Further, ACR exposure (1-5 mM, 3 d) caused robust oxidative stress as evidenced by markedly elevated levels of reactive oxygen species and hypdroperoxides in head/body regions. Enhanced lipid peroxidation, perturbations in the activities of antioxidant enzymes accompanied with depletion of reduced glutathione levels in head region at high concentrations suggested induction of oxidative stress. Further, marked diminution in the activities of complexes I-III, Succinic dehydrogenase, with concomitant reduction in MTT suggested the propensity of ACR to impair mitochondrial function. Furthermore, ACR-induced neurotoxic effects were discernible in terms of diminished ATPase activity, enhanced activity of acetylcholinesterase and dopamine depletion. In a satellite study, employing a co-exposure paradigm, we tested the propensity of spice actives namely eugenol (EU) and isoeugenol (IE) to ameliorate ACR-induced neurotoxicity. EU/IE enriched diet offered marked protection against ACR-induced mortality, locomotor dysfunctions and oxidative stress. Furthermore, the spice actives prevented the depletion of reduced GSH levels, maintained the activity of AChE enzyme and dopamine levels in head region. Collectively, these findings clearly demonstrate that ACR induced neurotoxicity in Drosophila may be mediated through oxidative stress mechanisms and the potential of spice actives to abrogate the condition. These data suggest that Drosophila may serve as a suitable model to understand the possible mechanism/s associated with ACR associated neuropathy.