Neuroprotective effects of ginsenoside Rb1 on transient cerebral ischemia in rats

Ginsenosides from American ginseng: chemical and pharmacological diversity

Ginseng occupies a prominent position in the list of best-selling natural products in the world. Compared to the long history of use and widespread research on Asian ginseng, the study of American ginseng is relatively limited. In the past decade, some promising advances have been achieved in understanding the chemistry, pharmacology and structure-function relationship of American ginseng. To date, there is no systematic review of American ginseng. In this review, the different structures of the ginsenosides in American ginseng are described, including naturally occurring compounds and those resulting from steaming or biotransformation. Preclinical and clinical studies published in the past decade are also discussed. Highlighted are the chemical and pharmacological diversity and potential structural-activity relationship of ginsenosides. The goal is that this article is a useful reference to chemists and biologists researching American ginseng, and will open the door to agents in drug discovery.

Rb1 postconditioning attenuates liver warm ischemia-reperfusion injury through ROS-NO-HIF pathway

AIMS

Ginsenoside Rb1 could prevent ischemic neuronal death and focal cerebral ischemia, but its roles to liver warm I/R injury remain to be defined. We determined if Rb1 would attenuate warm I/R injury in mice.

MAIN METHODS

Mice were divided into sham, I/R, Rb1+I/R (Rb1 postconditioning, 20mg/kg, i.p. after ischemia), sham+L-NAME, I/R+L-NAME, and Rb1+I/R+L-NAME groups using 60min of the liver median and left lateral lobes ischemia. Serum levels of alanine aminotransferase (ALT) were measured and morphology changes of livers were evaluated. Contents of nitric oxide (NO) and nitric oxide synthase (NOS), malondialdehye (MDA) and activity of superoxide dismutase (SOD) were measured. Expressions of Akt, p-Akt, iNOS, HIF-1alpha, tumor necrosis factor-a (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) were also determined by western blot or immunohistochemistry.

KEY FINDINGS

Rb1 postconditioning attenuated the dramatically functional and morphological injuries. The levels of ALT were significantly reduced in Rb1 group (p<0.05). Rb1 upregulated the concentrations of NO, iNOS in serum, iNOS, and activity of SOD in hepatic tissues (p<0.05), while it dramatically reduced the concentration of MDA (p<0.05). Protein expressions of p-Akt, iNOS and HIF-1alpha were markedly enhanced in Rb1 group. Protein and mRNA expressions of TNF-α and ICAM-1 were markedly suppressed by Rb1 (p<0.05).

SIGNIFICANCE

We found that Rb1 postconditioning could protect liver from I/R injury by upregulating the content of NO and NOS, and also HIF-1alpha protein expression. These protective effects could be abolished by L-NAME. These findings suggested Rb1 may have the therapeutic potential through ROS-NO-HIF pathway for management of liver warm I/R injury.

Active ingredients in Chinese medicines promoting blood circulation as Na+/K+ -ATPase inhibitors

The positive inotropic effect of cardiac glycosides lies in their reversible inhibition on the membrane-bound Na(+)/K(+)-ATPase in human myocardium. Steroid-like compounds containing a core structure similar to cardiac glycosides are found in many Chinese medicines conventionally used for promoting blood circulation. Some of them are demonstrated to be Na(+)/K(+)-ATPase inhibitors and thus putatively responsible for their therapeutic effects via the same molecular mechanism as cardiac glycosides. On the other hand, magnesium lithospermate B of danshen is also proposed to exert its cardiac therapeutic effect by effectively inhibiting Na(+)/K(+)-ATPase. Theoretical modeling suggests that the number of hydrogen bonds and the strength of hydrophobic interaction between the effective ingredients of various medicines and residues around the binding pocket of Na(+)/K(+)-ATPase are crucial for the inhibitory potency of these active ingredients. Ginsenosides, the active ingredients in ginseng and sanqi, substantially inhibit Na(+)/K(+)-ATPase when sugar moieties are attached only to the C-3 position of their steroid-like structure, equivalent to the sugar position in cardiac glycosides. Their inhibitory potency is abolished, however, when sugar moieties are linked to C-6 or C-20 position of the steroid nucleus; presumably, these sugar attachments lead to steric hindrance for the entrance of ginsenosides into the binding pocket of Na(+)/K(+)-ATPase. Neuroprotective effects of cardiac glycosides, several steroid-like compounds, and magnesium lithospermate B against ischemic stroke have been accordingly observed in a cortical brain slice-based assay model, and cumulative data support that effective inhibitors of Na(+)/K(+)-ATPase in the brain could be potential drugs for the treatment of ischemic stroke.

Inactivation of GABA(A) receptor reduces ginsenoside Rb3 neuroprotection in mouse hippocampal slices after oxygen-glucose deprivation

AIM OF THE STUDY

To investigate the effect of ginsenoside Rb(3) on synaptic transmission after oxygen-glucose deprivation in vitro.

MATERIALS AND METHODS

The population spike (PS) was recorded in the stratum pyramidale of mouse hippocampal slices using extracellular recordings.

RESULTS

Ginsenoside Rb(3) depressed the basal synaptic transmission, which also promoted the recovery amplitude of PS after OGD in a concentration-dependent manner. The GABA(A) receptor agonist muscimol improved the recovery, which was similar to that of ginsenoside Rb(3). Moreover, the effect of ginsenoside Rb(3) in combination with muscimol was not additive. Treatment with the GABA(A) receptor antagonist bicuculline or picrotoxin, which prevented the depression of PS caused by ginsenoside Rb(3), also reduced the neuroprotection.

CONCLUSION

The results indicate that the activation of the GABA(A) receptor is correlated with the neuroprotective mechanisms of ginsenoside Rb(3).

Ginseng total saponins enhance neurogenesis after focal cerebral ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng, the root of Panax ginseng C.A. Meyer, is one of the most commonly used healing herbs for stroke and chronic debilitating conditions in China. Ginsenosides are the main active principles for ginseng's efficacy, but the mechanisms have not been fully clarified.

AIM OF THE STUDY

To test the hypothesis whether or not the administration of Ginseng total saponins (GTS) can enhance neurogenesis after focal cerebral ischemia, and thereby improve neurological deficits.

MATERIALS AND METHODS

Male Wistar rats received intraperitoneal injections of GTS dissolved at a dose of 25 mg kg(-1) d(-1) or normal saline (NS) of same volume 3 days before the permanent middle cerebral artery occlusion (MCAO) model establishment until the animals were killed at the time points of 1d, 3d, 7d and 14d. The neurological function was assessed blindly. BrdU immunostaining and double staining were performed by following the 3-steps method.

RESULTS

(A) GTS-treated rats have better neurological scores compared with those in NS group at 14d time point (p<0.05); (B) the number of BrdU(+) cells and BrdU(+)/NeuN(+) cells in GTS group were significantly higher than those in NS group in the ipsilateral subventricular zone and in the ipsilateral infarct area after MCAO, respectively (p<0.05 or p<0.01); (C) the increase of the number of BrdU(+)/NeuN(+) cells highly correlated with the decrease of neurological scores. Coefficient correlation r=-0.828 (p<0.01).

CONCLUSION

GTS can improve neurological deficits after focal cerebral ischemia by inducing endogenous neural stem cells activation and thereby enhance adult central nervous system regeneration.

Ginsenoside Rb1 improves spatial learning and memory by regulation of cell genesis in the hippocampal subregions of rats

Ginsenoside Rb1 (Rb1) is known to improve learning and memory in hippocampus-dependent tasks. However, the cellular mechanism remains unknown. Cell genesis in hippocampus is involved in spatial learning and memory. In the present study, Rb1 was orally administrated to adult rats for 30days. The behavioral training tests indicated that Rb1 improved spatial cognitive performance of rats in Morris water maze (MWM). Furthermore, we investigated the effects of Rb1 on cell genesis in adult rats' hippocampus, using thymidine analog bromodeoxyuridine (BrdU) as a marker for dividing cells. It has been shown that hippocampal cell genesis can be influenced by several factors such as learning and exercise. In order to avoid the effects of the interfering factors, only the rats treated with Rb1 without training in MWM were used to investigate cell genesis in hippocampus. When BrdU was given to the rats 30days prior to being killed, it was shown that oral administration of Rb1 significantly increased cell survival in dentate gyrus and hippocampal subregion CA3. However, when BrdU was injected 2h prior to sacrifice, the results indicated that Rb1 had no significant influence on cell proliferation in the hippocampal subregions. Thus, an increase of cell survival in hippocampus stimulated by Rb1 may be one of the mechanisms by which ginseng facilitates spatial learning and memory. Our study also indicates that Rb1 may be developed as a therapeutic agent for patients with memory impairment.

Treatment with ginsenoside rb1, a component of panax ginseng, provides neuroprotection in rats subjected to subarachnoid hemorrhage-induced brain injury

OBJECTIVE

recent trials have shown Ginsenoside Rb1 (GRb1), an active component of a well known Chinese medicine Panax Ginseng, plays a significant role in improving the complications seen after an ischemic brain event. In the present study, we investigated the use of GRb1 as a treatment modality to reduce brain edema, reduce arterial vasospasm, and improve neurobehavioral function after subarachnoid hemorrhage-induced brain injury (SAH) in rats.

METHOD

male Sprague-Dawley rats weighing between 250 and 300 g were randomly assigned to three groups: (1) Sham group (n = 10), (2) Vehicle group (SAH + no treatment; n = 12); (3) Treatment group (SAH + GRb1 treatment at 20 mg/kg; n = 11). Subarachnoid hemorrhage was induced using the modified double hemorrhage model followed by treatment administration intravenously. Post-operative assessment included neurobehavioral testing using the spontaneous activity scoring system, brain water content, and histological examination of the basilar artery.

RESULTS

post-operative findings indicated treatment with GRb1 had significantly reduced brain edema and improved neurobehavioral functioning. In addition, histological examination revealed a significant reduction in basilar artery vasospasm and lumen thickness with treatment.

CONCLUSION

the results of the study suggest that GRb1 treatment reduces brain edema, improves neurobehavioral function, and blocks vasculature thickening and spasm after SAH in rats. Given the novelty of the study, further research will be needed to confirm the benefits of treatment and mechanisms behind neuroprotection.

Ginsenosides and their CNS targets

Ginsenosides are a special group of triterpenoid saponins attributed to medical effects of ginseng. Therefore, they have been research targets over the last three decades to explain ginseng actions and a wealth of literature has been presented reporting on ginsenosides' effects on the human body. Recently, there is increasing evidence on beneficial effects of ginsenosides to the central nervous system (CNS). Using a wide range of in vitro and in vivo models, researchers have attributed these effects to specific pharmacological actions of ginsenosides on cerebral metabolism, oxidative stress and radical formation, neurotransmitter imbalance and membrane stabilizing effects, and even antiapoptotic effects. Modulating these particular mechanisms by ginsenosides has thus been reported to exert either general stimulatory effects on the brain functions or protecting the CNS against various disease conditions. In this review, we try to address the recently reported ginsenosides' actions on different CNS targets particularly those supporting possible therapeutic efficacies in CNS disorders and neurodegenerative diseases.

Ginsenoside Rb1 regulates the expressions of brain-derived neurotrophic factor and caspase-3 and induces neurogenesis in rats with experimental cerebral ischemia

AIM OF THE STUDY

Recent studies have revealed that ginsenoside Rb1 (GRb1) is neuroprotective for cerebral ischemia. However, the mechanism underlying of this function is unclear. We assessed whether this neuroprotective effect of GRb1 was mediated by the levels of brain-derived neurotrophic factor (BDNF), by the levels of caspase-3 proteins and by induced neurogenesis in rats following transient cerebral ischemia or not.

MATERIALS AND METHODS

Cerebral ischemia was prepared by a 2 h occlusion of the middle cerebral artery and reperfusion, followed by infusion of GRb1 (40 mg/kg) and saline (GRb1 and ischemia groups, respectively). All rats were sacrificed at 3 and 12 h, 1, 2, 3, 5, and 10 days after reperfusion. Normal and sham-operated rats were used in control group. Modified Neurological Severity Scores (mNSS) test and hematoxylin and eosin staining were respectively performed to evaluate neurological function and histological feature. Immunohistochemistry was used to identify intrinsic neurogenesis by nestin antibody. Western blotting was used to detect BDNF and caspase-3 protein content.

RESULTS

GRb1 infusion after cerebral ischemia significantly promoted recoveries of neurological functions at 3 and 5 days after reperfusion compared to ischemic rats. The number of nestin-positive cells was apparently increased after GRb1 infusion compared to ischemia rats at given time. Moreover, BDNF was significantly increased in GRb1-treated rats compared to ischemia rats at different time points. In contrast, GRb1 infusion after the onset of reperfusion, caspase-3 at a given time was significantly reduced compared to ischemia rats, but still significantly increased compared to control rats.

CONCLUSIONS

Promotion of the neurogenesis and regulation of the expressions of BDNF and caspase-3 may be involved in GRb1-induced neuroprotection against cerebral ischemia.

Ginseng compounds: an update on their molecular mechanisms and medical applications

Ginseng is one of the most widely used herbal medicines and is reported to have a wide range of therapeutic and pharmacological applications. Ginsenosides, the major pharmacologically active ingredients of ginseng, appear to be responsible for most of the activities of ginseng including vasorelaxation, antioxidation, anti-inflammation and anti-cancer. Approximately 40 ginsenoside compounds have been identified. Researchers now focus on using purified individual ginsenoside to reveal the specific mechanism of functions of ginseng instead of using whole ginseng root extracts. Individual ginsenosides may have different effects in pharmacology and mechanisms due to their different chemical structures. Among them the most commonly studied ginsenosides are Rb1, Rg1, Rg3, Re, Rd and Rh1. The molecular mechanisms and medical applications of ginsenosides have attracted much attention and hundreds of papers have been published in the last few years. The general purpose of this update is to provide information of recently described effects of ginsenosides on antioxidation, vascular system, signal transduction pathways and interaction with receptors. Their therapeutic applications in animal models and humans as well as the pharmacokinetics and toxicity of ginsenosides are also discussed in this review. This review concludes with some thoughts for future directions in the further development of ginseng compounds as effective therapeutic agents.

Ginseng compounds: an update on their molecular mechanisms and medical applications

Ginseng is one of the most widely used herbal medicines and is reported to have a wide range of therapeutic and pharmacological applications. Ginsenosides, the major pharmacologically active ingredients of ginseng, appear to be responsible for most of the activities of ginseng including vasorelaxation, antioxidation, anti-inflammation and anti-cancer. Approximately 40 ginsenoside compounds have been identified. Researchers now focus on using purified individual ginsenoside to reveal the specific mechanism of functions of ginseng instead of using whole ginseng root extracts. Individual ginsenosides may have different effects in pharmacology and mechanisms due to their different chemical structures. Among them the most commonly studied ginsenosides are Rb1, Rg1, Rg3, Re, Rd and Rh1. The molecular mechanisms and medical applications of ginsenosides have attracted much attention and hundreds of papers have been published in the last few years. The general purpose of this update is to provide information of recently described effects of ginsenosides on antioxidation, vascular system, signal transduction pathways and interaction with receptors. Their therapeutic applications in animal models and humans as well as the pharmacokinetics and toxicity of ginsenosides are also discussed in this review. This review concludes with some thoughts for future directions in the further development of ginseng compounds as effective therapeutic agents.

Neuroprotective effect of grafting GDNF gene-modified neural stem cells on cerebral ischemia in rats

Previous studies indicated the beneficial effects of glial cell line-derived neurotrophic factor (GDNF) and transplanted neural stem cells (NSCs) on stroke. Here, we explored whether transplantation of neural stem cells (NSCs) modified by GDNF gene provides a better therapeutic effect than native NSCs after stroke. Primary rat NSCs were transfected with GDNF plasmid (GDNF/NSCs, labeled by green fluorescent protein from AdEasy-1, GFP). Adult rats were subjected to two-hour middle cerebral artery occlusion and reperfusion, followed by infusion of NSCs (labeled with5-bromo-2'-deoxyuridine before infusion, BrdU), GDNF/NSCs and saline at 3 days after reperfusion (NSCs group, GDNF/NSCs group, control group), respectively. All rats were sacrificed at 1, 2, 3, 5, and 7 weeks after reperfusion. Modified Neurological Severity Scores (mNSS) test and H and E staining were respectively performed to evaluate neurological function and lesion volume. Immunohistochemistry was used to identify implanted cells and observe the expressions of Synaptophysin (Syp) and postsynaptic density-95 (PSD-95) and caspase-3. TdT-mediated dUTP-biotin nick-end labeling (TUNEL) was employed to observe apoptotic cells. Western blotting was used to detect brain-derived neurotrophic factor (BDNF) and NT-3 protein expression. Significant recovery of mNSS was found in GDNF/NSCs rats at 2 and 3 weeks after reperfusion compared with NSCs rats. Lesion volume in the NSCs and GDNF/NSCs groups was reduced significantly compared with control group. The number of NSCs in the GDNF/NSCs group was significantly increased in comparison with NSCs group. Moreover, Syp-immunoreactive product at 2 and 3 weeks after reperfusion and PSD-95 immunoreactive product in the GDNF/NSCs group were significantly increased compared with NSCs group. In contrast, caspase-3 positive cells and TUNEL-positive cells in the GDNF/NSCs group were significantly decreased compared with NSCs group. Significant increase of BDNF protein in the GDNF/NSCs and NSCs groups was observed compared to the control group at different time points of reperfusion, and GDNF/NSCs grafting significantly increased BDNF protein expression compared to NSCs grafting. In addition, significant increase of NT-3 protein in GDNF/NSCs and NSCs groups was detected only at 1 week of reperfusion compared to control group. The results demonstrate that grafting NSCs modified by GDNF gene provides better neuroprotection for stroke than NSCs grafting alone.

Reduction of cyclophosphamide-induced DNA damage and apoptosis effects of ginsenoside Rb(1) on mouse bone marrow cells and peripheral blood leukocytes

The present study investigated the protective effects of ginsenoside Rb(1) (GRb(1)) against genotoxicity induced by cyclophosphamide (CP). Single cell gel electrophoresis, flow cytometry assay with annexin V-FITC/propidine iodide (PI) and acridine orange (AO)/ethidium bromide (EB) staining assay were employed to measure DNA damage and cell apoptosis, respectively. The activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) and the malondialdehyde (MDA) content were also investigated by a number of colormetric methods. The results showed that the CP produced significant DNA damage and cell apoptosis in mouse bone marrow cells or peripheral blood leukocytes, markedly inhibited the activities of T-SOD and GPx, and markedly increased the MDA content. GRb(1) significantly inhibited DNA damages and cell apoptosis in mouse bone marrow cells or peripheral blood leukocytes induced by CP and antagonized the reduction of CP-induced T-SOD and GPx activities, and inhibited the increase in MDA content induced by CP. The anti-tumor study of GRb(1) showed that GRb(1) did not affect the anti-tumor activities of CP. In conclusion, GRb(1) had significant protective effects against DNA damage and apoptosis induced by CP.

Effect of sugar positions in ginsenosides and their inhibitory potency on Na+/K+-ATPase activity

AIM

To determine whether ginsenosides with various sugar attachments may act as active components responsible for the cardiac therapeutic effects of ginseng and sanqi (the roots of Panax ginseng and Panax notoginseng) via the same molecular mechanism triggered by cardiac glycosides, such as ouabain and digoxin.

METHODS

The structural similarity between ginsenosides and ouabain was analyzed. The inhibitory potency of ginsenosides and ouabain on Na+/K+-ATPase activity was examined and compared. Molecular modeling was exhibited for the docking of ginsenosides to Na+/K+-ATPase.

RESULTS

Ginsenosides with sugar moieties attached only to the C-3 position of the steroid-like structure, equivalent to the sugar position in cardiac glycosides, and possessed inhibitory potency on Na+/K+-ATPase activity. However, their inhibitory potency was significantly reduced or completely abolished when a monosaccharide was linked to the C-6 or C-20 position of the steroid-like structure; replacement of the monosaccharide with a disaccharide molecule at either of these positions caused the disappearance of the inhibitory potency. Molecular modeling and docking confirmed that the difference in Na+/K+-ATPase inhibitory potency among ginsenosides was due to the steric hindrance of sugar attachment at the C-6 and C-20 positions of the steroid-like structure.

CONCLUSION

The cardiac therapeutic effects of ginseng and sanqi should be at least partly attributed to the effective inhibition of Na+/K+-ATPase by their metabolized ginsenosides with sugar moieties attached only to the C-3 position of the steroid-like structure.

Optimization of lipase-catalyzed synthesis of ginsenoside Rb1 esters using response surface methodology

In the lipase (Novozyme 435)-catalyzed synthesis of ginsenoside Rb1 esters, different acyl donors were found to affect not only the degree of conversion but also the regioselectivity. The reaction of acyl donors with short carbon chain was more effective, showing higher conversion than those with long carbon chain. Among the three solvent systems, the reaction in tert-amyl alcohol showed the highest conversion rate, while the reaction in the mixed solvent of t-BuOH and pyridine (1:1) had the lowest conversion rate. To allow the increase of GRb1 lipophilicity, we decided to further study the optimal condition of synthesis of GRb1 with vinyl decanoate with 10 carbon chain fatty acids in tert-amyl alcohol. Response surface methodology (RSM) was employed to optimize the synthesis condition. From the ridge analysis with maximum responses, the maximum GRb1 conversion was predicted to be 61.51% in a combination of factors (40.2 h, 52.95 degrees C, substrate mole ratio 275.57, and enzyme amount 39.81 mg/mL). Further, the adequacy of the predicted model was examined by additional independent experiments at the predicted maximum synthesis conditions. Results showed that the RSM was effective to optimize a combination of factors for lipase-catalyzed synthesis of ginsenoside Rb1 with vinyl decanoate.

Ginsenoside Rb1 preconditioning protects against myocardial infarction after regional ischemia and reperfusion by activation of phosphatidylinositol-3-kinase signal transduction

BACKGROUND

Ginsenoside Rb1, a major bioactive component of Panax ginseng, bears various beneficial effects on the cardiovascular system. This study investigated whether ginsenoside Rb1 preconditioning has protective effects on myocardial ischemia-reperfusion injury and its potential mechanism.

METHODS

Rats subjected to 45 min of myocardial ischemia followed by 120 min of reperfusion were assigned to the following groups: sham-operated, ischemia-reperfusion (I/R), ginsenoside Rb1+I/R, wortmannin(a specific PI3K inhibitor)+I/R, wortmannin drug vehicle (dimethyl sulfoxide, DMSO), wortmannin+sham, ginsenoside Rb1+ wortmannin +I/R. Infarct size was assessed by triphenyltetrazolium chloride staining. Plasma creatine kinase (CK), creatine kinase isoenzyme MB (CK-MB), lactate dehydrogenase (LDH), and troponin T levels were also measured. Akt phosphorylation expression was assessed by immunoblotting.

RESULTS

Ginsenoside Rb1 preconditioning reduced infarct size compared with that in the I/R group: 30 +/- 2.6% versus 51 +/- 2.7% (p < 0.01). Ginsenoside Rb1 preconditioning also markedly reduced the plasma CK, CK-MB, LDH and troponin T levels in blood. Akt phosphorylation expression increased after ginsenoside Rb1 preconditioning. These effects of ginsenoside Rb1 preconditioning were significantly inhibited by wortmannin.

CONCLUSION

This is the first study to demonstrate that ginsenoside Rb1 preconditioning has protective effects on myocardial ischemia and reperfusion injury, partly by mediating the activation of the PI3K pathway and phosphorylation of Akt.