Search Results (14)

Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the two main neurodegenerative diseases and cause disability and death in patients worldwide. Neurodegeneration is characterized by a progressive loss of neuronal function and structure, causing enormous impairment in cognitive–motor function. Magnolol and honokiol are isomeric biphenyl neolignans and have exhibited neuroprotective activity in previous studies. Hence, we assessed and compared honokiol, magnolol, and mixtures of honokiol and magnolol in honokiol/magnolol molar ratios of 1:3, 1:1, and 3:1 in terms of their neurotoxicity, using the cell counting kit-8 (CCK-8) assay, and of their neuroprotective effect on intracellular reactive oxygen species (iROS) against amyloid-beta (Aβ)- and 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced neurotoxicity in SH-SY5Y cells, using the 2′,7′-dichlorodihydrofluorescein diacetate (H₂DCF-DA) assay. The results showed that honokiol (H) and magnolol (M) at 0.1 μM and the mixtures of honokiol and magnolol in H/M ratios of 1:3, 1:1, and 3:1 at 0.0001 μM exhibited a significant neuroprotective effect of reducing iROS in SH-SY5Y cells where neurotoxicity was induced by Aβ- and MPP⁺ (p-value with respect to Aβ-treated cells < 0.005 and p-value with respect to MPP⁺-treated cells < 0.0001). Moreover, magnolol and honokiol possess antioxidant properties according to computational molecular analysis with Highest Occupied Molecular Orbital (HOMO)- Lowest Unoccupied Molecular Orbital (LUMO) prediction, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Ferric Reducing Antioxidant Power (FRAP) assays. The mixtures of honokiol and magnolol exerted synergistic neuroprotective ability at all ratios while showing better antioxidation ability than that of pure magnolol alone but comparable to that of pure honokiol alone. Drug-likeness, Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) prediction, and toxicity profiles showed that both compounds are promising neuroprotective agents and that one of the possible targeting mechanisms is the ROS-mediated oxidative stress pathway. Additional neuronal cell lines and in vivo models are required to determine similar effects or other protective mechanisms involving the neuroprotective ability of honokiol and magnolol. Full article

As our population ages, there is an increased unmet clinical need surrounding neurodegenerative diseases such as Parkinson’s disease (PD). To tackle this ever-increasing problem, we must ensure that the cell models that we use to develop therapeutics in vitro are robust, reliable, and replicable. In this study, we compared SH-SY5Y cells with LUHMES cells in response to 6-Hydroxydopamine (6OHDA) and 1-Methyl-4-phenylpyridinium (MPP+), two common Parkinson’s insults used in in vitro analysis. Both these cell types have apparent dopaminergic phenotypes, which could aid us in understanding their potential in this race to novel therapies. The LUHMES cells showed consistent dopaminergic (DA) expression through tyrosine hydroxylase (TH) positivity, alongside depleted ATP levels and elevated reactive oxygen species (ROS) production, whereas the SH-SH5Y cells displayed resilience to both chemical insults, raising questions about their utility in accurately modelling PD pathology. Further electrophysiological analysis revealed comparable firing rates and ion channel signalling between both cell types; however, LUHMES cells demonstrated stronger calcium signalling responses, further supporting their use as a more robust PD model. While SH-SY5Y cells showed some adaptability in vitro, their inconsistent DA phenotype and limited response to chemical insults limit their suitability for advanced research, suggesting that LUHMES cells should and must take their place as a hallmark in Parkinson’s disease research. Full article

Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in reduced dopamine levels in the striatum and eventual onset of motor symptoms. Linalool (3,7-dimethyl-1,6-octadien-3-ol) is a monoterpene in aromatic plants exhibiting antioxidant, antidepressant, and anti-anxiety properties. The objective of this study is to evaluate the neuroprotective impacts of linalool on dopaminergic SH-SY5Y cells, primary mesencephalic and cortical neurons treated with 1-methyl-4-phenylpyridinium ion (MPP⁺), as well as in PD-like mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Cell viability, α-tubulin staining, western blotting, immunohistochemistry and behavioral experiments were performed. In MPP⁺-treated SH-SY5Y cells, linalool increased cell viability, reduced neurite retraction, enhanced antioxidant defense by downregulation of apoptosis signaling (B-cell lymphoma 2 (Bcl-2), cleaved caspase-3 and poly ADP-ribose polymerase (PARP)) and phagocyte NADPH oxidase (gp91^phox), as well as upregulation of neurotrophic signaling (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) and nuclear factor-erythroid 2 related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. In MPP⁺-treated primary mesencephalic neurons, linalool enhanced the expressions of tyrosine hydroxylase (TH), Sirtuin 1 (SirT1), and parkin. In MPP⁺-treated primary cortical neurons, linalool upregulated protein expression of SirT1, γ-Aminobutyric acid type A-α1 (GABA_A-α1), and γ-Aminobutyric acid type B (GABA_B). In PD-like mice, linalool attenuated the loss of dopamine neurons in SNpc. Linalool improved the motor and nonmotor behavioral deficits and muscle strength of PD-like mice. These findings suggest that linalool potentially protects dopaminergic neurons and improves the impairment symptoms of PD. Full article

With the goal of combating the multi-faceted Alzheimer’s disease (AD), a series of Rivastigmine-Benzimidazole (RIV–BIM) hybrids was recently reported by us as multitarget-directed ligands, thanks to their capacity to tackle important hallmarks of AD. In particular, they exhibited antioxidant activity, acted as cholinesterase inhibitors, and inhibited amyloid-β (Aβ) aggregation. Herein, we moved forward in this project, studying their ability to chelate redox-active biometal ions, Cu(II) and Fe(III), with widely recognized roles in the generation of oxidative reactive species and in protein misfolding and aggregation in both AD and Parkinson’s disease (PD). Although Cu(II) chelation showed higher efficiency for the positional isomers of series 5 than those of series 4 of the hybrids, the Aβ-aggregation inhibition appears more dependent on their capacity for fibril intercalation than on copper chelation. Since monoamine oxidases (MAOs) are also important targets for the treatment of AD and PD, the capacity of these hybrids to inhibit MAO-A and MAO-B was evaluated, and they showed higher activity and selectivity for MAO-A. The rationalization of the experimental evaluations (metal chelation and MAO inhibition) was supported by computational molecular modeling studies. Finally, some compounds showed also neuroprotective effects in human neuroblastoma (SH-SY5Y cells) upon treatment with 1-methyl-4-phenylpyridinium (MPP⁺), a neurotoxic metabolite of a Parkinsonian-inducing agent. Full article

The low effectiveness of symptomatic pharmacotherapy for Parkinson’s disease (PD), which compensates for dopamine (DA) deficiency under degeneration of nigrostriatal dopaminergic (DAergic) neurons, could apparently be improved with neuroprotective therapy, which slows down neurodegeneration and PD progression. For this, it is necessary to have a DAergic cell line for the development of a PD model to screen neuroprotectors. We used immortalized human embryonic mesencephalon LUHMES cells (LCs) differentiated into DAergic neurons. The aim of this study was to characterize the phenotype of differentiated LCs and develop an 1-methyl-4-phenylpyridinium iodide (MPP⁺)-based test system for screening neuroprotectors. Using polymerase chain reaction (PCR) and immunocytochemistry, it has been shown that all differentiated LCs express genes and synthesize proteins characteristic of all neurons (microtubule-associated protein 2, bIII-tubulin, synaptotagmin 1) and specifically of DAergic neurons (tyrosine hydroxylase, aromatic L-amino acid decarboxylase, DA transporter, vesicular monoamine transporter 2). Furthermore, LCs are able to produce a small amount of DA, but under special conditions. To assess the mechanisms of neurodegeneration and neuroplasticity under the influence of toxins and antiparkinsonian drugs, including neuroprotectors, we have developed an LCs-based MPP⁺ PD model and proposed an original panel of markers for testing functional and structural cell disorders. Full article

Primary cilia help to maintain cellular homeostasis by sensing conditions in the extracellular environment, including growth factors, nutrients, and hormones that are involved in various signaling pathways. Recently, we have shown that enhanced primary ciliogenesis in dopamine neurons promotes neuronal survival in a Parkinson’s disease model. Moreover, we performed fecal metabolite screening in order to identify several candidates for improving primary ciliogenesis, including L-carnitine and acetyl-L-carnitine. However, the role of carnitine in primary ciliogenesis has remained unclear. In addition, the relationship between primary cilia and neurodegenerative diseases has remained unclear. In this study, we have evaluated the effects of carnitine on primary ciliogenesis in 1-methyl-4-phenylpyridinium ion (MPP⁺)-treated cells. We found that both L-carnitine and acetyl-L-carnitine promoted primary ciliogenesis in SH-SY5Y cells. In addition, the enhancement of ciliogenesis by carnitine suppressed MPP⁺-induced mitochondrial reactive oxygen species overproduction and mitochondrial fragmentation in SH-SY5Y cells. Moreover, carnitine inhibited the production of pro-inflammatory cytokines in MPP⁺-treated SH-SY5Y cells. Taken together, our findings suggest that enhanced ciliogenesis regulates MPP⁺-induced neurotoxicity and inflammation. Full article

Autophagy is a cellular homeostatic process by which cells degrade and recycle their malfunctioned contents, and impairment in this process could lead to Parkinson’s disease (PD) pathogenesis. Dioscin, a steroidal saponin, has induced autophagy in several cell lines and animal models. The role of dioscin-mediated autophagy in PD remains to be investigated. Therefore, this study aims to investigate the hypothesis that dioscin-regulated autophagy and autophagy-related (ATG) proteins could protect neuronal cells in PD via reducing apoptosis and enhancing neurogenesis. In this study, the 1-methyl-4-phenylpyridinium ion (MPP⁺) was used to induce neurotoxicity and impair autophagic flux in a human neuroblastoma cell line (SH-SY5Y). The result showed that dioscin pre-treatment counters MPP⁺-mediated autophagic flux impairment and alleviates MPP⁺-induced apoptosis by downregulating activated caspase-3 and BCL2 associated X, apoptosis regulator (Bax) expression while increasing B-cell lymphoma 2 (Bcl-2) expression. In addition, dioscin pre-treatment was found to increase neurotrophic factors and tyrosine hydroxylase expression, suggesting that dioscin could ameliorate MPP⁺-induced degeneration in dopaminergic neurons and benefit the PD model. To conclude, we showed dioscin’s neuroprotective activity in neuronal SH-SY5Y cells might be partly related to its autophagy induction and suppression of the mitochondrial apoptosis pathway. Full article

Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide. Rumex japonicus Houtt. (RJ) has been used to treat gastrointestinal and inflammatory diseases in East Asia. However, it is unknown whether RJ can prevent PD. We investigated the neuroprotective effects of RJ in cellular and animal PD models, focused on mitochondrial function and the gut–brain axis. SH-SY5Y cells were treated with RJ (0.01 mg/mL) for 24 h, after which they were treated with the 1-methyl-4-phenylpyridinium ion (MPP⁺). MPP⁺-induced apoptosis increased mitochondrial reactive oxygen species and decreased ATP, PINK1, and DJ-1, which were inhibited by RJ. Ten-week-old C57BL/6N male mice were treated with 30 mg/kg of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 5 days and orally administered 50 or 100 mg/kg of RJ for 14 days. RJ alleviated MPTP-induced behavioral impairment, dopaminergic neuronal death, and mitochondrial dysfunction in the substantia nigra (SN) and suppressed the MPTP-induced increase in lipopolysaccharide, interleukin-1β, tumor necrosis factor-α, α-synuclein, and apoptotic factors in the SN and colon. Moreover, RJ inhibited the MPTP-mediated disruption of the tight junction barrier in the colon and blood–brain barrier of mice. Therefore, RJ alleviates MPTP-induced inflammation and dopaminergic neuronal death by maintaining mitochondrial function and tight junctions in the brain and colon. Full article

Coreopsis lanceolata L. is a perennial plant of the family Asteraceae, and its flower is known to contain flavonoids with various bioactivities. We evaluated the effect of Coreopsis lanceolata L. flower (CLF) extracts on H₂O₂-induced oxidative stress (OS) in neuronal cells and mouse neurons. The flowering part of CL was used as CLF1 (70% ethanol extract) and CLF2 (water extract), and 10 types of phenolic compounds were quantified using high-performance liquid chromatography. To evaluate the neuroprotective effects of CLF, the antioxidant activities of the extracts were measured, and the expression levels of antioxidant enzymes and proteins related to OS-induced apoptosis in neuronal cells and mouse neurons treated with the extracts were investigated. In the in vitro study, CLF ameliorated H₂O₂-induced oxidative stress and induced the expression of antioxidant enzymes in PC12 cells. Furthermore, CLF1 enhanced the expression of the Bcl-xL protein but reduced the expression of Bax and the cleavage of caspase-3. In the same manner, CLF1 showed neuroprotective effects against OS in vivo. Pretreatment with CLF1 (200 mg/kg) increased the Bcl-2 protein and decreased Bax compared with the 1-methyl-4-phenylpyridinium ion (MPP+)-treated C57BL/6 mice model group. Our results suggest that the protective effects of CLF1 on MPP+-induced apoptosis may be due to its anti-apoptotic activity, through regulating the expression of the Bcl-2 family. CLF1 exerts neuroprotective effects against OS-induced apoptosis in PC12 cells in a Parkinson’s disease model mouse. This effect may be attributable to the upregulation of Bcl-2 protein expression, downregulation of Bax expression, and inhibition of caspase-3 activation. These data indicate that CLF may provide therapeutic value for the treatment of progressive neurodegenerative diseases. Full article

Parkinson’s disease (PD) is characterized by the progressive degeneration of dopaminergic neurons. The cause of PD is still unclear. Oxidative stress and mitochondrial dysfunction have been linked to the development of PD. Luteolin, a non-toxic flavonoid, has become interested in an alternative medicine, according to its effects on anti-oxidative stress and anti-apoptosis, although the underlying mechanism of luteolin on PD has not been fully elucidated. This study aims to investigate whether luteolin prevents neurotoxicity induction by 1-methyl-4-phenylpyridinium iodide (MPP⁺), a neurotoxin in neuroblastoma SH-SY5Y cells. The results reveal that luteolin significantly improved cell viability and reduced apoptosis in MPP⁺-treated cells. Increasing lipid peroxidation and superoxide anion (O₂⁻), including mitochondrial membrane potential (Δψm) disruption, is ameliorated by luteolin treatment. In addition, luteolin attenuated MPP⁺-induced neurite damage via GAP43 and synapsin-1. Furthermore, Cdk5 is found to be overactivated and correlated with elevation of cleaved caspase-3 activity in MPP⁺-exposed cells, while phosphorylation of Erk1/2, Drp1, Fak, Akt and GSK3β are inhibited. In contrast, luteolin attenuated Cdk5 overactivation and supported phosphorylated level of Erk1/2, Drp1, Fak, Akt and GSK3β with reducing in cleaved caspase-3 activity. Results indicate that luteolin exerts neuroprotective effects via Cdk5-mediated Erk1/2/Drp1 and Fak/Akt/GSK3β pathways, possibly representing a potential preventive agent for neuronal disorder. Full article

In Parkinson’s disease, mitochondrial oxidative stress-mediated apoptosis is a major cause of dopaminergic neuronal loss in the substantia nigra (SN). G protein-coupled receptor 4 (GPR4), previously recognised as an orphan G protein coupled-receptor (GPCR), has recently been claimed as a member of the group of proton-activated GPCRs. Its activity in neuronal apoptosis, however, remains undefined. In this study, we investigated the role of GPR4 in the 1-methyl-4-phenylpyridinium ion (MPP⁺) and hydrogen peroxide (H₂O₂)-treated apoptotic cell death of stably GPR4-overexpressing and stably GPR4-knockout human neuroblastoma SH-SY5Y cells. In GPR4-OE cells, MPP⁺ and H₂O₂ were found to significantly increase the expression levels of both mRNA and proteins of the pro-apoptotic Bcl-2-associated X protein (Bax) genes, while they decreased the anti-apoptotic B-cell lymphoma 2 (Bcl-2) genes. In addition, MPP⁺ treatment activated Caspase-3, leading to the cleavage of poly (ADP-ribose) polymerase (PARP) and decreasing the mitochondrial membrane potential (ΔΨm) in GPR4-OE cells. In contrast, H₂O₂ treatment significantly increased the intracellular calcium ions (Ca²⁺) and reactive oxygen species (ROS) in GPR4-OE cells. Further, chemical inhibition by NE52-QQ57, a selective antagonist of GPR4, and knockout of GPR4 by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 decreased the Bax/Bcl-2 ratio and ROS generation, and stabilised the ΔΨm, thus protecting the SH-SY5Y cells from MPP⁺- or H₂O₂-induced apoptotic cell death. Moreover, the knockout of GPR4 decreased the proteolytic degradation of phosphatidylinositol biphosphate (PIP₂) and subsequent release of the endoplasmic reticulum (ER)-stored Ca²⁺ in the cytosol. Our results suggest that the pharmacological inhibition or genetic deletion of GPR4 improves the neurotoxin-induced caspase-dependent mitochondrial apoptotic pathway, possibly through the modulation of PIP₂ degradation-mediated calcium signalling. Therefore, GPR4 presents a potential therapeutic target for neurodegenerative disorders such as Parkinson’s disease. Full article

TFEB (transcription factor EB), which is a master regulator of autophagy and lysosome biogenesis, is considered to be a new therapeutic target for Parkinson’s disease (PD). However, only several small-molecule TFEB activators have been discovered and their neuroprotective effects in PD are unclear. In this study, a curcumin derivative, named E4, was identified as a potent TFEB activator. Compound E4 promoted the translocation of TFEB from cytoplasm into nucleus, accompanied by enhanced autophagy and lysosomal biogenesis. Moreover, TFEB knockdown effectively attenuated E4-induced autophagy and lysosomal biogenesis. Mechanistically, E4-induced TFEB activation is mainly through AKT-MTORC1 inhibition. In the PD cell models, E4 promoted the degradation of α-synuclein and protected against the cytotoxicity of MPP⁺ (1-methyl-4-phenylpyridinium ion) in neuronal cells. Overall, the TFEB activator E4 deserves further study in animal models of neurodegenerative diseases, including PD. Full article

2-aryl-N-alkylbenzimidazole derivatives synthesized by CuI/PPh₃ promoted direct coupling of N-alkylbenzimidazoles with aryl bromides. In vitro neurotoxicities of 20 compounds were evaluated, and the neuroprotective abilities of low-neurotoxic compounds (3b, 3g, 3h, 3i, 3j, 3k, 3o, 3q, 3s and 3t) were investigated against toxicity induced by 1-methyl-4-phenylpyridinium ion (MPP⁺) in SH-SY5Y neuronal cells. In silico studies revealed that compound 3g could have molecule docking with the following proteins: the bone morphogenetic protein receptor type 1B (BMPR1B), human cytochrome P450 1B1(CYP1B1), Metabotropic glutamate receptor 7 (GRM7), histone deacetylase 6 (HDAC6), 5-hydroxytryptamine receptor 5A (HTR5A), human topoisomerase II beta (TOP2B). A molecular docking simulation of model compound 3g and model protein CYP1B1 has been shown. Full article

Studies have shown that saponins from Panax japonicus (SPJ) possess neuroprotective effects. However, whether Chikusetsu saponin V (CsV), the most abundant member of SPJ, can exert neuroprotective effects against 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced cytotoxicity is not known. In this study, we aimed to investigate the neuroprotective effects of CsV on MPP⁺-induced cytotoxicity in human neuroblastoma SH-SY5Y cells and explore its possible mechanisms. Our results show that CsV attenuates MPP⁺-induced cytotoxicity, inhibits ROS accumulation, and increases mitochondrial membrane potential dose-dependently. We also found that levels of Sirt1 protein and Mn-SOD mRNA significantly decreased in MPP⁺-treated group but were restored with CsV treatment in a dose-dependent manner. Furthermore, GRP78 protein and Caspase-12 mRNA levels were elevated by MPP⁺ exposure but reversed by CsV treatment. CsV inhibited the MPP⁺-induced downregulation of Bcl-2 and up-regulation of Bax in a dose-dependent manner and, thus, increased the ratio of Bcl-2/Bax. Overall, these results suggest that Sirt1/Mn-SOD and GRP78/Caspase-12 pathways might be involved in the CsV-mediated neuroprotective effects. Full article