Neuroprotective Effect of Baicalein on Hydrogen Peroxide-Mediated Oxidative Stress and Mitochondrial Dysfunction in PC12 Cells

Exploring the anti-ischemic stroke potential of wogonoside: Insights from Nrf2/Sirt3 signaling pathway and UPLC-TripleTOF-MS/MS-based metabolomics

Ischemic stroke, accounting for 80 % of all strokes, is a major cause of morbidity and mortality worldwide. However, effective and safe pharmacotherapy options for ischemic injury are limited. This study investigated the therapeutic effects of wogonoside, a compound derived from Radix Scutellariae, on ischemia/reperfusion (I/R) injury. The results showed that wogonoside treatment had significant therapeutic effects in rats with middle cerebral artery occlusion. It effectively reduced mortality rates, neurological deficits, cerebral infarct size, and brain water content. In an in vitro model using PC12 cells, wogonoside activated the Nrf2/Sirt3 signaling pathway. This activation contributed to the attenuation of oxidative damage and inflammation. Metabolomics analysis revealed increased levels of γ-aminobutyric acid (GABA) and glutathione in response to wogonoside treatment, suggesting their potential as therapeutic biomarkers for ischemic stroke. Additionally, wogonoside restored perturbed energy metabolism, including the tricarboxylic acid cycle. Wogonoside has the potential to ameliorate cerebral ischemic injury by targeting GABA-related amino acid metabolism, energy metabolism, and glutathione metabolism, maintaining redox homeostasis, and attenuating oxidative stress. These findings provide valuable insights into the protective mechanisms of wogonoside in cerebral I/R injury and highlight the promising therapeutic approach of wogonoside in the treatment of ischemic stroke.

Cryopreservation of ram semen: baicalein efficiency on oxidative stress, chromatin integrity, viability and motility post thaw

Baicalein (B) has potential antioxidant properties, but it has not been tested as a ram semen extender. This study aimed to assess the impact of B on various sperm parameters and determine its potential influence on semen quality after the freeze-thawing process. During the breeding season, ejaculates were obtained from four rams with the aid of an artificial vagina. The collected mixed semen samples were divided into four groups: control (C; 0), B0.5 (0.5 mM), B1 (1 mM), and B2 (2 mM). After semen extension, the samples were loaded into 0.25 mL straws and stored for 2 h at 4°C prior to freezing in liquid nitrogen vapor and thawed in a water bath at 37°C. Among the groups, B0.5 demonstrated the highest progressive motility results, while B1 and B2 exhibited reduced motility (p < 0.05). In terms of high mitochondrial membrane potential, plasma membrane and acrosome integrity, and viability, B0.5 showed significantly superior outcomes to the other B groups (p < 0.05), although it was not significantly better than C. B1 displayed the highest plasma membrane integrity levels (p < 0.05). Notably, B2 displayed the lowest total antioxidant status levels among the groups (p < 0.05). The findings of this study suggested that the in vitro spermatological characteristics of ram spermatozoa such as progressive motility and chromatin integrity can be protected from the freeze-thawing process by using the 0.5 mM dose of baicalein as a semen extender. The treatment of sperm freezing might benefit from further in-depth research on the role of B in the improvement of cryoinjury and its underlying processes.

Regulation of mitophagy and mitochondrial function: Natural compounds as potential therapeutic strategies for Parkinson's disease

Mitochondrial damage is associated with the development of Parkinson's disease (PD), indicating that mitochondrial-targeted treatments could hold promise as disease-modifying approaches for PD. Notably, natural compounds have demonstrated the ability to modulate mitochondrial-related processes. In this review article, we discussed the possible neuroprotective mechanisms of natural compounds against PD in modulating mitophagy and mitochondrial function. A comprehensive literature search on natural compounds related to the treatment of PD by regulating mitophagy and mitochondrial function was conducted from PubMed, Web of Science and Chinese National Knowledge Infrastructure databases from their inception until April 2023. We summarize recent advancements in mitophagy's molecular mechanisms, including upstream and downstream processes, and its relationship with PD-related genes or proteins. Importantly, we highlight how natural compounds can therapeutically regulate various mitochondrial processes through multiple targets and pathways to alleviate oxidative stress, neuroinflammation, Lewy's body aggregation and apoptosis, which are key contributors to PD pathogenesis. Unlike the single-target strategy of modern medicine, natural compounds provide neuroprotection against PD by modulating various mitochondrial-related processes, including ameliorating mitophagy by targeting the PINK1/parkin pathway, the NIX/BNIP3 pathway, and autophagosome formation (i.e., LC3 and p62). Given the prevalence of mitochondrial damage in various neurodegenerative diseases, exploring the exact mechanism of natural compounds on mitophagy and mitochondrial dysfunction could shed light on the development of highly effective disease-modifying or adjuvant therapies targeting PD and other neurodegenerative disorders.

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.

Herbal and Natural Treatments for the Management of the Glaucoma: An Update

Glaucoma causes the degeneration of the retinal ganglion cells (RGCs) and their axons, inducing a tissue reshaping that affects both the retina and the optic nerve head. Glaucoma care especially focuses on reducing intraocular pressure, a significant risk factor for progressive damage to the optic nerve. The use of natural treatments, such as herbs, vitamins, and minerals, is becoming increasingly popular today. While plants are a rich source of novel biologically active compounds, only a small percentage of them have been phytochemically examined and evaluated for their medicinal potential. It is necessary for eye care professionals to inform their glaucoma patients about the therapy, protection, and efficacy of commonly used herbal medicines, considering the widespread use of herbal medicines. The purpose of this review is to examine evidence related to the most widely used herbal medicines for the management and treatment of glaucoma, to better understand the potential benefits of these natural compounds as supplementary therapy.

New perspective for an old drug: Can naloxone be considered an antioxidant agent?

Background

Experimental evidence indicates that Naloxone (NLX) holds antioxidant properties. The present study aims at verifying the hypothesis that NLX could prevent oxidative stress induced by hydrogen peroxide (H2O2) in PC12 cells.

Methods

To investigate the antioxidant effect of NLX, initially, we performed electrochemical experiments by means of platinum-based sensors in a cell-free system. Subsequently, NLX was tested in PC12 cells on H2O2-induced overproduction of intracellular levels of reactive-oxygen-species (ROS), apoptosis, modification of cells' cycle distribution and damage of cells' plasma membrane.

Results

This study reveals that NLX counteracts intracellular ROS production, reduces H2O2-induced apoptosis levels, and prevents the oxidative damage-dependent increases of the percentage of cells in G2/M phase. Likewise, NLX protects PC12 cells from H2O2- induced oxidative damage, by preventing the lactate dehydrogenase (LDH) release. Moreover, electrochemical experiments confirmed the antioxidant properties of NLX.

Conclusion

Overall, these findings provide a starting point for studying further the protective effects of NLX on oxidative stress.

Mechanistic Effects of Baicalein on Aqueous Humor Drainage and Intraocular Pressure

Elevated intraocular pressure (IOP) is a major risk factor for glaucoma that results from impeded fluid drainage. The increase in outflow resistance is caused by trabecular meshwork (TM) cell dysfunction and excessive extracellular matrix (ECM) deposition. Baicalein (Ba) is a natural flavonoid and has been shown to regulate cell contraction, fluid secretion, and ECM remodeling in various cell types, suggesting the potential significance of regulating outflow resistance and IOP. We demonstrated that Ba significantly lowered the IOP by about 5 mmHg in living mice. Consistent with that, Ba increased the outflow facility by up to 90% in enucleated mouse eyes. The effects of Ba on cell volume regulation and contractility were examined in primary human TM (hTM) cells. We found that Ba (1–100 µM) had no effect on cell volume under iso-osmotic conditions but inhibited the regulatory volume decrease (RVD) by up to 70% under hypotonic challenge. In addition, Ba relaxed hTM cells via reduced myosin light chain (MLC) phosphorylation. Using iTRAQ-based quantitative proteomics, 47 proteins were significantly regulated in hTM cells after a 3-h Ba treatment. Ba significantly increased the expression of cathepsin B by 1.51-fold and downregulated the expression of D-dopachrome decarboxylase and pre-B-cell leukemia transcription factor-interacting protein 1 with a fold-change of 0.58 and 0.40, respectively. We suggest that a Ba-mediated increase in outflow facility is triggered by cell relaxation via MLC phosphorylation along with inhibiting RVD in hTM cells. The Ba-mediated changes in protein expression support the notion of altered ECM homeostasis, potentially contributing to a reduction of outflow resistance and thereby IOP.

A novel nanoparticle system targeting damaged mitochondria for the treatment of Parkinson's disease

Mitochondrial damage is one of the primary causes of neuronal cell death in Parkinson's disease (PD). In PD patients, the mitochondrial damage can be repaired or irreversible. Therefore, mitochondrial damage repair becomes a promising strategy for PD treatment. In this research, hyaluronic acid nanoparticles (HA-NPs) of different molecular weights are used to protect the mitochondria and salvage the mild and limited damage in mitochondria. The HA-NPs with 2190 k Dalton (kDa) HA can improve the mitochondrial function of SH-SY5Y cells and PTEN induced putative kinase 1 (PINK1) knockout mouse embryo fibroblast (MEF) cells. In cases of irreversible damage, NPs with ubiquitin specific peptidase 30 (USP30) siRNA are used to promote mitophagy. Meanwhile, by adding PINK1 antibodies, the NPs can selectively target the irreversibly damaged mitochondria, preventing the excessive clearance of healthy mitochondria.

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.

Potential neuroprotective effect of stem cells from apical papilla derived extracellular vesicles enriched by lab-on-chip approach during retinal degeneration

Retinal degeneration (RD) is recognized as a frequent cause of visual impairments, including inherited (Retinitis pigmentosa) and degenerative (age-related macular) eye diseases. Dental stem cells (DSCs) have recently demonstrated a promising neuroprotection potential for ocular diseases through a paracrine manner carried out by extracellular vesicles (EVs). However, effective isolation of EVs is still challenging, and isolation methods determine the composition of enriched EVs and the subsequent biological and functional effects. In the present study, we assessed two enrichment methods (micro-electromechanical systems and ultrafiltration) to isolate the EVs from stem cells from apical papilla (SCAP). The size distribution of the corresponding isolates exhibited the capability of each method to enrich different subsets of EVs, which significantly impacts their biological and functional effects. We confirmed the neuroprotection and anti-inflammatory capacity of the SCAP-EVs in vitro. Further experiments revealed the possible therapeutic effects of subretinal injection of SCAP-EVs in the Royal College of Surgeons (RCS) rat model. We found that EVs enriched by the micro-electromechanical-based device (MEMS-EVs) preserved visual function, reduced retinal cell apoptosis, and prevented thinning of the outer nuclear layer (ONL). Interestingly, the effect of MEMS-EVs was extended to the retinal ganglion cell/retinal nerve fiber layer (GCL/RNFL). This study supports the use of the microfluidics approach to enrich valuable subsets of EVs, together with the choice of SCAP as a source to derive EVs for cell-free therapy of RD.

Dietary Plant Polyphenols as the Potential Drugs in Neurodegenerative Diseases: Current Evidence, Advances, and Opportunities

Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), are characterized by the progressive degeneration of neurons. Although the etiology and pathogenesis of neurodegenerative diseases have been studied intensively, the mechanism is still in its infancy. In general, most neurodegenerative diseases share common molecular mechanisms, and multiple risks interact and promote the pathologic process of neurogenerative diseases. At present, most of the approved drugs only alleviate the clinical symptoms but fail to cure neurodegenerative diseases. Numerous studies indicate that dietary plant polyphenols are safe and exhibit potent neuroprotective effects in various neurodegenerative diseases. However, low bioavailability is the biggest obstacle for polyphenol that largely limits its adoption from evidence into clinical practice. In this review, we summarized the widely recognized mechanisms associated with neurodegenerative diseases, such as misfolded proteins, mitochondrial dysfunction, oxidative damage, and neuroinflammatory responses. In addition, we summarized the research advances about the neuroprotective effect of the most widely reported dietary plant polyphenols. Moreover, we discussed the current clinical study and application of polyphenols and the factors that result in low bioavailability, such as poor stability and low permeability across the blood-brain barrier (BBB). In the future, the improvement of absorption and stability, modification of structure and formulation, and the combination therapy will provide more opportunities from the laboratory into the clinic for polyphenols. Lastly, we hope that the present review will encourage further researches on natural dietary polyphenols in the treatment of neurodegenerative diseases.

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.

Phenolic acids and flavonoids-rich Glechoma hederacea L. (Lamiaceae) water extract against H2 O2 -induced apoptosis in PC12 cells

Reactive oxygen species (ROS)-induced oxidative stress is reportedly associated with progressive neuronal cell damage. Glechoma hederacea L. (Lamiaceae), belonging to the Labiatae family, has demonstrated several biologic activities including depigmentation, antimelanogenic, antitumor, antioxidative, hepatoprotective, and anti-inflammatory activities. Previously, we reported that rosmarinic acid, chlorogenic acid, caffeic acid, rutin, genistin, and ferulic acids were the most abundant phytochemicals detected in hot water extracts of G. hederacea L. (HWG). This study aimed to study the neuroprotective effects of phenolic acids and flavonoid-rich HWG against hydrogen peroxide (H₂ O₂ )-induced oxidative damage in PC12 cells and its inhibitory effect on acetylcholinesterase (AChE). The experiment analyzed cytotoxicity, ROS production, mitochondrial transmembrane potential (MMP) level, and caspase-3 activity and used comet assay and antioxidant enzyme activity to determine the redox status of PC12 cells. Results showed that the inhibitory effect of HWG on AChE was in a competitive pattern (IC₅₀ , 23.23 mg/ml). HWG antagonized H₂ O₂ -mediated cytotoxicity and DNA damage, reduced ROS production, stabilized MMP, and inhibited caspase-3 activity and apoptosis. Furthermore, HWG inhibited the release of cytochrome C and apoptosis-inducing factors (AIF) and decreased the malondialdehyde levels in PC12 cells. Collectively, HWG rich in antioxidant phenolic acids and flavonoids may have neuroprotective effects. PRACTICAL APPLICATIONS: Polyphenolic compounds are one of the most important natural products, known to possess a range of health-promoting effects. In this study, it was found that HWG, which is rich in antioxidant phenolic acids and flavonoids, can protect PC12 cells from oxidative stress induced by H₂ O₂ and may have neuroprotective effects.

Endoplasmic Reticulum Stress Is Involved in Glucocorticoid-Induced Apoptosis in PC12 Cells

Objective

The present study selected PC12 cells to construct a neuronal injury model induced by glucocorticoids (GC) in vitro, aiming to explore whether the endoplasmic reticulum stress (ERS) PKR-like endoplasmic reticulum kinase (PERK)-activating transcription factor 4 (ATF4)-C/EBP-homologous protein (CHOP) and inositol requirement 1 (IRE1)-apoptosis signal regulating kinase 1 (ASK1)-C-Jun amino-terminal kinase (JNK) signaling pathways are associated with the neuronal injury process induced by GC and provide morphological evidence.

Methods

Cell models with different doses and different durations of GC exposure were established. The viability of PC12 cells was detected by the CCK-8 assay, and the apoptosis rate of PC12 cells was detected by the flow cytometry assay. The expression of microtubule-associated protein 2 (Map2); glucocorticoids receptor (GR); cellular oncogene fos (C-fos); and ERS-related proteins, glucose-regulated protein 78 (GRP78), p-PERK, p-IRE1, ATF4, ASK1, JNK, and CHOP, was observed by immunofluorescence staining.

Results

The results of immunofluorescence staining showed that PC12 cells abundantly expressed Map2 and GR. The CCK-8 assay revealed that high-concentration GC exposure significantly inhibited the cell viability of PC12 cells. The flow cytometry assay indicated that high-concentration GC exposure significantly increased the apoptosis rate of PC12 cells. Immunofluorescence staining showed that GC exposure significantly increased the expression of C-fos, GRP78, p-PERK, p-IRE1, ATF4, ASK1, JNK, and CHOP. Treatment with ERS inhibitor 4-phenylbutyric acid (4-PBA) and GR inhibitor RU38486 attenuated related damage and downregulated the expression of the abovementioned proteins.

Conclusion

High-concentration GC exposure can significantly inhibit the viability of PC12 cells and induce apoptosis. PERK-ATF4-CHOP and IRE1-ASK1-JNK pathways are involved in the above damage process.

Cordycepin Exerts Neuroprotective Effects via an Anti-Apoptotic Mechanism based on the Mitochondrial Pathway in a Rotenone-Induced Parkinsonism Rat Model

BACKGROUND

Cordycepin (Cor), one of the major bioactive components of the traditional Chinese medicine Cordyceps militaris, has been used in clinical practice for several years. However, its neuroprotective effect remains unknown.

AIMS

The purpose of the study was to evaluate the neuroprotective effects of Cor using a rotenoneinduced Parkinson's Disease (PD) rat model and to delineate the possible associated molecular mechanisms.

METHODS

In vivo, behavioural tests were performed based on the 10-point scale and grid tests. Levels of dopamine and its metabolites in the striatum and the numbers of TH-positive neurons in the Substantia Nigra pars compacta (SNpc) were investigated by high-performance liquid chromatography with electrochemical detection and immunohistochemical staining, respectively. In vitro, cell apoptosis rates and Mitochondrial Membrane Potential (MMP) were analysed by flow cytometry and the mRNA and protein levels of Bax, Bcl-2, Bcl-xL, Cytochrome c (Cyt-c), and caspase-3 were determined by quantitative real-time PCR and western blotting.

RESULTS

Showed that Cor significantly improved dyskinesia, increased the numbers of TH-positive neurons in the SNpc, and maintained levels of dopamine and its metabolites in the striatum in rotenone- induced PD rats. We also found that apoptosis was suppressed and the loss of MMP was reversed with Cor treatment. Furthermore, Cor markedly down-regulated the expression of Bax, upregulated Bcl-2 and Bcl-xL, inhibited the activation of caspase-3, and decreased the release of Cyt-c from the mitochondria to the cytoplasm, as compared to those in the rotenone-treated group.

CONCLUSION

Therefore, Cor protected dopamine neurons against rotenone-induced apoptosis by improving mitochondrial dysfunction in a PD model, demonstrating its therapeutic potential for this disease.

Baicalein Attenuates Neuroinflammation by Inhibiting NLRP3/caspase-1/GSDMD Pathway in MPTP Induced Mice Model of Parkinson's Disease

BACKGROUND

Inflammasome-induced neuroinflammation is a major pathogenic mechanism underlying the degeneration of nigral dopaminergic neurons in Parkinson's disease (PD). Baicalein is a flavonoid isolated from the traditional Chinese medicinal herbal Scutellaria baicalensis Georgi with known anti-inflammatory and neuroprotective efficacy in models of neurodegenerative diseases, including PD. However, its effects on inflammasome-induced neuroinflammation during PD remain unclear.

METHODS

We used N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to induce PD-like pathology in mice. Behavioral assessments including the pole test, rotarod test and open filed test were conducted to evaluate the effects of baicalein on MPTP-induced motor dysfunction. The efficacies of baicalein against MPTP-induced dopaminergic neuron loss and glial cell activation in the substantia nigra compact (SNc) were examined by immunohistochemistry, effects on proinflammatory cytokines by qPCR and enzyme-linked immunosorbent assay (ELISA), effects on inflammasome pathway activation by immunoblotting and flow cytometry.

RESULTS

Administration of baicalein reversed MPTP-induced motor dysfunction, loss of dopaminergic neurons, and pro-inflammatory cytokine elevation. Baicalein also inhibited NLRP3 and caspase-1 activation and suppressed gasdermin D (GSDMD)-dependent pyroptosis. Additionally, baicalein inhibited the activation and proliferation of disease-associated proinflammatory microglia.

CONCLUSIONS

These findings suggest that baicalein can reverse MPTP-induced neuroinflammation in mice by suppressing NLRP3/caspase-1/GSDMD pathway. Our study provides potential insight of baicalein in PD therapy.

Baicalein as a Potential Inhibitor against BACE1 and AChE: Mechanistic Comprehension through In Vitro and Computational Approaches

One of the major neurodegenerative features of Alzheimer's disease (AD) is the presence of neurotoxic amyloid plaques composed of amyloid beta peptide (Aβ). β-Secretase (BACE1) and acetylcholinesterase (AChE), which promote Aβ fibril formation, have become attractive therapeutic targets for AD. P-glycoprotein (P-gp), the major efflux pump of the blood-brain barrier (BBB), plays a critical role in limiting therapeutic molecules. In pursuit of discovering a natural anti-AD candidate, the bioactivity, physicochemical, drug-likeness, and molecular docking properties of baicalein, a major compound from Scutellaria baicalensis, was investigated. Baicalein exhibited strong BACE1 and AChE inhibitory properties (IC50 23.71 ± 1.91 µM and 45.95 ± 3.44 µM, respectively) and reacted in non-competitive and competitive manners with substrates, respectively. in Silico docking analysis was in full agreement with the in vitro results, demonstrating that the compound exhibited powerful binding interaction with target enzymes. Particularly, three continuous hydroxyl groups on the A ring demonstrated strong H-bond binding properties. It is also noteworthy that baicalein complied with all requirements of Lipinski's rule of five by its optimal physicochemical properties for both oral bioavailability and blood-brain barrier permeability. Overall, the present study strongly demonstrated the possibility of baicalein having in vivo pharmacological efficacy for specific targets in the prevention and/or treatment of AD.

Multi-targeting effects of a new synthetic molecule (JM-20) in experimental models of cerebral ischemia

Ischemic stroke is a major cause of death and disability worldwide. Thrombolysis by tissue plasminogen activator is the only pharmacological treatment approved for clinical practice, but has a narrow therapeutic window and poor efficacy when the cell death cascade is activated. Numerous drugs that are thought to protect neurons against injury have previously failed in human trials despite showing efficacy in experimental models of stroke. Herein, we reviewed the main pre-clinical results of the neuroprotective effects of JM-20, a new hybrid molecule, against brain ischemia. JM-20 appears to protect the brain from ischemic damage by interfering with several elements of the ischemic cascade: antiexcitotoxic, anticalcic, antioxidant, antiapoptotic, and anti-inflammatory. Its ability to protect not only neurons but also glial cells together with its ability to target and preserve mitochondrial function makes JM-20 a promising molecule that may be able to shield the whole neurovascular unit. The multimodal and multi-cell action of JM-20 may explain the high degree of protection observed in a rat model of brain ischemia, as assayed through histological (hematoxylin-eosin, and luxol fast blue staining), neurochemical (glutamate and aspartate levels in cerebrospinal fluid), mitochondrial functionality and behavioural (neurological scale) analysis at doses of 4 and 8mg/kg. Furthermore, the wide therapeutic window of JM-20 of 8h also suggests that this molecule could be of potential interest in situations where brain perfusion is compromised.

Nicotine alleviates chronic stress-induced anxiety and depressive-like behavior and hippocampal neuropathology via regulating autophagy signaling

Recently, we reported that chronic nicotine significantly improved chronic stress-induced impairments of cognition and the hippocampal synaptic plasticity in mice, however, the underlying mechanism still needs to be explored. In the present study, 32 male C57BL/6 mice were divided into four groups: control (CON), stress (CUS), stress with chronic nicotine administration (CUS + Nic) and chronic nicotine administration (Nic). The anxiety-like behavior and neuropathological alteration of DG neurons were examined. Moreover, PC12 cells were examined with corticosterone in the presence or absence of nicotine. Both cell viability and apoptosis were determined. When treated simultaneously with an unpredictable chronic mild stress (CUS), nicotine (0.2 mg/kg/d) attenuated behavioral deficits and neuropathological alterations of DG neurons. Moreover, Western blotting showed that chronic nicotine also elevated the level of autophagy makers including Beclin-1 and LC3 II triggered by CUS. In addition, concomitant treatment with nicotine (10 μM) significantly attenuated the loss of PC12 cell viability (p < .01) and apoptosis compared to that of corticosterone treatment alone. Besides, chronic nicotine also enhanced the protein and RNA expression levels of autophagy makers triggered by corticosterone, such as Beclin-1, LC3 II and p62/SQSTM1. However, the above improvements were significantly blocked by autophagy inhibitor 3-MA. Importantly, the activation of the PI3K/Akt/mTOR signaling was carefully tested to illuminate the effects of chronic nicotine. Consequently, chronic nicotine played a role of neuroprotection in either CUS mice or corticosterone cells associating with the enhancement of the autophagy signaling, which was involved in activating the PI3K/Akt/mTOR signaling.

Effects of baicalein on IL-1β-induced inflammation and apoptosis in rat articular chondrocytes

In osteoarthritis (OA), activated synoviocytes and articular chondrocytes produce pro-inflammatory cytokines, such as IL-1β, that promote chondrocyte apoptosis and activate the NF-κB signaling pathway to induce catabolic factors. In this study, we examined the anti-inflammatory and anti-apoptotic effect of baicalein on IL-1β signaling and NF-κB-regulated gene products in rat chondrocytes. Rat chondrocytes were pretreated with 10 ng/ml IL-1β for 24 h and then co-treated with 10 ng/ml IL-1β and 50 μM baicalein for 0, 12, 24, 36 and 48h. The expression levels of poly(ADP-ribose) polymerase (PARP), Bcl-2, caspase-3, matrix metalloproteinase (MMP)-9, MMP-3, cyclooxygenase (COX)-2 and SOX-9 were detected by Western blot and quantitative reverse transcription-PCR (qPCR). The effects of baicalein on the translocation and phosphorylation of the NF-κB system were studied by Western blotting and immunofluorescence. Baicalein stimulated the expression of anti-apoptotic genes and reduced the pro-apoptotic and pro-inflammatory gene products in chondrocytes. Baicalein promoted SOX-9 expression in a time-dependent manner in chondrocytes. Baicalein inhibited the NF-κB activation that was induced by IL-1β in a time-dependent manner in chondrocytes. Our results suggest that the anti-inflammatory and anti-apoptotic effects of baicalein are mediated through the inhibition of the translocation of phosphorylated p65 to the nucleus.

Current Perspective in the Discovery of Anti-aging Agents from Natural Products

Aging is a process characterized by accumulating degenerative damages, resulting in the death of an organism ultimately. The main goal of aging research is to develop therapies that delay age-related diseases in human. Since signaling pathways in aging of Caenorhabditis elegans (C. elegans), fruit flies and mice are evolutionarily conserved, compounds extending lifespan of them by intervening pathways of aging may be useful in treating age-related diseases in human. Natural products have special resource advantage and with few side effect. Recently, many compounds or extracts from natural products slowing aging and extending lifespan have been reported. Here we summarized these compounds or extracts and their mechanisms in increasing longevity of C. elegans or other species, and the prospect in developing anti-aging medicine from natural products.

The Mechanisms of Traditional Chinese Medicine Underlying the Prevention and Treatment of Parkinson's Disease

Parkinson's disease (PD), characterized with bradykinesia, static tremor, rigidity and disturbances in balance, is the second most common neurodegenerative disorder. Along with the largely aging population in the world, the incidence is increasing year by year, which imposes the negative impacts on patients, their families and the whole society. Traditional Chinese medicine (TCM) has a positive prospect for the prevention and cure of PD due to its advantages of less side effects and multi-target effects. At present, the pathogenesis of PD is not yet fully discovered. This paper elaborates the mechanisms of TCM underlying the prevention and treatment of PD with regards to the inhibition of oxidative stress, the regulation of mitochondrial dysfunction, the reduction of toxic excitatory amino acids (EAA), the inhibition of neuroinflammation, the inhibition of neuronal apoptosis, and the inhibition of abnormal protein aggregation.

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.

Therapeutic Potential of Baicalein in Alzheimer's Disease and Parkinson's Disease

Alzheimer's disease and Parkinson's disease are the two most common, progressive central neurodegenerative diseases affecting the population over the age of 60 years. Apart from treatments that temporarily improve symptoms, there is no medicine currently available to inhibit or reverse the progression of Alzheimer's disease and Parkinson's disease. In traditional Chinese medicine, the root of Scutellaria baicalensis Georgi is a classic compatible component in the decoction of herbal medicine used for treating central nervous system diseases. Modern pharmacokinetic studies have confirmed that baicalein (5,6,7-trihydroxyflavone) is a major bioactive flavone constituent root of S. baicalensis Georgi. Studies showed that baicalein possesses a range of key pharmacological properties, such as reducing oxidative stress, anti-inflammatory properties, inhibiting aggregation of disease-specific amyloid proteins, inhibiting excitotoxicity, stimulating neurogenesis and differentiation action, and anti-apoptosis effects. Based on these properties, baicalein shows therapeutic potential for Alzheimer's disease and Parkinson's disease. In this review, we summarize the pharmacological protective actions of baicalein that make it suitable for the treatment of Alzheimer's disease and Parkinson's disease, and discuss the potential mechanisms underlying the effects.

Neuroprotective effect of trans-N-caffeoyltyramine from Lycium chinense against H2O2 induced cytotoxicity in PC12 cells by attenuating oxidative stress

Natural products play a critical role in the promotion of good health as regards the prevention and management of oxidative stress related and neurodegenerative disorders. Oxidative stress has been implicated in several apoptotic pathways associated with cell damages in neuronal disorders. The aim of this study was to investigate the antioxidant effect of trans-N-caffeoyltyramine (TNC) isolated from Cortex lycii against hydrogen peroxide (H₂O₂) induced cell damages in PC12 cells as well as its mechanism of action. The results obtained indicated that pretreatment with TNC before the exposure of cells to H₂O₂ toxicity lead to a significant increase in the cell viability and the antioxidant enzyme activities catalase (CAT), superoxide dismutase (SOD), glutathione (GSH) and reduced the level of malondialdehyde (MDA). Furthermore, TNC attenuated the influx of Ca²⁺, ROS formation and restored the impaired mitochondria membrane potential (MMP). Thus TNC may be used as an alternative therapy for the prevention and treatment of neuronal disorders elicited by oxidative stress.

Protective effects of lichen metabolites evernic and usnic acids against redox impairment-mediated cytotoxicity in central nervous system-like cells

Lichens species produce unique secondary metabolites that attract increasing pharmacological interest, including their redox modulatory activities. Current work evaluated for the first time the in vitro cytoprotective properties, based on the antioxidant activities, of the Parmeliaceae lichens Evernia prunastri and Usnea ghattensis and the mechanism of action of their major phenolic constituents: the evernic and usnic acids, respectively. In two models of central nervous system-like cells (U373-MG and SH-SY5Y cell lines), exogenous H₂O₂ induced oxidative stress-mediated cytotoxicity. We first assessed their radical scavenging capacities (ORAC and DPPH tests) and the phenolic content of the extracts. At the optimal concentrations, pretreatments with evernic acid displayed significant protection against H₂O₂-induced cytotoxic damage in both models. It reversed the alterations in oxidative stress markers (including ROS generation, glutathione system and lipid peroxidation levels) and cellular apoptosis (caspase-3 activity). Such effects were in part mediated by a notable enhancement of the expression of intracellular phase-II antioxidant enzymes; a plausible involvement of the Nrf2 cytoprotective pathway is suggested. Usnic acid exerted similar effects, to some extent more moderate. Results suggest that lichen polyketides evernic and usnic acids merit further research as promising antioxidant candidates in the therapy of oxidative stress-related diseases, including the neurodegenerative disorders.

Analgesia effect of baicalein against NTG-induced migraine in rats

BACKGROUND

Migraine is a complex nervous system disease characterized by typical throbbing and unilateral headache, which causes severe healthy and social issues worldwide. The purpose of this study was to investigate the effect of baicalein (BAI) on the treatment of migraine.

MATERIAL AND METHODS

Twenty-four rats were randomly divided equally into four groups, including a blank group, model group, positive group (ibuprofen tablets 82mg/kg), and BAI group (60mg/kg). All rats were intragastrically treated with the corresponding treatment for 10 consecutive days, and they were subcutaneously injected with NTG (10mg/kg) 1h after the last treatment, except in the blank group. After model establishment, the behaviors of all rats, including scratching head and shaking body were observed continuously for 100min. Four hours after NTG treatment, all rats were anaesthetized and the blood was collected. Thereafter, nitric oxide (NO) in plasma was determined by colorimetric method, the level of calcitonin gene-related peptide (CGRP) and endothelin (ET) were detected by radioimmunoassay method. In addition, immunohistochemistry was applied to detect c-Fos neuronal activity in trigeminal nucleus caudalis (TNC).

RESULTS

Behavioral research showed that BAI administration alleviated the hyperalgesia in migraine rats. Compared with the model group, the levels of NO and CGRP in BAI administration groups were markedly decreased (p<0.01), and the levels of ET was significantly increased (p<0.01). Meanwhile, immunohistochemistry results showed that NTG treatment significantly activated c-Fos neurons while BAI treatment inhibited the expression of c-Fos.

CONCLUSIONS

BAI could alleviate the migraine-like headache induced by NTG, which is related to the regulation of vasoactive substances. These findings may contribute to the further study of BAI as a potential drug for migraine pharmacotherapy.

In vitro neuroprotective potential of lichen metabolite fumarprotocetraric acid via intracellular redox modulation

The lichen-forming fungi Cetraria islandica has been largely used in folk medicines, and it has recently showed promising in vitro antioxidant effects in glial-like cells. Current work aimed at investigating the neuroprotective potential of its major isolated secondary metabolite: the depsidone fumarprotocetraric acid (FUM). H₂O₂ was used herein to induce oxidative stress (OS)-mediated cytotoxicity in two models of neurons and astrocytes cells (SH-SY5Y and U373-MG cell lines). We found that a pre-treatment with FUM significantly enhanced cell viability compared to H₂O₂-treated cells, and we selected the optimal concentrations in each model (1 and 25μg/ml, respectively) for assessing its cytoprotective mechanisms. FUM, which exerted effective peroxyl radical scavenging effect in the chemical oxygen radical antioxidant capacity (ORAC) assay, alleviated the alterations in OS markers provoked by H₂O₂. It attenuated intracellular ROS formation, lipid peroxidation and GSH depletion. At mitochondrial level, FUM prevented from the dissipation of mitochondrial membrane potential and the increase in mitochondrial calcium, implying a protective role against oxidative damage in mitochondrial membrane. Similarly, FUM pre-treatment diminished H₂O₂-induced apoptosis, as evidenced by the reduction in caspase-3 activity and expression; inmunoblot analysis also revealed a decrease in Bax and an increase in Bcl-2 proteins levels. Furthermore, FUM up-regulated the expression of the antioxidant enzymes catalase, superoxide dismutase-1, and hemeoxigenase-1. These findings and the activation of Nrf2 binding activity in nuclear extracts suggest a plausible involvement of Nrf2 signaling pathway in the cytoprotection by FUM. In conclusion, FUM emerges as a potential drug candidate in the therapy of OS-related diseases, such as the neurodegenerative disorders.

Baicalein attenuates α-synuclein aggregation, inflammasome activation and autophagy in the MPP+-treated nigrostriatal dopaminergic system in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Neuroinflammation, oxidative stress, and protein aggregation form a vicious cycle in the pathophysiology of Parkinson's disease (PD); activated microglia is the main location of neuroinflammation. A Chinese medicine book, "Shanghan Lun", known as the "Treatises on Cold damage Diseases" has suggested that Scutellaria baicalensis Georgi is effective in treating CNS diseases. The anti-inflammatory mechanisms of baicalein, a phenolic flavonoid in the dried root of Scutellaria baicalensis Georgi, remain to be explored.

AIM OF THE STUDY

The neuroprotective mechanisms of baicalein involving α-synuclein aggregation, inflammasome activation, and programmed cell death were investigated in the nigrostriatal dopaminergic system of rat brain in vivo.

MATERIALS AND METHODS

Intranigral infusion of 1-methyl-4-phenylpyridinium (MPP⁺, a Parkinsonian neurotoxin) was performed on anesthetized Sprague-Dawley rats. Baicalein was daily administered via intraperitoneal injection. Striatal dopamine levels were measured using high performance liquid chromatography coupled with electrochemical detection. Cellular signalings were measured by Western blot assay, immunofluorescent staining assay and enzyme-linked immunosorbent assay.

RESULTS

Systemic administration of baicalein attenuated MPP⁺-induced reductions in striatal dopamine content and tyrosine hydroxylase (a biomarker of dopaminergic neurons) in the infused substantia nigra (SN). Furthermore, MPP⁺-induced elevations in α-synuclein aggregates (a pathological hallmark of PD), ED-1 (a biomarker of activated microglia), activated caspase-1 (a proinflammatory caspase), IL-1β and cathepsin B (a cysteine lysosomal protease) in the infused SN were attenuated in the baicalein-treated rats. Moreover, intense immunoreactivities of caspase 1 and cathepsin B were co-localized with that of ED-1 in the MPP⁺-infused SN. At the same time, baicalein inhibited MPP⁺-induced increases in active caspases 9 and 12 (biomarkers of apoptosis) as well as LC3-II levels (a biomarker of autophagy) in the rat nigrostriatal dopaminergic system.

CONCLUSION

Our in vivo study showed that baicalein possesses anti-inflammatory activities by inhibiting α-synuclein aggregation, inflammasome activation and cathepsin B production in the MPP⁺-infused SN. Moreover, baicalein is of therapeutic significance because it inhibits MPP⁺-induced apoptosis and autophagy in the nigrostriatal dopaminergic system of rat brain.

Baicalin may have a therapeutic effect in attention deficit hyperactivity disorder

Baicalin is a flavonoid purified from Scutellaria baicalensis Georgi. It possesses a variety of pharmacological properties, such as anti-inflammatory, antioxidant, antiapoptotic, and neuro-protective properties, and provides protection against cerebral hemorrhage. However, it is seldom considered a therapeutic in mental disorders. Recent studies showed that baicalin protects cerebral functions against ischemia and has sedative and anxiolytic-like effects. Animal experiments showed that it protects dopaminergic neurons in the striatum, hippocampus and substantia nigra. It also has effects such as anti-depressive and anti-epileptic and offers resistance to Parkinson's disease. Attention deficit hyperactivity disorder (ADHD) pathogenesis is closely related to dopamine deficiency. However, the therapeutic effect of baicalin in ADHD has not been studied. We hypothesize that baicalin may protect dopaminergic neurons and increase brain dopamine levels, thus serving as an effective novel treatment for ADHD.

Schisandrin B protects PC12 cells against oxidative stress of neurodegenerative diseases

Increasing evidence places Schisandrin B (Sch B) at an important position in nerve protection, indicating that Sch B might play a positive role in the therapy of neurodegenerative diseases. However, there is little information on it. Our studies showed that pretreatment with Sch B could reduce lactate dehydrogenase, malondialdehyde, and reactive oxygen species release and significantly increase the cell viability and the superoxide dismutase level. Sch B (10 μM) markedly inhibited cell apoptosis, whereas LY294002 (20 μM), a phosphatidylinositol-3 kinase inhibitor, blocked the antiapoptotic effect. More importantly, Sch B (10 μM) increased the phosphoprotein kinase B/protein kinase B (Akt) and B-cell lymphoma-2/Bcl-2 associated X protein ratios on preincubation with cells for 2 h, which was then inhibited by LY294002 (20 μM). Results indicate that Sch B can protect PC12 cells from apoptosis by activating the phosphatidylinositol-3 kinase/Akt signaling pathway and may emerge as a potential drug for neurodegenerative diseases.

Cocktail of Four Active Components Derived from Sheng Mai San Inhibits Hydrogen Peroxide-Induced PC12 Cell Apoptosis Linked with the Caspase-3/ROCK1/MLC Pathway

SMXZF, a combination of four active components including ginsenoside Rb1, ginsenoside Rg1, schizandrin, and DT-13 (6:9:5:4) that is derived from Sheng Mai San, has previously been shown to exhibit a neuroprotective effect against focal ischemia/reperfusion injury. Due to the key role of oxidative stress-induced neuronal apoptosis in the pathogenesis of stroke, we examined the effect of SMXZF in oxidative stress responses and related signaling pathways in differentiated pheochromocytoma (PC12) cells. Our results showed that incubation with 100 μM hydrogen peroxide (H2O2) for 12 hr could reduce cell viability and superoxide dismutase (SOD) activity with an increase of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA). In contrast, SMXZF alleviated oxidative stress by reducing the over-production of ROS and MDA in parallel to concentration dependently increasing SOD activity. In addition, SMXZF significantly attenuated H2O2-induced caspase-3 cleavage, Rho-associated coiled-coil-containing protein kinase-1 (ROCK1) activation, and myosin light-chain (MLC) phosphorylation. Inhibiting either caspase-3 or ROCK1 mimicked the effect. Consequently, our results suggest that SMXZF inhibits H2O2-induced neuronal apoptosis linked with the caspase-3/ROCK1/MLC pathway, which has also been confirmed to be a positive feedback loop in oxidative stress-injured PC12 cells. These findings support the pharmacological potential of SMXZF for neurodegenerative diseases and stroke.

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.

Serum containing Tongqiaohuoxue decoction suppresses glutamate-induced PC12 cell injury

Glutamate application is an established method of inducing PC12 cell injury. PC12 cells were cultured with serum containing Tongqiaohuoxue decoction consisting of moschus, Carthamus tinctorius, Rhizoma chuanxiong, Semen pruni persicae, and Radix Paeoniae Rubra. After 24 hours of co-cultivation, glutamate (12.5 mM) was added to the culture medium. We found that serum containing Tongqiaohuoxue decoction prevented the increase in reactive oxygen species, and the decreases in superoxide dismutase and Na⁺-K⁺-ATPase activity, induced by glutamate. It also reduced the concentration of malondialdehyde, enhanced the mitochondrial transmembrane potential, inhibited the elevation of cellular calcium, and decreased phosphorylation of calmodulin-dependent protein kinase II. Thus, serum containing Tongqiaohuoxue decoction had protective effects on cell proliferation and membrane permeability in glutamate-injured PC12 cells.

Neuroprotective effect of water extract of Panax ginseng on corticosterone-induced apoptosis in PC12 cells and its underlying molecule mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Panax ginseng C.A. Meyer (Family Araliaceae) is an important medicinal plant which has been employed as a panacea for more than 2,000 years in China. It has the actions of invigorating primordial qi, recovering pulse and desertion, engendering liquid, and calming spirit. The water extract of Panax ginseng (WEG) has been used to treat kinds of central nervous system disorders, such as depression, insomnia, Alzheimer׳s disease and Parkinson׳s disease. Our previous work has demonstrated that WEG possessed antidepressant-like activities in both acute and chronic stress models of depression. Nevertheless, there are no studies on the cytoprotection and potential mechanisms of WEG on corticosterone-induced apoptosis. The present study focuses on cytoprotection against corticosterone-induced neurotoxicity in PC12 cells and its underlying molecule mechanisms of the antidepressant-like effect of WEG.

MATERIALS AND METHODS

The PC12 cells were treated with 250 μmol/L corticosterone in the absence or presence of WEG for 24h, then 3-(4,5-dimethy thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) detection, Hoechst33342 staining and TUNEL staining were investigated to confirm the neuroprotection of WEG. Then, mitochondrial permeability transition pore (mPTP), mitochondrial membrane potential (MMP), intracellular Ca(2+) ([Ca(2+)]i), reactive oxygen species (ROS) concentration, and the expression level of glucocorticoid receptor (GR), heat shock protein 90 (Hsp90), histone deactylase 6 (HDAC6), glucose-regulated protein 78 (GRP78), growth arrest and DNA damage inducible protein 153 (GADD153), X-box DNA-binding protein-1 (XBP-1), caspase-12, cytochrome C, inhibitor of caspase-activated deoxyribonuclease (ICAD), caspase-3 and caspase-9 were assessed by Western Blot analysis to understand the molecule mechanisms of neuroprotection of WEG.

RESULTS

WEG partly reversed corticosterone-induced damage in PC12 cells, which increased cell viability, decreased LDH release, and attenuated corticosterone-induced apoptosis as compared with the corticosterone-treated group. Mechanistically, compared with the corticosterone-treated group, WEG strongly attenuated [Ca(2+)]i overload and ROS level, and restored mitochondrial function, including mPTP and MMP. Furthermore, WEG strongly up-regulated the expression of GR and HDAC6, and down-regulated the expression of Hsp90, cytochrome C, ICAD, caspase-3, caspase-9 as well as endoplasmic reticulum (ER) stress-related proteins, such as GADD153, GRP78, XBP-1, and caspase-12.

CONCLUSION

WEG possessed neuroprotection against corticosterone-induced damage in PC12 cells, and the underlying molecule mechanisms was depended on the intervening of HDAC6 and HSP90 of the GR-related function proteins, and subsequent restoration of ER and mitochondria functions.

Scutellaria baicalensis in stroke management: nature's blessing in traditional Eastern medicine

Scutellaria baicalensis Georgi is the most widely used medicinal plant in traditional Eastern medicine, especially in Chinese medicine. The major phytochemicals isolated from S. baicalensis are flavonoids, glycosides and their glucoronides such as baicalin, baicalein, wogonin etc. More than 30 different kinds of flavonoids are isolated from this plant. S. baicalensis and its flavonoids are reported to have several pharmacological activities, which includes anti-allergic, antioxidant, anti apoptic, anti-inflammatory effects and many more. Recently, S. baicalensis and its isolated flavonoids have been studied for their neuroprotective effects, through a variety of in vitro and in vivo models of neurodegenerative diseases, plausibly suggesting that S. baicalensis has salutary effect as a nature's blessing for neuroprotection. In this review, we are focousing on the neuroprotective effects of S. baicalensis and its flavonoids in ischemia or stroke-induced neuronal cell death. We aimed at compiling all the information regarding the neuroprotective effect of S. baicalensis in various experimental models of cerebral ischemia or stroke.

Neuroprotective effects of Gua Lou Gui Zhi decoction against glutamate-induced apoptosis in BV-2 cells

Gua Lou Gui Zhi decoction (GLGZD), a traditional Chinese medicine consisting of different herbal medicines, has been used for centuries in the treatment of muscular spasticity following stroke, epilepsy or spinal cord injury. However, the precise mechanisms involved remain poorly understood. In the present study, we investigated the neuroprotective effects of GLGZD on glutamate-induced apoptosis in cultured BV-2 cells, as well as the underlying mechanisms. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was applied to assess the viability of the cells. An Annexin V/propidium iodide (PI) assay was utilized to analyze cellular apoptosis. Mitochondrial membrane potential (MMP) was evaluated by flow cytometry and laser scanning confocal microscopy. The gene and protein expression of the apoptosis-related genes, Bcl-2 and Bax, was analyzed by RT-PCR and western blot analysis, respectively. Furthermore, the expression of cleaved caspase-3 protein was detected by immunofluorescence. Glutamate treatment induced the loss of BV-2 cell viability, which was associated with an increase in the apoptotic rate, as well as an increase in the Bax/Bcl-2 ratio and the extracellular levels of cleaved caspase-3. Treatment with GLGZD significantly reversed these phenotypes, with its maximum protective effects observed at the concentration of 1,000 µg/ml. These results indicate that GLGZD protects BV-2 cells from glutamate-induced cytotoxicity. These protective effects may be ascribed to its anti-apoptotic activities, in part, associated with the decrease in the Bax/Bcl-2 ratio and caspase-3 expression, as well as with the stability of high mitochondrial membrane potential.

Kaurane diterpenes from Sideritis spp. exert a cytoprotective effect against oxidative injury that is associated with modulation of the Nrf2 system

Kaurane diterpenes have been shown to possess antioxidant properties. As a part of our ongoing studies on the identification of biologically active diterpenes from Sideritis spp., we have previously isolated and structurally elucidated the major kaurane diterpenes foliol, linearol and sidol, in a previous study from the aerial parts of Sideritis linearifolia and Sideritis leucantha. We have now examined the ability of these compounds to protect PC12 cells in an H2O2-induced oxidative stress model. Linearol and sidol (5 and 10 μM, 24 h) significantly attenuated loss of mitochondrial function (MTT assay) and membrane integrity (LDH assay) and morphological changes associated with H2O2-mediated cytotoxicity. Moreover, pretreatments with linearol and sidol effectively reduced intracellular ROS production, decreased MDA levels (lipid peroxidation product) and restored GSH/GSSG ratio. Furthermore, analysis of the effect of diterpenes on antioxidant enzymes showed that linearol and sidol induced the upregulation and protein expression of the main antioxidant enzymes CAT, SOD, GPx, GR and HO-1. Considering molecular mechanisms for maintaining cellular redox homeostasis by linearol and sidol, it would appear that the Nrf2 transcription factor seems to be involved. These results indicate that linearol and sidol are potential cytoprotective compounds, through antioxidant mechanisms, under H2O2-induced oxidative stress.

Baicalein reduces lipopolysaccharide-induced inflammation via suppressing JAK/STATs activation and ROS production

OBJECTIVE

To investigate the precise molecular mechanisms by which baicalein exerts beneficial biochemical activities in RAW264.7 macrophages treated with LPS.

MATERIALS AND METHODS

RAW264.7 cells were cultured in the absence or presence of baicalein together with or without LPS. iNOS and COX-2 expression were measured by western blot and RT-PCR analyses. TNF-α, IL-1β, and IL-6 were determined by using double-antibody sandwich ELISA. Phosphorylations of JAK1 and JAK2, and of STAT1 and STAT3 were detected by western blotting. Nuclear translocation of STAT1 and STAT3 was visualized by confocal microscopy. ROS production was detected by ROS assay.

RESULTS

Baicalein significantly reduced the phosphorylation of STAT1 and STAT3 and the phosphorylation of JAK1 and JAK2, but without affecting MAPKs phosphorylation in LPS-stimulated RAW264.7 cells. Baicalein suppressed the nuclear translocation of STAT1 and STAT3 and inhibited production of iNOS upon LPS-stimulation, resulting in the inhibition of releases of NO and pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α, in a dose-dependent manner. In addition, we found that baicalein reduced the LPS-induced accumulation of ROS, confirming that baicalein serves as an antioxidant.

CONCLUSIONS

Our results suggested that suppressing JAK/STATs activation and interfering with ROS production might contribute to the anti-inflammatory action of baicalein in macrophages.

Calpain mediates caspase-dependent apoptosis initiated by hydrogen peroxide in pancreatic acinar AR42J cells

Several studies have shown that oxidative stress induces apoptosis in many cellular systems including pancreatic acinar cells. However, the exact molecular mechanisms leading to apoptosis remain partially understood. This study aimed to investigate the role of the cytosolic cysteine protease calpain in H2O2-induced apoptosis in pancreatic AR42J cells. Apoptosis was evaluated using flow cytometric analysis of sub-G1 DNA populations, electron-microscopic analysis, caspase-3-specific αII-spectrin breakdown, and measuring the proteolytic activities of the initiator caspase-12 and caspase-8, and the executioner caspase-3. H2O2 induced an increase in the calpain proteolytic activity immediately after starting the experiments that tended to return to a nearly normal level after 8 h and could be attributed to m-calpain. Whereas no caspase-12, caspase-8 and caspase-3 activations could be detected within the first 0.5 h, significantly increased proteolytic activities were observed after 8 h compared with the control. At the same time, the cells showed first ultrastructural hallmarks of apoptosis and a decreased viability. In addition, αII-spectrin fragmentation was identified using immunoblotting that could be attributed to both calpain and caspase-3. Calpain inhibition reduced the activities of caspase-12, caspase-8, and caspase-3 leading to a decrease in the number of apoptotic cells. Immunoblotting analyses of caspase-12 and caspase-8 indicate that calpain may be involved in the activation process of both proteases. The results suggest that H2O2-induced apoptosis of AR42J cells requires activation of m-calpain initiating the endoplasmic reticulum stress-induced caspase-12 pathway and a caspase-8-dependent pathway. The findings also suggest that calpain may be involved in the execution phase of apoptosis.

Phosphatidylinositol 3 kinase/protein kinase B is responsible for the protection of paeoniflorin upon H₂O₂-induced neural progenitor cell injury

Promoting neural stem/progenitor cell (NSC/NPC) survival in the pro-apoptotic environment is critical to stem cell replacement for neurodegenerative disease therapy. Paeoniflorin (PF), one of the principal bioactive components in Paeoniae Radix, has been used widely in central nervous system (CNS) diseases treatment and serves as an antioxidant to protect neurons against oxidative stress. The present study investigated the protective effects of PF on NPC injury induced by hydrogen peroxide (H₂O₂). After challenge with 200 μM H₂O₂ for 2h, loss of cell viability and excessive apoptotic cell death were observed in cultured NPC, PF treatment conferred protective effects against the loss of cellular viability in a concentration-dependent manner. PF pretreatment also inhibited NPC apoptosis induced by H₂O₂ by reversing the decreased level of Procaspase-3 and balancing Bcl-2 and Bax expression. Furthermore, PF-mediated NPC protection was associated with an increase in phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt-1) phosphorylation in a time- and concentration-dependent manner. Selective inhibition of PI3K using LY294002 abolished PF-mediated phosphorylation of Akt-1 and NPC protection upon oxidative stress. These data suggest that PF-mediated NPC protection on H₂O₂ injury is reliant on the activation of the PI3K/Akt-1 pathway, giving insight to an essential role of PF in NPC protection.

Baicalein Triggers Mitochondria-Mediated Apoptosis and Enhances the Antileukemic Effect of Vincristine in Childhood Acute Lymphoblastic Leukemia CCRF-CEM Cells

Acute lymphoblastic leukemia (ALL) accounts for approximately 75% of childhood leukemia, and chemotherapy remains the mainstay therapy. Baicalein is an active flavonoid used in traditional Chinese medicine and has recently been found to have anticancer, anti-inflammatory, and antiallergic properties. This study aims to investigate the molecular apoptotic mechanisms of baicalein in CCRF-CEM leukemic cells and to evaluate the combined therapeutic efficacy of baicalein with several commonly used chemotherapeutic drugs in CCRF-CEM cells. Our results demonstrate that baicalein induces mitochondria-dependent cleavage of caspases-9 and -3 and PARP with concomitant decreases in IAP family proteins, survivin, and XIAP. Furthermore, our results present for the first time that baicalein triggers a convergence of the intrinsic and extrinsic apoptotic pathways via the death receptor-caspase 8-tBid signaling cascade in CCRF-CEM cells. In addition, we also present for the first time that the combination of baicalein and vincristine results in a synergistic therapeutic efficacy. Overall, this combination strategy is recommended for future clinical trials in the treatment of pediatric leukemia owing to baicalein's beneficial effects in alleviating the vomiting, nausea, and skin rashes caused by chemotherapy.

Ac-cel, a novel antioxidant, protects against hydrogen peroxide-induced injury in PC12 cells via attenuation of mitochondrial dysfunction

Oxidative stress has been implicated in pathophysiology of many neurodegenerative diseases (ND) and increased oxidative stress is closely associated with mitochondrial dysfunction. As a result, looking for potent antioxidants, especially those targeting mitochondria, has become an attractive strategy in ND therapy. In this study, we explored protective effects and potential mechanism of Ac-cel, a novel compound, against hydrogen peroxide (H(2)O(2))-induced injury in PC12 cells. Pretreatment of PC12 cells with Ac-cel prior to 24 h of H(2)O(2) exposure markedly attenuated cytotoxicity induced by H(2)O(2) as evidenced by morphological changes and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Ac-cel also exhibited potent antiapoptotic effect demonstrated by results of annexin V and PI staining. The above beneficial effects of Ac-cel were accompanied by improved mitochondrial function, reduced caspase-3 cleavage as well as upregulated ratio of Bcl-2/Bax protein expression. Moreover, Ac-cel pretreatment markedly reversed intracellular reactive oxygen species (ROS) accumulation following 30 min of H(2)O(2) exposure in PC12 cells. Further, subcellular investigation indicated that Ac-cel significantly reduced production of mitochondrial ROS in isolated rat cortical mitochondria. Taken together, the present study, for the first time, reports that Ac-cel pretreatment inhibits H(2)O(2)-stimulated early accumulation of intracellular ROS possibly via reducing mitochondrial ROS production directly and leads to subsequent preservation of mitochondrial function. These results indicate that Ac-cel is a potential drug candidate for treatment of oxidative stress-associated ND.