Polydatin alleviates parkinsonism in MPTP-model mice by enhancing glycolysis in dopaminergic neurons

Natural products for the treatment of neurodegenerative diseases

BACKGROUND

Neurodegenerative diseases are among the most common diseases in older adults worldwide. Alzheimer's disease (AD) and Parkinson's disease (PD) are two of the most common neurodegenerative diseases, and are accompanied by cerebral cortical atrophy, neuronal loss, protein accumulation, and excessive accumulation of metal ions. Natural products exhibit outstanding performance in improving cerebral circulatory disorders, promoting cerebral haematoma absorption, repairing damaged nerve tissue, and improving damaged nerve function. In recent years, studies have shown that neuroinflammatory mechanisms and signalling pathways closely related to the occurrence and development of neurological diseases include microglial activation, nuclear factor-κB (NF-κB) pathway, mitogen activated protein kinases (MAPK) pathway, reactive oxygen pathway, nucleotide binding oligomerisation domain-like receptor protein3 (NLRP3) inflammasomes, toll-like receptor4 (TLR4) pathway, nuclear factor erythroid 2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) pathway, phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway, and intestinal flora. Therefore, this study considered the mechanism of neurological diseases as the starting point to review the mechanism of action of natural products in the prevention and treatment of AD and PD in recent years to provide a theoretical basis for clinical prevention and treatment.

AIM

Natural products are a promising source of novel lead structures that have long been used to treat various nervous system diseases.

METHODOLOGY

This review collected literature on neurological diseases and natural products from 2012 to 2022, which were mainly searched through databases such as ScienceDirect, Springer, PubMed, SciFinder, China National Knowledge Infrastructure (CNKI), Wanfang, Google Scholar, and Baidu Academic. The following keywords were searched: neurological disorders, natural products, signalling pathway, mechanism of action.

RESULTS

This review summarises the pathogenesis of degenerative neurological diseases, recent findings on natural products used in neurodegenerative diseases, and the molecular mechanisms underlying these effects.

Polydatin Alleviates Chronic Stress-Induced Depressive and Anxiety-like Behaviors in a Mouse Model

We aimed to investigate whether polydatin could suppress stress-induced depression- and anxiety-like behaviors in a mouse model. Mice were divided into the control group, chronic unpredictable mild stress (CUMS) exposure group, and CUMS mice treated with polydatin group. Following CUMS exposure and polydatin treatment, mice were subjected to behavioral assays to assess depressive-like and anxiety-like behaviors. Synaptic function was determined by the levels of brain-derived neurotrophic factor (BDNF), postsynaptic density protein 95 (PSD95), and synaptophysin (SYN) in the hippocampus and cultured hippocampal neurons. The number and length of dendrites were assessed in cultured hippocampal neurons. Finally, we investigated the effect of polydatin on CUMS-induced inflammation and oxidative stress in the hippocampus by measuring inflammatory cytokine levels, oxidative stress markers such as reactive oxygen species, glutathione peroxidase, catalase, and superoxide dismutase, as well as components of the Nrf2 signaling pathway. Polydatin alleviated CUMS-induced depressive-like behaviors in forced swimming, tail suspension and sucrose preference tests, and anxiety-like behaviors in marble-burying and elevated plus maze tests. Polydatin increased the number and length of dendrites of cultured hippocampal neurons from mice exposed to CUMS and alleviated CUMS-induced synaptic deficits by restoring BDNF, PSD95, and SYN levels in vivo and in vitro. Importantly, polydatin inhibited CUMS-induced hippocampal inflammation and oxidative stress and suppressed the activation of NFκB and Nrf2 pathways. Our study suggests that polydatin may be an effective drug for the treatment of affective disorders through inhibiting neuroinflammation and oxidative stress. Our current findings warrant further study to investigate the potential clinical application of polydatin.

Metabolomics study based on GC-MS reveals a protective function of luteolin against glutamate-induced PC12 cell injury

Oxidative stress response is closely related to neurodegenerative diseases. This study aimed to investigate the cytoprotective effects of luteolin on glutamate-induced oxidative stress injury in PC12 cells. GC-MS combined with multivariate statistical approaches was used to perform metabolomics studies to assess the possible mechanisms. Our results identified 23 metabolites as differential expressed metabolites in the glutamate group, including cysteine content in cells that decreased drastically. This suggests that glutathione synthesis, which balances the redox state of cells, was affected. Luteolin inhibits the reduction in viability in glutamate-induced PC12 cells and regulates 13 differential expressed metabolites in glutamate-induced cell damage. These metabolites associated with luteolin included glycine, serine, and threonine metabolism; glyoxylate and dicarboxylate metabolism; aminoacyl-tRNA biosynthesis; cysteine and methionine metabolism; inositol phosphate metabolism; and starch and sucrose metabolism. In summary, the systemic antioxidant capacity of luteolin in PC12 cells is related to its regulation of amino acid, glucose, and nucleotide metabolism pathways.

Polydatin: Pharmacological Mechanisms, Therapeutic Targets, Biological Activities, and Health Benefits

Polydatin is a natural potent stilbenoid polyphenol and a resveratrol derivative with improved bioavailability. Polydatin possesses potential biological activities predominantly through the modulation of pivotal signaling pathways involved in inflammation, oxidative stress, and apoptosis. Various imperative biological activities have been suggested for polydatin towards promising therapeutic effects, including anticancer, cardioprotective, anti-diabetic, gastroprotective, hepatoprotective, neuroprotective, anti-microbial, as well as health-promoting roles on the renal system, the respiratory system, rheumatoid diseases, the skeletal system, and women's health. In the present study, the therapeutic targets, biological activities, pharmacological mechanisms, and health benefits of polydatin are reviewed to provide new insights to researchers. The need to develop further clinical trials and novel delivery systems of polydatin is also considered to reveal new insights to researchers.

Polydatin as a therapeutic alternative for central nervous system disorders: A systematic review of animal studies

Polydatin, or piceid, is a natural stilbene found in grapes, peanuts, and wines. Polydatin presents pharmacological activities, including neuroprotective properties, exerting preventive and/or therapeutic effects in central nervous system (CNS) disorders. In the present study, we summarize and discuss the neuroprotective effects of polydatin in CNS disorders and related pathological conditions in preclinical animal studies. A systematic review was performed by searching online databases, returning a total of 110 records, where 27 articles were selected and discussed here. The included studies showed neuroprotective effects of polydatin in experimental models of neurological disorders, including cerebrovascular disorders, Parkinson's disease, traumatic brain injuries, diabetic neuropathy, glioblastoma, and neurotoxicity induced by chemical agents. Most studies were focused on stroke (22.2%) and conducted in male rodents. The intervention protocol with polydatin was mainly acute (66.7%), with postdamage induction treatment being the most commonly used regimen (55.2%). Overall, polydatin ameliorated behavioral dysfunctions and/or promoted neurological function by virtue of its antioxidant and antiinflammatory properties. In summary, this review offers important scientific evidence for the neuroprotective effects and distinct pharmacological mechanisms of polydatin that not only enhances the present understanding but is also useful for the development of future preclinical and clinical investigations.

The potential applications of traditional Chinese medicine in Parkinson's disease: A new opportunity

Parkinson's disease (PD) presents a common challenge for people all over the world and has become a major research hotspot due to the large population affected by the illness and the difficulty of clinical treatment. The prevalence of PD is increasing every year, the pathogenesis is complex, and the current treatment is ineffective. Therefore, it has become imperative to find effective drugs for PD. With the advantages of low cost, high safety and high biological activity, Chinese medicine has great advantages in the prevention and treatment of PD. This review systematically summarizes the potential of Chinese medicine for the treatment of PD, showing that Chinese medicine can exert anti-PD effects through various pathways, such as anti-inflammatory and antioxidant pathways, reducing mitochondrial dysfunction, inhibiting endoplasmic reticulum stress and iron death, and regulating intestinal flora. These mainly involve HMGB1/TLR4, PI3K/Akt, NLRP3/ caspase-1/IL-1β, Nrf2/HO-1, SIRT1/Akt1, PINK1/parkin, Bcl-2/Bax, BDNF-TrkB and other signaling pathways. In sum, based on modern phytochemistry, pharmacology and genomic proteomics, Chinese medicine is likely to be a potential candidate for PD treatment, which requires more clinical trials to further elucidate its importance in the treatment of PD.

Old dog, new tricks: Polydatin as a multitarget agent for current diseases

Polydatin (PD) is a natural single-crystal product that is primarily extracted from the traditional plant Polygonum cuspidatum Sieb. et Zucc. Early research showed that PD exhibited a variety of biological activities. PD has attracted increasing research interest since 2014, but no review comprehensively summarized the new findings. A great gap between its biological activities and drug development remains. It is necessary to summarize new findings on the pharmacological effects of PD on current diseases. We propose that PD will most likely be used in cardiac and cerebral ischaemia/reperfusion-related diseases and atherosclerosis in the future. The present work classified these new findings according to diseases and summarized the main effects of PD via specific mechanisms of action. In summary, we found that PD played a therapeutic role in a variety of diseases, primarily via five mechanisms: antioxidative effects, antiinflammatory effects, regulation of autophagy and apoptosis, maintenance of mitochondrial function, and lipid regulation.

Environmental exposure to 17β-trenbolone during adolescence inhibits social interaction in male mice

Puberty is a critical period for growth and development. This period is sensitive to external stimuli, which ultimately affects the development of nerves and the formation of social behaviour. 17β-Trenbolone (17β-TBOH) is an endocrine disrupting chemicals (EDCs), which had been widely reported in aquatic vertebrates. But there is little known about the effects of 17β-TBOH on mammals, especially on adolescent neurodevelopment. In this study, we found that 17β-TBOH acute 1 h exposure can cause the activation of the dopamine circuit in pubertal male balb/c mice. At present, there is little known about the effects of puberty exposure of endocrine disruptors on these neurons/nerve pathways. Through a series of behavioural tests, exposure to 80 μgkg^-1 d^-1 of 17β-TBOH during adolescence increased the anxiety-like behaviour of mice and reduced the control of wheel-running behaviour and the response of social interaction behaviour. The results of TH immunofluorescence staining showed that exposure to 17β-TBOH reduced dopamine axon growth in the medial prefrontal cortex (mPFC). In addition, the results of real-time PCR showed that exposure to 17β-TBOH not only down-regulated the expression of dopamine axon development genes, but also affected the balance of excitatory/inhibitory signals in mPFC. In this research, we reveal the effects of 17β-TBOH exposure during adolescence on mammalian behaviour and neurodevelopment, and provide a reference for studying the origin of adolescent diseases.

Polydatin protects neuronal cells from hydrogen peroxide damage by activating CREB/Ngb signaling

Oxidative stress‑induced neuronal cell death contributes significantly to the physiological processes of a number of neurological disorders. Polydatin (PD) has been reported to protect against Alzheimer's disease (AD), ischemic stroke and traumatic brain injury. However, the underlying neuroprotective mechanisms remain to be elucidated. The current study suggested that PD activates AKT/cAMP response element‑binding protein (CREB) signaling and induces neuroglobin (Ngb) to protect neuronal cells from hydrogen peroxide (H₂O₂) in vitro. PD inhibited the H₂O₂‑induced neuronal cell death of primary mouse cortical neurons and N2a cells. Functional studies showed that PD attenuated H₂O₂‑induced mitochondrial dysfunction and mitochondrial reactive oxygen species production. Mechanistically, PD was verified to induce the phosphorylation of AKT and CREB and increase the protein level of Ngb. The luciferase assay results showed that Ngb transcriptional activity was activated by CREB, especially after PD treatment. It was further indicated that PD increased the transcription of Ngb by enhancing the binding of CREB to the promoter region of Ngb. Finally, Ngb knockdown largely attenuated the neuroprotective role of PD against H₂O₂. The results indicated that PD protected neuronal cells from H₂O₂ by activating CREB/Ngb signaling in neuronal cells, indicating that PD has a neuroprotective effect against neurodegenerative diseases.

The Neuroprotective Role of Polydatin: Neuropharmacological Mechanisms, Molecular Targets, Therapeutic Potentials, and Clinical Perspective

Neurodegenerative diseases (NDDs) are one of the leading causes of death and disability in humans. From a mechanistic perspective, the complexity of pathophysiological mechanisms contributes to NDDs. Therefore, there is an urgency to provide novel multi-target agents towards the simultaneous modulation of dysregulated pathways against NDDs. Besides, their lack of effectiveness and associated side effects have contributed to the lack of conventional therapies as suitable therapeutic agents. Prevailing reports have introduced plant secondary metabolites as promising multi-target agents in combating NDDs. Polydatin is a natural phenolic compound, employing potential mechanisms in fighting NDDs. It is considered an auspicious phytochemical in modulating neuroinflammatory/apoptotic/autophagy/oxidative stress signaling mediators such as nuclear factor-κB (NF-κB), NF-E2–related factor 2 (Nrf2)/antioxidant response elements (ARE), matrix metalloproteinase (MMPs), interleukins (ILs), phosphoinositide 3-kinases (PI3K)/protein kinase B (Akt), and the extracellular regulated kinase (ERK)/mitogen-activated protein kinase (MAPK). Accordingly, polydatin potentially counteracts Alzheimer’s disease, cognition/memory dysfunction, Parkinson’s disease, brain/spinal cord injuries, ischemic stroke, and miscellaneous neuronal dysfunctionalities. The present study provides all of the neuroprotective mechanisms of polydatin in various NDDs. Additionally, the novel delivery systems of polydatin are provided regarding increasing its safety, solubility, bioavailability, and efficacy, as well as developing a long-lasting therapeutic concentration of polydatin in the central nervous system, possessing fewer side effects.

Do naturally occurring antioxidants protect against neurodegeneration of the dopaminergic system? A systematic revision in animal models of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease and is characterized by a significant decrease in dopamine levels, caused by progressive degeneration of the dopaminergic neurons in the nigrostriatal pathway. Multiple mechanisms have been implicated in its pathogenesis, including oxidative stress, neuroinflammation, protein aggregation, mitochondrial dysfunction, insufficient support for neurotrophic factors and cell apoptosis. The absence of treatments capable of slowing or stopping the progression of PD has increased the interest in the natural antioxidant substances present in the diet, since they have multiple beneficial properties and it is possible that they can influence the mechanisms responsible for the dysfunction and death of dopaminergic neurons. Thus, the purpose of this systematic review is to analyze the results obtained in a set of studies carried out in the last years, which describe the neuroprotective, antioxidant and regenerative functions of some naturally occurring antioxidants in experimental models of PD. The results show that the exogenous no enzymatic antioxidants can significantly modify the biochemical and behavioral mechanisms that contribute to the pathophysiology of Parkinsonism in experimental animals. Therefore, it is possible that they may contribute to effective neuroprotection by providing a significant improvement in neuropathological markers. In conclusion, the results of this review suggest that exogenous antioxidants can be promising therapeutic candidates for the prevention and treatment of PD.