The Neuroprotective Effects of Agmatine on Parkinson's Disease: Focus on Oxidative Stress, Inflammation and Molecular Mechanisms

Agmatine (AGM), a naturally occurring polyamine derived from L-arginine, has shown significant potential for neuroprotection in Parkinson's Disease (PD) due to its multifaceted biological activities, including antioxidant, anti-inflammatory, and anti-apoptotic effects. This review explores the therapeutic potential of AGM in treating PD, focusing on its neuroprotective mechanisms and evidence from preclinical studies. AGM has been demonstrated to mitigate the neurotoxic effects of rotenone (ROT) by improving motor function, reducing oxidative stress markers, and decreasing levels of pro-inflammatory cytokines in animal models. Additionally, AGM protects against the loss of TH + neurons, crucial for dopamine synthesis. The neuroprotective properties of AGM are attributed to its ability to modulate several key pathways implicated in PD pathogenesis, such as inhibition of NMDA receptors, activation of Nrf2, and suppression of the HMGB1/ RAGE/ TLR4/ MyD88/ NF-κB signaling cascade. Furthermore, the potential of agmatine to promote neurorestoration is highlighted by its role in enhancing neuroplasticity elements such as CREB, BDNF, and ERK1/2. This review highlights agmatine's promising therapeutic potential in PD management, suggesting that it could offer both symptomatic relief and neuroprotective benefits, thereby modifying the disease course and improving the quality of life for patients. Further research is warranted to translate these preclinical findings into clinical applications.

Pharmacodynamical research of extracts and compounds in traditional Chinese medicines for Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease (AD). Currently, there is no cure for PD, and medications can only control the progression of the disease. Various experimental studies have shown the significant efficacy of TCM in treating PD, and combination with western medicine can enhance the effects and reduce toxicity. Thus, exploring effective anti-PD compounds from TCM has become a popular research fields. This review summarizes commonly used TCM extracts and natural products for the treatment of PD, both domestically and internationally. Furthermore, it delves into various mechanisms of TCM in treating PD, such as anti-oxidative stress, anti-inflammatory, anti-apoptotic, improve mitochondrial dysfunction, inhibits α-synuclein (α-Syn) misfolding and aggregation, regulating neurotransmitters, regulates intestinal flora, enhances immunity, and so on. The results reveal that most TCMs exert their neuroprotective effects through anti-inflammatory and anti-oxidative stress actions, thereby slowing down the progression of the disease. These TCM may hold the key to improving PD therapy and have tremendous potential to be developed as novel anti-PD drugs.

Based on network pharmacology and molecular docking to explore the potential mechanism of shikonin in periodontitis

OBJECTIVES

To investigate the potential mechanisms of shikonin in preventing and treating periodontitis using network pharmacology and molecular docking methods.

MATERIALS AND METHODS

The targets of shikonin were obtained in TCMSP and SEA databases, and targets of periodontitis were gathered from the OMIM, GeneCards and Drugbank Databases. The intersecting targets were entered into the DAVID database to obtain the relevant biological functions and pathways by GO and KEGG enrichment analysis. The obtained targets were analysed the protein-protein interaction (PPI) in STRING platform. In Cytoscape 3.8.0, the network analysis function with the MCODE plug-in were used to obtain the key targets, of shikonin and periodontitis. Molecular docking and molecular dynamics simulation (MD) were used to assess the affinity between the shikonin and the key targets.

RESULTS

Shikonin was screened for 22 targets and periodontitis was screened for 944 targets, the intersecting targets were considered as potential therapeutic targets. The targets played important roles in cellular response to hypoxia, response to xenobiotic stimulus and positive regulates of apoptotic process by GO enrichment analysis. 10 significant pathways were analyzed by KEGG, such as human cytomegalovirus infection and PI3K-Akt signaling pathway, etc. Cytoscape software screened the key genes including AKT1, CCL5, CXCR4, PPARG, PTEN, PTGS2 and TP53. Molecular docking and MD results showed that shikonin could bind stably to the targets.

CONCLUSIONS

The present study enriched the molecular mechanisms in periodontitis with shikonin, providing potential therapeutic targets for periodontitis.

Targeting chemokine-receptor mediated molecular signaling by ethnopharmacological approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Infection and inflammation are critical to global human health status and the goal of current pharmacological interventions intends formulating medications/preventives as a measure to deal with this situation. Chemokines and their cognate receptors are major regulatory molecules in many of these ailments. Natural products have been a keen source to the drug development industry, every year contributing significantly to the growing list of FDA approved drugs. A multiverse of natural resource is employed as a part of curative regimen in folk/traditional/ethnomedicine which can be employed to discover, repurpose, and design potent medications for the diseases of clinical concern.

AIM OF THE STUDY

This review aims to systematically document the ethnopharmacologically active agents targeting the infectious-inflammatory diseases through the chemokine-receptor nexus.

MATERIALS AND METHODS

Articles related to chemokine/receptor modulating ethnopharmacological anti-inflammatory, anti-infectious natural sources, bioactive compounds, and formulations have been examined with special emphasis on women related diseases. The available literature has been thoroughly scrutinized for the application of traditional medicines in chemokine associated experimental methods, their regulatory outcomes, and pertinence to women's health wherever applicable. Moreover, the potential traditional regimens under clinical trials have been critically assessed.

RESULTS

A systematic and comprehensive review on the chemokine-receptor targeting ethnopharmaceutics from the available literature has been provided. The article discusses the implication of traditional medicine in the chemokine system dynamics in diverse infectious-inflammatory disorders such as cardiovascular diseases, allergic diseases, inflammatory diseases, neuroinflammation, and cancer. On this note, critical evaluation of the available data surfaced multiple diseases prevalent in women such as osteoporosis, rheumatoid arthritis, breast cancer, cervical cancer and urinary tract infection. Currently there is no available literature highlighting chemokine-receptor targeting using traditional medicinal approach from women's health perspective. Moreover, despite being potent in vitro and in vivo setups there remains a gap in clinical translation of these formulations, which needs to be strategically and scientifically addressed to pave the way for their successful industrial translation.

CONCLUSIONS

The review provides an optimistic global perspective towards the applicability of ethnopharmacology in chemokine-receptor regulated infectious and inflammatory diseases with special emphasis on ailments prevalent in women, consecutively addressing their current status of clinical translation and future directions.

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review

Currently, skin injuries have a serious impact on people's lives and socio-economic stress. Shikonin, a naphthoquinone compound derived from the root of the traditional Chinese medicine Shikonin, has favorable biological activities such as anti-inflammatory, antibacterial, immunomodulatory, anticancer, and wound-healing-promoting pharmacological activities. It has been reported that Shikonin can be used for repairing skin diseases due to its wide range of pharmacological effects. Moreover, the antimicrobial activity of Shikonin can play a great role in food and can also reduce the number of pathogenic bacteria in food. This paper summarizes the research on the pharmacological effects of Shikonin in recent years, as well as research on the mechanism of action of Shikonin in the treatment of certain skin diseases, to provide certain theoretical references for the clinical application of Shikonin, and also to provides research ideas for the investigation of the mechanism of action of Shikonin in other skin diseases.

Meclizine moderates lipopolysaccharide-induced neuroinflammation in mice through the regulation of AKT/ NF-κβ/ERK/JNK signaling pathway

Neuroinflammation is identified as significant inflammatory reactions occurring in the central nervous system. Lipopolysaccharide (LPS) stimulates innate immune reactions and is used as an in vivo animal model for the investigation of inflammation. Meclizine (MCLZ) is a histamine antagonist with potential neuroprotective qualities. Forty adult male Swiss albino mice were divided into four groups (n = 10). Group 1 served as a control negative group. Groups 2-4 were injected with LPS (5 mg/kg; i.p). Group 2 served as LPS-control. Groups 3 & 4 were given MCLZ (12.5 & 25 mg/kg; p.o) respectively for 14 days. LPS administration resulted in significant neuroinflammation in mice as was revealed by significant inflammatory histopathological changes and positive immunohistochemical staining of glial fibrillary acidic proteins (GFAP) accompanied by significant elevations of brain tissue contents of interleukin-1-beta (IL-1β), tumor necrosis factor-alpha (TNF-α), nuclear factor kappa-beta (NF-κβ), protein kinase B (AKT), extracellular signal-regulated kinase (ERK) and C-Jun N-Terminal Kinases (JNK). MCLZ treatment significantly down-regulated all the aforementioned parameters in mice brains. Moreover, MCLZ treatment ameliorated the inflammatory histopathological changes and GFAP immunostaining in brain tissues. The current study identifies for the first time the protective anti-neuroinflammatory effects of MCLZ against LPS-induced neuroinflammation in mice. MCLZ protected against neuroinflammation via the amelioration of inflammatory histopathological changes as well as neuronal GFAP immunostaining and down-regulated the AKT/NF-κβ/ERK/JNK signaling pathway. MCLZ is anticipated as a potential protective candidate for the addition to the treatment protocol of neuroinflammation.

Bear bile powder alleviates Parkinson's disease-like behavior in mice by inhibiting astrocyte-mediated neuroinflammation

Parkinson's disease (PD) is a common neurodegenerative disease in middle-aged and elderly people. In particular, increasing evidence has showed that astrocyte-mediated neuroinflammation is involved in the pathogenesis of PD. As a precious traditional Chinese medicine, bear bile powder (BBP) has a long history of use in clinical practice. It has numerous activities, such as clearing heat, calming the liver wind and anti-inflammation, and also exhibits good therapeutic effect on convulsive epilepsy. However, whether BBP can prevent the development of PD has not been elucidated. Hence, this study was designed to explore the effect and mechanism of BBP on suppressing astrocyte-mediated neuroinflammation in a mouse model of PD. PD-like behavior was induced in the mice by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (30 mg·kg-1) for five days, followed by BBP (50, 100, and 200 mg·kg-1) treatment daily for ten days. LPS stimulated rat C6 astrocytic cells were used as a cell model of neuroinflammation. THe results indicated that BBP treatment significantly ameliorated dyskinesia, increased the levels of tyrosine hydroxylase (TH) and inhibited astrocyte hyperactivation in the substantia nigra (SN) of PD mice. Furthermore, BBP decreased the protein levels of glial fibrillary acidic protein (GFAP), cyclooxygenase 2 (COX2) and inducible nitric oxide synthase (iNOS), and up-regulated the protein levels of takeda G protein-coupled receptor 5 (TGR5) in the SN. Moreover, BBP significantly activated TGR5 in a dose-dependent manner, and decreased the protein levels of GFAP, iNOS and COX2, as well as the mRNA levels of GFAP, iNOS, COX2, interleukin (IL) -1β, IL-6 and tumor necrosis factor-α (TNF-α) in LPS-stimulated C6 cells. Notably, BBP suppressed the phosphorylation of protein kinase B (AKT), inhibitor of NF-κB (IκBα) and nuclear factor-κB (NF-κB) proteins in vivo and in vitro. We also observed that TGR5 inhibitor triamterene attenuated the anti-neuroinflammatory effect of BBP on LPS-stimulated C6 cells. Taken together, BBP alleviates the progression of PD mice by suppressing astrocyte-mediated inflammation via TGR5.

Research progress on gas signal molecular therapy for Parkinson's disease

The pathogenesis of Parkinson's disease (PD) remains unclear. Among the pathological manifestations is the progressive degeneration of the nigrostriatal dopaminergic pathway, leading to massive loss of neurons in the substantia nigra pars compacta and dopamine (DA) depletion. Therefore, the current drug treatment is primarily based on DA supplementation and delaying the progression of the disease. However, as patients' symptoms continue to worsen, the drug effect will gradually decrease or even disappear, thereby further aggravating clinical symptoms. Gas signaling molecules, such as hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and hydrogen (H2), exhibit pleiotropic biological functions and play crucial roles in physiological and pathological effects. In common neurodegenerative diseases including Alzheimer's disease and PD, gas signal molecules can prevent or delay disease occurrence via the primary mechanisms of antioxidation, anti-inflammatory response, and antiapoptosis. This article reviews the therapeutic progress of gas signaling molecules in PD models and discusses the possibility of their clinical applications.

Neuroprotective effects of fermented tea in MPTP-induced Parkinson's disease mouse model via MAPK signaling-mediated regulation of inflammation and antioxidant activity

Parkinson's disease (PD) is a neurodegenerative disorder that is characterized by dopaminergic neuronal damage. In this study, three tea extracts from Hadong, Korea, were evaluated in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity damage model (C57BL/6 mice) for their therapeutic effects against PD: green tea (GT), semi-fermented tea (SFT), and fermented tea (FT). Theaflavin content in the teas increased but catechin content decreased with the degree of fermentation. In addition, SFT showed the highest theanine and γ-aminobutyric acid contents. SFT at a concentration of 25 μg/mL showed the highest activity in the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay among all samples. Furthermore, the 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activity of 25 μg/mL SFT was higher than that of l-ascorbic acid. Fermented tea suppressed the expression of inflammatory cytokines, such as interleukin-6, tumor necrosis factor-alpha, inducible nitric oxide synthase, cyclooxygenase-2, and macrophage-1, as well as inhibited overexpression of apoptotic signals, including p-53, cleaved caspase-3, and poly (ADP-ribose) polymerase-1. Moreover, GT, SFT, and FT regulated the MPTP-induced oxidative stress-related factors, including superoxide dismutase, glutathione-S-transferase, and nicotinamide adenine dinucleotide phosphate oxidase 4. Fermented tea also alleviated MPTP-induced behavioral impairment and dopaminergic neuronal damage and reduced α-synuclein levels. These results indicate that fermented tea is effective for the treatment of neuro-inflammatory, neuro-apoptotic, and neuro-oxidative disorders.