Neuroprotective effects of genistein on dopaminergic neurons in the mice model of Parkinson's disease

Unveiling the neuroprotective properties of isoflavones: current evidence, molecular mechanisms and future perspectives

Neurodegenerative diseases encompass a wide range of debilitating and incurable brain disorders characterized by the progressive deterioration of the nervous system's structure and function. Isoflavones, which are naturally occurring polyphenolic phytochemicals, have been found to regulate various cellular signaling pathways associated with the nervous system. The main objective of this comprehensive review is to explore the neuroprotective effects of isoflavones, elucidate the underlying mechanisms, and assess their potential for treating neurodegenerative disorders. Relevant data regarding isoflavones and their impact on neurodegenerative diseases were gathered from multiple library databases and electronic sources, including PubMed, Google Scholar, Web of Science, and Science Direct. Numerous isoflavones, including genistein, daidzein, biochanin A, and formononetin, have exhibited potent neuroprotective properties against various neurodegenerative diseases. These compounds have been found to modulate neurotransmitters, which in turn contributes to their ability to protect against neurodegeneration. Both in vitro and in vivo experimental studies have provided evidence of their neuroprotection mechanisms, which involve interactions with estrogenic receptors, antioxidant effects, anti-inflammatory properties, anti-apoptotic activity, and modulation of neural plasticity. This review aims to provide current insights into the neuroprotective characteristics of isoflavones and shed light on their potential therapeutic applications in future clinical scenarios.

The Interaction Between Nutraceuticals and Gut Microbiota: a Novel Therapeutic Approach to Prevent and Treatment Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons, leading to motor and non-motor symptoms. Emerging research has shed light on the role of gut microbiota in the pathogenesis and progression of PD. Nutraceuticals such as curcumin, berberine, phytoestrogens, polyphenols (e.g., resveratrol, EGCG, and fisetin), dietary fibers have been shown to influence gut microbiota composition and function, restoring microbial balance and enhancing the gut-brain axis. The mechanisms underlying these benefits involve microbial metabolite production, restoration of gut barrier integrity, and modulation of neuroinflammatory pathways. Additionally, probiotics and prebiotics have shown potential in promoting gut health, influencing the gut microbiome, and alleviating PD symptoms. They can enhance the gut's antioxidant capacity of the gut, reduce inflammation, and maintain immune homeostasis, contributing to a neuroprotective environment. This paper provides an overview of the current state of knowledge regarding the potential of nutraceuticals and gut microbiota modulation in the prevention and management of Parkinson's disease, emphasizing the need for further research and clinical trials to validate their effectiveness and safety. The findings suggest that a multifaceted approach involving nutraceuticals and gut microbiota may open new avenues for addressing the challenges of PD and improving the quality of life for affected individuals.

Articulating the Pharmacological and Nanotechnological Aspects of Genistein: Current and Future Prospectives

Throughout the past several centuries, herbal constituents have been the subject of scientific interest and the latest research into their therapeutic potential is underway. Genistein is a soy-derived isoflavone found in huge amounts in soy, along with the plants of the Fabaceae family. Scientific studies have demonstrated the beneficial effects of genistein on various health conditions. Genistein presents a broad range of pharmacological activities, including anticancer, neuroprotective, cardioprotective, antiulcer, anti-diabetic, wound healing, anti-bacterial, antiviral, skin, and radioprotective effects. However, the hydrophobic nature of genistein results in constrained absorption and restricts its therapeutic potential. In this review, the number of nanocarriers for genistein delivery has been explored, such as polymeric nanoparticles, nanostructured lipid carriers, solid lipid nanoparticles, liposomes, micelles, transferosomes, and nanoemulsions and nanofibers. These nano-formulations of genistein have been utilized as a potential strategy for various disorders, employing a variety of ex vivo, in vitro, and in vivo models and various administration routes. This review concluded that genistein is a potential therapeutic agent for treating various diseases, including cancer, neurodegenerative disorders, cardiovascular disorders, obesity, diabetes, ulcers, etc., when formulated in suitable nanocarriers.

Effect of Flavonoids against Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder. It is characterized by the depletion of striatal dopamine content and aggregation of alphasynuclein in the substantia nigra (SN). It is possible to treat the symptoms of PD with a variety of medications, but they often result in complications and are not able to cure or stop the progression of the disease. Flavonoids (the phytocomponents present in almost all fruits and vegetables) are the class of secondary metabolites that have generated a peak of interest because of their medicinal properties, including a reduction in the risk of PD. Several flavonoids such as quercetin, kaempferol, hesperitin, anthocyanin and many more have been reported for their anti- Parkinson's effect. This review deals with the neuroprotective benefits of different classes of flavonoids against PD.

Emerging Role of Plant-Based Bioactive Compounds as Therapeutics in Parkinson's Disease

Neurological ailments, including stroke, Alzheimer's disease (AD), epilepsy, Parkinson's disease (PD), and other related diseases, have affected around 1 billion people globally to date. PD stands second among the common neurodegenerative diseases caused as a result of dopaminergic neuron loss in the midbrain's substantia nigra regions. It affects cognitive and motor activities, resulting in tremors during rest, slow movement, and muscle stiffness. There are various traditional approaches for the management of PD, but they provide only symptomatic relief. Thus, a survey for finding new biomolecules or substances exhibiting the therapeutic potential to patients with PD is the main focus of present-day research. Medicinal plants, herbal formulations, and natural bioactive molecules have been gaining much more attention in recent years as synthetic molecules orchestrate a number of undesired effects. Several in vitro, in vivo, and in silico studies in the recent past have demonstrated the therapeutic potential of medicinal plants, herbal formulations, and plant-based bioactives. Among the plant-based bioactives, polyphenols, terpenes, and alkaloids are of particular interest due to their potent anti-inflammatory, antioxidant, and brain-health-promoting properties. Further, there are no concise, elaborated articles comprising updated mechanism-of-action-based reviews of the published literature on potent, recently investigated (2019-2023) medicinal plants, herbal formulations, and plant based-bioactive molecules, including polyphenols, terpenes, and alkaloids, as a method for the management of PD. Therefore, we designed the current review to provide an illustration of the efficacious role of various medicinal plants, herbal formulations, and bioactives (polyphenols, terpenes, and alkaloids) that can become potential therapeutics against PD with greater specificity, target approachability, bioavailability, and safety to the host. This information can be further utilized in the future to develop several value-added formulations and nutraceutical products to achieve the desired safety and efficacy for the management of PD.

Casein Reactivates Dopaminergic Nerve Injury and Intestinal Inflammation with Disturbing Intestinal Microflora and Fecal Metabolites in a Convalescent Parkinson's Disease Mouse Model

Parkinson's disease (PD) is the fastest-growing neurodegenerative disease, with pathogenic causes elusive and short of effective treatment options. Investigations have found that dairy products positively correlate with the onset of PD, but the mechanisms remain unexplored. As casein is an antigenic component in dairy products, this study assessed if casein could exacerbate PD-related symptoms by stimulating intestinal inflammation and unbalanced intestinal flora and be a risk factor for PD. Using a convalescent PD mouse model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), the results showed casein reduced motor coordination, caused gastrointestinal dysfunction, reduced dopamine content, and induced intestinal inflammation. Meanwhile, casein disturbed gut microbiota homeostasis by increasing the Firmicutes/Bacteroidetes ratio, decreasing α-diversity, and caused abnormal alterations in fecal metabolites. However, these adverse effects of casein attenuated much when it had hydrolyzed by acid or when antibiotics inhibited the intestinal microbiota of the mice. Therefore, our results suggested that casein could reactivate dopaminergic nerve injury and intestinal inflammation and exacerbate intestinal flora disorder and its metabolites in convalescent PD mice. These damaging effects might be related to disordered protein digestion and gut microbiota in these mice. These findings will provide new insights into the impact of milk/dairy products on PD progression and supply information on dietary options for PD patients.

Exploring therapeutic strategies for infantile neuronal axonal dystrophy (INAD/PARK14)

Infantile neuroaxonal dystrophy (INAD) is caused by recessive variants in PLA2G6 and is a lethal pediatric neurodegenerative disorder. Loss of the Drosophila homolog of PLA2G6, leads to ceramide accumulation, lysosome expansion, and mitochondrial defects. Here, we report that retromer function, ceramide metabolism, the endolysosomal pathway, and mitochondrial morphology are affected in INAD patient-derived neurons. We show that in INAD mouse models, the same features are affected in Purkinje cells, arguing that the neuropathological mechanisms are evolutionary conserved and that these features can be used as biomarkers. We tested 20 drugs that target these pathways and found that Ambroxol, Desipramine, Azoramide, and Genistein alleviate neurodegenerative phenotypes in INAD flies and INAD patient-derived neural progenitor cells. We also develop an AAV-based gene therapy approach that delays neurodegeneration and prolongs lifespan in an INAD mouse model.

Analysis of phenolic compounds in Parkinson's disease: a bibliometric assessment of the 100 most cited papers

Objective

The aim of this study was to identify and characterize the 100 most cited articles on Parkinson's disease (PD) and phenolic compounds (PCs).

Methods

Articles were selected in the Web of Science Core Collection up to June 2022 based on predetermined inclusion criteria, and the following bibliometric parameters were extracted: the number of citations, title, keywords, authors, year, study design, tested PC and therapeutic target. MapChart was used to create worldwide networks, and VOSviewer software was used to create bibliometric networks. Descriptive statistical analysis was used to identify the most researched PCs and therapeutic targets in PD.

Results

The most cited article was also the oldest. The most recent article was published in 2020. Asia and China were the continent and the country with the most articles in the list (55 and 29%, respectively). In vitro studies were the most common experimental designs among the 100 most cited articles (46%). The most evaluated PC was epigallocatechin. Oxidative stress was the most studied therapeutic target.

Conclusion

Despite the demonstrations in laboratorial studies, the results obtained point to the need for clinical studies to better elucidate this association.

Genistein suppresses microglial activation and inhibits apoptosis in different brain regions of hypoxia-exposed mice model of amnesia

Genistein (GE) or 4',5,7-trihydroxyflavone, a plant derived isoflavone, is a biologically active compound having several beneficial properties. Studies showed that GE possesses anti-neoplastic, anti-tumor, anti-helminthic, anti-oxidant, and anti-inflammatory activities. Herein, we investigated the neuroprotective effects of GE in a mouse model of hypoxia-induced amnesia. Mice were exposed to hypoxic conditions (10% O2) in a designated hypoxia chamber and co-treated with GE (10, 20, or 30 mg/kg) for 4 weeks. Following this, behavioral tests were performed to evaluate memory performance. We assessed microglial activation in the hippocampus, amygdala, and pre-frontal cortex (PFC) regions by evaluating the Iba-1 and GFAP transcript levels, and MIP-1β, Cox-2, and IL6 protein levels. Apoptosis was assessed by evaluating Bax, BAD, and Bcl-2 mRNA levels, and caspase-3 activity. To uncover the underlying molecular mechanism, we evaluated the levels of Nrf2, HO-1, and NQO1 in different brain regions of mice from all groups. Results showed that hypoxia-exposed mice have reduced performance in the behavioral tests and GE treatment enhanced the memory performance in hypoxia-exposed mice. Moreover, hypoxia-exposed mice showed increased expression of microglial activation markers and enhanced apoptosis in the hippocampus, amygdala, and PFC. GE treatment suppressed microglial activation and prevented apoptosis in the brain of hypoxia-exposed mice. Furthermore, hypoxia-exposure reduced the expression of Nrf2, NQO1, and HO-1 while GE treatment ameliorated this decrease in different regions of hypoxia-exposed mice brain. In conclusion, GE prevents cognitive dysfunction by suppressing microglial activation and inhibiting apoptosis in the hypoxia-exposed mice brain.

Protective effects of functional foods against Parkinson's disease: A narrative review on pharmacology, phytochemistry, and molecular mechanisms

In Persian Medicine (PM), PD (brain-based tremor) is a known CNS disorder with several therapeutic and preventive options. In their medical textbooks and pharmacopeias, Persian great scientists such as Rhazes (854-925 AD), Avicenna (980-1037 AD), and Jorjani (1042-1136 AD), have discussed pharmacological and nutritional strategies for the prevention, slowing progression, and treatment of PD. In the present study, we surveyed plant- and animal-based foods recommended by PM for the prevention and treatment of CNS-related tremors. In vivo and in-vitro pharmacological evidence supporting the beneficial effects of PM-recommended foods in prevention and alleviating PD, major active phytochemicals along with the relevant mechanisms of action were studied. Several PM plants possess potent antioxidant, antiinflammatory, and PD preventing properties. Garlic and allicin, cabbage and isothiocyanates, chickpea seed and its O-methylated isoflavones biochanin A and formononetin, cinnamon, and cinnamaldehyde, saffron and its crocin, crocetin, and safranal, black cumin and its thymoquinone, black pepper and piperine, pistachio and genistein and daidzein, and resveratrol are among the most effective dietary itemsagainst PD. They act through attenuating neurotoxin-induced memory loss and behavioral impairment, oxidative stress, and dopaminergic cell death. PM-recommended foods can help alleviate PD progression and also discovering and developing new neuroprotective anti-PD pharmaceuticals.

Parkinson's Disease: Is there a Role for Dietary and Herbal Supplements?

Parkinson's Disease (PD) is characterised by degeneration of the neurons of the nigrostriatal dopaminergic pathway of the brain. The pharmacological cornerstone of PD management is mainly the use of dopamine precursors, dopamine receptor agonists, and agents that inhibit the biochemical degradation of dopamine. While these drugs initially provide relief to the symptoms and improve the quality of life of the patients, progression of the underlying pathological processes, such as oxidative stress and neuroinflammation (which have been strongly associated with PD and other neurodegenerative disorders), eventually reduce their benefits, making further benefits achievable, only at high doses due to which the magnitude and frequency of side-effects are amplified. Also, while it is becoming obvious that mainstream pharmacological agents may not always provide the much-needed answer, the question remains what succour can nature provide through dietary supplements, nutraceuticals and herbal remedies? This narrative review examines current literature for evidence of the possible roles (if any) of nutraceuticals, dietary supplements and herbal remedies in the prevention or management of PD by examining how these compounds could modulate key factors and pathways that are crucial to the pathogenesis and/or progression of PD. The likely limitations of this approach and its possible future roles in PD prevention and management are also considered.

Tremor and Rigidity in Patients with Parkinson's Disease: Emphasis on Epidemiology, Pathophysiology and Contributing Factors

Parkinson's disease (PD) is the second most prominent neurodegenerative movement disorder after Alzheimer's disease, involving 2-3% of the population aged above 65 years. This is mainly triggered by the depletion of dopaminergic neurons located in substantia nigra pars compacta (SNpc) in the region of basal ganglia. At present, diagnosis for symptoms of PD is clinical, contextual, unspecified and therapeutically incomprehensive. Analysis of various causes of PD is essential for an accurate examination of the disease. Among the different causes, such as tremors and rigidity, unresponsiveness to the current treatment approach contributes to mortality. In the present review article, we describe various key factors of pathogenesis and physiology associated with tremors and rigidity necessary for the treatment of PI (postural instability) in patients with PD. Additionally, several reports showing early tremor and rigidity causes, particularly age, cortex lesions, basal ganglia lesions, genetic abnormalities, weakened reflexes, nutrition, fear of fall, and altered biomechanics, have been explored. By summarizing the factors that contribute to the disease, histopathological studies can assess rigidity and tremor in PD. With a clear understanding of the contributing factors, various prospective studies can be done to assess the incidence of rigidity and tremors.

The VTA dopaminergic system as diagnostic and therapeutical target for Alzheimer's disease

Neuropsychiatric symptoms (NPS) occur in nearly all patients with Alzheimer's Disease (AD). Most frequently they appear since the mild cognitive impairment (MCI) stage preceding clinical AD, and have a prognostic importance. Unfortunately, these symptoms also worsen the daily functioning of patients, increase caregiver stress and accelerate the disease progression from MCI to AD. Apathy and depression are the most common of these NPS, and much attention has been given in recent years to understand the biological mechanisms related to their appearance in AD. Although for many decades these symptoms have been known to be related to abnormalities of the dopaminergic ventral tegmental area (VTA), a direct association between deficits in the VTA and NPS in AD has never been investigated. Fortunately, this scenario is changing since recent studies using preclinical models of AD, and clinical studies in MCI and AD patients demonstrated a number of functional, structural and metabolic alterations affecting the VTA dopaminergic neurons and their mesocorticolimbic targets. These findings appear early, since the MCI stage, and seem to correlate with the appearance of NPS. Here, we provide an overview of the recent evidence directly linking the dopaminergic VTA with NPS in AD and propose a setting in which the precocious identification of dopaminergic deficits can be a helpful biomarker for early diagnosis. In this scenario, treatments of patients with dopaminergic drugs might slow down the disease progression and delay the impairment of daily living activities.

Neuroprotective mechanisms of red clover and soy isoflavones in Parkinson's disease models

Parkinson's disease (PD) is a neurodegenerative disorder characterized by nigrostriatal degeneration and the spreading of aggregated forms of the presynaptic protein α-synuclein (aSyn) throughout the brain. PD patients are currently only treated with symptomatic therapies, and strategies to slow or stop the progressive neurodegeneration underlying the disease's motor and cognitive symptoms are greatly needed. The time between the first neurobiochemical alterations and the initial presentation of symptoms is thought to span several years, and early neuroprotective dietary interventions could delay the disease onset or slow PD progression. In this study, we characterized the neuroprotective effects of isoflavones, a class of dietary polyphenols found in soy products and in the medicinal plant red clover (Trifolium pratense). We found that isoflavone-rich extracts and individual isoflavones rescued the loss of dopaminergic neurons and the shortening of neurites in primary mesencephalic cultures exposed to two PD-related insults, the environmental toxin rotenone and an adenovirus encoding the A53T aSyn mutant. The extracts and individual isoflavones also activated the Nrf2-mediated antioxidant response in astrocytes via a mechanism involving inhibition of the ubiquitin-proteasome system, and they alleviated deficits in mitochondrial respiration. Furthermore, an isoflavone-enriched soy extract reduced motor dysfunction exhibited by rats lesioned with the PD-related neurotoxin 6-OHDA. These findings suggest that plant-derived isoflavones could serve as dietary supplements to delay PD onset in at-risk individuals and mitigate neurodegeneration in the brains of patients.

GPER and IGF-1R mediate the anti-inflammatory effect of genistein against lipopolysaccharide (LPS)-induced nigrostriatal injury in rats

Neuroinflammation plays an important role in the pathogenesis of Parkinson's disease (PD). Genistein is an estrogen-like phytoestrogen that can exert biological effects via the crosstalk of estrogen receptor and insulin-like growth factor 1 receptor (IGF-1R). The present study aimed to evaluate the involvement of G protein-coupled estrogen receptor (GPER) and IGF-1R in the anti-inflammatory effects of genistein against lipopolysaccharide (LPS)-induced nigrostriatal injury in ovariectomized rats. Our results showed that genistein treatment could ameliorate the apomorphine-induced rotational behavior in LPS-induced inflammatory PD rat model. Genistein attenuated LPS-induced decrease of the contents of dopamine (DA) and its metabolites in striatum as well as the loss of tyrosine hydroxylase-immunoreactive (TH-IR) neurons in the substantia nigra (SN) of the lesioned side, which could be blocked by GPER antagonist G15 or IGF-1R antagonist JB1. Meanwhile, G15 or JB1 could attenuate the anti-inflammatory effects of genistein in LPS-induced microglial activation and production of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, genistein could inhibit the LPS-induced phosphorylation of p38, JNK, ERK and IκB in the lesioned side of SN and these effects could also be blocked by G15 or JB1. Taken together, our data provide the first evidence that genistein can inhibit the increase of microglia and protect dopaminergic neurons at least in part via GPER and IGF-1R signaling pathways in ovariectomized PD rat model.

The Proper Diet and Regular Physical Activity Slow Down the Development of Parkinson Disease

From year to year, we know more about neurodegeneration and Parkinson’s disease (PD). A positive influence of various types of physical activity is more often described in the context of neuroprotection and prevention as well as the form of rehabilitation in Parkinson’s patients. Moreover, when we look at supplementation, clinical nutrition and dietetics, we will see that balancing consumed products and supplementing the vitamins or minerals is necessary. Considering the biochemical pathways in skeletal muscle, we may see that many researchers desire to identify molecular mediators that have an impact through exercise and balanced diet on human health or development of the neurodegenerative disease. Therefore, it is mandatory to study the potential mechanism(s) related to diet and factors resulted from physical activity as molecular mediators, which play a therapeutic role in PD. This review summarizes the available literature on mechanisms and specific pathways involved in diet-exercise relationship and discusses how therapy, including appropriate exercises and diet that influence molecular mediators, may significantly slow down the progress of neurodegenerative processes. We suggest that a proper diet combined with physical activity will be a good solution for psycho-muscle BALANCE not only in PD but also in other neurodegenerative diseases.

Isoflavones derived from plant raw materials: bioavailability, anti-cancer, anti-aging potentials, and microbiome modulation

Isoflavones are secondary metabolites that represent the most abundant category of plant polyphenols. Dietary soy, kudzu, and red clover contain primarily genistein, daidzein, glycitein, puerarin, formononetin, and biochanin A. The structural similarity of these compounds to β-estradiol has demonstrated protection against age-related and hormone-dependent diseases in both genders. Demonstrative shreds of evidence confirmed the fundamental health benefits of the consumption of these isoflavones. These relevant activities are complex and largely driven by the source, active ingredients, dose, and administration period of the bioactive compounds. However, the preclinical and clinical studies of these compounds are greatly variable, controversial, and still with no consensus due to the non-standardized research protocols. In addition, absorption, distribution, metabolism, and excretion studies, and the safety profile of isoflavones have been far limited. This highlights a major gap in understanding the potentially critical role of these isoflavones as prospective replacement therapy. Our general review exclusively focuses attention on the crucial role of isoflavones derived from these plant materials and critically highlights their bioavailability, possible anticancer, antiaging potentials, and microbiome modulation. Despite their fundamental health benefits, plant isoflavones reveal prospective therapeutic effects that worth further standardized analysis.

Identification of ortho catechol-containing isoflavone as a privileged scaffold that directly prevents the aggregation of both amyloid β plaques and tau-mediated neurofibrillary tangles and its in vivo evaluation

In this study, polyhydroxyisoflavones that directly prevent the aggregation of both amyloid β (Aβ) and tau were expediently synthesized via divergent Pd(0)-catalyzed Suzuki-Miyaura coupling and then biologically evaluated. By preliminary structure-activity relationship studies using thioflavin T (ThT) assays, an ortho-catechol containing isoflavone scaffold was proven to be crucial for preventing both Aβ aggregation and tau-mediated neurofibrillary tangle formation. Additional TEM experiment confirmed that ortho-catechol containing isoflavone 4d significantly prevented the aggregation of both Aβ and tau. To investigate the mode of action (MOA) of 4d, which possesses an ortho-catechol moiety, ¹H-¹⁵N HSQC NMR analysis was thoroughly performed and the result indicated that 4d could directly inhibit both the formation of Aβ₄₂ fibrils and the formation of tau-derived neurofibrils, probably through the catechol-mediated nucleation of tau. Finally, 4d was demonstrated to alleviate cognitive impairment and pathologies related to Alzheimer's disease in a 5XFAD transgenic mouse model.

Obesity and aging: Molecular mechanisms and therapeutic approaches

The epidemic of obesity is a major challenge for health policymakers due to its far-reaching effects on population health and potentially overwhelming financial burden on healthcare systems. Obesity is associated with an increased risk of developing acute and chronic diseases, including hypertension, stroke, myocardial infarction, cardiovascular disease, diabetes, and cancer. Interestingly, the metabolic dysregulation associated with obesity is similar to that observed in normal aging, and substantial evidence suggests the potential of obesity to accelerate aging. Therefore, understanding the mechanism of fat tissue dysfunction in obesity could provide insights into the processes that contribute to the metabolic dysfunction associated with the aging process. Here, we review the molecular and cellular mechanisms underlying both obesity and aging, and how obesity and aging can predispose individuals to chronic health complications. The potential of lifestyle and pharmacological interventions to counter obesity and obesity-related pathologies, as well as aging, is also addressed.

Fermented Soy Products: Beneficial Potential in Neurodegenerative Diseases

Fermented soybean products, such as cheonggukjang (Japanese natto), doenjang (soy paste), ganjang (soy sauce), and douchi, are widely consumed in East Asian countries and are major sources of bioactive compounds. The fermentation of cooked soybean with bacteria (Bacillus spp.) and fungi (Aspergillus spp. and Rhizopus spp.) produces a variety of novel compounds, most of which possess health benefits. This review is focused on the preventive and ameliorative potential of fermented soy foods and their components to manage neurodegenerative diseases, including Alzheimer's and Parkinson's diseases.

Involvement of α7nAChR in the Protective Effects of Genistein Against β-Amyloid-Induced Oxidative Stress in Neurons via a PI3K/Akt/Nrf2 Pathway-Related Mechanism

Abnormal excessive production and deposition of β-amyloid (Aβ) peptides in selectively susceptible brain regions are thought to be a key pathogenic mechanism underlying Alzheimer's disease (AD), resulting in memory deficits and cognitive impairment. Genistein is a phytoestrogen with great promise for counteracting diverse Aβ-induced insults, including oxidative stress and mitochondrial dysfunction. However, the exact molecular mechanism or mechanisms underlying the neuroprotective effects of genistein against Aβ-induced insults are largely uncharacterized. To further elucidate the possible mechanism(s) underlying these protective effects, we investigated the neuroprotective effects of genistein against Aβ-induced oxidative stress mediated by orchestrating α7 nicotinic acetylcholine receptor (α7nAChR) signaling in rat primary hippocampal neurons. Genistein significantly increased cell viability, reduced the number of apoptotic cells, decreased accumulation of reactive oxygen species (ROS), decreased contents of malondialdehyde (MDA) and lactate dehydrogenase (LDH), upregulated BCL-2 expression, and suppressed Caspase-3 activity occurring after treatment with 25 μM Aβ25-35. Simultaneously, genistein markedly inhibited the decreases in α7nAChR mRNA and protein expression in cells treated with Aβ25-35. In addition, α7nAChR signaling was intimately involved in the genistein-mediated activation of phosphatidylinositol 3-kinase (PI3K)/Akt and Nrf2/keap1 signaling. Thus, α7nAChR activity together with the PI3K/Akt/Nrf2 signaling cascade likely orchestrates the molecular mechanism underlying the neuroprotective effects of genistein against Aβ-induced oxidative injury.

Role of Flavonoids in Neurodegenerative Diseases: Limitations and Future Perspectives

BACKGROUND

Flavonoids, a group of natural dietary polyphenols, are known for their beneficial effects on human health. By virtue of their various pharmacological effects, like anti-oxidative, antiinflammatory, anti-carcinogenic and neuroprotective effects, flavonoids have now become an important component of herbal supplements, pharmaceuticals, medicinals and cosmetics. There has been enormous literature supporting neuroprotective effect of flavonoids. Recently their efficacy in various neurodegenerative diseases, like Alzheimer's disease and Parkinson diseases, has received particular attention.

OBJECTIVE

The mechanism of flavanoids neuroprotection might include antioxidant, antiapoptotic, antineuroinflammatory and modulation of various cellular and intracellular targets. In in-vivo systems, before reaching to brain, they have to cross barriers like extensive first pass metabolism, intestinal barrier and ultimately blood brain barrier. Different flavonoids have varied pharmacokinetic characteristics, which affect their pharmacodynamic profile. Therefore, brain accessibility of flavonoids is still debatable.

METHODS

This review emphasized on current trends of research and development on flavonoids, especially in neurodegenerative diseases, possible challenges and strategies to encounter using novel drug delivery system.

RESULTS

Various flavonoids have elicited their therapeutic potential against neurodegenerative diseases, however by using nanotechnology and novel drug delivery systems, the bioavailability of favonoids could be enhanced.

CONCLUSION

This study bridges a significant opinion on medicinal chemistry, ethanopharmacology and new drug delivery research regarding use of flavonoids in management of neurodegeneration.

A mechanistic insight of phytoestrogens used for Rheumatoid arthritis: An evidence-based review

Assessment of the potential therapeutic benefits offered by naturally occurring phytoestrogens necessitate inspection of their potency and sites of action in impeding the chronic, systemic, autoimmune, joint destructing disorder Rheumatoid arthritis (RA). Possessing structural and functional similarity with human estrogen, phytoestrogen promisingly replaces the use of hormone therapy in eradicating RA symptoms with their anti-inflammatory, anti-oxidative, anti-proliferative, anti-angiogenesis, immunomodulatory, joint protection properties abolishing the harmful side effects of synthetic drugs. Scientific evidences revealed that use of phytoestrogens from different chemical categories including flavonoids, alkaloids, stilbenoids derived from different plant species manifest beneficial effects on RA through various cellular mechanisms including suppression of pro-inflammatory cytokines in particular tumor necrosis factor (TNF-α), interleukin(IL-6) and nuclear factor kappa B (NF-κB) and destructive metalloproteinases, inhibition of oxidative stress, suppressing inflammatory signalling pathways, attenuating osteoclastogenesis ameliorating cartilage degradation and bone erosion. This review summarizes the evidences of different phytoestrogen treatment and their pharmacological mechanisms in both in vitro and in vivo studies along with discussing clinical evaluations in RA patients showing phytoestrogen as a promising agent for RA therapy. Further investigations and more clinical trials are mandatory to clarify the utility of these plant derived compounds in RA prevention and in managing oestrogen deficient diseases in patients.

Equol, a Blood-Brain Barrier Permeable Gut Microbial Metabolite of Dietary Isoflavone Daidzein, Exhibits Neuroprotective Effects against Neurotoxins Induced Toxicity in Human Neuroblastoma SH-SY5Y Cells and Caenorhabditis elegans

Emerging data support that plant food based isoflavones have ameliorating effects on a variety of neurodegenerative diseases including Parkinson's disease (PD). Our previous investigation revealed that dietary isoflavones including genistein (GEN), daidzein (DAI), and equol (EQL; a gut microbial metabolite of DAI) showed promising blood-brain barrier permeability and anti-neuroinflammatory activity in murine microglial BV2 cells. However, the neuroprotective effects of EQL against neurotoxins induced toxicity in PD related models remains unclear. Herein, EQL, along with GEN and DAI, were evaluated for their cytoprotective effect in a non-contact co-culture model with LPS-BV2-conditioned media and human neuroblastoma SH-SY5Y cells. In addition, their neuroprotective effects against PD related neurotoxins including 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenylpyridinium (MPP⁺) induced cytotoxicity were evaluated in SH-SY5Y cells. Furthermore, EQL was evaluated for its neuroprotective effects against MPP⁺ induced neurotoxicity using in vivo PD model including Caenorhabditis elegans lifespan assay. DAI (10 μM) and EQL (10 and 20 μM) showed cytoprotective effects by decreasing LPS-BV2-conditioned media induced cytotoxicity in SH-SY5Y cells by 29.2, 32.4 and 27.2%, respectively. EQL (10 and 20 μM) also showed neuroprotective effects by decreasing 6-OHDA and MPP⁺ induced cytotoxicity in SH-SY5Y cells by 30.6-34.5 and 17.9-18.9%, respectively. Additionally, data from the in vivo assay supported EQL's neuroprotective effect as it increases survival of C. elegans exposed to MPP⁺ from 72 to 108 h. Our findings support a growing body of evidence of the neuroprotective effects of dietary isoflavones and further studies are warranted to elucidate their mechanisms of action.

Nose-to-brain Delivery of Natural Compounds for the Treatment of Central Nervous System Disorders

BACKGROUND

Several natural compounds have demonstrated potential for the treatment of central nervous system disorders such as ischemic cerebrovascular disease, glioblastoma, neuropathic pain, neurodegenerative diseases, multiple sclerosis and migraine. This is due to their well-known antioxidant, anti-inflammatory, neuroprotective, anti-tumor, anti-ischemic and analgesic properties. Nevertheless, many of these molecules have poor aqueous solubility, low bioavailability and extensive gastrointestinal and/or hepatic first-pass metabolism, leading to a quick elimination as well as low serum and tissue concentrations. Thus, the intranasal route emerged as a viable alternative to oral or parenteral administration, by enabling a direct transport into the brain through the olfactory and trigeminal nerves. With this approach, the blood-brain barrier is circumvented and peripheral exposure is reduced, thereby minimizing possible adverse effects.

OBJECTIVE

Herein, brain-targeting strategies for nose-to-brain delivery of natural compounds, including flavonoids, cannabinoids, essential oils and terpenes, will be reviewed and discussed. Brain and plasma pharmacokinetics of these molecules will be analyzed and related to their physicochemical characteristics and formulation properties.

CONCLUSION

Natural compounds constitute relevant alternatives for the treatment of brain diseases but often require loading into nanocarrier systems to reach the central nervous system in sufficient concentrations. Future challenges lie in a deeper characterization of their therapeutic mechanisms and in the development of effective, safe and brain-targeted delivery systems for their intranasal administration.

Genistein attenuates cognitive deficits and neuroapoptosis in hippocampus induced by ketamine exposure in neonatal rats

Ketamine is a frequently used anesthetic in pediatric patients that can cause cognitive impairment. Genistein, a bioactive component of soy products, has been shown to suppress neuronal death through regulating the expression of apoptosis related genes. In this study, we hypothesized that genistein could alleviate ketamine-induced cognitive impairment by ameliorating hippocampal neuronal loss and tested this hypothesis in rats. Neonatal rats were treated with ketamine and genistein. Hippocampal tissue was harvested for histological and biochemical analysis to determine neuronal apoptosis and proteins involved in the apoptotic pathways. Behavioral assays including contextual fear conditioning test and Morris water maze test were performed to assess cognitive functions, including learning and memory. We found that in fear conditioning test, genistein restored freezing time in ketamine treated rats in a dose dependent manner. Similarly, genistein attenuated impaired learning and memory in Morris water maze test in rats treated with ketamine. Additionally, ketamine-induced neuronal apoptosis in rat hippocampus was attenuated by genistein treatment. Finally, we found that genistein partially restored proteins associated with apoptosis, including Bax, Bcl-2, cleaved caspase 3, and phosphorylated GSK-3ß and Akt. Genistein suppresses hippocampal neuronal loss and cognitive disruption induced by ketamine in rats.

Control of Reactive Oxygen Species for the Prevention of Parkinson's Disease: The Possible Application of Flavonoids

Oxidative stress reflects an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense systems, and it can be associated with the pathogenesis and progression of neurodegenerative diseases such as multiple sclerosis, stroke, and Parkinson's disease (PD). The application of antioxidants, which can defend against oxidative stress, is able to detoxify the reactive intermediates and prevent neurodegeneration resulting from excessive ROS production. There are many reports showing that numerous flavonoids, a large group of natural phenolic compounds, can act as antioxidants and the application of flavonoids has beneficial effects in the adult brain. For instance, it is well known that the long-term consumption of the green tea-derived flavonoids catechin and epigallocatechin gallate (EGCG) can attenuate the onset of PD. Also, flavonoids such as ampelopsin and pinocembrin can inhibit mitochondrial dysfunction and neuronal death through the regulation of gene expression of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Additionally, it is well established that many flavonoids exhibit anti-apoptosis and anti-inflammatory effects through cellular signaling pathways, such as those involving (ERK), glycogen synthase kinase-3β (GSK-3β), and (Akt), resulting in neuroprotection. In this review article, we have described the oxidative stress involved in PD and explained the therapeutic potential of flavonoids to protect the nigrostriatal DA system, which may be useful to prevent PD.

miR-30b protects nigrostriatal dopaminergic neurons from MPP(+)-induced neurotoxicity via SNCA

OBJECTIVE

To explore the function of miR-30b in pathogenesis of Parkinson's disease (PD) and its underlying molecular mechanism.

MATERIALS AND METHODS

We used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPP(+)) as a tool for constructing the PD cell model, using miR-30b mimics or inhibitors to manipulate miR-30b level for an experimental model of acquisition. The cell viability of SH-SY5Y was detected by CCK, and luciferase was used to screen the binding of target genes. The protein levels of SNCA were measured by Western blot. Then, we investigate the changes in pro- and anti-apoptotic markers with or without miR-30b treatment.

RESULTS

There was a significant low expression of MiR-30b in MPP(+)-induced cells. SH-SY5Y cell viability was rescued by MiR-30b overexpression. Luciferase experiments showed that MiR-30b may bind to the 3'-UTR side of SNCA and inhibited its expression. By Western blot, the SNCA level was markedly decreased by miR-30b. miR-30b attenuated the upregulation of Bax and the depletion of Bcl-2 induced by MPP(+).

Beyond Metabolism: The Complex Interplay Between Dietary Phytoestrogens, Gut Bacteria, and Cells of Nervous and Immune Systems

The human body has a large, diverse community of microorganisms which not only coexist with us, but also perform many important physiological functions, including metabolism of dietary compounds that we are unable to process ourselves. Furthermore, these bacterial derived/induced metabolites have the potential to interact and influence not only the local gut environment, but the periphery via interaction with and modulation of cells of the immune and nervous system. This relationship is being further appreciated every day as the gut microbiome is researched as a potential target for immunomodulation. A common feature among inflammatory diseases including relapsing-remitting multiple sclerosis (RRMS) is the presence of gut microbiota dysbiosis when compared to healthy controls. However, the specifics of these microbiota-neuro-immune system interactions remain unclear. Among all factors, diet has emerged as a strongest factor regulating structure and function of gut microbial community. Phytoestrogens are one class of dietary compounds emerging as potentially being of interest in this interaction as numerous studies have identified depletion of phytoestrogen-metabolizing bacteria such as Adlercreutzia, Parabacteroides and Prevotella in RRMS patients. Additionally, phytoestrogens or their metabolites have been reported to show protective effects when compounds are administered in the animal model of MS, Experimental Autoimmune Encephalomyelitis (EAE). In this review, we will illustrate the link between MS and phytoestrogen metabolizing bacteria, characterize the importance of gut bacteria and their mechanisms of action in the production of phytoestrogen metabolites, and discuss what is known about the interactions of specific compounds with cells immune and nervous system. A better understanding of gut bacteria-mediated phytoestrogen metabolism and mechanisms through which these metabolites facilitate their biological actions will help in development of novel therapeutic options for MS as well as other inflammatory diseases.

G protein-coupled estrogen receptor is involved in the neuroprotective effect of IGF-1 against MPTP/MPP+-induced dopaminergic neuronal injury

Insulin-like growth factor-1 (IGF-1), an endogenous peptide, exerts important role in brain development, neurogenesis and neuroprotection. There are accumulating evidence for the interaction of IGF-1 and 17β-estradiol systems. IGF-1/IGF-1 receptor (IGF-1R) signaling has been reported to regulate G-protein estrogen receptor (GPER) expression in cancer cells. Whether GPER is involved in the neuroprotective effect of IGF-1 against MPTP/MPP⁺-induced dopaminergic neuronal injury remains unclear. We showed that IGF-1 could improve MPTP-induced motor deficits and ameliorate the decreased contents of DA and its metabolites in striatum as well as the loss of TH-IR neurons in the substantia nigra (SN). IGF-1 pretreatment also reversed the changes of Bcl-2 and Bax protein expressions in SN in MPTP mice. These effects were abolished by IGF-1 receptor (IGF-1R) antagonist JB-1 or GPER antagonist G15 except the inhibitory effect of G15 on Bax protein expression. Moreover, IGF-1 pretreatment enhanced cell survival against MPP⁺-induced neurotoxicity in SH-SY5Y cells. IGF-1 exerted anti-apoptotic effects by restoring MPP⁺-induced changes of Bcl-2 and Bax protein expressions as well as mitochondria membrane potential. Co-treatment with JB-1 or G15 could block these effects. Furthermore, IGF-1 regulated the protein expression of GPER through activation of phosphatidylinositol 3-kinase (PI3-K) and mitogen-activated protein kinase (MAPK) signaling pathways. Overall, we show for the first time that GPER may contribute to the neuroprotective effects of IGF-1 against MPTP/MPP⁺-induced dopaminergic neuronal injury.

Doenjang, A Korean Traditional Fermented Soybean Paste, Ameliorates Neuroinflammation and Neurodegeneration in Mice Fed a High-Fat Diet

Obesity is considered a risk factor for neurodegeneration. Because fermentation of soybean increases contents of various bioactive compounds with anti-obesity and anti-diabetic activities, we investigated the protective effect of doenjang, a Korean traditional fermented soybean paste, against neuroinflammation and neurodegeneration in the cortex and hippocampus of mice fed a high-fat (HF) diet. C57BL/6J mice were fed a low-fat diet, an HF diet, an HF-containing steamed soybean diet, or an HF-containing doenjang (DJ) diet for 11 weeks. Doenjang consumption alleviated hippocampal neuronal loss, which was increased by the HF diet. Accordingly, we observed higher cell proliferation and neurotrophic factor mRNA levels in the DJ group. Contents of oxidative metabolites and mRNA levels of oxidative stress- and neuroinflammation-related genes were lower in the DJ group compared to the HF group. Dietary doenjang reduced β-amyloid peptide (Aβ) levels by regulating gene expressions involved in Aβ production and degradation. Furthermore, doenjang consumption reduced tau hyperphosphorylation induced by HF feeding. Overall, doenjang was more effective than steamed soybean in suppressing neuroinflammation and neurodegeneration in mice fed an HF diet. These results suggest that bioactive compounds produced during the fermentation and aging of soybean may be involved in the enhanced neuroprotective effects of doenjang.

Potential plant-derived catecholaminergic activity enhancers for neuropharmacological approaches: A review

BACKGROUND

Catecholamines (CAs) have been reported to be involved in numerous functions including central nervous system. CA release from the intra neuronal storage vesicles aid in the therapy of various neurological and neuropsychiatric disorders where the catecholaminergic neurotransmission is compromised. Bioavailability of CA at the synapse can be increased through stimulated neurotransmitter release, monoamine oxidase and CA reuptake inhibition. Plant based galenicals are reported to have similar CA enhancement activities and have been used for the management of neurological disorders.

AIM

To review evidence-based literature with plant extracts, bioactive compounds, and composite extracts that modulate central catecholaminergic system, thereby enhancing CA activity for beneficial neurological effect.

METHODS

Electronic databases such as PubMed, Scopus, and ScienceDirect were used to search scientific contributions until January 2018, using relevant keywords. Literature focusing plant-derived CA enhancing compounds, extracts and/or composite extracts were identified and summarized. In all cases, dose, route of administration, the model system and type of extract were accounted.

RESULTS

A total of 49 plant extracts, 31 compounds and 16 herbal formulations have shown CA activity enhancement. Stimulated CA release from the storage vesicles, monoamine oxidase and CA reuptake inhibition were the major mechanisms involved in the increase of CA bioavailability by these phytoconstituents.

CONCLUSION

This review provides an overview on the phytoconstituents with CA enhancement property that have been used for neuropsychiatric disorders. Such herbal remedies will provide an avenue for cost effective and easily available medication which have holistic approach towards disease management. There is also scope for alternate medicines or prototype drug development utilizing these phytomedicines for treating neurodegenerative diseases. However, hurdles are to be met for analyzing the mode and mechanism of action associated with these phytomedicines and their proper scientific documentation.

Ginsenoside Rb1 protects dopaminergic neurons from inflammatory injury induced by intranigral lipopolysaccharide injection

Accumulating studies suggest that neuroinflammation characterized by microglial overactivation plays a pivotal role in the pathogenesis of Parkinson’s disease. As such, inhibition of microglial overactivation might be a promising treatment strategy to delay the onset or slow the progression of Parkinson’s disease. Ginsenoside Rb1, the most active ingredient of ginseng, reportedly exerts neuroprotective effects by suppressing inflammation in vitro. The present study aimed to evaluate the neuroprotective and anti-inflammatory effects of ginsenoside Rb1 in a lipopolysaccharide-induced rat Parkinson’s disease model. Rats were divided into four groups. In the control group, sham-operated rats were intraperitoneally administered normal saline for 14 consecutive days. In the ginsenoside Rb1 group, ginsenoside Rb1 (20 mg/kg) was intraperitoneally injected for 14 consecutive days after sham surgery. In the lipopolysaccharide group, a single dose of lipopolysaccharide was unilaterally microinjected into the rat substantial nigra to establish the Parkinson’s disease model. Lipopolysaccharide-injected rats were treated with normal saline for 14 consecutive days. In the ginsenoside Rb1 + lipopolysaccharide group, lipopolysaccharide was unilaterally microinjected into the rat substantial nigra. Subsequently, ginsenoside Rb1 was intraperitoneally injected for 14 consecutive days. To investigate the therapeutic effects of ginsenoside Rb1, behavioral tests were performed on day 15 after lipopolysaccharide injection. We found that ginsenoside Rb1 treatment remarkably reduced apomorphine-induced rotations in lipopolysaccharide-treated rats compared with the lipopolysaccharide group. To investigate the neurotoxicity of lipopolysaccharide and potential protective effect of ginsenoside Rb1, contents of dopamine and its metabolites in the striatum were measured by high-performance liquid chromatography. Compared with the lipopolysaccharide group, ginsenoside Rb1 obviously attenuated the lipopolysaccharide-induced depletion of dopamine and its metabolites in the striatum. To further explore the neuroprotective effect of ginsenoside Rb1 against lipopolysaccharide-induced neurotoxicity, immunohistochemistry and western blot assay of tyrosine hydroxylase were performed to evaluate dopaminergic neuron degeneration in the substantial nigra par compacta. The results showed that lipopolysaccharide injection caused a large loss of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra and a significant decrease in overall tyrosine hydroxylase expression. However, ginsenoside Rb1 noticeably reversed these changes. To investigate whether the neuroprotective effect of ginsenoside Rb1 was associated with inhibition of lipopolysaccharide-induced microglial activation, we examined expression of the microglia marker Iba-1. Our results confirmed that lipopolysaccharide injection induced a significant increase in Iba-1 expression in the substantia nigra; however, ginsenoside Rb1 effectively suppressed lipopolysaccharide-induced microglial overactivation. To elucidate the inhibitory mechanism of ginsenoside Rb1, we examined expression levels of inflammatory mediators (tumor necrosis factor-α, interleukin-1β, inducible nitric oxide synthase, and cyclooxygenase 2) and phosphorylation of nuclear factor kappa B signaling-related proteins (IκB, IKK) in the substantia nigra with enzyme-linked immunosorbent and western blot assays. Our results revealed that compared with the control group, phosphorylation and expression of inflammatory mediators IκB and IKK in the substantia nigra of lipopolysaccharide group rats were significantly increased; whereas, ginsenoside Rb1 obviously reduced lipopolysaccharide-induced changes on the lesioned side of the substantial nigra par compacta. These findings confirm that ginsenoside Rb1 can inhibit inflammation induced by lipopolysaccharide injection into the substantia nigra and protect dopaminergic neurons, which may be related to its inhibition of the nuclear factor kappa B signaling pathway. This study was approved by the Experimental Animal Ethics Committee of Shandong University of China in April 2016 (approval No. KYLL-2016-0148).

Possible role of phytoestrogens in breast cancer via GPER-1/GPR30 signaling

Estrogens generated within endocrine organs and the reproductive system act as ligands for at least three types of estrogen receptors. Estrogen receptors α (ERα) and β (ERβ) belong to the so-called classical family of estrogen receptors, whereas the G protein-coupled receptor GPR30, also known as GPER-1, has been described as a novel estrogen receptor sited in the cell membrane of target cells. Furthermore, these receptors are under stimulation of a family of exogenous estrogens, known as phytoestrogens, which are a diverse group of non-steroidal plant compounds derived from plant food consumed by humans and animals. Because phytoestrogens are omnipresent in our daily diet, they are becoming increasingly important in both human health and disease. Recent evidence indicates that in addition to classical estrogen receptors, phytoestrogens also activate GPER-1 a relevant observation since GPER-1 is involved in several physiopathological disorders and especially in estrogen-dependent diseases such as breast cancer.The first estrogen receptors discovered were the classical ERα and ERβ, but from an evolutionary point of view G protein-coupled receptors trace their origins in history to over a billion years ago suggesting that estrogen receptors like GPER-1 may have been the targets of choice for ancient phytoestrogens and/or estrogens.This review provides a comprehensive and systematic literature search on phytoestrogens and its relationship with classical estrogen receptors and GPER-1 including its role in breast cancer, an issue still under discussion.

Nutritional Regulators of Bcl-xL in the Brain

B-cell lymphoma-extra large (Bcl-xL) is an anti-apoptotic Bcl-2 protein found in the mitochondrial membrane. Bcl-xL is reported to support normal brain development and protects neurons against toxic stimulation during pathological process via its roles in regulation of mitochondrial functions. Despite promising evidence showing neuroprotective properties of Bcl-xL, commonly applied molecular approaches such as genetic manipulation may not be readily applicable for human subjects. Therefore, findings at the bench may be slow to be translated into treatments for disease. Currently, there is no FDA approved application that specifically targets Bcl-xL and treats brain-associated pathology in humans. In this review, we will discuss naturally occurring nutrients that may exhibit regulatory effects on Bcl-xL expression or activity, thus potentially providing affordable, readily-applicable, easy, and safe strategies to protect the brain.

Genistein Loaded Nanofibers Protect Spinal Cord Tissue Following Experimental Injury in Rats

Innovative drug-delivery systems offer a unique approach to effectively provide therapeutic drug dose over the needed time to achieve better tissue protection and enhanced recovery. The hypothesis of the current study was to test the antioxidant and anti-inflammatory effects of genistein and nanofibers on the spinal cord tissue following experimental spinal cord injury (SCI). Rats were treated post SCI with genistein that is loaded on chitosan/polyvinyl alcohol (CS/PVA) nanofibers as an implantable drug-delivery system. SCI caused marked oxidative damage and inflammation, as is evident by the reduction in the super oxide dismutase (SOD) activity and the level of interleukin-10 (IL-10) in injured spinal cord tissue, as well as the significant increase in the levels of nitric oxide (NO), malondialdehyde (MDA), and tumor necrosis factor-alpha (TNF-α). Treatment of rats post SCI with genistein and CS/PVA nanofibers improved most of the above-mentioned biochemical parameters and shifted them toward the control group values. Genistein induced an increase in the activity of SOD and the level of IL-10, while causing a decrease in NO, MDA, and TNF-α in injured spinal cord tissue. Genistein and CS/PVA nanofibers provide a novel combination for treating inflammatory nervous tissue conditions, especially when combined as an implantable drug-delivery system.

Polyphenols in Parkinson's Disease: A Systematic Review of In Vivo Studies

Parkinson’s disease (PD) is the second most common neurodegenerative disorder. However, therapeutic options treating only its symptoms are very disappointing. Therefore there is an ongoing search for compounds capable of tackling the multi-dimensional features of PD. Recently natural polyphenols have gained great interest as potential therapeutic agents. Herein, we have attempted to summarize results obtained in different animal models demonstrating their neuroprotective effects. The in vivo findings presented below are supported by human subject data and reports regarding the ability of polyphenols to cross the blood-brain barrier. The beneficial effects of polyphenols are demonstrated by the results of behavioral examinations, mainly related to motor and cognitive capabilities, histopathological and immunohistochemical examination concerning the protection of dopaminergic neurons, analyses of dopamine and the concentration of its metabolites, as well as mechanistic studies regarding the modulation of oxidative stress, neuroinflammation, cellular iron management, proteinopathy, and additionally the regulation of signaling pathways. Importantly, data about brain distribution of the metabolic derivatives of the reviewed polyphenols are crucial for the justification of their nutritional intake in neuroprotective intervention, as well as for the identification of potential targets for a novel therapeutic approach to Parkinson’s disease.

Genistein: A Dual Inhibitor of Both Amyloid β and Human Islet Amylin Peptides

Abnormal misfolding and aggregation of amyloid peptides into amyloid fibrils are common and critical pathological events in many neurodegenerative diseases. Most inhibitors or drugs have been developed to prevent amyloid aggregation of a specific peptide, showing sequence-dependent inhibition mechanisms. It is more challenging to develop or discover inhibitors capable of preventing the aggregation of two or more different amyloid peptides. Genistein, a major phytoestrogen in soybean, has been widely used as an anti-inflammation and cerebrovascular drug due to its antioxidation and antiacetylcholinesterase effects. Herein, we examine the inhibitory effects of genistein on the aggregation of amyloid-β (Aβ, associated with Alzheimer's disease) and human islet amylin (hIAPP, associated with type 2 diabetes) and Aβ- and hIAPP-induced neurotoxicity using a combination of experimental and computational approaches. Collective experimental results from thioflavin T (ThT), atomic force microscopy (AFM), and circular dichroism (CD) demonstrate that genistein shows strong inhibition ability to prevent the conformational transition of both Aβ and hIAPP monomers to β-sheet structures, thus reducing final amyloid fibrillization from Aβ and hIAPP monomer aggregation by 40-63%. Further 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH), and large unilamellar vesicle (LUV) assays show that genistein helps to increase cell viability, decrease cell apoptosis, and reduce cell membrane leakage, where the cell protection effect of genistein is likely correlated with its reduced membrane leakage. Comparative molecular dynamics (MD) simulations reveal that genistein prefers to bind the β-sheet groove, a common structural motif of amyloid fibrils, of both Aβ and hIAPP oligomers to interfere with their self-aggregation. This work for the first time demonstrates genistein as a dual inhibitor of Aβ and hIAPP aggregation. Further structural optimization and refinement of genistein may generate a series of effective sequence-independent inhibitors against the aggregation and toxicity of different amyloid peptides.

G protein-coupled estrogen receptor is involved in the anti-inflammatory effects of genistein in microglia

BACKGROUND

Genistein (GEN), a phytoestrogen that is extracted from leguminous plants, can bind to estrogen receptor and exert biological effects. G protein-coupled estrogen receptor (GPER), a novel membrane estrogen receptor, has been reported to be involved in the anti-inflammatory process. In the present study, using BV2 microglial cell line and primary microglial culture, we evaluated the involvement of GPER in the anti-inflammatory effects of genistein against lipopolysaccharide (LPS)-induced microglia activation.

METHODS

The anti-inflammatory effects of genistein were investigated in LPS-induced microglial activation in murine BV2 microglial cell line and primary microglial culture. Anti-inflammatory properties of genistein were determined by MTT, real time PCR, ELISA and western blot analysis. The pharmacological blockade and lentivirus-mediated siRNA knockdown of GPER were used to study the underlying mechanism.

RESULTS

The results showed that genistein exerted inhibitory effects on LPS-induced expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide (iNOS), tumor necrosis factor-α (TNF-α), interleukin-1 β (IL-1β) and interleukin-6 (IL-6). Pre-treatment with GPER antagonist G15 could significantly block the anti-inflammatory effects of genistein. Moreover, the inhibitory effects of genistein on LPS-induced activation of MAPKs and NF-κB signaling pathways could also be blocked by G15. Lentivirus-mediated siRNA knockdown of GPER significantly inhibited the anti-inflammatory effects of genistein in BV2 cells. Further study revealed that genistein treatment could increase the gene and protein expressions of GPER in BV2 cells.

CONCLUSION

Taken together, these data provide the first evidence that genistein exerts anti-inflammatory effects in microglial cells via GPER activation. These beneficial effects of genistein may represent a new strategy for the treatment of neuroinflammatory diseases.

The effects of soy and tamoxifen on apoptosis in the hippocampus and dentate gyrus in a pentylenetetrazole-induced seizure model of ovariectomized rats

The effects of tamoxifen and soy on apoptosis of the hippocampus and dentate gyrus of ovariectomized rats after repeated seizures were investigated. Female rats were divided into: (1) Control, (2) Sham, (3) Sham-Tamoxifen (Sham-T), (4) Ovariectomized (OVX), (5) OVX-Tamoxifen (OVX-T), (6)OVX-Soy(OVX-S) and (7) OVX-S-T. The animals in the OVX-S, OVX-T and OVX-S-T groups received soy extract (60 mg/kg; i.p.), tamoxifen (10 mg/kg) or both for 2 weeks before induction of seizures. The animals in these groups additionally received the mentioned treatments before each injection of pentylenetetrazole (PTZ; 40 mg/kg) for 6 days. The animals in the Sham and OVX groups received a vehicle of tamoxifen and soy. A significant decrease in the seizure score and TUNEL-positive neurons was seen in the OVX group compared to the Sham (P < 0.001). The animals in both the OVX-T and OVX-S groups had a significantly higher seizure score as well as number of TUNEL-positive neurons compared to the OVX group (P < 0.01-P < 0.001). Co-treatment of the OVX rats by the extract and tamoxifen decreased the seizure score and number of TUNEL-positive neurons compared to OVX-S (P < 0.001). Treatment of the OVX rats by either soy or tamoxifen increased the seizure score as well as the number of TUNEL-positive neurons in the hippocampal formation. Co-administration of tamoxifen and soy extract inhibited the effects of the soy extract and tamoxifen when they were administered alone. It might be suggested that both soy and tamoxifen have agonistic effects on estrogen receptors by changing the seizure severity.

Repositioning drugs by targeting network modules: a Parkinson's disease case study

Background

Much effort has been devoted to the discovery of specific mechanisms between drugs and single targets to date. However, as biological systems maintain homeostasis at the level of functional networks robustly controlling the internal environment, such networks commonly contain multiple redundant mechanisms designed to counteract loss or perturbation of a single member of the network. As such, investigation of therapeutics that target dysregulated pathways or processes, rather than single targets, may identify agents that function at a level of the biological organization more relevant to the pathology of complex diseases such as Parkinson’s Disease (PD). Genome-wide association studies (GWAS) in PD have identified common variants underlying disease susceptibility, while gene expression microarray data provide genome-wide transcriptional profiles. These genomic studies can illustrate upstream perturbations causing the dysfunction in signaling pathways and downstream biochemical mechanisms leading to the PD phenotype. We hypothesize that drugs acting at the level of a gene expression module specific to PD can overcome the lack of efficacy associated with targeting a single gene in polygenic diseases. Thus, this approach represents a promising new direction for module-based drug discovery in human diseases such as PD.

Results

We built a framework that integrates GWAS data with gene co-expression modules from tissues representing three brain regions—the frontal gyrus, the lateral substantia, and the medial substantia in PD patients. Using weighted gene correlation network analysis (WGCNA) software package in R, we conducted enrichment analysis of data from a GWAS of PD. This led to the identification of two over-represented PD-specific gene co-expression network modules: the Brown Module (Br) containing 449 genes and the Turquoise module (T) containing 905 genes. Further enrichment analysis identified four functional pathways within the Br module (cellular respiration, intracellular transport, energy coupled proton transport against the electrochemical gradient, and microtubule-based movement), and one functional pathway within the T module (M-phase). Next, we utilized drug-protein regulatory relationship databases (DMAP) and developed a Drug Effect Sum Score (DESS) to evaluate all candidate drugs that might restore gene expression to normal level across the Br and T modules. Among the drugs with the 12 highest DESS scores, 5 had been reported as potential treatments for PD and 6 hold potential repositioning applications.

Conclusion

In this study, we present a systems pharmacology framework which draws on genetic data from GWAS and gene expression microarray data to reposition drugs for PD. Our innovative approach integrates gene co-expression modules with biomolecular interaction network analysis to identify network modules critical to the PD pathway and disease mechanism. We quantify the positive effects of drugs in a DESS score that is based on known drug-target activity profiles. Our results illustrate that this modular approach is promising for repositioning drugs for use in polygenic diseases such as PD, and is capable of addressing challenges of the hindered gene target in drug repositioning approaches to date.

Electronic supplementary material

The online version of this article (10.1186/s12859-017-1889-0) contains supplementary material, which is available to authorized users.

Current understanding of the molecular mechanisms in Parkinson's disease: Targets for potential treatments

Gradual degeneration and loss of dopaminergic neurons in the substantia nigra, pars compacta and subsequent reduction of dopamine levels in striatum are associated with motor deficits that characterize Parkinson’s disease (PD). In addition, half of the PD patients also exhibit frontostriatal-mediated executive dysfunction, including deficits in attention, short-term working memory, speed of mental processing, and impulsivity. The most commonly used treatments for PD are only partially or transiently effective and are available or applicable to a minority of patients. Because, these therapies neither restore the lost or degenerated dopaminergic neurons, nor prevent or delay the disease progression, the need for more effective therapeutics is critical. In this review, we provide a comprehensive overview of the current understanding of the molecular signaling pathways involved in PD, particularly within the context of how genetic and environmental factors contribute to the initiation and progression of this disease. The involvement of molecular chaperones, autophagy-lysosomal pathways, and proteasome systems in PD are also highlighted. In addition, emerging therapies, including pharmacological manipulations, surgical procedures, stem cell transplantation, gene therapy, as well as complementary, supportive and rehabilitation therapies to prevent or delay the progression of this complex disease are reviewed.

Genistein: mechanisms of action for a pleiotropic neuroprotective agent in stroke

Genistein is a plant estrogen promoted as an alternative to post-menopausal hormone therapy because of a good safety profile and its promotion as a natural product. Several preclinical studies of cerebral ischemia and other models of brain injury support a beneficial role for genistein in protecting the brain from injury whether administered chronically or acutely. Like estrogen, genistein is a pleiotropic molecule that engages several different mechanisms to enhance brain health, including reduction of oxidative stress, promotion of growth factor signaling, and immune suppression. These actions occur in endothelial, glial, and neuronal cells to provide a coordinated beneficial action to ischemic challenge. Though many of these protective actions are associated with estrogen-like actions of genistein, additional activities on other receptors and intracellular targets suggest that genistein is more than a mere estrogen-mimic. Importantly, genistein lacks some of the detrimental effects associated with post-menopausal estrogen treatment and may provide an alternative to hormone therapy in those patients at risk for ischemic events.

Pikuni-Blackfeet traditional medicine: Neuroprotective activities of medicinal plants used to treat Parkinson's disease-related symptoms

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a multifactorial neurodegenerative disorder affecting 5% of the population over the age of 85 years. Current treatments primarily involve dopamine replacement therapy, which leads to temporary relief of motor symptoms but fails to slow the underlying neurodegeneration. Thus, there is a need for safe PD therapies with neuroprotective activity. In this study, we analyzed contemporary herbal medicinal practices used by members of the Pikuni-Blackfeet tribe from Western Montana to treat PD-related symptoms, in an effort to identify medicinal plants that are affordable to traditional communities and accessible to larger populations.

AIM OF THE STUDY

The aims of this study were to (i) identify medicinal plants used by the Pikuni-Blackfeet tribe to treat individuals with symptoms related to PD or other CNS disorders, and (ii) characterize a subset of the identified plants in terms of antioxidant and neuroprotective activities in cellular models of PD.

MATERIALS AND METHODS

Interviews of healers and local people were carried out on the Blackfeet Indian reservation. Plant samples were collected, and water extracts were produced for subsequent analysis. A subset of botanical extracts was tested for the ability to induce activation of the Nrf2-mediated transcriptional response and to protect against neurotoxicity elicited by the PD-related toxins rotenone and paraquat.

RESULTS

The ethnopharmacological interviews resulted in the documentation of 26 medicinal plants used to treat various ailments and diseases, including symptoms related to PD. Seven botanical extracts (out of a total of 10 extracts tested) showed activation of Nrf2-mediated transcriptional activity in primary cortical astrocytes. Extracts prepared from Allium sativum cloves, Trifolium pratense flowers, and Amelanchier arborea berries exhibited neuroprotective activity against toxicity elicited by rotenone, whereas only the extracts prepared from Allium sativum and Amelanchier arborea alleviated PQ-induced dopaminergic cell death.

CONCLUSIONS

Our findings highlight the potential clinical utility of plants used for medicinal purposes over generations by the Pikuni-Blackfeet people, and they shed light on mechanisms by which the plant extracts could slow neurodegeneration in PD.

Genistein, a dietary soy isoflavone, exerts antidepressant-like effects in mice: Involvement of serotonergic system

Genistein, a principal isoflavone property of soybeans, possesses multiple pharmacological activities such as neuroprotection. Recently, it was reported that genistein exerted antidepressant-like effects in animal models, but the mechanism of action remains ambiguous. The purpose of this study was to investigate the antidepressant-like effect of genistein in mice and explore the underlying mechanism(s), using two mouse models of depression, i.e. forced swim test (FST) and tail suspension test (TST). Chronic, but not acute (single dose), genistein treatment (5, 15 or 45 mg/kg, p.o., once per day for three weeks) exerted dose-dependently antidepressant-like effect in mice, concomitant with escalated levels of brain monoamines and suppressed monoamine oxidase (MAO) activity. Chemical depletion of brain serotonin by PCPA abrogated the antidepressant-like action of genistein, but it was not the case for ablation of NA by DSP-4. Moreover, the anti-depression by genistein was preferentially counteracted by co-administration of 5-HT_1A receptor antagonist WAY-100635, suggesting a pivotal role for 5-HT system coupled with 5-HT_1A receptors in mediating such genistein anti-depression. This point was further validated by the fact that genistein action was potentiated by co-treatment with 8-OH-DPAT, a selective 5-HT_1A receptor agonist. Collectively, these findings confirm that chronic genistein administration to mice engenders antidepressant-like efficacy evidenced by lessened behavioral despair. Serotonergic system that preferentially couples with 5-HT_1A receptors may be critically responsible for the present genistein anti-depression.