Antioxidants inhibit neuronal toxicity in Parkinson's disease-linked LRRK2

Effects of Rhazya Stricta plant organic extracts on human induced pluripotent stem cells derived neural stem cells

Rhazya Stricta (R. stricta) has been employed as a natural remedy for several diseases for centuries. Numerous studies revealed that R. stricta extracts contain alkaloids, tannins, and flavonoids that possess antimicrobial, anticancer, antihypertensive, and antioxidant activities. In this study, we examined the effects of organic extracts from different parts of R. stricta plant on human pluripotent stem cells (hiPSCs)-derived neural stem cells (NSCs) for medical purposes. NSCs were incubated with different concentrations of organic extracts from the leaves, stem, and fruits, and we assessed the growth and viability of the cells by using MTS assay and the chemical composition of the potential plant extract by using gas chromatography-mass spectrometry (GC/MS). Our results revealed that the methanolic extract from the stem increased NSCs growth significantly, particularly at a concentration of 25 μg/ml. GC/MS analysis was utilized to identify the potential compounds of the methanolic extract. In conclusion, our results demonstrated for the first time that methanolic stem extract of R. stricta contains compounds that can positively impact NSCs growth. These compounds can be further investigated to determine the potential bioactive compounds that can be used for research and medical purposes.

Allele-dependent interaction of LRRK2 and NOD2 in leprosy

Leprosy, caused by Mycobacterium leprae, rarely affects children younger than 5 years. Here, we studied a multiplex leprosy family that included monozygotic twins aged 22 months suffering from paucibacillary leprosy. Whole genome sequencing identified three amino acid mutations previously associated with Crohn’s disease and Parkinson’s disease as candidate variants for early onset leprosy: LRRK2 N551K, R1398H and NOD2 R702W. In genome-edited macrophages, we demonstrated that cells expressing the LRRK2 mutations displayed reduced apoptosis activity following mycobacterial challenge independently of NOD2. However, employing co-immunoprecipitation and confocal microscopy we showed that LRRK2 and NOD2 proteins interacted in RAW cells and monocyte-derived macrophages, and that this interaction was substantially reduced for the NOD2 R702W mutation. Moreover, we observed a joint effect of LRRK2 and NOD2 variants on Bacillus Calmette-Guérin (BCG)-induced respiratory burst, NF-κB activation and cytokine/chemokine secretion with a strong impact for the genotypes found in the twins consistent with a role of the identified mutations in the development of early onset leprosy.

Screening of Spirulina Components for Anti-Parkinson's and Anti-Alzheimer's Activity by in Silico Methods and Docking Studies

Spirulina platensis was first isolated from Lake Texcoco by Aztecs in the sixteenth century. In 2012, spirulina was considered to be safe dietary supplement by the Food and Drug Administration (FDA). Spirulina is a cyanophytic microalgae that is often considered as single cell protein. It contains many essential amino acids, proteins, fatty acids, antioxidant pigments, carotenoids, and cyanogenic pigments, that is, phycocyanobilins and phycocyanins (Eriksen, Appl Microbiol Biotechnol, 80(1):1-4, 2008). Components of spirulina are investigated for many health benefits and for pharmaceutical uses (Karkos et al., Spirulina in clinical practice: evidence-based human applications). Spirulina has been found to have a role in growth, immunity (Wu et al., Arch Toxicol, 90(8):1817-40, 2016), antioxidant (Wu et al., Arch Toxicol, 90(8):1817-40, 2016), antiviral (Ayehunie et al., J Acquir Immune Defic Syndr Hum Retrovirol, 18(1):7-12, 1998), antitoxicologic, anti-cancerogenic (Hirahashi et al., Int Immunopharmacol, 2(4):423-34, 2002), antidiabetic (Layam and Reddy, Diabetol Croat, 35(2):29-33, 2006), and neuroprotective properties. In this study, we focused on spirulina components in anti-Parkinson's and anti-Alzheimer's activity. Four potential targets, two for each activity, that is, structure of parkinE3 ligase (PDB ID:4I1H) and structure of BACE bound to 5-(3-(5-chloropyridin-3-yl)phenyl)-5-cyclopropyl-2-imino-3-methylimidazolidin-4one (PDBI D:4DJx) for anti-Parkinson's activity and structure of human MAO B in complex with selective inhibitor safinamide (PDB ID:2V5Z) and crystal structure of human BACE-1 in complex with CNP520(PDB ID:6EQM) for anti-Alzheimer's activity, have been selected. The in silico results and scoring of virtual screening, that is, molecular docking, were compared with commonly used marketed drugs such as levodopa for Parkinson's disease (PD) and rivastigmine (Rösler et al., BMJ, 318(7184):633-40, 1999) for Alzheimer's disease.

Mitophagy and reactive oxygen species interplay in Parkinson's disease

Mitophagy impairment and oxidative stress are cardinal pathological hallmarks in Parkinson's disease (PD), a common age-related neurodegenerative condition. The specific interactions between mitophagy and reactive oxygen species (ROS) have attracted considerable attention even though their exact interplay in PD has not been fully elucidated. We highlight the interactions between ROS and mitophagy, with a focus on the signalling pathways downstream to ROS that triggers mitophagy and draw attention to potential therapeutic compounds that target these pathways in both experimental and clinical models. Identifying a combination of ROS inhibitors and mitophagy activators to provide a physiologic balance in this complex signalling pathways may lead to a more optimal outcome. Deciphering the exact temporal relationship between mitophagy and oxidative stress and their triggers early in the course of neurodegeneration can unravel mechanistic clues that potentially lead to the development of compounds for clinical drug trials focusing on prodromic PD or at-risk individuals.

Animal Models of Neurodegenerative Disease: Recent Advances in Fly Highlight Innovative Approaches to Drug Discovery

Neurodegenerative diseases represent a formidable challenge to global health. As advances in other areas of medicine grant healthy living into later decades of life, aging diseases such as Alzheimer's disease (AD) and other neurodegenerative disorders can diminish the quality of these additional years, owed largely to the lack of efficacious treatments and the absence of durable cures. Alzheimer's disease prevalence is predicted to more than double in the next 30 years, affecting nearly 15 million Americans, with AD-associated costs exceeding $1 billion by 2050. Delaying onset of AD and other neurodegenerative diseases is critical to improving the quality of life for patients and reducing the burden of disease on caregivers and healthcare systems. Significant progress has been made to model disease pathogenesis and identify points of therapeutic intervention. While some researchers have contributed to our understanding of the proteins and pathways that drive biological dysfunction in disease using in vitro and in vivo models, others have provided mathematical, biophysical, and computational technologies to identify potential therapeutic compounds using in silico modeling. The most exciting phase of the drug discovery process is now: by applying a target-directed approach that leverages the strengths of multiple techniques and validates lead hits using Drosophila as an animal model of disease, we are on the fast-track to identifying novel therapeutics to restore health to those impacted by neurodegenerative disease.

Thymoquinone in Ocular Neurodegeneration: Modulation of Pathological Mechanisms via Multiple Pathways

Thymoquinone is a naturally occurring compound and is the major component of Nigella sativa, also known as black seed or black cumin. For centuries thymoquinone has been used especially in the Middle East traditionally to treat wounds, asthma, allergies, fever, headache, cough, hypertension, and diabetes. Studies have suggested beneficial effects of thymoquinone to be attributed to its antioxidant, antibacterial, anti-oxidative stress, anti-inflammatory, and neuroprotective properties. Recently, there has been a surge of interest in thymoquinone as a treatment for neurodegeneration in the brain, such as that seen in Alzheimer’s (AD) and Parkinson’s diseases (PD). In vitro and in vivo studies on animal models of AD and PD suggest the main neuroprotective mechanisms are based on the anti-inflammatory and anti-oxidative properties of thymoquinone. Neurodegenerative conditions of the eye, such as Age-related Macular Degeneration (AMD) and glaucoma share at least in part similar mechanisms of neuronal cell death with those occurring in AD and PD. This review aims to summarize and critically analyze the evidence to date of the effects and potential neuroprotective actions of thymoquinone in the eye and ocular neurodegenerations.

Esculetin: A review of its pharmacology and pharmacokinetics

Esculetin is a natural dihydroxy coumarin; it is mainly extracted from twig skin and the trunk bark of the Chinese herbal medicine Fraxinus rhynchophylla Hance. Emerging evidence suggests that esculetin has a wide range of pharmacological activities. Based on its fundamental properties, including antioxidant, antiinflammatory, antiapoptotic, anticancer, antidiabetic, neuroprotective, and cardiovascular protective activities, as well as antibacterial activity, among others, esculetin is expected to be a therapeutic drug for specific disease indications, such as cancer, diabetes, atherosclerosis, Alzheimer's disease (AD), Parkinson's disease (PD), nonalcoholic fatty liver disease (NAFLD), and other diseases. The oral bioavailability of esculetin was shown by studies to be low. The extensive glucuronidation was described to be the main metabolic pathway of esculetin and C-7 phenolic hydroxyl to be its major metabolic site. With the development of scientific research technology, the pharmacological effects of esculetin are identified and its potential for the treatment of diseases is demonstrated. The underlining mechanisms of action and biological activities as well as the pharmacokinetic data of the analyzed compound reported so far are highlighted in this review with the aim of becoming a proven, and applicable insight and reference for further studies on the utilization of esculetin.

Piceatannol ameliorates behavioural, biochemical and histological aspects in cisplatin-induced peripheral neuropathy in rats

Peripheral neurotoxicity is a dose-limiting and a potentially lifelong persistent toxicity of cisplatin. This study investigated the possible protective effect of piceatannol (PIC) in a model of cisplatin-induced peripheral neuropathy in rats. PIC (10 mg/kg, i.p.) was given for 7 days, starting 2 days before cisplatin single injection (7 mg/kg, i.p.). Behavioural, biochemical and histological examinations were conducted. Cisplatin administration resulted in thermal hypoalgesia evidenced by increased paw and tail withdrawal latency times in the hotplate and tail flick tests, respectively, and reduced the abdominal constrictions in response to the acetic acid injection. Moreover, cisplatin treatment decreased rat locomotor activity and grip strength. These behavioural alterations were reversed by PIC coadministration. In addition, PIC decreased cisplatin-induced elevation in serum neurotensin and platinum accumulation in sciatic nerve. Also, PIC reversed, to a large extent, cisplatin-induced microscopical alterations in nerve axons and restored normal myelin thickness. Therefore, PIC may protect against cisplatin-induced peripheral neuropathy.

Nonsteroidal Anti-inflammatory Use and LRRK2 Parkinson's Disease Penetrance

BACKGROUND

The penetrance of leucine rich repeat kinase 2 (LRRK2) mutations is incomplete and may be influenced by environmental and/or other genetic factors. Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to reduce inflammation and may lower Parkinson's disease (PD) risk, but their role in LRRK2-associated PD is unknown.

OBJECTIVES

The objective of this study is to evaluate the association of regular NSAID use and LRRK2-associated PD.

METHODS

Symptomatic ("LRRK2-PD") and asymptomatic ("LRRK2-non-PD") participants with LRRK2 G2019S, R1441X, or I2020T variants (definitely pathogenic variant carriers) or G2385R or R1628P variants (risk variant carriers) from 2 international cohorts provided information on regular ibuprofen and/or aspirin use (≥2 pills/week for ≥6 months) prior to the index date (diagnosis date for PD, interview date for non-PD). Multivariate logistic regression was used to evaluate the relationship between regular NSAID use and PD for any NSAID, separately for ibuprofen and aspirin in all carriers and separately in pathogenic and risk variant groups.

RESULTS

A total of 259 LRRK2-PD and 318 LRRK2-non-PD participants were enrolled. Regular NSAID use was associated with reduced odds of PD in the overall cohort (odds ratio [OR], 0.34; 95% confidence interval [CI], 0.21-0.57) and in both pathogenic and risk variant carriers (OR_Pathogenic , 0.38; 95% CI, 0.21-0.67 and OR_RiskVariant , 0.19; 95% CI, 0.04-0.99). Similar associations were observed for ibuprofen and aspirin separately (OR_Ibuprofen , 0.19; 95% CI, 0.07-0.50 and OR_Aspirin , 0.51; 95% CI, 0.28-0.91).

CONCLUSIONS

Regular NSAID use may be associated with reduced penetrance in LRRK2-associated PD. The LRRK2 protein is involved in inflammatory pathways and appears to be modulated by regular anti-inflammatory use. Longitudinal observational and interventional studies of NSAID exposure and LRRK2-PD are needed to confirm this association. © 2020 International Parkinson and Movement Disorder Society.

In Vivo Visual Screen for Dopaminergic Rab ↔ LRRK2-G2019S Interactions in Drosophila Discriminates Rab10 from Rab3

LRRK2 mutations cause Parkinson's, but the molecular link from increased kinase activity to pathological neurodegeneration remains undetermined. Previous in vitro assays indicate that LRRK2 substrates include at least 8 Rab GTPases. We have now examined this hypothesis in vivo in a functional, electroretinogram screen, expressing each Rab with/without LRRK2-G2019S in selected Drosophila dopaminergic neurons. Our screen discriminated Rab10 from Rab3. The strongest Rab/LRRK2-G2019S interaction is with Rab10; the weakest with Rab3. Rab10 is expressed in a different set of dopaminergic neurons from Rab3. Thus, anatomical and physiological patterns of Rab10 are related. We conclude that Rab10 is a valid substrate of LRRK2 in dopaminergic neurons in vivo We propose that variations in Rab expression contribute to differences in the rate of neurodegeneration recorded in different dopaminergic nuclei in Parkinson's.

Resveratrol Derivatives as Potential Treatments for Alzheimer's and Parkinson's Disease

Neurodegenerative diseases are characterized by the progressive loss of neurons in different regions of the nervous system. Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the two most prevalent neurodegenerative diseases, and the symptoms associated with these pathologies are closely related to the regions that are most affected by the process of neurodegeneration. Despite their high prevalence, currently, there is no cure or disease-modifying drugs for the treatment of these conditions. In the last decades, due to the need for the development of new treatments for neurodegenerative diseases, several authors have investigated the neuroprotective actions of naturally occurring molecules, such as resveratrol. Resveratrol is a stilbene found in several plants, including grapes, blueberries, raspberries, and peanuts. Studies have shown that resveratrol presents neuroprotective actions in experimental models of AD and PD, however, its clinical application is limited due to its rapid metabolism and low bioavailability. In this context, studies have proposed that structural changes in the resveratrol molecule, including glycosylation, alkylation, halogenation, hydroxylation, methylation, and prenylation could lead to the development of derivatives with enhanced bioavailability and pharmacological activity. Therefore, this review article aims to discuss how resveratrol derivatives could represent viable molecules in the search for new drugs for the treatment of AD and PD.

Biotransformation of Piceatannol, a Dietary Resveratrol Derivative: Promises to Human Health

SCOPE

To evaluate the health-promoting potentials of piceatannol (PIC), a dietary resveratrol derivative, its biotransformation is examined.

METHODS AND RESULTS

The biotransformation is tested in human/rat hepatic microsomes and cytosols; its pharmacokinetic profiles are assessed in rats. Although limited phase I metabolism exists in microsomes, PIC is rapidly converted to two pharmacologically active metabolites, namely rhapontigenin (RHA) and isorhapontigenin (ISO) in cytosols. Such biotransformation is completely blocked by entacapone, a well-known catechol-O-methyltransferase (COMT) inhibitor, demonstrating that the O-methylation is mediated by COMT. Moreover, PIC is identified as a substrate inhibitor of COMT, suggesting its potential benefits in Alzheimer's disease. Due to extensive phase II metabolism including glucuronidation, sulfation, and O-methylation, PIC displays rapid clearance and at least 4.02% ± 0.61% and 17.70% ± 0.91% of PIC is converted to RHA and ISO, respectively, in rats after intravenous administration. Similarly, PIC serves as an effective precursor of ISO upon oral administration.

CONCLUSION

Since PIC and its metabolites possess pleiotropic health-promoting activities, it has emerged as a promising nutraceutical candidate for further development. This study also reinforces the importance of in vivo testing in nutritional researches as the active metabolite(s) may be absent from the in vitro system.

Amelioration of Mitochondrial Quality Control and Proteostasis by Natural Compounds in Parkinson's Disease Models

Parkinson’s disease (PD) is a well-known age-related neurodegenerative disorder associated with longer lifespans and rapidly aging populations. The pathophysiological mechanism is a complex progress involving cellular damage such as mitochondrial dysfunction and protein homeostasis. Age-mediated degenerative neurological disorders can reduce the quality of life and also impose economic burdens. Currently, the common treatment is replacement with levodopa to address low dopamine levels; however, this does not halt the progression of PD and is associated with adverse effects, including dyskinesis. In addition, elderly patients can react negatively to treatment with synthetic neuroprotection agents. Recently, natural compounds such as phytochemicals with fewer side effects have been reported as candidate treatments of age-related neurodegenerative diseases. This review focuses on mitochondrial dysfunction, oxidative stress, hormesis, proteostasis, the ubiquitin‒proteasome system, and autophagy (mitophagy) to explain the neuroprotective effects of using natural products as a therapeutic strategy. We also summarize the efforts to use natural extracts to develop novel pharmacological candidates for treatment of age-related PD.

Using Drosophila as a platform for drug discovery from natural products in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder with no cure. Despite intensive research, most of the currently available therapies are only effective in alleviating symptoms with no effect on disease progression. There is an urgent need for new therapeutics to impede disease progression. Natural products are valuable sources of bioactive compounds that can be exploited for novel therapeutic potential in PD pathogenesis. However, rapid screening of plant-derived natural products and characterization of bioactive compounds is costly and challenging. Drosophila melanogaster, commonly known as the fruit fly, has recently emerged as an excellent model for human neurodegenerative diseases, including PD. The high degree of conserved molecular pathways with mammalian models make Drosophila PD models an inexpensive solution to preliminary phases of target validation in the drug discovery pipeline. The present review provides an overview of drug discovery from natural extracts using Drosophila as a screening platform to evaluate the therapeutic potential of phytochemicals against PD.

Nutrigenomics as a tool to study the impact of diet on aging and age-related diseases: the Drosophila approach

Aging is a complex phenomenon caused by the time-dependent loss of cellular homeodynamics and consequently of physiological organismal functions. This process is affected by both genetic and environmental (e.g., diet) factors, as well as by their constant interaction. Consistently, deregulation of nutrient sensing and signaling pathways is considered a hallmark of aging. Nutrigenomics is an emerging scientific discipline that studies changes induced by diet on the genome and thus it considers the intersection of three topics, namely health, diet, and genomics. Model organisms, such as the fruit fly Drosophila melanogaster, have been successfully used for in vivo modeling of higher metazoans aging and for nutrigenomic studies. Drosophila is a well-studied organism with sophisticated genetics and a fully annotated sequenced genome, in which ~ 75% of human disease-related genes have functional orthologs. Also, flies have organs/tissues that perform the equivalent functions of most mammalian organs, while discrete clusters of cells maintain insect carbohydrate homeostasis in a way similar to pancreatic cells. Herein, we discuss the mechanistic connections between nutrition and aging in Drosophila, and how this model organism can be used to study the effect of different diets (including natural products and/or their derivatives) on higher metazoans longevity.

Thymoquinone prevents neurodegeneration against MPTP in vivo and modulates α-synuclein aggregation in vitro

Parkinson's disease (PD) is a common neurodegenerative disease characterized by progressive dopaminergic neurodegeneration with a concomitant increase in oxidative stress and neuroinflammation in the substantia nigra pars compacta (SNc). Recent studies have focused on targeting neuroinflammation and oxidative stress to effectively treat PD. The present study evaluated the neuroprotective effect of thymoquinone (TQ) against 1-methyl-4-phenyl 1,2,3,6 tetrahydropyridine (MPTP)-induced oxidative stress and neuroinflammation in a PD mouse model. TQ (10 mg/kg body weight [b. wt.]) was administered for 1 week prior to MPTP (25 mg/kg b. wt.). MPTP administration caused oxidative stress as evidenced by decreased activities of superoxide dismutase and catalase, a depletion of reduced glutathione, and a concomitant rise in malondialdehyde. It also significantly increased pro-inflammatory cytokines and elevated inflammatory mediators such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in the striatum. Immunohistochemical analysis revealed dopamine neuron loss in the SNc and decreased dopamine transporters in the striatum following MPTP administration; however, these were rescued by TQ treatment. TQ treatment further restored antioxidant enzymes, prevented glutathione depletion, inhibited lipid peroxidation, and attenuated pro-inflammatory cytokines. TQ also decreased the raised levels of inflammatory mediators, such as COX-2 and iNOS. Therefore, TQ is thought to protect against MPTP-induced PD and the observed neuroprotective effects are attributed to its potent antioxidant and anti-inflammatory properties. Moreover, the in vitro analysis found that TQ significantly inhibited α-synuclein aggregation and prevented cell death induced by pre-formed fibrils. Thus, TQ not only scavenges the MPTP-induced toxicity but also prevents α-synuclein-fibril formation and its associated toxicity.

An assessment of the translational relevance of Drosophila in drug discovery

INTRODUCTION

Drosophila melanogaster offers a powerful expedient and economical system with facile genetics. Because of the high sequence and functional conservation with human disease-associated genes, it has been cardinal in deciphering disease mechanisms at the genetic and molecular level. Drosophila are amenable to and respond well to pharmaceutical treatment which coupled to their genetic tractability has led to discovery, repositioning, and validation of a number of compounds. Areas covered: This review summarizes the generation of fly models of human diseases, their advantages and use in elucidation of human disease mechanisms. Representative studies provide examples of the utility of this system in modeling diseases and the discovery, repositioning and testing on pharmaceuticals to ameliorate them. Expert opinion: Drosophila offers a facile and economical whole animal system with many homologous organs to humans, high functional conservation and established methods of generating and validating human disease models. Nevertheless, it remains relatively underused as a drug discovery tool probably because its relevance to mammalian systems remains under question. However, recent exciting success stories using Drosophila disease models for drug screening, repositioning and validation strongly suggest that fly models should figure prominently in the drug discovery pipeline from bench to bedside.

The Potential Use of Plant Natural Products and Plant Extracts with Antioxidant Properties for the Prevention/Treatment of Neurodegenerative Diseases: In Vitro, In Vivo and Clinical Trials

Neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease and Huntington's disease, present a major health issue and financial burden for health care systems around the world. The impact of these diseases will further increase over the next decades due to increasing life expectancies. No cure is currently available for the treatment of these conditions; only drugs, which merely alleviate the symptoms. Oxidative stress has long been associated with neurodegeneration, whether as a cause or as part of the downstream results caused by other factors. Thus, the use of antioxidants to counter cellular oxidative stress within the nervous system has been suggested as a potential treatment option for neurological disorders. Over the last decade, significant research has focused on the potential use of natural antioxidants to target oxidative stress. However, clinical trial results have lacked success for the treatment of patients with neurological disorders. The knowledge that natural extracts show other positive molecular activities in addition to antioxidant activity, however, has led to further research of natural extracts for their potential use as prevention or treatment/management of neurodegenerative diseases. This review will cover several in vitro and in vivo research studies, as well as clinical trials, and highlight the potential of natural antioxidants.

The phytochemistry, pharmacokinetics, pharmacology and toxicity of Euphorbia semen

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia semen, the dried and ripe seed of Euphorbia lathyris Linnaeus, is widely cultivated for traditional medicine use. This semen is used to expel water, help with phlegm retention, promote blood circulation, remove blood stasis, cure tinea and scabies, and treat amenorrhea, snakebites, terminal schistosomiasis, anuria and constipation.

AIM OF THE REVIEW

This review provides updated, comprehensive and categorized information on the local and traditional uses, phytochemistry, pharmacokinetics, pharmacological activities and toxicity of Euphorbia semen. Future research to deepen the recognition and utilization of Euphorbia semen is proposed.

MATERIALS AND METHODS

This article conducted a literature review on information about Euphorbia semen in multiple Internet databases, including PubMed, Web of Science, Wiley, Science Direct, Elsevier, ACS publications, SciFinder, Google Scholar and China National Knowledge Internet, until March of 2018. In this manuscript, a number of books, PhD and MSc dissertations, and Chinese Pharmacopeia were also used as references.

RESULTS

Approximately 240 chemical constituents have been isolated and identified from Euphorbia semen, namely, diterpenoids, coumarins, flavonoids, fatty acids, amino acids, and steroids. Pharmacokinetic study focused on investigating absorption, distribution, metabolism and excretion (ADME). The chemical constituents have extensive pharmacological effects, such as diuresis and anti-hyperuricaemia, anti-inflammation, antiviral, anticancer, antioxidant, antipigmentation, anti-platelet aggregation and anti-allergic activities, as well as hepatoprotection and neuroprotection. The toxicity of Euphorbia semen, including acute toxicity, target organ irritation and cocareinogenic effects, have been reported, and the detoxification methods are reviewed.

CONCLUSION

Euphorbia semen has extensive pharmacological activity and excellent clinical value, along with intense intestinal irritation. Although plenty of chemical constituents have been isolated and identified, the exact pharmacological and toxicological mechanisms still need to be explored.

Parkinson's Disease Model

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. It is known that there are many factors, either genetic or environmental factors, involved in PD, but the mechanism of PD is still not fully understood. Several animal models have been established to study the mechanisms of PD. Among these models, Drosophila melanogaster has been utilized as a valuable model to get insight into important features of PD. Drosophila melanogaster possesses a well-developed dopaminergic (DA) neuron system which is known to play an important role in PD pathogenesis. The well understanding of DA neurons from early larval through adult stage makes Drosophila as a powerful model for investigating the progressive neurodegeneration in PD. Besides, the short life cycle of Drosophila melanogaster serves an advantage in studying epidemiological features of PD. Most of PD symptoms can be mimicked in Drosophila model such as progressive impairment in locomotion, DA neuron degeneration, and some other non-motor symptoms. The Drosophila models of PD, therefore, show a great potential in application for PD genetic and drug screening.

Therapeutic Versatility of Resveratrol Derivatives

Resveratrol, a natural phytoalexin, exhibits a remarkable range of biological activities, such as anticancer, cardioprotective, neuroprotective and antioxidant properties. However, the therapeutic application of resveratrol was encumbered for its low bioavailability. Therefore, many researchers focused on designing and synthesizing the derivatives of resveratrol to enhance the bioavailability and the pharmacological activity of resveratrol. During the past decades, a large number of natural and synthetic resveratrol derivatives were extensively studied, and the methoxylated, hydroxylated and halogenated derivatives of resveratrol received particular more attention for their beneficial bioactivity. So, in this review, we will summarize the chemical structure and the therapeutic versatility of resveratrol derivatives, and thus provide the related structure activity relationship reference for their practical applications.

Targeting LRRK2 in Parkinson's disease: an update on recent developments

INTRODUCTION

LRRK2 research has progressed significantly in recent years with more reports of LRRK2 interactors and the development of more specific and sophisticated LRRK2 kinase inhibitors. Identification of bone fide LRRK2 substrates will provide new therapeutic targets in LRRK2-linked Parkinson's disease (PD). Areas covered: This review aims to put current LRRK2 research into perspective. Beginning with recent LRRK2 mammalian models employed for in vivo validation of LRRK2 substrates, followed by updates on reported LRRK2 interactors and their inferred mechanisms. Finally an overview of commonly used LRRK2 kinase inhibitors will be depicted. Expert opinion: Identification of LRRK2 non-kinase functions suggests the possibility of alternative LRRK2 drug target sites and these should be further explored. Studies on the effects of LRRK2 kinase inhibition on its non-kinase function and its self-regulatory role will provide further insights on its pathophysiologic mechanisms. Development of robust measurements of LRRK2 inhibitor efficacy will be required. These would include identification of specific imaging ligands or direct biochemical assays that can accurately capture its intrinsic activity. Testing of new therapeutic drug targets in both LRRK2 carriers and non LRRK2-linked patients will be important since their phenotype is similar.

Knockdown transgenic Lrrk Drosophila resists paraquat-induced locomotor impairment and neurodegeneration: A therapeutic strategy for Parkinson's disease

Leucine-rich repeat kinase 2 (LRRK2) has been linked to familial and sporadic Parkinson's disease. However, it is still unresolved whether LRRK2 in dopaminergic (DAergic) neurons may or may not aggravate the phenotype. We demonstrate that knocking down (KD) the Lrrk gene by RNAi in DAergic neurons untreated or treated with paraquat (PQ) neither affected the number of DAergic clusters, tyrosine hydroxylase (TH) protein levels, lifespan nor locomotor activity when compared to control (i.e. TH/+) flies. KD transgenic Lrrk flies dramatically increased locomotor activity in presence of TH enzyme inhibitor alpha-methyl-para-tyrosine (aMT), whereas no effect on lifespan was observed in both fly lines. Most importantly, KD Lrrk flies had reduced lipid peroxidation (LPO) index alone or in presence of PQ and the antioxidant minocycline (MC, 0.5mM). Taken together, these findings suggest that Lrrk appears unessential for the viability of DAergic neurons in D. melanogaster. Moreover, Lrrk might negatively regulate homeostatic levels of dopamine, thereby dramatically increasing locomotor activity, extending lifespan, and reducing oxidative stress (OS). Our data also indicate that reduced expression of Lrrk in the DAergic neurons of transgenic TH>Lrrk-RNAi/+ flies conferred PQ resistance and absence of neurodegeneration. The present findings support the notion that reduced/suppressed LRRK2 expression might delay or prevent motor symptoms and/or frank Parkinsonism in individuals at risk to suffer autosomal dominant Parkinsonism (AD-P) by blocking OS-induced neurodegenerative processes in the DAergic neurons.

Polymer brain-nanotherapeutics for multipronged inhibition of microglial α-synuclein aggregation, activation, and neurotoxicity

Neuroinflammation, a common neuropathologic feature of neurodegenerative disorders including Parkinson disease (PD), is frequently exacerbated by microglial activation. The extracellular protein α-synuclein (ASYN), whose aggregation is characteristic of PD, remains a key therapeutic target, but the control of synuclein trafficking and aggregation within microglia has been challenging. First, we established that microglial internalization of monomeric ASYN was mediated by scavenger receptors (SR), CD36 and SRA1, and was rapidly accompanied by the formation of ASYN oligomers. Next, we designed a nanotechnology approach to regulate SR-mediated intracellular ASYN trafficking within microglia. We synthesized mucic acid-derivatized sugar-based amphiphilic molecules (AM) with optimal stereochemistry, rigidity, and charge for enhanced dual binding affinity to SRs and fabricated serum-stable nanoparticles via flash nanoprecipitation comprising hydrophobe cores and amphiphile shells. Treatment of microglia with AM nanoparticles decreased monomeric ASYN internalization and intracellular ASYN oligomer formation. We then engineered composite deactivating NPs with dual character, namely shell-based SR-binding amphiphiles, and core-based antioxidant poly (ferrulic acid), to investigate concerted inhibition of oxidative activation. In ASYN-challenged microglia treated with NPs, we observed decreased ASYN-mediated acute microglial activation and diminished microglial neurotoxicity caused by exposure to aggregated ASYN. When the composite NPs were administered in vivo within the substantia nigra of fibrillar ASYN-challenged wild type mice, there was marked attenuation of activated microglia. Overall, SR-targeting AM nanotechnology represents a novel paradigm in alleviating microglial activation in the context of synucleinopathies like PD and other neurodegenerative diseases.