Ginsenoside Rd attenuates redox imbalance and improves stroke outcome after focal cerebral ischemia in aged mice

Ginsenoside Rd Protects Against Cerebral Ischemia-Reperfusion Injury Via Decreasing the Expression of the NMDA Receptor 2B Subunit and its Phosphorylated Product

Ginsenoside Rd (GSRd) is one of the active ingredients in ginseng. Recent studies have shown that GSRd can protect against cerebral ischemia through several pathways, one of which is mediated by the N-methyl-D-aspartate receptor (NMDAR). In this study, we aimed to investigate the effects of GSRd on the phosphorylation of the NMDAR 2B subunit (NR2B subunit) in cerebral ischemia. Ischemia-reperfusion injury (IRI) models induced by transient middle cerebral artery occlusion (MCAO) and oxygen glucose deprivation (OGD) were used to mimic in vivo or in vitro injury during cerebral ischemia. The models were pretreated or post-treated with GSRd after MCAO or OGD. As a vehicle control, 1,3-propanediol was used. The expression levels of the NR2B subunit and the phosphorylated NR2B subunit were determined using western blotting. GSRd significantly improved the behavior score, infarct volume, and viability of the cultured neurons after ischemia. GSRd inhibited the hyperphosphorylation of NR2B subunit and decreased the expression levels of NR2B subunit in cell membrane but did not change their levels in the total proteins after IRI. GSRd protected Sprague-Dawley rats and cultured neurons from IRI via inhibiting the hyperphosphorylation of NR2B subunit and decreasing its expression levels in cell membrane.

Caveolin-1 is a checkpoint regulator in hypoxia-induced astrocyte apoptosis via Ras/Raf/ERK pathway

Astrocytes, the most numerous cells in the human brain, play a central role in the metabolic homeostasis following hypoxic injury. Caveolin-1 (Cav-1), a transmembrane scaffolding protein, has been shown to converge prosurvival signaling in the central nerve system. The present study aimed to investigate the role of Cav-1 in the hypoxia-induced astrocyte injury. We also examined how Cav-1 alleviates apoptotic astrocyte death. To this end, primary astrocytes were exposed to oxygen-glucose deprivation (OGD) for 6 h and a subsequent 24-h reoxygenation to mimic hypoxic injury. OGD significantly reduced Cav-1 expression. Downregulation of Cav-1 using Cav-1 small interfering RNA dramatically worsened astrocyte cell damage and impaired cellular glutamate uptake after OGD, whereas overexpression of Cav-1 with Cav-1 scaffolding domain peptide attenuated OGD-induced cell apoptosis. Mechanistically, the expressions of Ras-GTP, phospho-Raf, and phospho-ERK were sequestered in Cav-1 small interfering RNA-treated astrocytes, yet were stimulated after supplementation with caveolin peptide. MEK/ERK inhibitor U0126 remarkably blocked the Cav-1-induced counteraction against apoptosis following hypoxia, indicating Ras/Raf/ERK pathway is required for the Cav-1's prosurvival role. Together, these findings support Cav-1 as a checkpoint for the in hypoxia-induced astrocyte apoptosis and warrant further studies targeting Cav-1 to treat hypoxic-ischemic brain injury.

Method parameters' impact on mortality and variability in mouse stroke experiments: a meta-analysis

Although hundreds of promising substances have been tested in clinical trials, thrombolysis currently remains the only specific pharmacological treatment for ischemic stroke. Poor quality, e.g. low statistical power, in the preclinical studies has been suggested to play an important role in these failures. Therefore, it would be attractive to use animal models optimized to minimize unnecessary mortality and outcome variability, or at least to be able to power studies more exactly by predicting variability and mortality given a certain experimental setup. The possible combinations of methodological parameters are innumerous, and an experimental comparison of them all is therefore not feasible. As an alternative approach, we extracted data from 334 experimental mouse stroke articles and, using a hypothesis-driven meta-analysis, investigated the method parameters’ impact on infarct size variability and mortality. The use of Swiss and C57BL6 mice as well as permanent occlusion of the middle cerebral artery rendered the lowest variability of the infarct size while the emboli methods increased variability. The use of Swiss mice increased mortality. Our study offers guidance for researchers striving to optimize mouse stroke models.

Ginsenoside-Rd Promotes Neurite Outgrowth of PC12 Cells through MAPK/ERK- and PI3K/AKT-Dependent Pathways

Panax ginseng is a famous herbal medicine widely used in Asia. Ginsenosides have been identified as the principle active ingredients for Panax ginseng’s biological activity, among which ginsenoside Rd (Rd) attracts extensive attention for its obvious neuroprotective activities. Here we investigated the effect of Rd on neurite outgrowth, a crucial process associated with neuronal repair. PC12 cells, which respond to nerve growth factor (NGF) and serve as a model for neuronal cells, were treated with different concentrations of Rd, and then their neurite outgrowth was evaluated. Our results showed that 10 μM Rd significantly increased the percentages of long neurite- and branching neurite-bearing cells, compared with respective controls. The length of the longest neurites and the total length of neurites in Rd-treated PC12 cells were much longer than that of respective controls. We also showed that Rd activated ERK1/2 and AKT but not PKC signalings, and inhibition of ERK1/2 by PD98059 or/and AKT by LY294002 effectively attenuated Rd-induced neurite outgrowth. Moreover, Rd upregulated the expression of GAP-43, a neuron-specific protein involved in neurite outgrowth, while PD98059 or/and LY294002 decreased Rd-induced increased GAP-43 expression. Taken together, our results provided the first evidence that Rd may promote the neurite outgrowth of PC12 cells by upregulating GAP-43 expression via ERK- and ARK-dependent signaling pathways.

LC-ESI-TOF-MS-based metabolomic analysis of ginsenoside Rd-induced anaphylactoid reaction in mice

A ginsenoside Rd-induced anaphylactoid reaction in mice was investigated by LC-ESI-TOF-MS-based metabolomic analysis as well as general toxicological assessments.

Human Albumin Improves Long-Term Behavioral Sequelae After Subarachnoid Hemorrhage Through Neurovascular Remodeling

OBJECTIVE

Subarachnoid hemorrhage results in significant long-lasting neurologic sequelae. Here, we investigated whether human albumin improves long-term outcomes in experimental subarachnoid hemorrhage and whether neurovascular remodeling is involved in the protection of albumin.

DESIGN

Laboratory investigation.

SETTING

Hospital research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Rats underwent subarachnoid hemorrhage by endovascular perforation. Albumin of either 0.63 or 1.25 g/kg was injected IV immediately after the surgery. Modified Garcia test, beam-walking test, novel object recognition, and Morris water maze were employed to determine the behavioral deficits. The effects of albumin on early neurovascular dysfunction and chronic synaptic plasticity were also studied.

MEASUREMENTS AND MAIN RESULTS

Both doses of albumin significantly improved the sensorimotor scores (F = 31.277; p = 0.001) and cognitive performance (F = 7.982; p = 0.001 in novel object recognition test; and F = 3.431; p = 0.026 in the latency analysis of Morris water maze test) for at least 40 days after subarachnoid hemorrhage. There were remarkable microvasculature hypoperfusion, intracranial pressure rise, early vasoconstriction, neural apoptosis, and degeneration in subarachnoid hemorrhage rats, with albumin significantly attenuating such neurovascular dysfunction. Furthermore, albumin markedly prevented blood-brain barrier disruption, as indicated by less blood-brain barrier leakage, preserved blood-brain barrier-related proteins, and dampened gelatinase activities. The expressions of key synaptic elements were up-regulated with albumin supplementation in both acute and chronic phases. Accordingly, a higher dendritic spine density was observed in the prefrontal and hippocampal areas of albumin-treated subarachnoid hemorrhage animals.

CONCLUSIONS

Albumin at low-to-moderate doses markedly improves long-term neurobehavioral sequelae after subarachnoid hemorrhage, which may involve an integrated process of neurovascular remodeling.

Neuroprotective Effect of Xueshuantong for Injection (Lyophilized) in Transient and Permanent Rat Cerebral Ischemia Model

Xueshuantong for Injection (Lyophilized) (XST), a Chinese Materia Medica standardized product extracted from Panax notoginseng (Burk.), is used extensively for the treatment of cerebrovascular diseases such as acutely cerebral infarction clinically in China. In the present study, we evaluated the acute and extended protective effects of XST in different rat cerebral ischemic model and explored its effect on peroxiredoxin (Prx) 6-toll-like receptor (TLR) 4 signaling pathway. We found that XST treatment for 3 days could significantly inhibit transient middle cerebral artery occlusion (MCAO) induced infarct volume and swelling percent and regulate the mRNA expression of interleukin-1β (IL-1β), IL-17, IL-23p19, tumor necrosis factor-α (TNFα), and inducible nitric oxide synthase (iNOS) in brain. Further study demonstrated that treatment with XST suppressed the protein expression of peroxiredoxin (Prx) 6-toll-like receptor (TLR) 4 and phosphorylation level of p38 and upregulated the phosphorylation level of STAT3. In permanent MCAO rats, XST could reduce the infarct volume and swelling percent. Moreover, our results revealed that XST treatment could increase the rats' weight and improve a batch of functional outcomes. In conclusion, the present data suggested that XST could protect against ischemia injury in transient and permanent MCAO rats, which might be related to Prx6-TLR4 pathway.

Ginsenoside Rd and ischemic stroke; a short review of literatures

Panax ginseng is a well-known economic medical plant that is widely used in Chinese traditional medicine. This species contains a unique class of natural products-ginsenosides. Recent clinical and experimental studies have presented numerous lines of evidence on the promising role of ginsenosides on different diseases including neurodegenerative diseases, cardiovascular diseases, and certain types of cancer. Nowadays, most of the attention has focused on ginsenoside Rd as a neuroprotective agent to attenuate ischemic stroke damages. Some of the evidence showed that ginsenoside Rd ameliorates ischemic stroke-induced damages through the suppression of oxidative stress and inflammation. Ginsenoside Rd can prolong neural cells' survival through the upregulation of the endogenous antioxidant system, phosphoinositide-3-kinase/AKT and extracellular signal-regulated protein kinase 1/2 pathways, preservation of mitochondrial membrane potential, suppression of the nuclear factor-kappa B, transient receptor potential melastatin, acid sensing ion channels 1a, poly(ADP-ribose) polymerase-1, protein tyrosine kinase activation, as well as reduction of cytochrome c-releasing and apoptosis-inducing factor. In the current work, we review the available reports on the promising role of ginsenoside Rd on ischemic stroke. We also discuss its chemistry, source, and the molecular mechanism underlying this effect.

HO-1 Signaling Activation by Pterostilbene Treatment Attenuates Mitochondrial Oxidative Damage Induced by Cerebral Ischemia Reperfusion Injury

Ischemia reperfusion (IR) injury (IRI) is harmful to the cerebral system and causes mitochondrial oxidative stress. The antioxidant response element (ARE)-mediated antioxidant pathway plays an important role in maintaining the redox status of the brain. Heme oxygenase-1 (HO-1), combined with potent AREs in the promoter of HO-1, is a highly effective therapeutic target for protection against cerebral IRI. Pterostilbene (PTE), a natural dimethylated analog of resveratrol from blueberries, is a strong natural antioxidant. PTE has been shown to be beneficial for some nervous system diseases and may regulate HO-1 signaling. This study was designed to investigate the protective effects of PTE on cerebral IRI and to elucidate potential mechanisms underlying those effects. Mouse brains and cultured HT22 neuron cells were subjected to IRI. Prior to this procedure, the brains or cells were exposed to PTE in the absence or presence of the HO-1 inhibitor ZnPP or HO-1 small interfering RNA (siRNA). PTE conferred a cerebral protective effect, as shown by increased neurological scores, viable neurons and decreased brain edema as well as a decreased ion content and apoptotic ratio in vivo. PTE also increased the cell viability and decreased the lactate dehydrogenase (LDH) leakage and apoptotic ratio in vitro. ZnPP and HO-1 siRNA both blocked PTE-mediated cerebral protection by inhibiting HO-1 signaling and further inhibited two HO-1 signaling-related antioxidant molecules:

NAD(P)H

quinone oxidoreductase 1 (NQO1) and glutathione S-transferases (GSTs), which are induced by PTE. PTE also promoted a well-preserved mitochondrial membrane potential (MMP), mitochondria complex I activity, and mitochondria complex IV activity, increased the mitochondrial cytochrome c level, and decreased the cytosolic cytochrome c level. However, this PTE-elevated mitochondrial function was reversed by ZnPP or HO-1 siRNA treatment. In summary, our results demonstrate that PTE treatment attenuates cerebral IRI by reducing IR-induced mitochondrial oxidative damage through the activation of HO-1 signaling.

Caveolae: molecular insights and therapeutic targets for stroke

INTRODUCTION

Caveolae are specialized plasma membrane micro-invaginations of most mammalian cell types. The organization and function of caveolae are carried out by their coat proteins, caveolins and adaptor proteins, cavins. Caveolae/caveolins physically interact with membrane-associated signaling molecules and function in cholesterol incorporation, signaling transduction and macromolecular transport/permeability.

AREAS COVERED

Recent investigations have implicated a check-and-balance role of caveolae in the pathophysiology of cerebral ischemia. Caveolin knockout mice displayed exacerbated ischemic injury, whereas caveolin peptide exerted remarkable protection against ischemia/reperfusion injury. This review attempts to provide a comprehensive synopsis of how caveolae/caveolins modulate blood-brain barrier permeability, pro-survival signaling, angiogenesis and neuroinflammation, and how this may contribute to a better understanding of the participation of caveolae in ischemic cascade. The role of caveolin in the preconditioning-induced tolerance against ischemia is also discussed.

EXPERT OPINION

Caveolae represent a novel target for cerebral ischemia. It remains open how to manipulate caveolin expression in a practical way to recapitulate the beneficial therapeutic outcomes. Caveolin peptides and associated antagomirs may be efficacious and deserve further investigations for their potential benefits for stroke.

Ginseng: a promising neuroprotective strategy in stroke

Ginseng is one of the most widely used herbal medicines in the world. It has been used in the treatment of various ailments and to boost immunity for centuries; especially in Asian countries. The most common ginseng variant in traditional herbal medicine is ginseng, which is made from the peeled and dried root of Panax Ginseng. Ginseng has been suggested as an effective treatment for a vast array of neurological disorders, including stroke and other acute and chronic neurodegenerative disorders. Ginseng’s neuroprotective effects are focused on the maintenance of homeostasis. This review involves a comprehensive literature search that highlights aspects of ginseng’s putative neuroprotective effectiveness, focusing on stroke. Attenuation of inflammation through inhibition of various proinflammatory mediators, along with suppression of oxidative stress by various mechanisms, including activation of the cytoprotective transcriptional factor Nrf2, which results in decrease in reactive oxygen species, could account for its neuroprotective efficacy. It can also prevent neuronal death as a result of stroke, thus decreasing anatomical and functional stroke damage. Although there are diverse studies that have investigated the mechanisms involved in the efficacy of ginseng in treating disorders, there is still much that needs to be clarified. Both in vitro and in vivo studies including randomized controlled clinical trials are necessary to develop in-depth knowledge of ginseng and its practical applications.

Ginsenoside Rb3 attenuates oxidative stress and preserves endothelial function in renal arteries from hypertensive rats

BACKGROUND AND PURPOSE

Panax ginseng is commonly used to treat cardiovascular conditions in Oriental countries. This study investigated the mechanisms underlying the vascular benefits of ginsenoside Rb3 (Rb3) in hypertension.

EXPERIMENTAL APPROACH

Rings of renal arteries were prepared from spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats and were cultured ex vivo for 8 h. Contractile responses of the rings were assessed with myograph techniques. Expression of NADPH oxidases was assessed by Western blotting and immunohistochemistry. Reactive oxygen species (ROS) were measured using dihydroethidium fluorescence imaging and production of NO was determined using the fluorescent NO indicator DAF-FM diacetate in human umbilical vein endothelial cells.

KEY RESULTS

Ex vivo treatment with Rb3 concentration-dependently augmented endothelium-dependent relaxations, suppressed endothelium-dependent contractions and reduced ROS production and expressions of NOX-2, NOX-4 and p67(phox) in arterial rings from SHR. Rb3 treatment also normalized angiotensin II (Ang II)-stimulated elevation in ROS and expression of NOX-2 and NOX-4 in arterial rings from WKY rats. Rb3 inhibited Ang II-induced reduction of NO production and phosphorylation of endothelial NOS in cultures of human umbilical vein endothelial cells. Rb3 also inhibited oxidative stress in renal arterial rings from hypertensive patients or in Ang II-treated arterial rings from normotensive subjects.

CONCLUSION AND IMPLICATIONS

Ex vivo Rb3 treatment restored impaired endothelial function in arterial rings from hypertensives by reversing over-expression of NADPH oxidases and over-production of ROS, and improved NO bioavailability. Our findings suggest that medicinal plants containing Rb3 could decrease oxidative stress and protect endothelial function in hypertension.

Efficacy and Safety of Panax notoginseng Saponin Therapy for Acute Intracerebral Hemorrhage, Meta-Analysis, and Mini Review of Potential Mechanisms of Action

Intracranial/intracerebral hemorrhage (ICH) is a leading cause of death and disability in people with traumatic brain injury (TBI) and stroke. No proven drug is available for ICH. Panax notoginseng (total saponin extraction, PNS) is one of the most valuable herb medicines for stroke and cerebralvascular disorders in China. We searched for randomized controlled clinical trials (RCTs) involving PNS injection to treat cerebral hemorrhage for meta-analysis from various databases including the Chinese Stroke Trials Register, the trials register of the Cochrane Complementary Medicine Field, the Cochrane Central Register of Controlled Trials, MEDLINE, Chinese BioMedical disk, and China Doctorate/Master Dissertations Databases. The quality of the eligible trials was assessed by Jadad’s scale. Twenty (20) of the 24 identified randomized controlled trials matched the inclusive criteria including 984 ICH patients with PNS injection and 907 ICH patients with current treatment (CT). Compared to the CT groups, PNS-treated patients showed better outcomes in the effectiveness rate (ER), neurological deficit score, intracranial hematoma volume, intracerebral edema volume, Barthel index, the number of patients died, and incidence of adverse events. Conclusion: PNS injection is superior to CT for acute ICH. A review of the literature shows that PNS may exert multiple protective mechanisms against ICH-induced brain damage including hemostasis, anti-coagulation, anti-thromboembolism, cerebral vasodilation, invigorated blood dynamics, anti-inflammation, antioxidation, and anti-hyperglycemic effects. Since vitamin C and other brain cell activators (BCA) that are not considered common practice were also used as parts of the CT in several trials, potential PNS and BCA interactions could exist that may have made the effect of PNS therapy less or more impressive than by PNS therapy alone. Future PNS trials with and without the inclusion of such controversial BCAs as part of the CT could clarify the situation. As PNS has a long clinical track record in Asia, it could potentially become a therapy option to treat ICH in the US and Europe. Further clinical trials with better experimental design could determine the long-term effects of PNS treatment for TBI and stroke.

Melatonin prevents cell death and mitochondrial dysfunction via a SIRT1-dependent mechanism during ischemic-stroke in mice

Silent information regulator 1 (SIRT1), a type of histone deacetylase, is a highly effective therapeutic target for protection against ischemia reperfusion (IR) injury (IRI). Previous studies showed that melatonin preserves SIRT1 expression in neuronal cells of newborn rats after hypoxia-ischemia. However, the definite role of SIRT1 in the protective effect of melatonin against cerebral IRI in adult has not been explored. In this study, the brain of adult mice was subjected to IRI. Prior to this procedure, the mice were given intraperitoneal with or without the SIRT1 inhibitor, EX527. Melatonin conferred a cerebral-protective effect, as shown by reduced infarct volume, lowered brain edema, and increased neurological scores. The melatonin-induced upregulation of SIRT1 was also associated with an increase in the anti-apoptotic factor, Bcl2, and a reduction in the pro-apoptotic factor Bax. Moreover, melatonin resulted in a well-preserved mitochondrial membrane potential, mitochondrial Complex I activity, and mitochondrial cytochrome c level while it reduced cytosolic cytochrome c level. However, the melatonin-elevated mitochondrial function was reversed by EX527 treatment. In summary, our results demonstrate that melatonin treatment attenuates cerebral IRI by reducing IR-induced mitochondrial dysfunction through the activation of SIRT1 signaling.

Neuroprotective mechanism of BNG-1 against focal cerebral ischemia: a neuroimaging and neurotrophin study

BNG-1 is a herb complex used in traditional Chinese medicine to treat stroke. In this study, we attempted to identify the neuroprotective mechanism of BNG-1 by using neuroimaging and neurotrophin analyses of a stroke animal model. Rats were treated with either saline or BNG-1 for 7 d after 60-min middle cerebral artery occlusion by filament model. The temporal change of magnetic resonance (MR) imaging of brain was studied using a 7 Tesla MR imaging (MRI) system and the temporal expressions of neurotrophin-3 (NT-3), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) in brain were analyzed before operation and at 4 h, 2 d, and 7 d after operation. Compared with the saline group, the BNG-1 group exhibited a smaller infarction volume in the cerebral cortex in T2 image from as early as 4 h to 7 d, less edema in the cortex in diffusion weighted image from 2 to 7 d, earlier reduction of postischemic hyperperfusion in both the cortex and striatum in perfusion image at 4 h, and earlier normalization of the ischemic pattern in the striatum in susceptibility weighted image at 2 d. NT-3 and BDNF levels were higher in the BNG-1 group than the saline group at 7 d. We concluded that the protective effect of BNG-1 against cerebral ischemic injury might act through improving cerebral hemodynamics and recovering neurotrophin generation.

Neuroprotection by saponins

Saponins, an important group of bioactive plant natural products, are glycosides of triterpenoid or steroidal aglycones. Their diverse biological activities are ascribed to their different structures. Saponins have long been recognized as key ingredients in traditional Chinese medicine. Accumulated evidence suggests that saponins have significant neuroprotective effects on attenuation of central nervous system disorders, such as stroke, Alzheimer's disease, Parkinson's disease, and Huntington's disease. However, our understanding of the mechanisms underlying the observed effects remains incomplete. Based on recently reported data from basic and clinical studies, this review highlights the proposed mechanisms of their neuroprotective function including antioxidant, modulation of neurotransmitters, anti-apoptosis, anti-inflammation, attenuating Ca(2+) influx, modulating neurotrophic factors, inhibiting tau phosphorylation, and regeneration of neural networks.

Core bioactive components promoting blood circulation in the traditional Chinese medicine compound xueshuantong capsule (CXC) based on the relevance analysis between chemical HPLC fingerprint and in vivo biological effects

Compound xueshuantong capsule (CXC) is an oral traditional Chinese herbal formula (CHF) comprised of Panax notoginseng (PN), Radix astragali (RA), Salvia miltiorrhizae (SM), and Radix scrophulariaceae (RS). The present investigation was designed to explore the core bioactive components promoting blood circulation in CXC using high-performance liquid chromatography (HPLC) and animal studies. CXC samples were prepared with different proportions of the 4 herbs according to a four-factor, nine-level uniform design. CXC samples were assessed with HPLC, which identified 21 components. For the animal experiments, rats were soaked in ice water during the time interval between two adrenaline hydrochloride injections to reduce blood circulation. We assessed whole-blood viscosity (WBV), erythrocyte aggregation and red corpuscle electrophoresis indices (EAI and RCEI, respectively), plasma viscosity (PV), maximum platelet aggregation rate (MPAR), activated partial thromboplastin time (APTT), and prothrombin time (PT). Based on the hypothesis that CXC sample effects varied with differences in components, we performed grey relational analysis (GRA), principal component analysis (PCA), ridge regression (RR), and radial basis function (RBF) to evaluate the contribution of each identified component. Our results indicate that panaxytriol, ginsenoside Rb₁, angoroside C, protocatechualdehyde, ginsenoside Rd, and calycosin-7-O-β-D-glucoside are the core bioactive components, and that they might play different roles in the alleviation of circulation dysfunction. Panaxytriol and ginsenoside Rb₁ had close relevance to red blood cell (RBC) aggregation, angoroside C was related to platelet aggregation, protocatechualdehyde was involved in intrinsic clotting activity, ginsenoside Rd affected RBC deformability and plasma proteins, and calycosin-7-O-β-D-glucoside influenced extrinsic clotting activity. This study indicates that angoroside C, calycosin-7-O-β-D-glucoside, panaxytriol, and protocatechualdehyde may have novel therapeutic uses.

Ginsenoside Rd inhibits apoptosis following spinal cord ischemia/reperfusion injury

Ginsenoside Rd has a clear neuroprotective effect against ischemic stroke. We aimed to verify the neuroprotective effect of ginsenoside Rd in spinal cord ischemia/reperfusion injury and explore its anti-apoptotic mechanisms. We established a spinal cord ischemia/reperfusion injury model in rats through the occlusion of the abdominal aorta below the level of the renal artery for 1 hour. Successfully established models were injected intraperitoneally with 6.25, 12.5, 25 or 50 mg/kg per day ginsenoside Rd. Spinal cord morphology was observed at 1, 3, 5 and 7 days after spinal cord ischemia/reperfusion injury. Intraperitoneal injection of ginsenoside Rd in ischemia/reperfusion injury rats not only improved hindlimb motor function and the morphology of motor neurons in the anterior horn of the spinal cord, but it also reduced neuronal apoptosis. The optimal dose of ginsenoside Rd was 25 mg/kg per day and the optimal time point was 5 days after ischemia/reperfusion. Immunohistochemistry and western blot analysis showed ginsenoside Rd dose-dependently inhibited expression of pro-apoptotic Caspase 3 and down-regulated the expression of the apoptotic proteins ASK1 and JNK in the spinal cord of rats with spinal cord ischemia/reperfusion injury. These findings indicate that ginsenoside Rd exerts neuroprotective effects against spinal cord ischemia/reperfusion injury and the underlying mechanisms are achieved through the inhibition of ASK1-JNK pathway and the down-regulation of Caspase 3 expression.

Subanesthetic isoflurane reduces zymosan-induced inflammation in murine Kupffer cells by inhibiting ROS-activated p38 MAPK/NF-κB signaling

Volatile anesthetic isoflurane (ISO) has immunomodulatory effects. The fungal component zymosan (ZY) induces inflammation through toll-like receptor 2 or dectin-1 signaling. We investigated the molecular actions of subanesthetic (0.7%) ISO against ZY-induced inflammatory activation in murine Kupffer cells (KCs), which are known as the resident macrophages within the liver. We observed that ISO reduced ZY-induced cyclooxygenase 2 upregulation and prostaglandin E₂ release, as determined by western blot and radioimmunoassay, respectively. ISO also reduced the production of tumor necrosis factor-α, interleukin-1β, IL-6, high-mobility group box-1, macrophage inflammatory protein-1α, macrophage inflammatory protein-2, and monocyte chemoattractant protein-1 as assessed by enzyme-linked immunosorbent assays. ISO blocked the ZY-induced nuclear translocation and DNA-binding activity of nuclear factor- (NF)-κB p65. Moreover, ISO attenuated ZY-induced p38 mitogen-activated protein kinase (MAPK) activation partly by scavenging reactive oxygen species (ROS); the interregulation that ROS activated p38 MAPK followed by NF-κB activation was crucial for the ZY-induced inflammatory responses in KCs. An in vivo study by peritoneal injection of ZY into BALB/C mice confirmed the anti-inflammatory properties of 0.7% ISO against ZY in KCs. These results suggest that ISO ameliorates ZY-induced inflammatory responses in murine KCs by inhibiting the interconnected ROS/p38 MAPK/NF-κB signaling pathways.

Ginsenoside Rg1 provides neuroprotection against blood brain barrier disruption and neurological injury in a rat model of cerebral ischemia/reperfusion through downregulation of aquaporin 4 expression

Ginsenoside Rg1 is regarded as one of main bioactive compounds responsible for pharmaceutical actions of ginseng with little toxicity and has been shown to have possibly neuroprotective effects. However, the mechanism of its neuroprotection for acute ischemic stroke is still elusive. The purpose of present study is thus to assess the neuroprotective effects of the ginsenoside Rg1 against blood brain barrier disruption and neurological injury in a rat model of cerebral ischemia/reperfusion, and then to explore the mechanisms for these neuroprotective effects by targeting aquaporin 4. Focal cerebral ischemia was induced by middle cerebral artery occlusion. Neurological examinations were performed by using Longa's 5-point scale. Evans blue dye was used to investigate the effects of ginsenoside Rg1 on blood brain barrier permeability. Immunohistochemical analysis and real-time fluorescence quantitative polymerase chain reaction were used to assess aquaporin 4 expression. As a result, general linear model with repeated measures analysis of variance for neurological scores at 5 repeated measures showed that ginsenoside Rg1-treated group could significantly reduce the changing trend of neurological deficit scores when compared with the middle cerebral artery occlusion model group (p<0.05). Compared with the middle cerebral artery occlusion model group, ginsenoside Rg1 group has significantly decreased Evans blue content and reduced aquaporin 4 expression at each time point (p<0.05). In conclusion, ginsenoside Rg1 as a ginsenoside neuroprotective agent could improve neurological injury, attenuate blood brain barrier disruption and downregulate aquaporin 4 expression induced by cerebral ischemia/reperfusion insults in rats.

Ginsenoside Rd attenuates mitochondrial permeability transition and cytochrome C release in isolated spinal cord mitochondria: involvement of kinase-mediated pathways

Ginsenoside Rd (Rd), one of the main active ingredients in Panax ginseng, has multifunctional activity via different mechanisms and neuroprotective effects that are exerted probably via its antioxidant or free radical scavenger action. However, the effects of Rd on spinal cord mitochondrial dysfunction and underlying mechanisms are still obscure. In this study, we sought to investigate the in vitro effects of Rd on mitochondrial integrity and redox balance in isolated spinal cord mitochondria. We verified that Ca²⁺ dissipated the membrane potential, provoked mitochondrial swelling and decreased NAD(P)H matrix content, which were all attenuated by Rd pretreatment in a dose-dependent manner. In contrast, Rd was not able to inhibit Ca²⁺ induced mitochondrial hydrogen peroxide generation. The results of Western blot showed that Rd significantly increased the expression of p-Akt and p-ERK, but had no effects on phosphorylation of PKC and p38. In addition, Rd treatment significantly attenuated Ca²⁺ induced cytochrome c release, which was partly reversed by antagonists of Akt and ERK, but not p-38 inhibitor. The effects of bisindolylmaleimide, a PKC inhibitor, on Rd-induced inhibition of cytochrome c release seem to be at the level of its own detrimental activity on mitochondrial function. Furthermore, we also found that pretreatment with Rd in vivo (10 and 50 mg/kg) protected spinal cord mitochondria against Ca²⁺ induced mitochondrial membrane potential dissipation and cytochrome c release. It is concluded that Rd regulate mitochondrial permeability transition pore formation and cytochrome c release through protein kinases dependent mechanism involving activation of intramitochondrial Akt and ERK pathways.

Identification of the metabolites of myricitrin produced by human intestinal bacteria in vitro using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry

OBJECTIVE

To investigate the metabolic routes and metabolites of myricitrin, an important active ingredient of traditional herbal medicine, yielded by the isolated human intestinal bacteria, which have not been reported previously.

METHODS

Fresh human fecal samples were collected from a healthy female volunteer and about 100 different bacterial colonies were isolated. Ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry technique combined with Metabolynx™ software was used for analysis of the metabolic profile of myricitrin by the isolated human intestinal bacteria.

RESULTS

One hundred different bacterial colonies, which developed on plates, were picked up, and four of them were further identified by using the technique of 16S rRNA gene sequencing due to their relatively strong metabolic capacity toward myricitrin. Most of them belong to Escherichia. Parent compound and three metabolites (quercetin-3-O-rhamnoside, myricetin and quercetin) were detected in the isolated bacterial samples compared with blank samples. The metabolic pathways of myricitrin included deglycosylation and dehydroxylation.

CONCLUSIONS

These metabolites suggested that myricitrin was first dehydroxylated to quercetin-3-O-rhamnoside and subsequently deglycosylated to quercetin. Additionally, myricitrin could also be deglycosylated to the aglycon myricetin. Moreover, those metabolites might influence the biological effect of myricitrin in vivo, which led to affect the clinical effects of the medicinal plants and traditional herb medicines.

Herbal medicines for ischemic stroke: combating inflammation as therapeutic targets

Stroke is a debilitating disease for which limited therapeutic approaches are available currently. Thus, there is an urgent need for developing novel therapies for stroke. Astrocytes, endothelial cells and pericytes constitute a neurovascular network for metabolic requirement of neurons. During ischemic stroke, these cells contribute to post-ischemic inflammation at multiple stages of ischemic cascades. Upon ischemia onset, activated resident microglia and astrocytes, and infiltrated immune cells release multiple inflammation factors including cytokines, chemokines, enzymes, free radicals and other small molecules, not only inducing brain damage but affecting brain repair. Recent progress indicates that anti-inflammation is an important therapeutic strategy for stroke. Given a long history with direct experience in the treatment of human subjects, Traditional Chinese Medicine and its related natural compounds are recognized as important sources for drug discovery. Last decade, a great progress has been made to identify active compounds from herbal medicines with the properties of modulating post-ischemic inflammation for neuroprotection. Herein, we discuss the inflammatory pathway in early stage and secondary response to injured tissues after stroke from initial artery occlusion to brain repair, and review the active ingredients from natural products with anti-inflammation and neuroprotection effects as therapeutic agents for ischemic stroke. Further studies on the post-ischemic inflammatory mechanisms and corresponding drug candidates from herbal medicine may lead to the development of novel therapeutic strategies in stroke treatment.

Ginsenoside Rd for acute ischemic stroke: translating from bench to bedside

Numerous studies have identified pathophysiological mechanisms of acute ischemic stroke and have provided proof-of-principle evidence that strategies designed to impede the ischemic cascade, namely neuroprotection, can protect the ischemic brain. However, the translation of these therapeutic agents to the clinic has not been successful. Ginsenoside Rd, a dammarane-type steroid glycoside extracted from ginseng plants, has exhibited an encouraging neuroprotective efficacy in both laboratory and clinical studies. This article attempts to provide a synopsis of the physiochemical profile, pharmacokinetics, pharmacodynamics, clinical efficacy, safety and putative therapeutic mechanisms of Rd. Finally, the authors discuss the validity of Rd as a neuroprotective agent for acute ischemic stroke.

A subanesthetic dose of isoflurane during postconditioning ameliorates zymosan-induced neutrophil inflammation lung injury and mortality in mice

Anesthetic isoflurane (ISO) has immunomodulatory effects. In the present study, we investigated whether a subanesthetic dose of ISO (0.7%) protected against zymosan (ZY) induced inflammatory responses in the murine lung and isolated neutrophils. At 1 and 6 hrs after ZY administration intraperitoneally, ISO was inhaled for 1 hr, and 24 hrs later, lung inflammation and injury were assessed. We found that ISO improved the survival rate of mice and mitigated lung injury as characterized by the histopathology, wet-to-dry weight ratio, protein leakage, and lung function index. ISO significantly attenuated ZY-induced lung neutrophil recruitment and inflammation. This was suggested by the downregulation of (a) endothelial adhesion molecule expression and myeloperoxidase (MPO) activity in lung tissue and polymorphonuclear neutrophils (b) chemokines, and (c) proinflammatory cytokines in BALF. Furthermore, ZY-induced nuclear translocation and DNA-binding activity of NF- κ B p65 were also reduced by ISO. ISO treatment inhibited iNOS expression and activity, as well as subsequent nitric oxide generation. Consistent with these in vivo observations, in vitro studies confirmed that ISO blocked NF- κ B and iNOS activation in primary mouse neutrophils challenged by ZY. These results provide evidence that 0.7% ISO ameliorates inflammatory responses in ZY-treated mouse lung and primary neutrophils.

Biotransformation of ginsenoside Rb1 via the gypenoside pathway by human gut bacteria

Background

Bacterial conversion of ginsenosides is crucial for the health-promoting effects of ginsenosides. Previous studies on the biotransformation of ginsenoside Rb1 (Rb1) by gut bacteria have focused on the ginsenoside Rd (Rd) pathway (Rb1 → Rd → ginsenoside F2 (F2) → compound K (Cpd K)). This study aims to examine the gypenoside pathway in human gut bacteria in vitro.

Methods

The metabolic pathways of ginsenoside Rb1 and its metabolites ginsenoside Rd and gypenoside XVII in human gut bacteria were investigated by incubating the compounds anaerobically with pooled or individual gut bacteria samples from healthy volunteers. Ginsenoside Rb1, the metabolites generated by human gut bacteria, and degraded products in simulated gastric fluid (SGF) were qualitatively analyzed using an LC/MSD Trap system in the negative ion mode and quantitatively determined by HPLC-UV analysis.

Results

When incubated anaerobically with pooled gut bacteria, Rb1 generated five metabolites, namely Rd, F2, Cpd K, and the rare gypenosides XVII (G-XVII) and LXXV (G-LXXV). The gypenoside pathway (Rb1 → G-XVII → G-LXXV → Cpd K) was rapid, intermediate, and minor, and finally converted Rb1 to Cpd K via G-XVII → F2 (major)/G-LXXV (minor). Both the Rd and gypenoside pathways exhibited great inter-individual variations in age-and sex-independent manners (P > 0.05). Rb1 was highly acid-labile and degraded rapidly to form F2, ginsenoside Rg3, ginsenoside Rh2, and Cpd K, but did not generate the gypenosides in SGF. The formation of the gypenosides might be explained by the involvement of a gut bacteria-mediated enzymatic process.

Conclusions

Rb1 was metabolized to G-XVII, F2 (major) or G-LXXL (minor), and finally Cpd K by human gut bacteria in vitro.

Osthole attenuates spinal cord ischemia-reperfusion injury through mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction in rats

BACKGROUND

Osthole, the main bioactive compounds isolated from the traditional Chinese medical herb broad Cnidium monnieri (L.) cusson, has been shown to exert spectrum of pharmacologic activities. The aim of this study was to investigate the potential neuroprotective effects of osthole against spinal cord ischemia-reperfusion injury in rats.

MATERIALS AND METHODS

Osthole was administrated at the concentration of 0.1, 1, 10, 50, or 200 mg/kg (intraperitoneally) 1 h before spinal cord ischemia. The effects on spinal cord injury were measured by spinal cord water content, infarct volume, hematoxylin and eosin staining, and neurologic assessment. Mitochondria were purified from injured spinal cord tissue to determine mitochondrial function.

RESULTS

We found that treatment with osthole (10 and 50 mg/kg) significantly decreased spinal cord water content and infarct volume, preserved normal motor neurons, and improved neurologic functions. These protective effects can be also observed even if the treatment was delayed to 4 h after reperfusion. Osthole treatment preserved mitochondrial membrane potential level, reduced reactive oxygen species production, increased adenosine triphosphate generation, and inhibited cytochrome c release in mitochondrial samples. Moreover, osthole increased mitochondria respiratory chain complex activities in spinal cord tissue, with no effect on mitochondrial DNA content and the expression of mitochondrial-specific transcription factors.

CONCLUSIONS

All these findings demonstrate the neuroprotective effect of osthole in spinal cord ischemia-reperfusion injury model and suggest that oshtole-induced neuroprotection was mediated by mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction.

A comprehensive review of the therapeutic and pharmacological effects of ginseng and ginsenosides in central nervous system

Ginseng is one of the most widely used herbal medicines in human. Central nervous system (CNS) diseases are most widely investigated diseases among all others in respect to the ginseng’s therapeutic effects. These include Alzheimer’s disease, Parkinson’s disease, cerebral ischemia, depression, and many other neurological disorders including neurodevelopmental disorders. Not only the various types of diseases but also the diverse array of target pathways or molecules ginseng exerts its effect on. These range, for example, from neuroprotection to the regulation of synaptic plasticity and from regulation of neuroinflammatory processes to the regulation of neurotransmitter release, too many to mention. In general, ginseng and even a single compound of ginsenoside produce its effects on multiple sites of action, which make it an ideal candidate to develop multi-target drugs. This is most important in CNS diseases where multiple of etiological and pathological targets working together to regulate the final pathophysiology of diseases. In this review, we tried to provide comprehensive information on the pharmacological and therapeutic effects of ginseng and ginsenosides on neurodegenerative and other neurological diseases. Side by side comparison of the therapeutic effects in various neurological disorders may widen our understanding of the therapeutic potential of ginseng in CNS diseases and the possibility to develop not only symptomatic drugs but also disease modifying reagents based on ginseng.

Ginsenoside Rd attenuates beta-amyloid-induced tau phosphorylation by altering the functional balance of glycogen synthase kinase 3beta and protein phosphatase 2A

Neurofibrillary tangles are aggregates of hyperphosphorylated tau that are one of the pathological hallmarks of Alzheimer's disease (AD). Tau phosphorylation is regulated by a balance of kinase and phosphatase activities. Our previous study has demonstrated that ginsenoside Rd, one of the principal active ingredients of Pana notoginseng, inhibits okadaic acid-induced tau phosphorylation in vivo and in vitro, but the underlying mechanism(s) is unknown. In this study, we showed that ginsenoside Rd pretreatment inhibited tau phosphorylation at multiple sites in beta-amyloid (Aβ)-treated cultured cortical neurons, and in vivo in both a rat and transgenic mouse model. Ginsenoside Rd not only reduced Aβ-induced increased expression of glycogen synthase kinase 3beta (GSK-3β), the most important kinase involved in tau phosphorylation, but also inhibited its activity by enhancing and attenuating its phosphorylation at Ser9 and Tyr216, respectively. Moreover, ginsenoside Rd enhanced the activity of protein phosphatase 2A (PP-2A), a key phosphatase involved in tau dephosphorylation. Finally, an in vitro biochemical assay revealed that ginsenoside Rd directly affected GSK-3β and PP-2A activities. Thus, our findings provide the first evidence that ginsenoside Rd attenuates Aβ-induced pathological tau phosphorylation by altering the functional balance of GSK-3β and PP-2A.

Sevoflurane preconditioning improves mitochondrial function and long-term neurologic sequelae after transient cerebral ischemia: role of mitochondrial permeability transition

OBJECTIVE

Anesthetic preconditioning appears to be a viable strategy to treat ischemic cerebral injury. Here we investigated 1) whether the protection conferred by sevoflurane preconditioning sustains in time; 2) whether sevoflurane preconditioning diminishes mitochondrial dysfunction following cerebral ischemia; and 3) whether mitochondrial permeability transition pore plays a crucial role in the sevoflurane preconditioning.

DESIGN

Laboratory investigation.

SETTING

University research laboratory.

SUBJECTS

: Sprague-Dawley rats.

INTERVENTIONS

Rats underwent 2 hrs of focal cerebral ischemia induced by middle cerebral artery occlusion. Preconditioning was elicited with sevoflurane (2.3%) for 60 mins at 24 hrs before ischemia. The involvement of mitochondrial permeability transition pore was determined with a mitochondrial permeability transition pore opener atractyloside and a specific mitochondrial permeability transition pore inhibitor cyclosporin A. In vitro study was performed on acutely isolated mitochondria subjected to calcium overload.

MEASUREMENTS AND MAIN RESULTS

Sevoflurane preconditioning significantly decreased the infarct size by 35.9% (95% confidence interval 6.5-28.4, p < .001). This reduction of injury volume was associated with a long-term improvement of neurological function according to modified neurological severity score (F = 13.6, p = .001) and sticky-tape test (F = 29.1, p < .001) for 42 days after ischemia. Furthermore, sevoflurane preconditioning markedly protected mitochondria, as indicated by preserved respiratory chain complex activities and membrane potential, lowered mitochondrial hydrogen-peroxide production, and attenuated mitochondrial permeability transition pore opening. Isolated mitochondria also demonstrated a reduced sensitivity to Ca-induced mitochondrial permeability transition pore opening after pre-exposure to sevoflurane in vitro (95% confidence interval 24.2-196.5,p = .006). Inhibiting mitochondrial permeability transition pore using cyclosporin A resulted in protective effects similar to those seen with sevoflurane preconditioning, whereas pharmacologically opening the mitochondrial permeability transition pore with atractyloside abrogated all the positive effects of sevoflurane preconditioning and cyclosporin A, including suppression of mitochondrial permeability transition pore opening, counteraction of mitochondria-dependent apoptotic pathway, and subsequent histological and behavioral improvements.

CONCLUSIONS

Sevoflurane preconditioning protects mitochondria from cerebral ischemia/reperfusion injury and ameliorates long-term neurological deficits. Inhibition of mitochondrial permeability transition pore opening is a crucial step in mediating the neuroprotection of sevoflurane preconditioning.

Ginsenoside Rd maintains adult neural stem cell proliferation during lead-impaired neurogenesis

Lead exposure attracts a great deal of public attention due to its harmful effects on human health. Even low-level lead (Pb) exposure reduces the capacity for neurogenesis. It is well known that microglia-mediated neurotoxicity can impair neurogenesis. Despite this, few in vivo studies have been conducted to understand the relationship between acute Pb exposure and microglial activation. We investigated whether the acute Pb exposure altered the expression of a marker of activated microglial cells (Iba-1), and markers of neurogenesis (BrdU and doublecortin) in aging rats. As compared to controls, Pb exposure significantly enhanced the expression of Iba-1 immunoreactivity; increased the expression levels of IL-1β, IL-6, and TNF-α and decreased the numbers of BrdU(+) and doublecortin(+) cells. Our prior work demonstrated that ginsenoside Rd (Rd), one of the major active ingredients in Panax ginseng, was neuroprotective in a variety of paradigms involving anti-inflammatory mechanisms. Thus, we further examined whether Rd could attenuate Pb-induced phenotypes. Compared with the Pb exposure group, Rd pretreatment indeed attenuated the effects of Pb exposure. These results suggest that Rd may be neuroprotective in old rats following acute Pb exposure, which involves limitation of microglial activation and maintenance of NSC proliferation.

Current therapies in ischemic stroke. Part B. Future candidates in stroke therapy and experimental studies

Stroke still remains a major healthcare problem. The growing understanding of the mechanism of cell death in ischemia leads to new approaches in stroke treatment. The aim of neuroprotection is to reduce the post-stroke impairment and the overall costs that are accompanied in patients with severe disability. Despite encouraging data from experimental animal models, almost all neuroprotective therapies have, to date, not been established in clinical routine. In this part B of our review on stroke therapies we provide an overview on future candidates in stroke therapy and neuroprotective agents that are under investigation.

Ginsenoside-Rd improves outcome of acute ischaemic stroke - a randomized, double-blind, placebo-controlled, multicenter trial

BACKGROUND AND PURPOSE

 Ginsenoside-Rd is a receptor-operated calcium channel antagonist and has shown promise as a neuroprotectant in our phase II study. As an extended work, we sought to confirm its efficacy and safety of Ginsenoside-Rd in patients with acute ischaemic stroke.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial involving 390 patients with acute ischaemic stroke in a 3:1 ratio to receive a 14-day intravenous infusion of Ginsenoside-Rd or placebo within 72 h after the onset of stroke. Our primary end-point was the distribution of disability scores on the modified Rankin scale (mRs) at 90 days.

RESULTS

  The efficacy analysis was based on 386 patients (Ginsenoside-Rd group: 290; placebo group: 96). Ginsenoside-Rd significantly improved the overall distribution of scores on the mRs, as compared with the placebo (P = 0.02; odds ratios [OR], 1.74; 95% confidence interval [CI], 1.08-2.78). There were significant differences between the two groups when we categorized the scores into 0-1 vs. 2-5 (P = 0.01; OR, 2.32; 95% CI, 1.23-4.38; 66.8% vs. 53.1%). It also improved the National Institutes of Health Stroke Scale (NIHSS) at 15 days [P < 0.01; least squares mean (LSM), -0.77; 95% CI, -1.31 to -0.24]. Mortality and rates of adverse events were similar in the two groups.

CONCLUSIONS

  Ginsenoside-Rd improved the primary outcome of acute ischaemic stroke and had an acceptable adverse-event profile.

Stuck at the bench: Potential natural neuroprotective compounds for concussion

Background:

While numerous laboratory studies have searched for neuroprotective treatment approaches to traumatic brain injury, no therapies have successfully translated from the bench to the bedside. Concussion is a unique form of brain injury, in that the current mainstay of treatment focuses on both physical and cognitive rest. Treatments for concussion are lacking. The concept of neuro-prophylactic compounds or supplements is also an intriguing one, especially as we are learning more about the relationship of numerous sub-concussive blows and/or repetitive concussive impacts and the development of chronic neurodegenerative disease. The use of dietary supplements and herbal remedies has become more common place.

Methods:

A literature search was conducted with the objective of identifying and reviewing the pre-clinical and clinical studies investigating the neuroprotective properties of a few of the more widely known compounds and supplements.

Results:

There are an abundance of pre-clinical studies demonstrating the neuroprotective properties of a variety of these compounds and we review some of those here. While there are an increasing number of well-designed studies investigating the therapeutic potential of these nutraceutical preparations, the clinical evidence is still fairly thin.

Conclusion:

There are encouraging results from laboratory studies demonstrating the multi-mechanistic neuroprotective properties of many naturally occurring compounds. Similarly, there are some intriguing clinical observational studies that potentially suggest both acute and chronic neuroprotective effects. Thus, there is a need for future trials exploring the potential therapeutic benefits of these compounds in the treatment of traumatic brain injury, particularly concussion.