Baicalein antagonizes rotenone-induced apoptosis in dopaminergic SH-SY5Y cells related to Parkinsonism

Signaling pathways in Parkinson's disease: molecular mechanisms and therapeutic interventions

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, and its treatment remains a big challenge. The pathogenesis of PD may be related to environmental and genetic factors, and exposure to toxins and gene mutations may be the beginning of brain lesions. The identified mechanisms of PD include α-synuclein aggregation, oxidative stress, ferroptosis, mitochondrial dysfunction, neuroinflammation, and gut dysbiosis. The interactions among these molecular mechanisms complicate the pathogenesis of PD and pose great challenges to drug development. At the same time, the diagnosis and detection of PD are also one of obstacles to the treatment of PD due to its long latency and complex mechanism. Most conventional therapeutic interventions for PD possess limited effects and have serious side effects, heightening the need to develop novel treatments for this disease. In this review, we systematically summarized the pathogenesis, especially the molecular mechanisms of PD, the classical research models, clinical diagnostic criteria, and the reported drug therapy strategies, as well as the newly reported drug candidates in clinical trials. We also shed light on the components derived from medicinal plants that are newly identified for their effects in PD treatment, with the expectation to provide the summary and outlook for developing the next generation of drugs and preparations for PD therapy.

Scutellaria baicalensis and its constituents baicalin and baicalein as antidotes or protective agents against chemical toxicities: a comprehensive review

Scutellaria baicalensis (SB), also known as the Chinese skullcap, has a long history of being used in Chinese medicine to treat a variety of conditions ranging from microbial infections to metabolic syndrome and malignancies. Numerous studies have reported that treatment with total SB extract or two main flavonoids found in its root and leaves, baicalin (BA) and baicalein (BE), can prevent or alleviate the detrimental toxic effects of exposure to various chemical compounds. It has been shown that BA and BE are generally behind the protective effects of SB against toxicants. This paper aimed to review the protective and therapeutic effects of SB and its main components BA and BE against chemical compounds that can cause intoxication after acute or chronic exposure and seriously affect different vital organs including the brain, heart, liver, and kidneys. In this review paper, we had a look into a total of 221 in vitro and in vivo studies from 1995 to 2021 from the scientific databases PubMed, Scopus, and Web of Science which reported protective or therapeutic effects of BA, BE, or SB against drugs and chemicals that one might be exposed to on a professional or accidental basis and compounds that are primarily used to simulate disease models. In conclusion, the protective effects of SB and its flavonoids can be mainly attributed to increase in antioxidants enzymes, inhibition of lipid peroxidation, reduction of inflammatory cytokines, and suppression of apoptosis pathway.

Biomedicine and traditional Chinese medicine: a fruitful scientific and cultural interaction

Over the years, the approach of traditional Chinese medicine has changed, as has the concept of the health status. Particularly in this article we will focus on the importance of some techniques that we can define millennial, as acupuncture. We will highlight the relationship between a millenary system and the principles of modernity, emphasizing the relevance of a technique that appears to be in line with the latest scientific research and numerous studies of effectiveness, proposing therapeutic integration as a usable way. We will see how acupuncture has an anti-inflammatory effect, and has a beneficial role in subjects suffering from allergic or autoimmune diseases, including an antihistamine action and downregulation of proinflammatory cytokines (e.g. IL-1β, IL-6 and TNF-α). In addition, acupuncture could also act as an immunomodulatory agent, involving the neuroimmune network, T helper and natural killer cells. Traditional Chinese medicine, acupuncture in particular, is widely used within Western health systems and there are many studies done regarding its efficacy in the clinical field. In addition to scientific validation, however, a comparison on a cultural level is also necessary. To build a constructive dialogue, indeed, it is necessary to deconstruct the preconceptions and prejudices concerning both biomedicine and traditional Chinese medicine. In fact, only through deconstruction we can understand that biomedicine and traditional Chinese medicine are both culturally connoted knowledge. In this article it will first be underlined how clinical observations can be better understood if we pay attention to analyzing the cultural context of the medical systems that here interact with each other. (www.actabiomedica.it).

An overview of pharmacological activities of baicalin and its aglycone baicalein: New insights into molecular mechanisms and signaling pathways

The flavonoids, baicalin, and its aglycone baicalein possess multi-fold therapeutic properties and are mainly found in the roots of Oroxylum indicum (L.) Kurz and Scutellaria baicalensis Georgi. These flavonoids have been reported to possess various pharmacological properties, including antibacterial, antiviral, anticancer, anticonvulsant, anti-oxidant, hepatoprotective, and neuroprotective effects. The pharmacological properties of baicalin and baicalein are due to their abilities to scavenge reactive oxygen species (ROS) and interaction with various signaling molecules associated with apoptosis, inflammation, autophagy, cell cycle, mitochondrial dynamics, and cytoprotection. In this review, we summarized the molecular mechanisms underlying the chemopreventive and chemotherapeutic applications of baicalin and baicalein in the treatment of cancer and inflammatory diseases. In addition, the preventive effects of baicalin and baicalein on mitochondrial dynamics and functions were highlighted with a particular emphasis on their anti-oxidative and cytoprotective properties. The current review highlights could be useful for future prospective studies to further improve the pharmacological applications of baicalein and baicalin. These studies should define the threshold for optimal drug exposure, dose optimization and focus on therapeutic drug monitoring, objective disease markers, and baicalin/baicalein drug levels.

Research Paper5,6,7 trihydroxy flavone armoured neurodegeneration caused by Quinolinic acid induced huntington's like disease in rat striatum - reinstating the level of brain neurotrophins with special reference to cognitive-socio behaviour, biochemical and histopathological aspects

Huntington Disease (HD), a predominant Neurodegenerative Disorder which might be induced by endogenous neurotoxin called Quinolinic Acid (QA), an N-methyl-D aspartate receptor (NMDAR) agonist, the bilaterally intrastriatal administration (200 nm/2 μL of saline) offers rise to the toxic events like neuronal death, neuroinflammation by inflicting excitotoxicity and oxidative stress in the striatum of male Wistar rats by exhibiting the behavioural changes which was accessed by rotarod, open field analysis. In this study, the neuropharmacological effect of Baicalein (BC) against QA induced HD was evaluated. Baicalein (BC), scientifically 5,6,7 trihydroxy flavone present naturally in the edible plants like Scutellaria baicalensis and Oroxylum indicum possess a better neuroprotective effect in the dosage of 10 mg/kg and 30 mg/kg intraperitoneally in the striatum of HD induced rats. This study proved that BC is efficient to revive the level of enzymatic & non-enzymatic antioxidants and mitochondrial complexes by decreasing the number of inflammatory mediators such as MDA, protein carbonyls and Nitric Oxide at the significance of P < 0.01 and restores the amount of BDNF and GDNF thereby preventing the neurophysiological changes which were analysed by haematoxylin & eosin staining. Thus finally, the protective effect of Baicalein displays the up-gradation of psychological and behavioural changes induced by QA.

Baicalein Exerts Anti-Neuroinflammatory Effects by Inhibiting the TLR4-ROS /NF-κB-NLRP3 Inflammasome

Emerging evidence indicates that NOD-like receptor protein 3 (NLRP3) inflammasome-induced inflammation plays a critical role in the pathogenesis of Parkinson’s disease (PD). Baicalein has been considered as a possible option for PD treatment based on its anti-neuroinflammatory effects. However, no studies have elucidated the precise mechanisms underlying the anti-neuroinflammatory activity of baicalein, particularly inflammasome-mediated effects. In this present study, rotenone-induced PD mice and BV2 microglia were used to investigate the anti-neuroinflammatory effects of baicalein and explore its underlying mechanism in vivo and in vitro. The results demonstrated that baicalein alleviated motor impairments and attenuated several inflammatory responses in rotenone-induced PD mice. Also, baicalein inhibited the expression of NLRP3 and activated caspase-1 in brain tissues. Correspondingly, baicalein prominently suppressed the inflammatory response in BV2 microglia induced by rotenone. Furthermore, in vitro data showed that baicalein suppressed the expression of NLRP3 and activated caspase-1 by abrogating the upregulation of ROS, as well as by inhibiting the TLR4/NF-κB signaling cascade. Overall, the results of the present study indicated that baicalein exerted anti-neuroinflammatory effects partly by inhibiting activation of the NLRP3 inflammasome, and targeting NLRP3 inflammasome signaling offers a novel therapeutic strategy for PD treatment.

Identification of Molecular Network Associated with Neuroprotective Effects of Yashtimadhu (Glycyrrhiza glabra L.) by Quantitative Proteomics of Rotenone-Induced Parkinson's Disease Model

Parkinson's disease (PD) is a progressive neurodegenerative disorder, whose treatment with modern therapeutics leads to a plethora of side effects with prolonged usage. Therefore, the management of PD with complementary and alternative medicine is often pursued. In the Ayurveda system of alternative medicine, Yashtimadhu choorna, a Medhya Rasayana (nootropic), prepared from the dried roots of Glycyrrhiza glabra L. (licorice), is prescribed for the management of PD with a favorable outcome. We pursued to understand the neuroprotective effects of Yashtimadhu choorna against a rotenone-induced cellular model of PD using differentiated IMR-32 cells. Cotreatment with Yashtimadhu choorna extract rescued rotenone-induced apoptosis and hyperphosphorylation of ERK-1/2. Quantitative proteomic analysis of six peptide fractions from independent biological replicates acquired 1,561,169 mass spectra, which when searched resulted in 565,008 peptide-spectrum matches mapping to 30,554 unique peptides that belonged to 4864 human proteins. Proteins commonly identified in biological replicates and >4 PSMs were considered for further analysis, leading to a refined set of 3720 proteins. Rotenone treatment differentially altered 144 proteins (fold ≥1.25 or ≤0.8), involved in mitochondrial, endoplasmic reticulum, and autophagy functions. Cotreatment with Yashtimadhu choorna extract rescued 84 proteins from the effect of rotenone and an additional regulation of 4 proteins. Network analysis highlighted the interaction of proteins and pathways regulated by them, which can be targeted for neuroprotection. Validation of proteomics data highlighted that Yashtimadhu confers neuroprotection by preventing mitochondrial oxidative stress and apoptosis. This discovery will pave the way for understanding the molecular action of Ayurveda drugs and developing novel therapeutics for PD.

Constructing fine-grained entity recognition corpora based on clinical records of traditional Chinese medicine

Background

In this study, we focus on building a fine-grained entity annotation corpus with the corresponding annotation guideline of traditional Chinese medicine (TCM) clinical records. Our aim is to provide a basis for the fine-grained corpus construction of TCM clinical records in future.

Methods

We developed a four-step approach that is suitable for the construction of TCM medical records in our corpus. First, we determined the entity types included in this study through sample annotation. Then, we drafted a fine-grained annotation guideline by summarizing the characteristics of the dataset and referring to some existing guidelines. We iteratively updated the guidelines until the inter-annotator agreement (IAA) exceeded a Cohen’s kappa value of 0.9. Comprehensive annotations were performed while keeping the IAA value above 0.9.

Results

We annotated the 10,197 clinical records in five rounds. Four entity categories involving 13 entity types were employed. The final fine-grained annotated entity corpus consists of 1104 entities and 67,799 tokens. The final IAAs are 0.936 on average (for three annotators), indicating that the fine-grained entity recognition corpus is of high quality.

Conclusions

These results will provide a foundation for future research on corpus construction and named entity recognition tasks in the TCM clinical domain.

Neuroprotection of Rotenone-Induced Parkinsonism by Ursolic Acid in PD Mouse Model

BACKGROUND

Parkinson's Disease (PD) is characterized by both motor and non-motor symptoms. The presynaptic neuronal protein, α-Synuclein, plays a pivotal role in PD pathogenesis and is associated with both genetic and sporadic origin of the disease. Ursolic Acid (UA) is a well-known bioactive compound found in various medicinal plants, widely studied for its anti-inflammatory and antioxidant activities.

OBJECTIVE

In this research article, the neuroprotective potential of UA has been further explored in the Rotenone-induced mouse model of PD.

METHODS

To investigate our hypothesis, we have divided mice into 4 different groups, control, drug only control, Rotenone-intoxicated group, and Rotenone-intoxicated mice treated with UA. After the completion of dosing, behavioral parameters were estimated. Then mice from each group were sacrificed and the brains were isolated. Further, the biochemical tests were assayed to check the balance between the oxidative stress and endogenous anti-oxidants; and TH (Tyrosine Hydroxylase), α-Synuclein, Akt (Serine-threonine protein kinase), ERK (Extracellular signal-regulated kinase) and inflammatory parameters like Nuclear Factor-κB (NF-κB) and Tumor Necrosis Factor- α (TNF-α) were assessed using Immunohistochemistry (IHC). Western blotting was also done to check the expressions of TH and α-Synuclein. Moreover, the expression levels of PD related genes like α-Synuclein, β-Synuclein, Interleukin-1β (IL-1β), and Interleukin-10 (IL-10) were assessed by using Real-time PCR.

RESULTS

The results obtained in our study suggested that UA significantly reduced the overexpression of α-Synuclein and regulated the phosphorylation of survival-related kinases (Akt and ERK) apart from alleviating the behavioral abnormalities and protecting the dopaminergic neurons from oxidative stress and neuroinflammation.

CONCLUSION

Thus, our study shows the neuroprotective potential of UA, which can further be explored for possible clinical intervention.

Anti-Depressive Effectiveness of Baicalin In Vitro and In Vivo

Baicalin (BA), a major polyphenol compound isolated from the extracts of Scutellaria radix, has been previously reported to ameliorate depressive-like behaviors in mice with chronic unpredictable mild stress (CUMS). However, its underlying antidepressant mechanisms remain unclear. This study was designed to confirm the antidepressant-like effects of BA on CUMS induced behavioral abnormalities in mice, and sought to explore the pharmacological mechanisms in vivo and in vitro. The CUMS procedure was carried out to induce depression in mice. Afterwards, the tail suspension test (TST), forced swim test (FST), and open field test (OFT) were performed within 24 h, then sucrose preference test (SPT) was conducted. Additionally, PC12 cells were pretreated with BA for 2 h, then further stimulated with corticosterone for 24 h. The levels of Interleukin-1β (IL-1β), IL-6 and Tumor Necrosis Factor-α (TNF-α) in serum, hippocampus homogenate and cell culture medium were determined using the enzyme-linked immunosorbent assay (ELISA) method. The protein expressions of inhibition of high mobility group box 1 protein (HMGB1)/Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) pathways in hippocampus and PC12 cells were detected. Our results showed that CUMS-treated mice presented notable depressive-like symptoms, such as decreased sucrose consumption, increased FST and TST immobility time. While BA (25, 50 mg/kg) significantly attenuated these changes. Besides, BA treatment considerably inhibited inflammatory cytokinesl (IL-1β, IL-6, TNF-α) levels in serum, hippocampus homogenate and cell culture medium. Western blot analysis indicated that BA inhibited the expressions of HMGB1, TLR4, and p-NF-κBp65 both in vivo and in vitro. In conclusion, the present study confirmed that BA possessed efficient antidepressant effects on depression, which was possibly related to the inhibition of HMGB1/TLR4/NF-κB pathways.

Geraniol Protects Against the Protein and Oxidative Stress Induced by Rotenone in an In Vitro Model of Parkinson's Disease

Dysfunction of autophagy, mitochondrial dynamics and endoplasmic reticulum (ER) stress are currently considered as major contributing factors in the pathogenesis of Parkinson's disease (PD). Accumulation of oxidatively damaged cytoplasmic organelles and unfolded proteins in the lumen of the ER causes ER stress and it is associated with dopaminergic cell death in PD. Rotenone is a pesticide that selectively kills dopaminergic neurons by a variety of mechanism, has been implicated in PD. Geraniol (GE; 3,7-dimethylocta-trans-2,6-dien-1-ol) is an acyclic monoterpene alcohol occurring in the essential oils of several aromatic plants. In this study, we investigated the protective effect of GE on rotenone-induced mitochondrial dysfunction dependent oxidative stress leads to cell death in SK-N-SH cells. In addition, we assessed the involvement of GE on rotenone-induced dysfunction in autophagy machinery via α-synuclein accumulation induced ER stress. We found that pre-treatment of GE enhanced cell viability, ameliorated intracellular redox, preserved mitochondrial membrane potential and improves the level of mitochondrial complex-1 in rotenone treated SK-N-SH cells. Furthermore, GE diminishes autophagy flux by reduced autophagy markers, and decreases ER stress by reducing α-synuclein expression in SK-N-SH cells. Our results demonstrate that GE possess its neuroprotective effect via reduced rotenone-induced oxidative stress by enhanced antioxidant status and maintain mitochondrial function. Furthermore, GE reduced ER stress and improved autophagy flux in the neuroblastomal SK-N-SH cells. The present study could suggest that GE a novel therapeutic avenue for clinical intervention in neurodegenerative diseases especially for PD.

Targeting Cellular Stress Mechanisms and Metabolic Homeostasis by Chinese Herbal Drugs for Neuroprotection

Traditional Chinese medicine has been practiced for centuries in East Asia. Herbs are used to maintain health and cure disease. Certain Chinese herbs are known to protect and improve the brain, memory, and nervous system. To apply ancient knowledge to modern science, some major natural therapeutic compounds in herbs were extracted and evaluated in recent decades. Emerging studies have shown that herbal compounds have neuroprotective effects or can ameliorate neurodegenerative diseases. To understand the mechanisms of herbal compounds that protect against neurodegenerative diseases, we summarize studies that discovered neuroprotection by herbal compounds and compound-related mechanisms in neurodegenerative disease models. Those compounds discussed herein show neuroprotection through different mechanisms, such as cytokine regulation, autophagy, endoplasmic reticulum (ER) stress, glucose metabolism, and synaptic function. The interleukin (IL)-1β and tumor necrosis factor (TNF)-α signaling pathways are inhibited by some compounds, thus attenuating the inflammatory response and protecting neurons from cell death. As to autophagy regulation, herbal compounds show opposite regulatory effects in different neurodegenerative models. Herbal compounds that inhibit ER stress prevent neuronal death in neurodegenerative diseases. Moreover, there are compounds that protect against neuronal death by affecting glucose metabolism and synaptic function. Since the progression of neurodegenerative diseases is complicated, and compound-related mechanisms for neuroprotection differ, therapeutic strategies may need to involve multiple compounds and consider the type and stage of neurodegenerative diseases.

The Chinese herbal formula Free and Easy Wanderer ameliorates oxidative stress through KEAP1-NRF2/HO-1 pathway

Posttraumatic stress disorder (PTSD) gains a lot of attention due to high prevalence and strong psychological upset, but the etiology remains undefined and effective treatment is quite limited. Growing studies demonstrated the involvement of oxidative stress in various psychiatry diseases, suggesting anti-oxidation therapy might be a strategy for PTSD treatment. Free and Easy Wanderer (FAEW) is a poly-herbal drug clinically used in China for hundreds of years in the treatment of psychiatric disorder. We hypothesized that FAEW exerts clinical effects through the activity against oxidative stress with fluoxetine as antidepressant control drug. Our results revealed that FAEW significantly reduced both endogenous and H₂O₂-induced exogenous ROS levels in the human glioblastoma T98G and neuroblastoma SH-SY5Y cell lines. Transcriptome-wide microarray analysis indicated NRF2/HO-1 as the common target of FAEW and fluoxetine. Western blotting assay proved that the two drugs promoted NRF2 release from KEAP1 in the cytoplasm and translocation to the nuclei in a KEAP1-dependent manner, the expression of the protein HO-1 increased accordingly, suggesting the participation of KEAP1-NRF2/HO-1 pathway. The chemical constituents of FAEW (i.e. paeoniflorin, baicalin) bound to KEAP1 in silico, which hence might be the effective substances of FAEW. In conclusion, FAEW counteracted H₂O₂-induced oxidative stress through KEAP1-NRF2/HO-1 pathway.

Baicalein as a potent neuroprotective agent: A review

In recent times, neurodegenerative diseases are the most challenging global health problems. Neuronal cell death or damage is a key factor for many neurodegenerative disorders. Therefore, there has been a growing interest in the development of effective neuroprotective agents, especially from natural sources. In particular, phytochemicals have shown high efficacy with low side effects in various in vitro and in vivo studies. In the various phytoconstituents, flavonoids are important bioactive products and mainly found in various vegetables and fruits. Among them, baicalein is one of the important flavones, which is mainly found in the root of Scutellaria baicalensis Georgi. A number of studies have reported that baicalein has potent neuroprotective properties under in vitro as well as in vivo systems. Hence, the purpose of this paper is to provide a review of the existing literature in connection with the neuroprotective effects of baicalein and its molecular mechanisms of action. The current review highlights could be useful to identify novel therapeutic agents in relation to the treatment of neurotoxicity-mediated diseases.

Baicalein blocks α-synuclein secretion from SN4741 cells and facilitates α-synuclein polymerization to big complex

The secretion of α-synuclein (α-syn) acts as an essential driver in the propagation of synucleinopathies in brain. The clearance of extracellular α-syn or blockade of the cell-to-cell transmission of α-syn is a promising approach to prohibiting synucleinopathies propagation. Baicalein (BAI), a flavonoid from Chinese herb, has been reported to bind covalently to α-syn to inhibit α-syn fibrillation and degrade its fibrils. However, whether BAI inhibits α-syn secretion is unclear. Here we showed that BAI reduced α-syn in the media of dopaminergic cell lines (SN4741) overexpressing wild-type α-syn (W-syn) or A53T mutant type α-syn (A53T-syn), while increased α-syn expression in cell lysates, upregulated the cell viability and increased the ratio of LC3 II/LC3 I, the latter is an indicator reflects the macroautophagic level. Intriguingly, BAI did not clear extracellular α-syn directly but facilitated α-syn polymerization to big complex (over 72kDa), which revealed that BAI probably reduced α-syn transmission by facilitating α-syn polymerization to big complex. Taken together, BAI could be a potential drug to inhibit α-syn propagation among the neurons.

Neuroprotective Effects of Protein Tyrosine Phosphatase 1B Inhibition against ER Stress-Induced Toxicity

Several lines of evidence suggest that endoplasmic reticulum (ER) stress plays a critical role in the pathogenesis of many neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Protein tyrosine phosphatase 1B (PTP1B) is known to regulate the ER stress signaling pathway, but its role in neuronal systems in terms of ER stress remains largely unknown. Here, we showed that rotenone-induced toxicity in human neuroblastoma cell lines and mouse primary cortical neurons was ameliorated by PTP1B inhibition. Moreover, the increase in the level of ER stress markers (eIF2α phosphorylation and PERK phosphorylation) induced by rotenone treatment was obviously suppressed by concomitant PTP1B inhibition. However, the rotenone-induced production of reactive oxygen species (ROS) was not affected by PTP1B inhibition, suggesting that the neuroprotective effect of the PTP1B inhibitor is not associated with ROS production. Moreover, we found that MG132-induced toxicity involving proteasome inhibition was also ameliorated by PTP1B inhibition in a human neuroblastoma cell line and mouse primary cortical neurons. Consistently, downregulation of the PTP1B homologue gene in Drosophila mitigated rotenone- and MG132-induced toxicity. Taken together, these findings indicate that PTP1B inhibition may represent a novel therapeutic approach for ER stress-mediated neurodegenerative diseases.

Therapeutic potentials of baicalin and its aglycone, baicalein against inflammatory disorders

The flavonoids, baicalin (5,6-dihydroxy-2-phenyl-4H-1-benzopyran-4-one-7-O-d-β-glucuronic acid) 1 and its aglycone, baicalein 2 are found in edible medicinal plants, Scutellaria baicalensis Georgi and Oroxylum indicum (L.) Kurz in abundant quantities. The antioxidant and anti-inflammatory effects of these flavonoids have been demonstrated in various disease models, including diabetes, cardiovascular diseases, inflammatory bowel diseases, gout and rheumatoid arthritis, asthma, neurodegenerative-, liver- and kidney diseases, encephalomyelitis, and carcinogenesis. These flavonoids have almost no toxicity to human normal epithelial, peripheral and myeloid cells. Their antioxidant and anti-inflammatory activities are largely due to their abilities to scavenge the reactive oxygen species (ROS) and improvement of antioxidant status by attenuating the activity of NF-κB and suppressing the expression of several inflammatory cytokines and chemokines including monocyte chemotactic protein-1 (MCP-1), nitric oxide synthase, cyclooxygenases, lipoxygenases, cellular adhesion molecules, tumor necrosis factor and interleukins. In this review, we summarize the antioxidant and anti-inflammatory effects of baicalin and baicalein with molecular mechanisms for their chemopreventive and chemotherapeutic applications in the treatment of inflammatory-related diseases.

Amentoflavone protects dopaminergic neurons in MPTP-induced Parkinson's disease model mice through PI3K/Akt and ERK signaling pathways

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in substantia nigra pars compacta (SNpc). Mitochondrial dysfunction and cell apoptosis are suggested to be actively involved in the pathogenesis of PD. In the present study, the neuroprotective effect of amentoflavone (AF), a naturally occurring biflavonoid from Selaginella tamariscina, was examined in PD models both in vitro and in vivo. On SH-SY5Y cells, AF treatment dose-dependently reduced 1-methyl-4-phenylpyridinium (MPP⁺)-induced nuclear condensation and loss of cell viability without obvious cytotoxicity. It inhibited the activation of caspase-3 and p21 but increased the Bcl-2/Bax ratio. Further study disclosed that AF enhanced the phosphorylation of PI3K, Akt and ERK1/2 down-regulated by MPP⁺ in SH-SY5Y cells, the effect of which could be blocked by LY294002, the inhibitor of PI3K. Consistently, AF alleviated the behavioral deterioration in pole and traction tests and rescued the loss of dopaminergic neurons in SNpc and fibers in striatum in methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced mice. It also could enhance the activation of PI3K and Akt as well as Bcl-2/Bax ratio in SN. Moreover, AF alleviated gliosis as well as the gene expression levels of IL-1β and iNOS in SN. Collectively, these results suggested that AF protected dopaminergic neurons against MPTP/MPP⁺-induced neurotoxicity, which might be mediated through activation of PI3K/Akt and ERK signaling pathways in dopaminergic neurons and attenuation of neuroinflammation.

Baicalin Attenuates Ketamine-Induced Neurotoxicity in the Developing Rats: Involvement of PI3K/Akt and CREB/BDNF/Bcl-2 Pathways

Ketamine is widely used as an anesthetic in pediatric clinical practice. However, numerous studies have reported that exposure to ketamine during the developmental period induces neurotoxicity. Here we investigate the neuroprotective effects of baicalin, a natural flavonoid compound, against ketamine-induced apoptotic neurotoxicity in the cortex and hippocampus of the Sprague-Dawley postnatal day 7 (PND7) rat pups. Our results revealed that five continuous injections of ketamine (20 mg/kg) at 90-min intervals over 6 h induced obvious morphological damages of neuron by Nissl staining and apoptosis by TUNEL assays in the prefrontal cortex and hippocampus of PND7 rat pups. Baicalin (100 mg/kg) pretreatment alleviated ketamine-induced morphological change and apoptosis. Caspase-3 activity and caspase-3 mRNA expression increase induced by ketamine were also inhibited by baicalin treatment. LY294002, an inhibitor of PI3K, abrogated the effect of baicalin against ketamine-induced caspase-3 activity and caspase-3 mRNA expression increase. In addition, Western blot studies indicated that baicalin not only inhibited ketamine-induced p-Akt and p-GSK-3β decrease, but also relieved ketamine-induced p-CREB and BDNF expression decrease. Baicalin also attenuated ketamine-induced Bcl-2/Bax decrease and caspase-3 expression increase. Further in vitro experiments proved that baicalin mitigated ketamine-induced cell viability decrease in the MTT assay, morphological change by Rosenfeld's staining, and caspase-3 expression increase by Western blot in the primary neuron-glia mixed cultures. LY294002 abrogated the protective effect of baicalin. These data demonstrate that baicalin exerts neuroprotective effect against ketamine-induced neuronal apoptosis by activating the PI3K/Akt and its downstream CREB/BDNF/Bcl-2 signaling pathways. Therefore, baicalin appears to be a promising agent in preventing or reversing ketamine's apoptotic neurotoxicity at an early developmental stage.

Neuroprotective effect of asiatic acid on rotenone-induced mitochondrial dysfunction and oxidative stress-mediated apoptosis in differentiated SH-SYS5Y cells

Parkinson's disease (PD) is a chronic neurodegenerative disease, manifested due to the loss of dopaminergic neurons, which ultimately leads to impaired movement in elderly populations. The pathogenesis of PD is associated with numerous factors including oxidative stress, mitochondrial dysfunction and apoptosis. There is no effective therapy available to cure or halt the progression of this disease still now. Asiatic acid (AA) is a triterpene extracted from Centella asiatica has been reported as an antioxidant and anti-inflammatory agent, that offers neuroprotection against glutamate toxicity. Therefore, in this study, we have investigated the effect of AA in a rotenone (an inhibitor of mitochondrial complex I) induced in vitro model of PD. Following the exposure of SH-SY5Y cells to rotenone, there was a marked overproduction of ROS, mitochondrial dysfunction (as indexed by the decrease in mitochondrial membrane potential) and apoptosis (Hoechst and dual staining, comet assay; expressions of pro-apoptotic and anti-apoptotic indices). Pre-treatment with AA reversed these changes might be due to its antioxidant, mitoprotective and anti-apoptotic properties. However further extensive studies on in vivo models of PD are warranted to prove AA neuroprotective effect before entering into the clinical trial.

Pretreatment with baicalin attenuates hypoxia and glucose deprivation-induced injury in SH-SY5Y cells

OBJECTIVE

To explore the neuroprotective effects of baicalin against hypoxia and glucose deprivation-reperfusion (OGD/RO)-induced injury in SH-SY5Y cells.

METHODS

SH-SY5Y cells were divided into a control group, a OGD/RO group, which was subject to OGD/RO induction; and 3 baicalin groups subject to baicalin (1, 5, 25 μmol/L) for 2 h before induction of OGD/RO (low-, medium-, and high-dose baicalin groups). Cell viability was detected by thiazolyl blue tetrazolium bromide (MTT) assay and flow cytometric analysis was used to detect cell apoptosis. Real-time polymerase chain reaction was performed to determine the mRNA expression of caspase-3 gene. Western blot analysis was conducted to determine the expression of nuclear factor (NF)-κB and N-methyl-daspartic acid receptor-1 (NMDAR1).

RESULTS

Baicalin could significantly attenuate OGD/RO mediated apoptotic cell death in SH-SY5Y cells; the apoptosis rates in the low-, medium- and high-dose groups were 12.1%, 7.9%, and 5.4%, respectively. Western blot and real-time PCR analysis revealed that significant decrease in caspase-3 expression in the baicalin group compared with the OGD/RO group (P<0.01). Additionally, down-regulation of NF-κB and NMDAR1 was observed in the baicalin group compared with those obtained from the OGD/RO group. Compared with the low-dose baicalin group, remarkable decrease was noted in the medium- and high-dose groups (P<0.01).

CONCLUSION

Baicalin pre-treatment attenuates brain ischemia reperfusion injury by suppressing cellular apoptosis.

Neurosupportive Role of Vanillin, a Natural Phenolic Compound, on Rotenone Induced Neurotoxicity in SH-SY5Y Neuroblastoma Cells

Vanillin, a phenolic compound, has been reported to offer neuroprotection against experimental Huntington's disease and global ischemia by virtue of its antioxidant, anti-inflammatory, and antiapoptotic properties. The present study aims to elucidate the underlying neuroprotective mechanism of vanillin in rotenone induced neurotoxicity. Cell viability was assessed by exposing SH-SY5Y cells to various concentrations of rotenone (5–200 nM) for 24 h. The therapeutic effectiveness of vanillin against rotenone was measured by pretreatment of vanillin at various concentrations (5–200 nM) and then incubation with rotenone (100 nM). Using effective dose of vanillin (100 nM), mitochondrial membrane potential, levels of reactive oxygen species (ROS), and expression patterns of apoptotic markers were assessed. Toxicity of rotenone was accompanied by the loss of mitochondrial membrane potential, increased ROS generation, release of cyt-c, and enhanced expressions of proapoptotic and downregulation of antiapoptotic indices via the upregulation of p38 and JNK-MAPK pathway proteins. Our results indicated that the pretreatment of vanillin attenuated rotenone induced mitochondrial dysfunction, oxidative stress, and apoptosis. Thus, vanillin may serve as a potent therapeutic agent in the future by virtue of its multiple pharmacological properties in the treatment of neurodegenerative diseases including PD.

Baicalin protects against thrombin induced cell injury in SH-SY5Y cells

Baicalin, an extract from the dried root of Scutellaria baicalensis Georgi, was shown to be neuroprotective. However, the precise mechanisms are incompletely known. In this study, we determined the effect of baicalin on thrombin induced cell injury in SH-SY5Y cells, and explored the possible mechanisms. SH-SY5Y cells was treated with thrombin alone or pre-treated with baicalin (5, 10, 20 μM) for 2 h followed by thrombin treatment. Cells without thrombin and baicalin treatment were used as controls. Cell viability was detected by MTT assay. Cell apoptosis was analyzed by flow cytometry. Real-time PCR was performed to determine the mRNA expression of protease-activated receptor-1 (PAR-1). Western blotting was conducted to determine the protein expression of PAR-1, Caspase-3 and NF-κB. Baicalin reduced cell death following thrombin treatment in a dose-dependent manner, with concomitant inhibition of NF-κB activation and suppression of PAR-1 expression. In addition, baicalin reduced Caspase-3 expression. The above findings indicated that baicalin prevents against cell injury after thrombin stimulation possibly through inhibition of PAR-1 expression and NF-κB activation.

The effects of baicalein and baicalin on mitochondrial function and dynamics: A review

Mitochondria play an essential role in cell survival by providing energy, calcium buffering, and regulating apoptosis. A growing body of evidence shows that mitochondrial dysfunction and its consequences, including impairment of the mitochondrial respiratory chain, excessive generation of reactive oxygen species, and excitotoxicity, play a pivotal role in the pathogenesis of different diseases such as neurodegenerative diseases, neuropsychiatric disorders, and cancer. The therapeutical role of flavonoids on these diseases is gaining increasing acceptance. Numerous studies on experimental models have revealed the favorable role of flavonoids on mitochondrial function and structure. This review highlights the promising role of baicalin and its aglycone form, baicalein, on mitochondrial function and structure with a focus on its therapeutic effects. We also discuss their chemistry, sources and bioavailability.

Carbosilane dendrimers inhibit α-synuclein fibrillation and prevent cells from rotenone-induced damage

This study investigates the role of carbosilane dendrimers in fibrillation of α-synuclein and prevention of the mouse hippocampal cell (mHippoE-18) from rotenone-induced damage. Examining the interaction between carbosilane dendrimers and α-synuclein, we found that the dendrimers inhibit fibril formation. We also investigated cell viability, the production of reactive oxygen species (ROS), and mitochondrial membrane potential. mHippoE-18 cells were preincubated with carbosilane dendrimers before rotenone was added. All the dendrimers possess potential protection activity. Preincubation with dendrimers contributed to: increased viability, higher mitochondrial membrane potential, and reduced ROS level in cells. The probable mechanism of cell protection lies in the ability of dendrimers to capture rotenone by encapsulating or binding to its surface groups. The fact that dendrimers have prevention potential is important in the search for new pharmacological strategies against neurodegenerative disorders.

Baicalein alters PI3K/Akt/GSK3β signaling pathway in rats with diabetes-associated cognitive deficits

Our present investigation focused on assessing the neuroprotective potential of baicalein (BAC) against diabetes-associated cognitive deficit (DACD) using a diabetic model and further figure out the potential molecular mechanisms. Diabetic rat model was established by streptozotocin (STZ). Vehicle or BAC by the doses of 2 and 4 mg/kg was intraperitoneally injected once a day for seven consecutive weeks. Memory function was evaluated by Morris water maze test and avoidance passive test. The activities of acetylcholinesterase (AChE), choline acetylase (ChAT), caspase-9 and caspase-3 in STZ-induced diabetic rats' hippocampus were detected via responsive commercial kits. Western blot assay were used to determine the protein levels of phospho-phosphatidylinositol 3-kinase (p-PI3K), phospho-Akt (p-Akt), and phospho-glycogen synthase kinase-3β (p-GSK3β). Our results showed that BAC remarkably increased body weight and ChAT activity, decreased blood glucose level and AChE activity as well as improved cognitive deficits in diabetic rats. Additionally, it was also found that treatment with BAC to diabetes obviously stimulated the p-PI3K and p-Akt and inhibited the level of p-GSK3β. Furthermore, the neuronal apoptosis was also prevented after BAC treatment by decreasing caspase-9 and caspase-3 activities in diabetic rats' hippocampus. It is concluded that BAC exerted beneficial effects against DACD in rats and its neuroprotection might be linked with activating PI3K and Akt phosphorylation accompanied with suppressing the phosphorylated level of GSK3β. These results hint that BAC is likely to be served as an adjuvant therapy to conventional anti-hyperglycemic regimens as well as DACD.

Huang-Lian-Jie-Du-Decotion induced protective autophagy against the injury of cerebral ischemia/reperfusion via MAPK-mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-Lian-Jie-Du-Decotion (HLJDD, Hwangryun-Hae-Dok-Decotion in Japan), an ancient antipyretic and detoxifying traditional Chinese medicine formula, was reported to have protective effect on ischemic stroke.

AIM OF THE RESEARCH

To investigate the therapeutic effect of HLJDD on ischemic stroke and explore its mode of action.

MATERIAL AND METHODS

A model of ischemic stroke in the rat was established after transient middle cerebral artery occlusion (MCAO) followed by reperfusion. Rats were assigned randomly to groups of control, sham, transient ischemia/reperfusion (I/R), and three treatment groups by HLJDD at 2.5, 5.0, 10.0mg/kg. The neurological deficit, the cerebral infarct size, morphology abnormality, biochemical parameters were examined, and the levels of relevant proteins were determined by immunoblotting analysis to evaluate the protective effects of HLJDD on ischemic stroke and explore the underlying mechanism.

RESULTS

Compared with I/R group, HLJDD significantly ameliorated neurological deficit and histopathology changes, decreased infarct area, and restored the levels of biochemical indicators including nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), glutathione disulfide (GSSG), total superoxide dismutase (T-SOD), Cu/Zn-SOD, Mn-SOD and glutathione peroxidase (GSH-PX). HLJDD also notably elevated the levels of microtubule-associated protein 1 light chain 3 (LC3), Beclin-1, and other autophagy related genes (Atgs), promoted the activation of extracellular signal-regulated kinases (ERK), protein kinase B (Akt), 3-phosphoinositide-dependent kinase (PDK1), and inhibited the activation of mammalian target of rapamycin (mTOR), c-Jun N-terminal protein kinases (JNK), p38, phosphatase and tensin homolog (PTEN).

CONCLUSION

HLJDD showed neuroprotective effects on ischemic stroke, at least in part to the induced protective autophagy via the regulation of mitogen-activated protein kinase (MAPK) signals. This Akt-independent protective autophagy is favorable in the treatment of stroke, avoiding unfavorable side-effects associated with the inactivation of Akt. The efficacy of HLJDD on ischemic stroke and its safety warranted by its long-term clinical use in traditional Chinese medicine favored further study to develop HLJDD as an effective therapeutic agent to treat ischemic stroke.

Baicalein reduces airway injury in allergen and IL-13 induced airway inflammation

Background

Baicalein, a bioflavone present in the dry roots of Scutellaria baicalensis Georgi, is known to reduce eotaxin production in human fibroblasts. However, there are no reports of its anti-asthma activity or its effect on airway injury.

Methodology/Principal Findings

In a standard experimental asthma model, male Balb/c mice that were sensitized with ovalbumin (OVA), treated with baicalein (10 mg/kg, ip) or a vehicle control, either during (preventive use) or after OVA challenge (therapeutic use). In an alternate model, baicalein was administered to male Balb/c mice which were given either IL-4 or IL-13 intranasally. Features of asthma were determined by estimating airway hyperresponsiveness (AHR), histopathological changes and biochemical assays of key inflammatory molecules. Airway injury was determined with apoptotic assays, transmission electron microscopy and assessing key mitochondrial functions. Baicalein treatment reduced AHR and inflammation in both experimental models. TGF-β₁, sub-epithelial fibrosis and goblet cell metaplasia, were also reduced. Furthermore, baicalein treatment significantly reduced 12/15-LOX activity, features of mitochondrial dysfunctions, and apoptosis of bronchial epithelia.

Conclusion/Significance

Our findings demonstrate that baicalein can attenuate important features of asthma, possibly through the reduction of airway injury and restoration of mitochondrial function.