Holothuria scabra extracts exhibit anti-Parkinson potential in C. elegans: A model for anti-Parkinson testing

Nicotine-mediated therapy for Parkinson's disease in transgenic Caenorhabditis elegans model

Parkinson's disease resultant in the degeneration of Dopaminergic neurons and accumulation of α-synuclein in the substantia nigra pars compacta. The synthetic therapeutics for Parkinson's disease have moderate symptomatic benefits but cannot prevent or delay disease progression. In this study, nicotine was employed by using transgenic Caenorhabditis elegans Parkinson's disease models to minimize the Parkinson's disease symptoms. The results showed that the nicotine at 100, 150, and 200 μM doses reduced degeneration of Dopaminergic neurons caused by 6-hydroxydopamine (14, 33, and 40%), lowered the aggregative toxicity of α-synuclein by 53, 56, and 78%, respectively. The reduction in food-sensing behavioral disabilities of BZ555 was observed to be 18, 49, and 86%, respectively, with nicotine concentrations of 100 μM, 150 μM, and 200 μM. Additionally, nicotine was found to enhance Daf-16 nuclear translocation by 14, 31, and 49%, and dose-dependently increased SOD-3 expression by 10, 19, and 23%. In summary, the nicotine might a promising therapy option for Parkinson's disease.

Novel and experimental therapeutics for the management of motor and non-motor Parkinsonian symptoms

BACKGROUND  : Both motor and non-motor symptoms of Parkinson's disease (PD) have a substantial detrimental influence on the patient's quality of life. The most effective treatment remains oral levodopa. All currently known treatments just address the symptoms; they do not completely reverse the condition.

METHODOLOGY

In order to find literature on the creation of novel treatment agents and their efficacy for PD patients, we searched PubMed, Google Scholar, and other online libraries.

RESULTS

According to the most recent study on Parkinson's disease (PD), a great deal of work has been done in both the clinical and laboratory domains, and some current scientists have even been successful in developing novel therapies for PD patients.

CONCLUSION

The quality of life for PD patients has increased as a result of recent research, and numerous innovative medications are being developed for PD therapy. In the near future, we will see positive outcomes regarding PD treatment.

Exploring Caenorhabditis elegans as Parkinson's Disease Model: Neurotoxins and Genetic Implications

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, the first being Alzheimer's disease. Patients with PD have a loss of dopaminergic neurons in the substantia nigra of the basal ganglia, which controls voluntary movements, causing a motor impairment as a result of dopaminergic signaling impairment. Studies have shown that mutations in several genes, such as SNCA, PARK2, PINK1, DJ-1, ATP13A2, and LRRK2, and the exposure to neurotoxic agents can potentially increase the chances of PD development. The nematode Caenorhabditis elegans (C. elegans) plays an important role in studying the risk factors, such as genetic factors, aging, exposure to chemicals, disease progression, and drug treatments for PD. C. elegans has a conserved neurotransmission system during evolution; it produces dopamine, through the eight dopaminergic neurons; it can be used to study the effect of neurotoxins and also has strains that express human α-synuclein. Furthermore, the human PD-related genes, LRK-1, PINK-1, PDR-1, DJR-1.1, and CATP-6, are present and functional in this model. Therefore, this review focuses on highlighting and discussing the use of C. elegans an in vivo model in PD-related studies. Here, we identified that nematodes exposed to the neurotoxins, such as 6-OHDA, MPTP, paraquat, and rotenone, had a progressive loss of dopaminergic neurons, dopamine deficits, and decreased survival rate. Several studies have reported that expression of human LRRK2 (G2019S) caused neurodegeneration and pink-1, pdr-1, and djr-1.1 deletion caused several effects PD-related in C. elegans, including mitochondrial dysfunctions. Of note, the deletion of catp-6 in nematodes caused behavioral dysfunction, mitochondrial damage, and reduced survival. In addition, nematodes expressing α-synuclein had neurodegeneration and dopamine-dependent deficits. Therefore, C. elegans can be considered an accurate animal model of PD that can be used to elucidate to assess the underlying mechanisms implicated in PD to find novel therapeutic targets.

Cloning and functional characterization of the oxidative squalene cyclase gene in the deep-sea holothurian Chiridota sp

Saponins derived from holothurians have high potential medicinal value. However, the de novo synthesis of the derivatization of triterpenes is still unclear. Oxidative squalene cyclase (OSC) can catalyze 2,3-Oxidosqualene into diverse products that serve as important precursors for triterpene synthesis. However, the function of theOSCgene in Chiridotasp. hasnot been elucidated. In this study, an OSCgenederived from the deep-sea holothurianChiridota sp. was cloned and characterized functionally in a yeast system. The open reading frame of the OSC gene was 2086 bp, which encoded 695 amino acids. The Chiridota sp. OSC gene has a similarity of 66.89 % to the OSC of other holothurian species and 63.51 % to that of Acanthaster planci. The phylogenetic tree showed that the echinozoan OSCsclustered together, and then they formeda sister group to fungi and plant homologs. Chiridota sp. OSC catalyzed 2,3-Oxidosqualene into parkeol.Under high pressure, the relative enzymatic activity and stability of cyclase inChiridota sp. was higher than that in the shallow-sea holothurianStichopus horrens. The newly cloned OSC of Chiridota sp.provideskey information for the interpretation of the saponin synthesis pathway in deep-sea holothurians.

Disulfide bridge-targeted metabolome mining unravels an antiparkinsonian peptide

Peptides are a particular molecule class with inherent attributes of some small-molecule drugs and macromolecular biologics, thereby inspiring continuous searches for peptides with therapeutic and/or agrochemical potentials. However, the success rate is decreasing, presumably because many interesting but less-abundant peptides are so scarce or labile that they are likely 'overlooked' during the characterization effort. Here, we present the biochemical characterization and druggability improvement of an unprecedented minor fungal RiPP (ribosomally synthesized and post-translationally modified peptide), named acalitide, by taking the relevant advantages of metabolomics approach and disulfide-bridged substructure which is more frequently imprinted in the marketed peptide drug molecules. Acalitide is biosynthetically unique in the macrotricyclization via two disulfide bridges and a protease (AcaB)-catalyzed lactamization of AcaA, an unprecedented precursor peptide. Such a biosynthetic logic was successfully re-edited for its sample supply renewal to facilitate the identification of the in vitro and in vivo antiparkinsonian efficacy of acalitide which was further confirmed safe and rendered brain-targetable by the liposome encapsulation strategy. Taken together, the work updates the mining strategy and biosynthetic complexity of RiPPs to unravel an antiparkinsonian drug candidate valuable for combating Parkinson's disease that is globally prevailing in an alarming manner.

Citrus Flavonoid Hesperetin Inhibits α-Synuclein Fibrillogenesis, Disrupts Mature Fibrils, and Reduces Their Cytotoxicity: In Vitro and In Vivo Studies

Misfolding and subsequent fibrillogenesis of α-synuclein (αSN) significantly influence the development of Parkinson's disease (PD). This study reports the inhibitory effect of citrus flavonoid hesperetin (Hst) on αSN fibrillation. Based on thioflavin T fluorometry and atomic force microscopy studies, Hst inhibited αSN fibrillation by interfering with initial nucleation and slowing the elongation rate. Furthermore, the inhibitory effect was concentration-dependent with a half-maximal inhibitory concentration of 24.4 μM. Cytotoxicity experiments showed that 100 μM Hst significantly reduced the cytotoxicity of αSN aggregates and maintained 98.4% cell activity. In addition, Hst disassembled the preprepared αSN fibrils into smaller and less-toxic aggregates. Excitingly, supplementation with 100 μM Hst inhibited the accumulation of 36.3% αSN in NL5901 and restored the amyloid-induced reduction in NL5901 lipid abundance, extending the mean lifespan of NL5901 to 23 d. These findings could support the use of Hst as a dietary supplement to regulate αSN fibrillation and prevent the development of PD.

A Review on Natural Antioxidants for Their Role in the Treatment of Parkinson's Disease

The neurodegenerative condition known as Parkinson's disease (PD) is brought on by the depletion of dopaminergic neurons in the basal ganglia, which is the brain region that controls body movement. PD occurs due to many factors, from which one of the acknowledged effects of oxidative stress is pathogenic pathways that play a role in the development of Parkinson's disease. Antioxidants, including flavonoids, vitamins E and C, and polyphenolic substances, help to reduce the oxidative stress brought on by free radicals. Consequently, this lowers the risk of neurodegenerative disorders in the long term. Although there is currently no cure for neurodegenerative illnesses, these conditions can be controlled. The treatment of this disease lessens its symptoms, which helps to preserve the patient's quality of life. Therefore, the use of naturally occurring antioxidants, such as polyphenols, which may be obtained through food or nutritional supplements and have a variety of positive effects, has emerged as an appealing alternative management strategy. This article will examine the extent of knowledge about antioxidants in the treatment of neurodegenerative illnesses, as well as future directions for research. Additionally, an evaluation of the value of antioxidants as neuroprotective agents will be provided.

Potential Therapeutic Effects of Policosanol from Insect Wax on Caenorhabditis elegans Models of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. The standard treatments for PD focus on symptom relief rather than attempting to address the underlying degenerative processes completely. This study aimed to evaluate the potential therapeutic effects of policosanol derived from insect wax (PIW) by investigating improvements in disease symptoms represented in Caenorhabditis elegans models of PD. For our assessments, we used the following three models: NL5901, which is a transgenic model for α-synuclein aggregation; wild-type N2 induced with 6-hydroxydopamine (6-OHDA); and 6-OHDA-induced BZ555 as a model for loss of dopaminergic neurons (DNs). Specifically, we examined the effects of PIW treatment on α-synuclein aggregation, the loss of DNs, lipid abundance, and the lifespan of treated organisms. Further, we examined treatment-related changes in the levels of reactive oxygen species (ROS), malondialdehyde (MDA), adenosine triphosphate (ATP), glutathione S-transferase (GST), and superoxide dismutase (SOD), as well as the mRNA production profiles of relevant genes. A 10 µg/mL dose of PIW reduced the aggregation of α-synuclein in NL5901 and suppressed the loss of DNs in 6-OHDA-induced BZ555. Overall, PIW treatment decreased ROS and MDA levels, restored lipid abundance, and prolonged the lifespans of worms in all the three models, which may be associated with changes in the expression profiles of genes related to cell survival and oxidative stress response pathways. Our findings show that PIW alleviated the symptoms of PD in these models, possibly by regulating the stress responses initiated by injuries such as α-synuclein aggregation or 6-OHDA treatment.

Anti-Parkinson Effects of Holothuria leucospilota-Derived Palmitic Acid in Caenorhabditis elegans Model of Parkinson’s Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease which is still incurable. Sea cucumber-derived compounds have been reported to be promising candidate drugs for treating age-related neurological disorders. The present study evaluated the beneficial effects of the Holothuria leucospilota (H. leucospilota)-derived compound 3 isolated from ethyl acetate fraction (HLEA-P3) using Caenorhabditis elegans PD models. HLEA-P3 (1 to 50 µg/mL) restored the viability of dopaminergic neurons. Surprisingly, 5 and 25 µg/mL HLEA-P3 improved dopamine-dependent behaviors, reduced oxidative stress and prolonged lifespan of PD worms induced by neurotoxin 6-hydroxydopamine (6-OHDA). Additionally, HLEA-P3 (5 to 50 µg/mL) decreased α-synuclein aggregation. Particularly, 5 and 25 µg/mL HLEA-P3 improved locomotion, reduced lipid accumulation and extended lifespan of transgenic C. elegans strain NL5901. Gene expression analysis revealed that treatment with 5 and 25 µg/mL HLEA-P3 could upregulate the genes encoding antioxidant enzymes (gst-4, gst-10 and gcs-1) and autophagic mediators (bec-1 and atg-7) and downregulate the fatty acid desaturase gene (fat-5). These findings explained the molecular mechanism of HLEA-P3-mediated protection against PD-like pathologies. The chemical characterization elucidated that HLEA-P3 is palmitic acid. Taken together, these findings revealed the anti-Parkinson effects of H. leucospilota-derived palmitic acid in 6-OHDA induced- and α-synuclein-based models of PD which might be useful in nutritional therapy for treating PD.

Holothuria scabra extracts confer neuroprotective effect in C. elegans model of Alzheimer's disease by attenuating amyloid-β aggregation and toxicity

Background and aim

Alzheimer's disease (AD) is the most common aged-related neurodegenerative disorder that is associated with the toxic amyloid-β (Aβ) aggregation in the brain. While the efficacies of available drugs against AD are still limited, natural products have been shown to possess neuroprotective potential for prevention and therapy of AD. This study aimed to investigate the neuroprotective effects of H. scabra extracts against Aβ aggregation and proteotoxicity in C. elegans model of Alzheimer's diseases.

Experimental procedure

Whole bodies (WB) and body wall (BW) of H. scabra were extracted and fractionated into ethyl acetate (WBEA, BWEA), butanol (WBBU, BWBU), and ethanol (BWET). Then C. elegans AD models were treated with these fractions and investigated for Aβ aggregation and polymerization, biochemical and behavioral changes, and level of oxidative stress, as well as lifespan extension.

Results and conclusion

C. elegans AD model treated with H. scabra extracts, especially triterpene glycoside-rich ethyl acetate and butanol fractions, exhibited significant reduction of Aβ deposition. These H. scabra extracts also attenuated the paralysis behavior and improved the neurological defects in chemotaxis caused by Aβ aggregation. Immunoblot analysis revealed decreased level of Aβ oligomeric forms and the increased level of Aβ monomers after treatments with H. scabra extracts. In addition, H. scabra extracts reduced reactive oxygen species and increased the mean lifespan of the treated AD worms. In conclusion, this study demonstrated strong evidence of anti-Alzheimer effects by H. scabra extracts, implying that these extracts can potentially be applied as natural preventive and therapeutic agents for AD.

Taxonomy classification by EVISE

Alzheimer's disease, Neurodegenerative disorder, Traditional medicine, Experimental model systems, Molecular biology.

Potential of marine compounds in the treatment of neurodegenerative diseases: a review

Neurodegenerative diseases (ND) are characterized, especially, by the progressive loss of neurons, resulting in neuropsychomotor dysfunctions. Even with a high prevalence, NDs are treated with drugs that alleviate the symptoms of patients, but which develop adverse events and still do not inhibit the progression of the disease. Thus, within a new pharmacological perspective, this review aimed to verify the therapeutic potential of natural compounds of marine origin against ND. For this, an integrative review was carried out, according to the PRISMA methodology, which included steps such as: search, pre-selection and inclusion of articles. The results described revealed species such as Acaudina malpodioides, Holothuria scabra and Xylaria sp., which presented important evidence in relation to Alzheimer's, reducing the generation of ROS, presenting neuroprotective effects and reducing the concentration of Aβ peptide. Regarding Parkinson's disease (PD), another example of ND, the bioactive compounds from Holothuria scabra and Xylaria sp., showed to be able to reduce the degeneration of dopaminergic neurons, reduce the deposition of alpha synuclein and reduce the formation of Mutant Huntingtin protein (Mhtt). The other marine compounds and bioactive substances are also described in this review. In conclusion, the evaluated studies indicate that compounds of marine origin emerge as a promising source of bioactive compounds, revealing an important therapeutic potential for the treatment of ND.

Neuroprotective effects of a medium chain fatty acid, decanoic acid, isolated from H. leucospilota against Parkinsonism in C. elegans PD model

Sea cucumbers are marine organism that have long been used for food and traditional medicine in Asian countries. Recently, we have shown that ethyl acetate fraction (HLEA) of the crude extract of the black sea cucumber, Holothuria leucospilota, could alleviate Parkinsonism in Caenorhabditis elegans PD models. In this study, we found that the effective neuroprotective activity is attributed to HLEA-P1 compound chemically isolated and identified in H. leucospilota ethyl acetate. We reported here that HLEA-P1 could attenuate DAergic neurodegeneration, improve DAergic-dependent behaviors, reduce oxidative stress in 6-OHDA-induced C. elegans. In addition, HLEA-P1 reduced α-synuclein aggregation, improved behavior deficit and recovered lipid deposition in transgenic C. elegans overexpressing α-synuclein. We also found that HLEA-P1 activates nuclear localization of DAF-16 transcription factor of insulin/IGF-1 signaling (IIS) pathway. Treatment with 25 μg/ml of HLEA-P1 upregulated transcriptional activity of DAF-16 target genes including anti-oxidant genes (such as sod-3) and small heat shock proteins (such as hsp16.1, hsp16.2, and hsp12.6) in 6-OHDA-induced worms. In α-synuclein-overexpressed C. elegans strain, treatment with 5 μg/ml of HLEA-P1 significantly activated mRNA expression of sod-3 and hsp16.2. Chemical analysis demonstrated that HLEA-P1 compound is decanoic acid/capric acid. Taken together, our findings revealed that decanoic acid isolated from H. leucospilota exerts anti-Parkinson effect in C. elegans PD models by partly modulating IIS/DAF-16 pathway.

2-Butoxytetrahydrofuran and Palmitic Acid from Holothuria scabra Enhance C. elegans Lifespan and Healthspan via DAF-16/FOXO and SKN-1/NRF2 Signaling Pathways

Extracts from a sea cucumber, Holothuria scabra, have been shown to exhibit various pharmacological properties including anti-oxidation, anti-aging, anti-cancer, and anti-neurodegeneration. Furthermore, certain purified compounds from H. scabra displayed neuroprotective effects against Parkinson's and Alzheimer's diseases. Therefore, in the present study, we further examined the anti-aging activity of purified H. scabra compounds in a Caenorhabditis elegans model. Five compounds were isolated from ethyl acetate and butanol fractions of the body wall of H. scabra and characterized as diterpene glycosides (holothuria A and B), palmitic acid, bis (2-ethylhexyl) phthalate (DEHP), and 2-butoxytetrahydrofuran (2-BTHF). Longevity assays revealed that 2-BTHF and palmitic acid could significantly extend lifespan of wild type C. elegans. Moreover, 2-BTHF and palmitic acid were able to enhance resistance to paraquat-induced oxidative stress and thermal stress. By testing the compounds' effects on longevity pathways, it was shown that 2-BTHF and palmitic acid could not extend lifespans of daf-16, age-1, sir-2.1, jnk-1, and skn-1 mutant worms, indicating that these compounds exerted their actions through these genes in extending the lifespan of C. elegans. These compounds induced DAF-16::GFP nuclear translocation and upregulated the expressions of daf-16, hsp-16.2, sod-3 mRNA and SOD-3::GFP. Moreover, they also elevated protein and mRNA expressions of GST-4, which is a downstream target of the SKN-1 transcription factor. Taken together, the study demonstrated the anti-aging activities of 2-BTHF and palmitic acid from H. scabra were mediated via DAF-16/FOXO insulin/IGF and SKN-1/NRF2 signaling pathways.

Infections of Cryptococcus species induce degeneration of dopaminergic neurons and accumulation of α-Synuclein in Caenorhabditis elegans

Cryptococcosis in the central nervous system (CNS) can present with motor declines described as Parkinsonism. Although several lines of evidence indicate that dopaminergic (DA) neuron degeneration and α-synuclein accumulation contribute to the hallmark of Parkinsonism and Parkinson’s disease (PD), little is known about cryptococcal infections associated with neuronal degeneration. In this study, the effects of Cryptococcus neoformans and C. gattii infections on dopaminergic neuron degeneration, α-synuclein accumulation, and lifespan in Caenorhabditis elegans were investigated. The results showed that cryptococcal infections significantly (P<0.05) induced DA neuron degeneration similar to a selective cathecholamine neurotoxin 6-hydroxydopamine (6-OHDA) in C. elegans (BZ555 strain) when compared to mock infected controls. Cryptococcal infections also significantly (P< 0.05) induced α-synuclein aggregation in C. elegans (NL5901 strain). Moreover, lifespan of the infected worms was significantly decreased (P<0.0001). In conclusion, DA neurodegeneration and α-synuclein accumulation are associated with lifespan reduction during cryptococcal infection in C elegans.

Fucosylated Chondroitin Sulfate against Parkinson's Disease through Inhibiting Inflammation Induced by Gut Dysbiosis

Growing evidence for the importance of the gut-brain axis in Parkinson's disease (PD) has attracted researchers' interest in the possible application of microbiota-based treatment approaches. Using a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model, we looked into the prospect of treating PD with fucosylated chondroitin sulfate obtained from sea cucumbers Isostichopus badionotus (fCS-Ib). We showed that giving fCS-Ib polysaccharide orally greatly reduced the motor deficits, dopamine depletion, and alpha-synuclein increase caused by MPTP in the substantia nigra (SN). It appears that the anti-PD action of fCS-Ib polysaccharide could be attained by squelching inflammation. Glial cell hyperactivation in SN and overproduction of proinflammatory substances in serum could both be suppressed by fCS-Ib polysaccharide injection. The bacterial DNA in fresh colonic feces was submitted to 16S rRNA and untargeted metabolic analyses to confirm the participation of the microbiota-gut-brain axis in the aforementioned interpretation. The findings showed that the MPTP treatment-induced decrease in norank_f_Muribaculaceae and the increase in Staphylococcus were reversed by the administration of fCS-Ib polysaccharide. The NF-κB signaling pathway was shown to be involved in the fCS-Ib polysaccharide-induced anti-inflammation. In conclusion, our research demonstrated for the first time how fCS-Ib polysaccharide combats PD by reducing inflammation caused by gut microbial dysbiosis.

Caenorhabditis elegans as a model system to evaluate neuroprotective potential of nano formulations

The impact of neurodegenerative illnesses on society is significant, but the mechanisms leading to neuronal malfunction and death in these conditions remain largely unknown despite identifying essential disease genes. To pinpoint the mechanisms behind the pathophysiology of neurodegenerative diseases, several researchers have turned to nematode C. elegans instead of using mammals. Since C. elegans is transparent, free-living, and amenable to culture, it has several benefits. As a result, all the neurons in C. elegans can be easily identified, and their connections are understood. Human proteins linked to Neurodegeneration can be made to express in them. It is also possible to analyze how C. elegans orthologs of the genes responsible for human neurodegenerative diseases function. In this article, we focused at some of the most important C. elegans neurodegeneration models that accurately represent many elements of human neurodegenerative illness. It has been observed that studies using the adaptable C. elegans have helped us in better understanding of human diseases. These studies have used it to replicate several aspects of human neurodegeneration. A nanotech approach involves engineering materials or equipments interacting with biological systems at the molecular level to trigger physiological responses by increasing stimulation, responding, and interacting with target sites while minimizing side effects, thus revolutionizing the treatment and diagnosis of neurodegenerative diseases. Nanotechnologies are being used to treat neurological disorders and deliver nanoscale drugs. This review explores the current and future uses of these nanotechnologies as innovative therapeutic modalities in treatment of neurodegenerative diseases using C elegans as an experimental model.

Multifunctional role of natural products for the treatment of Parkinson's disease: At a glance

Natural substances originating from plants have long been used to treat neurodegenerative disorders (NDs). Parkinson's disease (PD) is a ND. The deterioration and subsequent cognitive impairments of the midbrain nigral dopaminergic neurons distinguish by this characteristic. Various pathogenic mechanisms and critical components have been reported, despite the fact that the origin is unknown, such as protein aggregation, iron buildup, mitochondrial dysfunction, neuroinflammation and oxidative stress. Anti-Parkinson drugs like dopamine (DA) agonists, levodopa, carbidopa, monoamine oxidase type B inhibitors and anticholinergics are used to replace DA in the current treatment model. Surgery is advised in cases where drug therapy is ineffective. Unfortunately, the current conventional treatments for PD have a number of harmful side effects and are expensive. As a result, new therapeutic strategies that control the mechanisms that contribute to neuronal death and dysfunction must be addressed. Natural resources have long been a useful source of possible treatments. PD can be treated with a variety of natural therapies made from medicinal herbs, fruits, and vegetables. In addition to their well-known anti-oxidative and anti-inflammatory capabilities, these natural products also play inhibitory roles in iron buildup, protein misfolding, the maintenance of proteasomal breakdown, mitochondrial homeostasis, and other neuroprotective processes. The goal of this research is to systematically characterize the currently available medications for Parkinson's and their therapeutic effects, which target diverse pathways. Overall, this analysis looks at the kinds of natural things that could be used in the future to treat PD in new ways or as supplements to existing treatments. We looked at the medicinal plants that can be used to treat PD. The use of natural remedies, especially those derived from plants, to treat PD has been on the rise. This article examines the fundamental characteristics of medicinal plants and the bioactive substances found in them that may be utilized to treat PD.

Neuroprotective effects of cannabidiol on dopaminergic neurodegeneration and α-synuclein accumulation in C. elegans models of Parkinson's disease

Parkinson disease (PD) is the second most progressive neurodegenerative disorder of the central nervous system (CNS) in the elderly, causing motor impediments and cognitive dysfunctions. Dopaminergic (DA) neuron degeneration and α-synuclein (α-Syn) accumulation in substantia nigra pars compacta (SNPc) are the major contributor to this disease. At present, the disease has no effective treatment. Many recent studies focus on identifying novel therapeutics that provide benefits to stop disease advancement in PD patients. Cannabidiol (CBD) is a cannabinoid derived from the Cannabis sativa plant and possesses anti-depressive, anti-inflammatory, and antioxidative effects. The present study aims to evaluate the neuroprotective effect of CBD in transgenic C. elegans PD models. We observed that CBD at 0.025 mM (24.66 %), 0.05 mM (52.41 %) and 0.1 mM (71.36 %) diminished DA neuron degenerations induced by 6-hydroxydopamine (6-OHDA), reduced (0.025, 27.1 %), (0.05, 38.9 %), (0.1, 51.3 %) food-sensing behavioural disabilities in BZ555, reduced 40.6 %, 56.3 %, 70.2 % the aggregative toxicity of α-Syn and expanded the nematodes' lifespan up to 11.5 %, 23.1 %, 28.8 %, dose-dependently. Moreover, CBD augmented the ubiquitin-like proteasomes 28.11 %, 43.27, 61.33 % and SOD-3 expressions by about 16.4 %, 21.2 %, 44.8 % in transgenic models. Further, we observed the antioxidative role of CBD by reducing 33.2 %, 41.4 %, 56.7 % reactive oxygen species in 6-OHDA intoxicated worms. Together, these findings supported CBD as an anti-parkinsonian drug and may exert its effects by raising lipid depositions to enhance proteasome activity and reduce oxidative stress via the antioxidative pathway.

High-Glucose Diet Attenuates the Dopaminergic Neuronal Function in C. elegans, Leading to the Acceleration of the Aging Process

Parkinson's disease (PD) is a neurodegenerative disease characterized by the selective degeneration of neurons, primarily in the substantia nigra. Environmental or exogenous factors that cause Parkinson's disease have not been sufficiently elucidated. Our study aims to investigate the causative effect of a high-glucose diet on Parkinson's disease-relevant dopaminergic neuronal system in Caenorhabditis elegans. Aging parameters were first observed by measuring the lifespan, body movement, and body sizes with and without the background of high glucose. The toxic effect of a high-glucose diet was further explored by observing the dopaminergic neurons using transgenic Pdat-1::gfp strains, BZ555, under a Zeiss microscope, and the experiments were extended by assessing dopamine-related behavioral analysis including basal slowing response and alcohol avoidance. The aggregation of the α-synucleins was also assessed by observing the NL5901 mutants. Worms fed with 250 mM glucose showed daf-2-independent regulation of aging, displaying a short lifespan (≤15 days), long body size (max. 140%), and slow movement (min. 30%, 10 bends/min). Anterior dopaminergic neurons were rapidly inactivated (70%) by a glucose-rich diet from 12 h of exposure, suggesting specific degeneration in ADE neurons. The dysregulation of neurons led to deteriorations in dopaminergic behaviors including basal slowing response (BSR). A high-glucose diet decreased dopamine synthesis (40 pg/mg vs 15 pg/mg protein) and induced α-synuclein aggregation in the muscles. Results demonstrate the potential of a high-glucose diet as a trigger of dopaminergic neuronal dysregulation conjugating aging acceleration.

Oxidation and Antioxidation of Natural Products in the Model Organism Caenorhabditiselegans

Natural products are small molecules naturally produced by multiple sources such as plants, animals, fungi, bacteria and archaea. They exert both beneficial and detrimental effects by modulating biological targets and pathways involved in oxidative stress and antioxidant response. Natural products’ oxidative or antioxidative properties are usually investigated in preclinical experimental models, including virtual computing simulations, cell and tissue cultures, rodent and nonhuman primate animal models, and human studies. Due to the renewal of the concept of experimental animals, especially the popularization of alternative 3R methods for reduction, replacement and refinement, many assessment experiments have been carried out in new alternative models. The model organism Caenorhabditis elegans has been used for medical research since Sydney Brenner revealed its genetics in 1974 and has been introduced into pharmacology and toxicology in the past two decades. The data from C. elegans have been satisfactorily correlated with traditional experimental models. In this review, we summarize the advantages of C. elegans in assessing oxidative and antioxidative properties of natural products and introduce methods to construct an oxidative damage model in C. elegans. The biomarkers and signaling pathways involved in the oxidative stress of C. elegans are summarized, as well as the oxidation and antioxidation in target organs of the muscle, nervous, digestive and reproductive systems. This review provides an overview of the oxidative and antioxidative properties of natural products based on the model organism C. elegans.

Global knowledge on the commercial sea cucumber Holothuria scabra

Holothuria scabra is one of the most intensively studied holothuroids, or sea cucumbers (Echinodermata: Holothuroidea), having been discussed in the literature since the early 19th century. The species is important for several reasons: (1) it is widely distributed and historically abundant in several shallow soft-bottom habitats throughout the Indo-Pacific, (2) it has a high commercial value on the Asian markets, where it is mainly sold as a dried product (beche-de-mer) and (3) it is the only tropical holothuroid species that can currently be mass-produced in hatcheries. Over 20 years have elapsed since the last comprehensive review on H. scabra published in 2001. Research on H. scabra has continued to accumulate, fuelled by intense commercial exploitation, and further declines in wild stocks over the entire distribution range. This review compiles data from over 950 publications pertaining to the biology, ecology, physiology, biochemical composition, aquaculture, fishery, processing and trade of H. scabra, presenting the most complete synthesis to date, including scientific papers and material published by local institutions and/or in foreign languages. The main goal of this project was to summarize and critically discuss the abundant literature on this species, making it more readily accessible to all stakeholders aiming to conduct fundamental and applied research on H. scabra, or wishing to develop aquaculture, stock enhancement and management programs across its geographic range.

Diterpene glycosides from Holothuria scabra exert the α-synuclein degradation and neuroprotection against α-synuclein-Mediated neurodegeneration in C. elegans model

ETHNOPHARMACOLOGICAL RELEVANCE

Holothuria (Metriatyla) scabra Jaeger (H. scabra), sea cucumber, is the marine organism that has been used as traditional food and medicine to gain the health benefits since ancient time. Although our recent studies have shown that crude extracts from H. scabra exhibited neuroprotective effects against Parkinson's disease (PD), the underlying mechanisms and bioactive compounds are still unknown.

AIM OF THE STUDY

In the present study, we examined the efficacy of purified compounds from H. scabra and their underlying mechanism on α-synuclein degradation and neuroprotection against α-synuclein-mediated neurodegeneration in a transgenic Caenorhabditis elegans PD model.

MATERIAL AND METHODS

The H. scabra compounds (HSEA-P1 and P2) were purified and examined for their toxicity and optimal dose-range by food-clearance and lifespan assays. The α-synuclein degradation and neuroprotection against α-synuclein-mediated neurodegeneration were determined using transgenic C. elegans model, Punc-54::α-syn and Pdat-1:: α-syn; Pdat-1::GFP, respectively, and then further investigated by determining the behavioral assays including locomotion rate, basal slowing rate, ethanol avoidance, and area-restricted searching. The underlying mechanisms related to autophagy were clarified by quantitative PCR and RNAi experiments.

RESULTS

Our results showed that HSEA-P1 and HSEA-P2 significantly diminished α-synuclein accumulation, improved motility deficits, and recovered the shortened lifespan. Moreover, HSEA-P1 and HSEA-P2 significantly protected dopaminergic neurons from α-synuclein toxicity and alleviated dopamine-associated behavioral deficits, i.e., basal slowing, ethanol avoidance, and area-restricted searching. HSEA-P1 and HSEA-P2 also up-regulated autophagy-related genes, including beclin-1/bec-1, lc-3/lgg-1, and atg-7/atg-7. RNA interference (RNAi) of these genes in transgenic α-synuclein worms confirmed that lc-3/lgg-1 and atg-7/atg-7 were required for α-synuclein degradation and DAergic neuroprotection activities of HSEA-P1 and HSEA-P2. NMR and mass spectrometry analysis revealed that the HSEA-P1 and HSEA-P2 contained diterpene glycosides.

CONCLUSION

These findings indicate that diterpene glycosides extracted from H. scabra decreases α-synuclein accumulation and protects α-synuclein-mediated DAergic neuronal loss and its toxicities via lgg-1 and atg-7.

Polystyrene nanoparticles induced neurodevelopmental toxicity in Caenorhabditis elegans through regulation of dpy-5 and rol-6

Micro- and nano- polystyrene particles have been widely detected in environment, posing potential threats to human health. This study was designed to evaluate the neurodevelopmental toxicity of polystyrene nanoparticles (NPs) in Caenorhabditis elegans (C. elegans), to screen crucial genes and investigate the underlying mechanism. In wild-type C. elegans, polystyrene NPs (diameter 50 nm) could concentration-dependently induce significant inhibition in body length, survival rate, head thrashes, and body bending, accompanying with increase of reactive oxygen species (ROS) production, lipofuscin accumulation, and apoptosis and decrease of dopamine (DA) contents. Moreover, pink-1 mutant was demonstrated to alleviate the locomotion disorders and oxidative damage induced by polystyrene NPs, indicating involvement of pink-1 in the polystyrene NPs-induced neurotoxicity. RNA sequencing results revealed 89 up-regulated and 56 down-regulated differently expressed genes (DEGs) response to polystyrene NPs (100 μg/L) exposure. Gene Ontology (GO) enrichment analysis revealed that predominant enriched DEGs were correlated with biological function of cuticle development and molting cycle. Furthermore, mutant strains test showed that the neurodevelopmental toxicity and oxidative stress responses induced by 50 nm polystyrene NPs were regulated by dpy-5 and rol-6. In general, polystyrene NPs induced obvious neurodevelopmental toxicity in C. elegans through oxidative damage and dopamine reduction. Crucial genes dpy-5 and rol-6 might participate in polystyrene NPs-induced neurodevelopmental toxicity through regulation on synthesis and deposition of cuticle collagen.

Neurorescue Effects of Frondoside A and Ginsenoside Rg3 in C. elegans Model of Parkinson's Disease

Parkinson’s disease (PD) is a currently incurable neurodegenerative disorder characterized by the loss of dopaminergic (DAergic) neurons in the substantia nigra pars compacta and α-synuclein aggregation. Accumulated evidence indicates that the saponins, especially from ginseng, have neuroprotective effects against neurodegenerative disorders. Interestingly, saponin can also be found in marine organisms such as the sea cucumber, but little is known about its effect in neurodegenerative disease, including PD. In this study, we investigated the anti-Parkinson effects of frondoside A (FA) from Cucumaria frondosa and ginsenoside Rg3 (Rg3) from Panax notoginseng in C. elegans PD model. Both saponins were tested for toxicity and optimal concentration by food clearance assay and used to treat 6-OHDA-induced BZ555 and transgenic α-synuclein NL5901 strains in C. elegans. Treatment with FA and Rg3 significantly attenuated DAergic neurodegeneration induced by 6-OHDA in BZ555 strain, improved basal slowing rate, and prolonged lifespan in the 6-OHDA-induced wild-type strain with downregulation of the apoptosis mediators, egl-1 and ced-3, and upregulation of sod-3 and cat-2. Interestingly, only FA reduced α-synuclein aggregation, rescued lifespan in NL5901, and upregulated the protein degradation regulators, including ubh-4, hsf-1, hsp-16.1 and hsp-16.2. This study indicates that both FA and Rg3 possess beneficial effects in rescuing DAergic neurodegeneration in the 6-OHDA-induced C. elegans model through suppressing apoptosis mediators and stimulating antioxidant enzymes. In addition, FA could attenuate α-synuclein aggregation through the protein degradation process.

Biophysical analysis of drug efficacy on C. elegans models for neurodegenerative and neuromuscular diseases

Caenorhabditis elegans has emerged as a powerful model organism for drug screening due to its cellular simplicity, genetic amenability and homology to humans combined with its small size and low cost. Currently, high-throughput drug screening assays are mostly based on image-based phenotyping with the focus on morphological-descriptive traits not exploiting key locomotory parameters of this multicellular model with muscles such as its thrashing force, a critical biophysical parameter when screening drugs for muscle-related diseases. In this study, we demonstrated the use of a micropillar-based force assay chip in combination with a fluorescence assay to evaluate the efficacy of various drugs currently used in treatment of neurodegenerative and neuromuscular diseases. Using this two-dimensional approach, we showed that the force assay was generally more sensitive in measuring efficacy of drug treatment in Duchenne Muscular Dystrophy and Parkinson’s Disease mutant worms as well as partly in Amyotrophic Lateral Sclerosis model. These results underline the potential of our force assay chip in screening of potential drug candidates for the treatment of neurodegenerative and neuromuscular diseases when combined with a fluorescence assay in a two-dimensional analysis approach.

Beneficial Effects of Cyclic Ether 2-Butoxytetrahydrofuran from Sea Cucumber Holothuria scabra against Aβ Aggregate Toxicity in Transgenic Caenorhabditis elegans and Potential Chemical Interaction

The pathological finding of amyloid-β (Aβ) aggregates is thought to be a leading cause of untreated Alzheimer’s disease (AD). In this study, we isolated 2-butoxytetrahydrofuran (2-BTHF), a small cyclic ether, from Holothuria scabra and demonstrated its therapeutic potential against AD through the attenuation of Aβ aggregation in a transgenic Caenorhabditis elegans model. Our results revealed that amongst the five H. scabra isolated compounds, 2-BTHF was shown to be the most effective in suppressing worm paralysis caused by Aβ toxicity and in expressing strong neuroprotection in CL4176 and CL2355 strains, respectively. An immunoblot analysis showed that CL4176 and CL2006 treated with 2-BTHF showed no effect on the level of Aβ monomers but significantly reduced the toxic oligomeric form and the amount of 1,4-bis(3-carboxy-hydroxy-phenylethenyl)-benzene (X-34)-positive fibril deposits. This concurrently occurred with a reduction of reactive oxygen species (ROS) in the treated CL4176 worms. Mechanistically, heat shock factor 1 (HSF-1) (at residues histidine 63 (HIS63) and glutamine 72 (GLN72)) was shown to be 2-BTHF’s potential target that might contribute to an increased expression of autophagy-related genes required for the breakdown of the Aβ aggregate, thus attenuating its toxicity. In conclusion, 2-BTHF from H. scabra could protect C. elegans from Aβ toxicity by suppressing its aggregation via an HSF-1-regulated autophagic pathway and has been implicated as a potential drug for AD.

Neurodevelopmental Toxicity of Polystyrene Nanoplastics in Caenorhabditis elegans and the Regulating Effect of Presenilin

As one of the most widely used materials, plastic polymer fragments can abrasively degrade into microplastic (MP) and smaller nanoplastic (NP) particles. The present study aimed to investigate the influence of particle size on neurodevelopmental toxicity induced by polystyrene nanoplastics (PS-NPs) in Caenorhabditis elegans and to explore the underlying potential mechanism. C. elegans were exposed to different concentrations of PS-NPs with various sizes (25, 50, and 100 nm) for 72 h. Our results showed that all of these PS-NPs could dose-dependently induce an increase in reactive oxygen species production and mitochondrial damage in C. elegans, resulting in inhibition of body length, head thrashes, body bending, and dopamine (DA) contents. A weaker neurotoxicity was found in 25 nm PS-NPs compared to 50 and 100 nm PS-NPs, which might be due to preferential cellular distribution and greater polymerization capability of the smaller particles. In addition, all these PS-NPs could induce lipofuscin accumulation and apoptosis independent of particle size, suggesting that oxidative damage and mitochondrial dysfunction may not be the only way responsible for NP-induced neurotoxic effects. Furthermore, the mutant test targeting two presenilin genes (sel-12 and hop-1) showed that sel-12 and hop-1 were involved in regulation of PS-NP-induced neurodevelopmental toxicity and mitochondrial damage. In conclusion, PS-NPs could induce neurodevelopmental toxicity dependent on particle sizes mediated by mitochondrial damage and DA reduction. Enhanced expression of presenilin plays a role in PS-NP-induced oxidative stress and neurodevelopmental toxicity.

Neuroprotective and Neurorestorative Effects of Holothuria scabra Extract in the MPTP/MPP+-Induced Mouse and Cellular Models of Parkinson's Disease

Extracts from Holothuria scabra (HS) have been shown to possess anti-inflammation, anti-oxidant and anti-cancer activities. More recently, it was shown to have neuroprotective potential in Caenorhabditis elegans PD model. Here, we assessed whether HS has neuroprotective and neurorestorative effects on dopaminergic neurons in both mouse and cellular models of PD. We found that both pre-treatment and post-treatment with HS improved motor deficits in PD mouse model induced with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as determined by grid walk test. This was likely mediated by HS protective and restorative effects on maintaining the numbers of dopaminergic neurons and fibers in both substantia nigra pars compacta (SNpc) and striatum. In a cellular model of PD, HS significantly attenuated 1-methyl-4-phenylpyridinium (MPP⁺)-induced apoptosis of DAergic-like neurons differentiated from SH-SY5Y cells by enhancing the expression of Bcl-2, suppressing the expression of cleaved Caspase 3 and preventing depolarization of mitochondrial membrane. In addition, HS could stimulate the expression of tyrosine hydroxylase (TH) and suppressed the formation of α-synuclein protein. Taken together, our in vivo and in vitro findings suggested that HS is an attractive candidate for the neuroprotection rather than neurorestoration in PD.

Wedelolactone Mitigates Parkinsonism Via Alleviating Oxidative Stress and Mitochondrial Dysfunction Through NRF2/SKN-1

Parkinsonism is an age-associated neurodegenerative disorder characterized by aggregation of α-synuclein (α-syn) protein in the substantia nigra region, degeneration of dopaminergic neurons, and deregulated lipid metabolism. Currently, only symptomatic relief has been provided by FDA-approved therapeutic approaches for Parkinson's disease (PD). The present study aims to evaluate the potential of wedelolactone (WDL), a natural occurring coumestan found in Eclipta alba to mitigate the parkinsonism in Caenorhabditis elegans disease model. In the present studies, supplementation with 37.5 μM WDL exhibited a reduction in the level of α-syn in an age-dependent manner (22% at day 5, p < 0.05; and 16% at day 10, p < 0.001, n = 30), along with improvement in neuronal health through basal movement, and elevated the dopamine levels evident through 1-nonanol repulsion results in wild-type and diseased worms. Moreover, WDL augmented the mitochondrial health in wild-type, PD-diseased, and mev-1 mutant worms that establish the inherent activity of WDL in the alleviation of oxidative stress. Furthermore, WDL supplementation significantly decreases the neutral lipid and triglyceride level and also alleviates protein carbonyl level in PD disease condition. The overall investigation will provide a pioneer to the future insights of PD research related to plant-based drugs. qPCR studies after WDL supplementation revealed alteration of genes involved in the regulation of various stress-responsive (sod-5, gst-4, skn-1), α-syn-suppressing (lrk-1, ymel-1, lagr-1, grk-1), and mitochondrial (pink-1) genes. All together, these findings support that the WDL is a promising candidate to combat age-related multi-factorial PD pathology associated with protein misfolding and accumulation. The results provide sufficient information in the development of therapeutic medicines from natural products for improving the health.

Hemiterpene compound, 3,3-dimethylallyl alcohol promotes longevity and neuroprotection in Caenorhabditis elegans

Terpenes and their derivatives have been used conventionally as potential dietary supplements to boost the nutritional value of endless food products. Several plant-based complex terpenoid and their derivatives have been reported for a wide range of medicinal and nutritional properties. However, their simple counterparts, whose production is relatively easy, sustainable, and economic from food-grade microbial sources, have not been studied yet for any such biological activities. The present study aimed to investigate the longevity-promoting property and neuromodulatory effects of 3,3-dimethylallyl alcohol (Prenol), one of the simplest forms of terpenoid and a constituent of fruit aroma, in the animal model Caenorhabditis elegans. Prenol supplementation (0.25 mM) augmented the lifespan of wild-type nematodes by 22.8% over the non-treated worms. Moreover, a suspended amyloid-β induced paralysis and reduced α-synuclein aggregation were observed in Prenol-treated worms. The lifespan extending properties of Prenol were correlated with ameliorated physiological parameters and increased stress (heat and oxidative) tolerance in C. elegans. In silico and gene-specific mutant studies showed that pro-longevity transcription factors DAF-16, HSF-1, and SKN-1 were involved in the improved lifespan and health-span of Prenol-treated worms. Transgenic green fluorescent protein-reporter gene expression analysis and relative mRNA quantification (using real-time PCR) demonstrated an increase in the expression of DAF-16, HSF-1, and SKN-1 transcription factors and their downstream target genes in Prenol-treated worms. Together, the findings suggest that small molecules, like Prenol, could be explored as a potential alternate to develop therapeutics against aging and age-related ailments.

Downregulation of eEF1A/EFT3-4 Enhances Dopaminergic Neurodegeneration After 6-OHDA Exposure in C. elegans Model

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the aggregation of α-synuclein protein and selective death of dopaminergic (DA) neurons in the substantia nigra of the midbrain. Although the molecular pathogenesis of PD is not completely understood, a recent study has reported that eukaryotic translation elongation factor 1 alpha (eEF1A) declined in the PD-affected brain. Therefore, the roles of eEF1A1 and eEF1A2 in the prevention of DA neuronal cell death in PD are aimed to be investigated. Herein, by using Caenorhabditis elegans as a PD model, we investigated the role of eft-3/eft-4, the worm homolog of eEF1A1/eEF1A2, on 6-hydroxydopamine (6-OHDA)-induced DA neuron degeneration. Our results demonstrated that the expressions of eft-3 and eft-4 were decreased in the 6-OHDA-induced worms. RNA interference (RNAi) of eft-3 and eft-4 resulted in dramatic exacerbation of DA neurodegeneration induced by 6-OHDA, as well as aggravated the food-sensing behavior, ethanol avoidance, and decreased lifespan when compared with only 6-OHDA-induced worms. Moreover, downregulation of eft-3/4 in 6-OHDA-induced worms suppressed the expression of the anti-apoptotic genes, including PI3K/age-1, PDK-1/pdk-1, mTOR/let-363, and AKT-1,2/akt-1,2, promoting the expression of apoptotic genes such as BH3/egl-1 and Caspase-9/ced-3. Collectively, these findings indicate that eEF1A plays an important role in the 6-OHDA-induced neurodegeneration through the phosphatidylinositol 3-kinase (PI3K)/serine/threonine protein kinase (Akt)/mammalian target of rapamycin (mTOR) pathway and that eEF1A isoforms may be a novel and effective pro-survival factor in protective DA neurons against toxin-induced neuronal death.

Saponin-rich extracts from Holothuria leucospilota mediate lifespan extension and stress resistance in Caenorhabditis elegans via daf-16

Saponins are secondary metabolite compounds that can be found in sea cucumbers (Holothuroidea spp.). However, little is known about how saponin-rich extracts from Holothuria leucospilota can delay and prolong the lifespan of the whole organism. In this study, anti-aging effects of H. leucospilota extracts were studied on Caenorhabditis elegans. NMR analysis revealed that body wall n-butanol-extract of H. leucospilota (BW-BU) is saponin-rich. BW-BU extracts exhibited antioxidant activities by 2,2'-diphenyl-2-picrylhydrazyl assay (EC₅₀  = 10.23 ± 0.12 mg/ml) and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid assay (EC₅₀  = 3.91 ± 0.04 mg/ml). BW-BU extracts increased lifespan of L4 and L1 C. elegans (5.92% and 15.76%, respectively), which also increased worm growth, stress resistance, and reduced biomarkers for aging. BW-BU extracts activated DAF-16 nuclear localization and upregulated daf-16 and DAF-16 target genes expression. Taken together, this study revealed the evidences on anti-aging activities of saponin-rich extracts from H. leucospilota, which can extend lifespan of C. elegans via daf-16. PRACTICAL APPLICATIONS: In recent years, age-associated chronic diseases have had a significant impact on quality of life. Many natural compounds exhibit anti-aging activities, especially in sea cucumber, H. leucospilota. Our results indicated that H. leucospilota is good for health. Extracts from H. leucospilota contain a bioactive compound that can be potentially used to promote longevity and disease prevention in aging.

Tyrosol, a simple phenol from EVOO, targets multiple pathogenic mechanisms of neurodegeneration in a C. elegans model of Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disorder involving α-synuclein (α-syn) aggregation, oxidative stress, dysregulation of redox metal homeostasis, and neurotoxicity. Different phenolic compounds with known antioxidant or antichelating properties have been shown to also interfere with aggregation of amyloid proteins and modulate intracellular signaling pathways. The present study aims to investigate for the first time the effect of tyrosol (TYR), a simple phenol present in extra-virgin olive oil, on α-syn aggregation in a Caenorhabditis elegans model of PD and evaluate its potential to prevent α-syn toxicity, neurodegeneration, and oxidative stress in this model organism. Our results show that TYR is effective in reducing α-syn inclusions, resulting in a lower toxicity and extended life span of treated nematodes. Moreover, TYR delayed α-syn-dependent degeneration of dopaminergic neurons in vivo. TYR treatment also reduced reactive oxygen species level and promoted the expression of specific chaperones and antioxidant enzymes. Overall, our study puts into perspective TYR potential to be considered as nutraceutical that targets pivotal causal factors in PD.

Studying Parkinson’s disease using Caenorhabditis elegans models in microfluidic devices

Parkinson’s disease (PD) is a progressive neurological disorder associated with the loss of dopaminergic neurons (DNs) in the substantia nigra and the widespread accumulation of α-synuclein (α-syn) protein, leading to motor impairments and eventual cognitive dysfunction. In-vitro cell cultures and in-vivo animal models have provided the opportunity to investigate the PD pathological hallmarks and identify different therapeutic compounds. However, PD pathogenesis and causes are still not well understood, and effective inhibitory drugs for PD are yet to be discovered. Biologically simple but pathologically relevant disease models and advanced screening technologies are needed to reveal the mechanisms underpinning protein aggregation and PD progression. For instance, Caenorhabditis elegans (C. elegans) offers many advantages for fundamental PD neurobehavioral studies including a simple, well-mapped, and accessible neuronal system, genetic homology to humans, body transparency and amenability to genetic manipulation. Several transgenic worm strains that exhibit multiple PD-related phenotypes have been developed to perform neuronal and behavioral assays and drug screening. However, in conventional worm-based assays, the commonly used techniques are equipment-intensive, slow and low in throughput. Over the past two decades, microfluidics technology has contributed significantly to automation and control of C. elegans assays. In this review, we focus on C. elegans PD models and the recent advancements in microfluidic platforms used for manipulation, handling and neurobehavioral screening of these models. Moreover, we highlight the potential of C. elegans to elucidate the in-vivo mechanisms of neuron-to-neuron protein transfer that may underlie spreading Lewy pathology in PD, and its suitability for in-vitro studies. Given the advantages of C. elegans and microfluidics technology, their integration has the potential to facilitate the investigation of disease pathology and discovery of potential chemical leads for PD.

Saponin-enriched extracts from body wall and Cuvierian tubule of Holothuria leucospilota reduce fat accumulation and suppress lipogenesis in Caenorhabditis elegans

BACKGROUND

Saponins have been shown to possess many pharmacological properties, including altered fat metabolism. The black sea cucumber, Holothuria leucospilota, is a marine animal that contains a specialized organ called a Cuvierian tubule that produces and secrete the bioactive saponins into the tubules and body wall. Therefore, the aims of this study are to investigate the anti-obesity effect of saponins extracted from body wall and Cuvierian tubules of H. leucospilota.

RESULTS

The butanol extracts of H. leucospilota body wall and Cuvierian tubules containing high amounts of saponins significantly reduced fat deposition and triglyceride levels in Caenorhabditis elegans fed with 50 mmol L^-1 glucose. Moreover, the saponin-enriched extracts of H. leucospilota significantly restored the lifespan of 2% glucose-fed worms (18.71%). Green fluorescence protein-labeled sbp-1 gene expression and nuclear translocation of daf-16 were also significantly decreased in H. leucospilota treatment. The saponin-enriched extracts downregulated the messenger RNA expressions of genes involved in fat storage and metabolism, including sbp-1, cebp, and daf-16 but upregulated the expression of nhr-49 gene.

CONCLUSION

Our results suggest that H. leucospilota-derived saponins may mediate the reduction of glucose-induced fat accumulation through sbp-1, cebp, daf-16 and nhr-9 pathways. Therefore, the H. leucospilota extracts could be used as nutraceuticals for anti-obesity prevention. © 2019 Society of Chemical Industry.

Marine-Derived Natural Compounds for the Treatment of Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder caused by the loss of dopaminergic neurons, leading to the motor dysfunctions of patients. Although the etiology of PD is still unclear, the death of dopaminergic neurons during PD progress was revealed to be associated with the abnormal aggregation of α-synuclein, the elevation of oxidative stress, the dysfunction of mitochondrial functions, and the increase of neuroinflammation. However, current anti-PD therapies could only produce symptom-relieving effects, because they could not provide neuroprotective effects, stop or delay the degeneration of dopaminergic neurons. Marine-derived natural compounds, with their novel chemical structures and unique biological activities, may provide anti-PD neuroprotective effects. In this study, we have summarized anti-PD marine-derived natural products which have shown pharmacological activities by acting on various PD targets, such as α-synuclein, monoamine oxidase B, and reactive oxygen species. Moreover, marine-derived natural compounds currently evaluated in the clinical trials for the treatment of PD are also discussed.

Holothuria scabra extracts possess anti-oxidant activity and promote stress resistance and lifespan extension in Caenorhabditis elegans

Holothuria scabra is a sea cucumber that is mostly found in the Indo-Pacific region including Thailand. Extracts from many sea cucumbers possess pharmacological activities proposed to benefit human health. In this study, we investigated the anti-oxidant and anti-ageing activities of extracts from H. scabra by using Caenorhabditis elegans as a model organism. Parts of H. scabra were solvent-extracted and divided into nine fractions including whole body-hexane (WBHE), whole body-ethyl acetate (WBEA), whole body-butanol (WBBU), body wall-hexane (BWHE), body wall-ethyl acetate (BWEA), body wall-butanol (BWBU), viscera-hexane (VIHE), viscera-ethyl acetate (VIEA), and viscera-butanol (VIBU). All fractions of the extracts were tested for anti-oxidant activities by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays and for anti-ageing effects by lifespan assays using C. elegans as a model. The results showed anti-oxidant properties in all fractions with the highest activity shown by the DPPH assay in WBBU (EC₅₀ = 3.12 ± 0.09 mg/ml), and by the ABTS assay in WBHE (EC₅₀ = 0.31 ± 0.10 mg/ml). In lifespan assays the highest anti-ageing effect was detected in WBBU- and BWEA-treated C. elegans with increased mean lifespans of 8.12% and 4.77%, respectively. Furthermore, WBBU and BWEA-treated C. elegans exhibited significantly higher resistance against heat shock and paraquat-induced oxidative stresses than controls. By using LC-MS/MS, both extracts were characterized to contain triterpene glycosides as the main bioactive components. To explore mechanisms of H. scabra extracts on longevity and stress resistance, worms with genetic mutations in anti-ageing pathways were analyzed and showed that WBBU and BWEA did not prolong the lifespan of daf-16, age-1, sir-2.1, jnk-1, sek-1, and osr-1 mutants, suggesting that these genetic pathways are involved in mediating the anti-ageing effects of the H. scabra extracts. Moreover, WBBU and BWEA enhanced the nuclear translocation of the FoxO/DAF-16 transcription factor, and increased mRNA expression of this gene and its downstream targets sod-3, hsp12.3, and hsp16.2. In conclusion, this study strongly demonstrates anti-oxidant and anti-ageing properties of H. scabra extracts containing triterpene glycosides, which, in the C. elegans model, may be mediated via the insulin/IGF-1 signaling (IIS)-DAF-16 pathway.

Caenorhabditis elegans as a model system for target identification and drug screening against neurodegenerative diseases

Over the past decades, Caenorhabditis elegans (C. elegans) has been widely used as a model system because of its small size, transparent body, short generation time and lifespan (~3 days and 3 weeks, respectively), completely sequenced genome and tractability to genetic manipulation. Protein misfolding and aggregation are key pathological features in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease and Amyotrophic lateral sclerosis. Animal models, including C. elegans, have been extensively used to discover and validate new drugs against neurodegenerative diseases. The well-defined and genetically tractable nervous system of C. elegans offers an effective model to explore basic mechanistic pathways of neurodegenerative diseases. Recent progress in high-throughput drug screening also provides a powerful approach for identifying chemical modulators of biological processes. Here, we summarize the latest progress of using C. elegans as a model system for target identification and drug screening in neurodegenerative diseases.