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

Protective effects of polydatin amphiphilic chitosan nanocarriers against an aluminum chloride-induced model of Alzheimer's disease in rats: relevance to its anti-inflammatory and antioxidant effects

Alzheimer's disease (AD) is the most frequent cause of dementia. Since there are complex pathophysiological mechanisms behind AD, and there is no effective treatment strategy, it is necessary to introduce novel multi-targeting agents with fewer side effects and higher efficacy. Polydatin (PD) is a naturally occurring resveratrol glucoside employing multiple mechanisms toward neuroprotection. In the current study, the anti-AD mechanisms of a novel amphiphilic chitosan nanocarrier formulation (ACN) of PD (NPD) were studied. After preparing the amphiphilic chitosan nanoformulation (i.e., NPD), physicochemical properties were assessed, including particle size, zeta potential, drug loading, drug release, MTT, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). For in vivo analysis, aluminum chloride (AlCl3) was injected intraperitoneally for 14 days to induce AD in male Albino Wistar rats. To examine the anti-AD mechanisms of NPD, a total of 36 rats were divided into six groups of six. Behavioral tests, including open field, Y-maze, elevated plus maze, and shuttle box were done on days 7, 8, 14, and 15. Additionally, zymography, biochemical analysis, and histological studies were done. NPD, as a newly synthesized formulation for PD, potentially improved memory and cognitive behavioral parameters and reduced the activity of inflammatory matrix metalloproteinase 9 (MMP9) and serum nitrite levels, while increasing anti-inflammatory MMP2, antioxidant catalase, and glutathione. NPD also prevented morphological changes and increased neuronal survival in the CA2, CA4, and DG regions of the rat hippocampus. In conclusion, NPD is a novel formulation against AD through anti-inflammatory, antioxidant, and neuroprotective mechanisms.

Polydatin protects against leukemia by inducing apoptosis and activating autophagy via p38-MAPK pathway

The clinical treatment of acute myeloid leukemia (AML) remains suboptimal, necessitating the exploration of novel therapeutic strategies. Polydatin, a major active component of the Chinese herb Polygonum cuspidatum, exhibits multiple antitumor properties. However, its potential anti-AML effects and underlying mechanisms remain unclear. In this study, MOLM-13 cells, a representative cell line for AML, were treated with polydatin, and its effects on cell proliferation, cell cycle, apoptosis, reactive oxygen species (ROS) generation, and mitochondrial membrane potential (Δψm) were assessed using the Cell Counting Kit-8 (CCK-8) assay and flow cytometry. The expression levels of key apoptotic and autophagic markers, including death receptors (DR4 and DR5), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), Bcl-2, Bax, LC3, Beclin1, and P62, were analyzed by western blotting. Furthermore, autophagy levels were evaluated using GFP-LC3 fluorescence and monodansylcadaverine staining. To elucidate the relationship between polydatin and autophagy, the autophagy inhibitor 3-MA and the p38-MAPK activator SB203580 were employed. Polydatin significantly inhibited AML cell proliferation, induced apoptosis and autophagic flux, caused cell cycle arrest in the S phase, reduced Δψm, and promoted ROS generation. Following polydatin treatment, the protein expression levels of DR4, TRAIL, Bax, LC3, and Beclin1 were significantly increased, while DR5, Bcl-2, and P62 were markedly reduced. Additionally, SB203580 promoted polydatin's effects on cell proliferation inhibition, ROS generation, and autophagic flux, whereas 3-MA reversed these effects. These findings demonstrate that polydatin exerts anti-leukemic effects by inhibiting cell proliferation and inducing apoptosis through the activation of autophagy via the p38-MAPK pathway in MOLM-13 AML cells. This suggests that polydatin could serve as a potential therapeutic agent for AML.

Polydatin Alleviates Cyclophosphamide-Induced Mouse Immunosuppression by Promoting Splenic Lymphocyte Proliferation and Thymic T Cell Development and Differentiation

Immunosuppression increases disease risk, and the natural compound polydatin (PD) has been reported to modulate immune-related disorders. In cyclophosphamide-induced immunosuppressed mice, PD was evaluated for its immunomodulatory effects. Immune organ indices were measured, while H&E staining and ELISA assessed spleen pathology and serum cytokine levels. The proliferation of splenic lymphocytes, both total and subpopulation, was determined using concanavalin A or lipopolysaccharide stimulation, with flow cytometry analyzing peripheral blood and splenic lymphocytes, thymic T cell subtypes, cell cycling, and bromodeoxyuridine incorporation. Western blotting was used to assess Ki67, PCNA expression, and MAPK activation. PD significantly alleviated cyclophosphamide-induced reductions in spleen and thymus indices, improved the organization of red and white pulp in the spleen, and restored TNF-α and IFN-γ levels. It reversed cyclophosphamide-induced cell cycle arrest, characterized by increased PCNA and decreased Ki67, and corrected the diminished numbers of B and T cells and the reduced CD4+/CD8+ ratio in the thymus. In vitro, PD directly promoted splenic lymphocyte proliferation and cell cycling via MAPK activation. Overall, our findings demonstrated that PD alleviated mouse immunosuppression by activating splenic lymphocyte proliferation and re-organizing thymic T cell development and differentiation.

Preclinical toxicological assessment of polydatin in zebrafish model

Polydatin (3,4',5-trihydroxystilbene-3-β-D-glucoside, piceid), a natural stilbenoid found in different plant sources, has gained increasing attention for its potential health benefits. However, prior to its widespread adoption in human therapeutics and consumer products, a comprehensive investigation of its toxicological effects is crucial. In this study, the toxicity of polydatin was investigated in a developmental toxicity test using zebrafish (Danio rerio) as a valuable model for preclinical assessments. We employed the Fish Embryo Test (FET test - OECD n°236) to investigate the effects of polydatin on survival, hatchability, development, and behavior of zebrafish embryo-larval stage. Remarkably, the results demonstrated that polydatin up to 435 μM showed no toxicity. Throughout the exposure period, zebrafish embryos exposed to polydatin exhibited normal development, with no significant mortality observed. Furthermore, hatching success and heartbeat rate were unaffected, and no morphological abnormalities were identified, signifying a lack of teratogenic effects and cardiotoxicity. Locomotion activity assessment revealed normal swimming patterns and response to stimuli, indicating no neurotoxic effects. Our study provides valuable insights into the toxicological profile of polydatin, suggesting that it may offer potential therapeutic benefits under a considerable concentration range. In addition, zebrafish model proves to be an efficient system for early-stage toxicological screening, guiding further investigations into the secure utilization of polydatin for human health and wellness.

Phytomedicine for neurodegenerative diseases: The road ahead

Neurodegenerative disorders (NDs) are among the most common causes of death across the globe. NDs are characterized by progressive damage to CNS neurons, leading to defects in specific brain functions such as memory, cognition, and movement. The most common NDs are Parkinson's, Alzheimer's, Huntington's, and amyotrophic lateral sclerosis (ALS). Despite extensive research, no therapeutics or medications against NDs have been proven to be effective. The current treatment of NDs involving symptom-based targeting of the disease pathogenesis has certain limitations, such as drug resistance, adverse side effects, poor blood-brain barrier permeability, and poor bioavailability of drugs. Some studies have shown that plant-derived natural compounds hold tremendous promise for treating and preventing NDs. Therefore, the primary objective of this review article is to critically analyze the properties and potency of some of the most studied phytomedicines, such as quercetin, curcumin, epigallocatechin gallate (EGCG), apigenin, and cannabinoids, and highlight their advantages and limitations for developing next-generation alternative treatments against NDs. Further extensive research on pre-clinical and clinical studies for developing plant-based drugs against NDs from bench to bedside is warranted.

Polydatin and Nicotinamide Rescue the Cellular Phenotype of Mitochondrial Diseases by Mitochondrial Unfolded Protein Response (mtUPR) Activation

Primary mitochondrial diseases result from mutations in nuclear DNA (nDNA) or mitochondrial DNA (mtDNA) genes, encoding proteins crucial for mitochondrial structure or function. Given that few disease-specific therapies are available for mitochondrial diseases, novel treatments to reverse mitochondrial dysfunction are necessary. In this work, we explored new therapeutic options in mitochondrial diseases using fibroblasts and induced neurons derived from patients with mutations in the GFM1 gene. This gene encodes the essential mitochondrial translation elongation factor G1 involved in mitochondrial protein synthesis. Due to the severe mitochondrial defect, mutant GFM1 fibroblasts cannot survive in galactose medium, making them an ideal screening model to test the effectiveness of pharmacological compounds. We found that the combination of polydatin and nicotinamide enabled the survival of mutant GFM1 fibroblasts in stress medium. We also demonstrated that polydatin and nicotinamide upregulated the mitochondrial Unfolded Protein Response (mtUPR), especially the SIRT3 pathway. Activation of mtUPR partially restored mitochondrial protein synthesis and expression, as well as improved cellular bioenergetics. Furthermore, we confirmed the positive effect of the treatment in GFM1 mutant induced neurons obtained by direct reprogramming from patient fibroblasts. Overall, we provide compelling evidence that mtUPR activation is a promising therapeutic strategy for GFM1 mutations.

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: 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.