Ginkgo biloba inhibits hydrogen peroxide-induced activation of nuclear factor kappa B in vascular endothelial cells

Neuroprotective potential of Ginkgo biloba on alteration of rat cerebellum following prenatal exposure to cyclophosphamide

The cytotoxicity of chemotherapeutic drugs is known due to its non-selective effect not only on cancer cells but also on healthy cells. This study investigated the cerebellar alteration in rats prenatally exposed to cyclophosphamide (SK, 20 mg/kg). We also evaluated the neuroprotective potential of Ginkgo biloba (GB, 80 mg/kg/day) against possible biological changes caused by SK in the cerebellar tissues. Twenty adult female rats (weighing 230-280 g, 12 weeks old) were divided into five groups: control, sham, SK, GB, and SK + GB. After mating, pregnant rats was treated with SK in the SK and SK + GB groups and GB in the GB and SK + GB groups from day 13 to day 21 of gestation. After parturition, eight female rats were randomly selected from each group. On day 32 after birth, the cerebellar tissues were dissected and then examined under light microscope using stereological and histopathological methods. Stereological findings showed that the total number of Purkinje cells and granular cells were significantly decreased in the SK group than the control group (p < 0.05). In addition, the mean volumes of molecular layer, granular layer, white matter, and cerebellum were significantly decreased in the SK group compared to the control group (p < 0.05). In the SK + GB group, the total number Purkinje cell, and granular cells, as well as the mean volumes of molecular layer, granular layer, white matter, and cerebellum were significantly increased than the SK group (p < 0.05). Histopathological evaluation also confirmed our stereological findings in the cerebellar tissues. Our results showed that prenatal exposure to SK caused significant changes in the cerebellar architectures of rats, and that GB administration significantly attenuated the deleterious effect of SK on the cerebellar tissues.

The role of inflammation in cadmium nephrotoxicity: NF-κB comes into view

Kidney diseases are major health problem and understanding the underlined mechanisms that lead to kidney diseases are critical research points with a marked potential impact on health. Cadmium (Cd) is a heavy metal that occurs naturally and can be found in contaminated food. Kidneys are the most susceptible organ to heavy metal intoxication as it is the main route of waste excretion. The harmful effects of Cd were previously well proved. Cd induces inflammatory responses, oxidative injury, mitochondrial dysfunction and disturbs Ca²⁺ homeostasis. The nuclear factor-kappa B (NF-κB) is a cellular transcription factor that regulates inflammation and controls the expression of many inflammatory cytokines. Therefore, great therapeutic benefits can be attained from NF-κB inhibition. In this review we focused on certain compounds including cytochalasin D, mangiferin, N-acetylcysteine, pyrrolidine dithiocarbamate, roflumilast, rosmarinic acid, sildenafil, sinapic acid, telmisartan and wogonin and certain plants as Astragalus Polysaccharide, Ginkgo Biloba and Thymus serrulatus that potently inhibit NF-κB and effectively counteracted Cd-associated renal intoxication. In conclusion, the proposed NF-κB involvement in Cd-renal intoxication clarified the underlined inflammation associated with Cd-nephropathy and the beneficial effects of NF-κB inhibitors that make them the potential to substantially optimize treatment protocols for Cd-renal intoxication.

Interactions between Ginkgo biloba L. and Scutellaria baicalensis Georgi in multicomponent mixtures towards cholinesterase inhibition and ROS scavenging

This study gives new insights to understand the type of interactions between Ginkgo biloba L. and Scutellaria baicalensis Georgi, two Chinese medicinal plants with well documented neuroprotective effects, on three targets in Alzheimer's disease (AD): acetylcholinesterase (AChE) and butyrylcholnesterase (BuChE) inhibition and hydrogen peroxide scavenging. Individual samples, binary mixtures with different proportions of both plant species, and also a commercial multicomponent combination containing both plants together with unroasted Coffea arabica L. and quercetin-3-O-rutinoside were used to perform this in vitro evaluation. Sample phenolic profiles were also determined by HPLC-DAD, showing the presence of several flavonoid glycosides, phenolic acids and a methylxanthine. In order to investigate the possible synergism/antagonism interaction, data obtained were analyzed by CompuSyn software. The results showed that G. biloba and S. baicalensis alone display better activities than in mixtures, most of the interactions exhibiting different degrees of antagonism. A slight synergism interaction was only observed for the commercial multicomponent mixture tested against H₂O₂. Further analysis was carried out to understand which compounds could be responsible for the antagonistic interaction. Seventeen single pure compounds present in all extracts were tested against AChE inhibition, most of them displaying weak or no activity. Only caffeine had a remarkable activity. Five different binary and quaternary mixture compositions were design to deepen the interaction between these compounds, revealing mainly phenolic acid-flavonoid, flavonoid-flavonoid and methylxanthine-flavonoid-phenolic acid antagonistic interactions. These results clearly show that, for the targets evaluated, there is no potentiation of the neuroprotective effect by combining S. baicalensis and G. biloba extracts.

Bilobalide Alleviated Dextran Sulfate Sodium-Induced Experimental Colitis by Inhibiting M1 Macrophage Polarization Through the NF-κB Signaling Pathway

Bilobalide, a unique Ginkgo biloba constituent has attracted significant interest as a novel therapeutic option for neuronal protection. However, there is paucity of data on its effect on colitis. This work sought to evaluate the effect of bilobalide on macrophage polarization in vitro and dextran sulfate sodium (DSS) induced colitis in vivo. Through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and annexin V/PI assay, it was shown that bilobalide has no significant toxicity on macrophage. Lipopolysaccharide (LPS) and interferon-gamma (IFN-γ) induced macrophage activation and polarization were significantly suppressed by bilobalide as indicated by reduced expression of cytokine, major histocompatibility complex II (MHC-II), and CD11c. Pertinently, the signaling pathway study showed that the phosphorylation of p65 and its nuclear translocation were decreased while STAT1 was not affected. In DSS-treated mice, administration (i.g) of three doses of bilobalide na\mely 1.25 mg/kg (low dose group), 2.5 mg/kg (medium dose group), and 5 mg/kg (high dose group) was performed daily starting from day 1 to day 10. Medium and high dose bilobalide markedly reduced the inflammation of colitis proved via elevation of bodyweight, decrement in disease activity index (DAI), alleviation of colon damage as well as reduction in activity of colon tissue myeloperoxidase activity. In accordance with the in vitro results, the levels of inflammatory cytokines such as interleukin 6 (IL-6), IL-1β, and tumor necrosis factor (TNF-α) in serum as well as messenger RNA (mRNA) expression in colon were obviously reduced in the bilobalide treated groups. Also, factor nuclear factor kappa B (NF-κB) signaling pathway was decreased significantly by bilobalide treatment. Collectively, these results indicated that administration of bilobalide improved experimental colitis via inhibition of M1 macrophage polarization through the NF-κB signaling pathway. Thus, bilobalide could act as a potential drug for the treatment of inflammatory bowel disease (IBD) in the not-too-distant future.

Ginkgo biloba L. Leaf Extract Protects HepG2 Cells Against Paraquat-Induced Oxidative DNA Damage

Ginkgo biloba L. leaf extracts and herbal infusions are used worldwide due to the health benefits that are attributed to its use, including anti-neoplastic, anti-aging, neuro-protection, antioxidant and others. The aim of this study was to evaluate the effect of an aqueous Ginkgo biloba extract on HepG2 cell viability, genotoxicity and DNA protection against paraquat-induced oxidative damage. Exposure to paraquat (PQ), over 24 h incubation at 1.0 and 1.5 µM, did not significantly reduce cell viability but induced concentration and time-dependent oxidative DNA damage. Ginkgo biloba leaf extract produced dose-dependent cytotoxicity (IC₅₀ = 540.8 ± 40.5 µg/mL at 24 h exposure), and short incubations (1 h) produced basal and oxidative DNA damage (>750 and 1500 µg/mL, respectively). However, lower concentrations (e.g., 75 µg/mL) of Ginkgo biloba leaf extract were not cytotoxic and reduced basal DNA damage, indicating a protective effect at incubations up to 4 h. On the other hand, longer incubations (24 h) induced oxidative DNA damage. Co-incubation of HepG2 cells for 4 h, with G. biloba leaf extract (75 µg/mL) and PQ (1.0 or 1.5 µM) significantly reduced PQ-induced oxidative DNA damage. In conclusion, the consumption of Ginkgo biloba leaf extract for long periods at high doses/concentrations is potentially toxic; however, low doses protect the cells against basal oxidative damage and against environmentally derived toxicants that induce oxidative DNA damage.

Comparison of Two Ginkgo biloba L. Extracts on Oxidative Stress and Inflammation Markers in Human Endothelial Cells

Atherosclerosis is characterized by interaction between immune and vascular endothelial cells which is mediated by adhesion molecules occurring on the surface of the vascular endothelium leading to massive release of proinflammatory mediators. Ginkgo biloba L. (Ginkgoaceae) standardized extracts showing beneficial effects are commonly prepared by solvent extraction, and acetone is used according to the European Pharmacopoeia recommendations; the well-known Ginkgo biloba acetone extract EGb761® is the most clinically investigated. However, in some countries, the allowed amount of solvent is limited to ethanol, thus implying that the usage of a standardized Ginkgo biloba ethanol extract may be preferred in all those cases, such as for food supplements. The present paper investigates if ethanol and acetone extracts, with comparable standardization, may be considered comparable in terms of biological activity, focusing on the radical scavenging and anti-inflammatory activities. Both the extracts showed high inhibition of TNFα-induced VCAM-1 release (41.1-43.9 μg/mL), which was partly due to the NF-κB pathway impairment. Besides ROS decrease, cAMP increase following treatment with ginkgo extracts was addressed and proposed as further molecular mechanism responsible for the inhibition of endothelial E-selectin. No statistical difference was observed between the extracts. The present study demonstrates for the first time that ethanol and acetone extracts show comparable biological activities in human endothelial cell, thus providing new insights into the usage of ethanol extracts in those countries where restrictions in amount of acetone are present.

Anti-inflammatory effects of Ginkgo biloba extract against trimethyltin-induced hippocampal neuronal injury

BACKGROUND

Despite the immense neuromodulatory potentials of Ginkgo biloba extract as a memory enhancer, its underlying mechanism seems inadequate particularly with regard to its anti-inflammatory properties.

AIM

The objective of the present study is to investigate the protective potentials of Ginkgo biloba extract (GBE) against hippocampal neuronal injury induced by trimethyltin (TMT), a potent neurotoxicant.

METHODS

Male SD rats were administered trimethyltin (8.5 mg kg^-1 b.wt) single intraperitoneal (i.p.) injection, followed by Ginkgo biloba extract (100 mg kg^-1 b.wt i.p) for 21 days.

RESULTS

The co-administration of GBE with TMT showed marked improvement in cognitive functions. Concomitantly, there was a significant decrease in oxidative stress as evident by reduction in MDA and total ROS levels. In addition, there was a marked suppression of astrocyte activation (GFAP), transcription factor NFκB and proinflammatory cytokines (TNF-α, IL-1α, 1L-6), which were found to be elevated by TMT administration. Histopathological observations showed remarkable improvement in hippocampal neuronal injury in the conjunctive group.

CONCLUSION

Therefore, it is suggested that Ginkgo biloba extract is an effective agent against trimethyltin-induced hippocampal neuronal loss owing to its antioxidative as well as anti-inflammatory properties.

α-Lipoic acid protects HAECs from high glucose-induced apoptosis via decreased oxidative stress, ER stress and mitochondrial injury

α-Lipoic acid (LA) has a wide range of benefits in treating diabetes mellitus (DM) and DM vascular diseases, however, the specific mechanisms are not clearly understood.

Ginkgo suppresses atherosclerosis through downregulating the expression of connexin 43 in rabbits

INTRODUCTION

Ginkgo biloba extract (GBE) EGb761 is widely used for cardiovascular prevention. Here, we investigated the effects of GBE on atherosclerotic lesion development in rabbits with a high-fat diet.

MATERIAL AND METHODS

Forty New Zealand white male rabbits were randomly divided into four groups. The first two were the normal diet group (C) and the high-fat group (HF). The remaining two groups were those who received a high cholesterol diet supplemented with either the standard drug (simvastatin 2 mg/kg/day) or GBE (3 mg/kg/day). At 12 weeks, histopathological and chemical analyses were performed.

RESULTS

Plasma lipid measurement showed that GBE inhibited high-fat diet-induced increase of serum triglyceride (TG), total cholesterol (TC), and low density lipoprotein cholesterol (LDL-C) by 59.1% (0.9 ±0.2 4 mmol/l vs. 2.2 ±0.4 mmol/l), 18.2% (31.1 ±1.4 mmol/l vs. 38.0 ±0.4 mmol/l) and 15% (28.9 ±1.3 mmol/l vs. 34.0±1.0 mmol/l), respectively, at 12 weeks (p < 0.01). The en face Sudan IV-positive lesion area of the aorta in the GBE group (51.7 ±3.1%) was significantly lower compared with that in the HF group (88.2 ±2.2%; p < 0.01). The mean atherosclerotic lesion area of the GBE group was reduced by 53.2% compared with the HF group (p < 0.01). Immunohistochemistry and western blot analysis showed that GBE markedly suppressed high-fat diet-induced upregulation of connexin 43 (Cx43) in rabbits (p < 0.01).

CONCLUSIONS

Thus, our study revealed that GBE prevented atherosclerosis progress through modulating plasma lipid, suppressing atherosclerotic lesion development, and attenuating the expression of Cx43 protein.

Ginkgo biloba extract reduces high-glucose-induced endothelial reactive oxygen species generation and cell adhesion molecule expression by enhancing HO-1 expression via Akt/eNOS and p38 MAP kinase pathways

AIM

Hyperglycemia is one of the major risk factors leading to vascular complications in clinical diabetes mellitus. Ginkgo biloba extract (GBE), an antioxidant herbal medicine, possesses anti-inflammatory effects. We examined whether GBE can reduce high glucose-induced endothelial adhesiveness to monocytes, an in vitro sign mimicking in vivo early atherogenesis, through selective regulation of heme oxygenase (HO)-1 expression.

METHODS

Human aortic endothelial cells (HAECs) were cultured with normal glucose or high glucose (25 mM) for 4 days and subsequently combined with GBE (EGb761, Dr. Willmar Schwabe, Karlsruhe, Germany) treatment in the last 18 h of the 4-day period. The endothelial reactive oxygen species (ROS) generation, adhesion molecule expression and the adhesiveness to monocytes were examined. The specific signal pathways such as HO-1 were also examined.

RESULTS

High glucose increased ROS generation, adhesion molecule expression and the adhesiveness to monocytes in HAECs. These high glucose-induced phenomena could be suppressed by GBE (100 μg/ml)-induced HO-1 expression in a dose-dependent and time-dependent manner. In addition, jun N-terminal kinases inhibitor or phosphoinositide 3 kinase inhibitor could reduce GBE-induced HO-1 expression. Furthermore, HO-1 inhibitor, HO-1 siRNA, endothelial nitric oxide synthase (eNOS) siRNA, or nuclear factor erythroid 2-related factor (Nrf) 2 siRNA blocked the cytoprotective effects of GBE. Meanwhile, p38/mitogen-activated protein kinase (MAPK) inhibitor could also reduce the effects of GBE on HO-1 induction.

CONCLUSION

GBE could reduce high glucose-induced endothelial adhesion via enhancing HO-1 expression through the Akt/eNOS and p38/MAPK pathways. Our findings suggest a potential strategy targeting on HO-1 induction by GBE for endothelial protection in the presence of high glucose such as that in diabetes mellitus.

In vivo effects of Ginkgo biloba extract on interleukin-6 cytokine levels in patients with neurological disorders

OBJECTIVE

To evaluate the effect of Ginkgo biloba extract (EGB) on the serum levels of cytokines in patients suffering from chronic, age-related neurological disorders (NDs).

MATERIALS AND METHODS

Patients received 9.6 mg of EGB twice daily for 8 weeks. Serum levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunosorbent assay (ELISA) before and after treatment.

RESULTS

The serum level of IL-6 was significantly higher in ND patients as compared to the healthy controls. After these patients underwent 4 and 8 weeks of EGB treatment, their IL-6 levels were shown a statistically significant (P<0.05) decline to near normal values. No significant changes were observed in serum levels of IL-1β and TNF-α after EGB treatment. We also observed an inverse relationship between ND and serum cholesterol levels.

CONCLUSIONS

EGB may exert its beneficial effects in patients suffering from NDs through down-regulation and suppression of IL-6 secretion.

Ginkgo biloba extract (GbE) enhances the anti-atherogenic effect of cilostazol by inhibiting ROS generation

In this study, the synergistic effect of 6-[4-(1-cyclohexyl- 1H-tetrazol-5-yl) butoxy]-3,4-dihydro-2(1H )-quinolinone (cilostazol) and Ginkgo biloba extract (GbE) was examined in apolipoprotein E (ApoE) null mice. Co-treatment with GbE and cilostazol synergistically decreased reactive oxygen species (ROS) production in ApoE null mice fed a high-fat diet. Co-treatment resulted in a significantly decreased atherosclerotic lesion area compared to untreated ApoE mice. The inflammatory cytokines and adhesion molecules such as monocyte chemoattractant-1 (MCP-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and VCAM-1 which can initiate atherosclerosis were significantly reduced by the co-treatment of cilostazol with GbE. Further, the infiltration of macrophages into the intima was decreased by co-treatment. These results suggest that co-treatment of GbE with cilostazol has a more potent anti-atherosclerotic effect than treatment with cilostazol alone in hyperlipidemic ApoE null mice and could be a valuable therapeutic strategy for the treatment of atherosclerosis.

Piper sarmentosum inhibits ICAM-1 and Nox4 gene expression in oxidative stress-induced human umbilical vein endothelial cells

BACKGROUND

Aqueous extract of Piper sarmentosum (AEPS) is known to possess antioxidant and anti-atherosclerotic activities but the mechanism responsible for it remains unclear. In early part of atherosclerosis, nuclear factor-kappa B (NF-κB) induces the expression of cellular adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1) and E-selectin. NADPH oxidase 4 (Nox4) is the predominant source of superoxide in the endothelial cells whereas superoxide dismutase 1 (SOD1), catalase (CAT) and glutathione peroxidase (GPx) are the antioxidant enzymes responsible for inactivating reactive oxygen species. The present study aimed to investigate the effects of AEPS on the gene expression of NF-κB, VCAM-1, ICAM-1, E-selectin, Nox4, SOD1, CAT and GPx in cultured human umbilical vein endothelial cells (HUVECs).

METHODS

HUVECs were divided into four groups:- control; treatment with 180 μM hydrogen peroxide (H₂O₂); treatment with 150 μg/mL AEPS and concomitant treatment with AEPS and H₂O₂ for 24 hours. Total RNA was extracted from all the groups of HUVEC using TRI reagent. Subsequently, qPCR was carried out to determine the mRNA expression of NF-κB, VCAM-1, ICAM-1, E-selectin, Nox4, SOD1, CAT and GPx. The specificity of the reactions was verified using melting curve analysis and agarose gel electrophoresis.

RESULTS

When stimulated with H₂O₂, HUVECs expressed higher level of ICAM-1 (1.3-fold) and Nox4 (1.2-fold) mRNA expression. However, AEPS treatment led to a reduction in the mRNA expression of ICAM-1 (p < 0.01) and Nox4 (p < 0.05) in the H₂O₂-induced HUVECs. AEPS also upregulated the mRNA expression of SOD1 (p < 0.05), CAT (p < 0.01) and GPx (p < 0.05) in oxidative stress-induced HUVECs. There was no significant change in the mRNA expression of VCAM-1 and E-selectin.

CONCLUSION

The expressional suppression of ICAM-1 and Nox4 and induction of antioxidant enzymes might be an important component of the vascular protective effect of AEPS.

Gingko biloba extract reduces VEGF and CXCL-8/IL-8 levels in keratinocytes with cumulative effect with epigallocatechin-3-gallate

In skin inflammation, vascular endothelial growth factor (VEGF) and CXCL-8/IL-8 play an important role and are produced by activated keratinocytes. Extracts from Ginkgo biloba leaves (GBE), widely used in phytotherapy, have been reported to exert antioxidant and anti-inflammatory properties in the skin. We therefore evaluated the effects of GBE on the release of VEGF and CXCL8/IL-8 by normal human keratinocytes (NHKs) activated by tumor necrosis factor alpha (TNFalpha). Moreover, as we previously showed that epigallocatechin-3-gallate (EGCG) reduces VEGF and CXCL8/IL-8 secretion in TNFalpha-activated NHKs, we also tested its effect in association with GBE. Our results showed that GBE exerted a potent inhibition on VEGF and CXCL8/IL-8 levels in activated cells. In association with EGCG, GBE down-regulated VEGF and CXCL8/IL-8 levels in a cumulative manner in TNFalpha-stimulated NHKs. These results suggest that GBE, alone or in association with EGCG may contribute to moderate inflammatory processes in skin diseases associated with angiogenesis.

Ferritin oxidation and proteasomal degradation: Protection by antioxidants

The accumulation of oxidatively damaged proteins is a well-known hallmark of aging and several neurodegenerative diseases including Alzheimer's, Parkinson's and Huntigton's diseases. These highly oxidized protein aggregates are in general not degradable by the main intracellular proteolytic machinery, the proteasomal system. One possible strategy to reduce the accumulation of such oxidized protein aggregates is the prevention of the formation of oxidized protein derivatives or to reduce the protein oxidation to a degree that can be handled by the proteasome. To do so an antioxidative strategy might be successful. Therefore, we undertook the present study to test whether antioxidants are able to prevent the protein oxidation and to influence the proteasomal degradation of moderate oxidized proteins. As a model protein we choose ferritin. H2O2 induced a concentration dependent increase of protein oxidation accompanied by an increased proteolytic susceptibility. This increase of proteolytic susceptibility is limited to moderate hydrogen peroxide concentrations, whereas higher concentrations are accompanied by protein aggregate formation. Protective effects of the vitamin E derivative Trolox, the pyridoindole derivative Stobadine and of the standardized extracts of flavonoids from bark of Pinus Pinaster Pycnogenol and from leaves of Ginkgo biloba (EGb 761) were studied on moderate damaged ferritin.

Effects of Ginkgo biloba extract on inflammatory mediators (SOD, MDA, TNF-alpha, NF-kappaBp65, IL-6) in TNBS-induced colitis in rats

Inflammatory mediators play a criticial role in ulcerative colitis immune and inflammatory processes. The aim of the study was to investigate the effects of Ginkgo biloba extract on inflammatory mediators (SOD, MDA, TNF-α, NF-κBp65, IL-6) in TNBS-induced colitis in rats. Colitis in rats was induced by colonic administration with 2,4,6-trinitrobenzene sulfonic acid (TNBS, 150 mg/kg). EGB in doses of (50, 100, 200 mg/kg) was administered for 4 weeks to protect colitis. The results showed that EGB could significantly ameliorate macroscopic and histological damage, evidently elevate the activities of SOD and reduce the contents of MDA, inhibit the protein and mRNA expressions of TNF-α, NF-κBp65, and IL-6 in the colon tissues of experimental colitis in a dose-dependent manner compared with the model group. We concluded that the probable mechanisms of EGB ameliorated inflammatory injury in TNBS-induced colitis in rats by its modulation of inflammatory mediators and antioxidation

Ginkgolide A attenuates homocysteine-induced endothelial dysfunction in porcine coronary arteries

BACKGROUND

Homocysteine is an independent risk factor for atherosclerosis. The objective of this study was to investigate whether ginkgolide A (GA), a major constituent of Ginkgo biloba, could block homocysteine-induced endothelial dysfunction in porcine coronary arteries.

METHODS

Porcine coronary artery rings were assigned to six treatment groups: control; homocysteine (50 micromol/L); low-dose (50 micromol/L) or high-dose (100 micromol/L) GA; and homocysteine plus low-dose or high-dose GA. After 24 hours' incubation, the rings were analyzed for vasomotor function in response to a thromboxane A2 analogue (U46619), bradykinin, and sodium nitroprusside. Endothelial nitric oxide synthase (eNOS) was studied by using real-time polymerase chain reaction and immunohistochemistry analysis. Superoxide anion production was assessed by chemoluminescence analysis.

RESULTS

Endothelium-dependent relaxation (bradykinin) was significantly reduced in ring segments treated with homocysteine as compared with the control (P < .05). When homocysteine was combined with either low-dose or high-dose GA, endothelium-dependent relaxation was markedly recovered. There was no significant difference in maximal contraction (U46619) or endothelium-independent relaxation (sodium nitroprusside) among all groups. In addition, superoxide anion production was increased by 113% in the homocysteine-treated group, whereas there was no statistically significant difference between the control and GA/homocysteine groups. Furthermore, eNOS messenger RNA and protein levels were substantially reduced in the homocysteine-treated group (P < .05), but not in the GA/homocysteine combined groups.

CONCLUSIONS

Homocysteine significantly impairs endothelium-dependent vasorelaxation through oxidative stress and downregulation of eNOS in porcine coronary arteries. GA effectively prevents homocysteine-induced endothelial dysfunction and molecular changes in porcine coronary arteries. This study underscores the potential clinical benefits and applications of GA in controlling homocysteine-associated vascular injury and cardiovascular disease.

CLINICAL RELEVANCE

Homocysteine is an independent risk factor for atherosclerosis. This study showed that ginkgolide A, a major constituent of Ginkgo biloba, effectively prevents homocysteine-induced endothelial dysfunction and molecular changes in porcine coronary arteries. This study underscores potential clinical benefits and applications of ginkgolide A in controlling homocysteine-associated vascular injury and cardiovascular disease.

Clinical Use and Molecular Mechanisms of Action of Extract of Ginkgo biloba Leaves in Cardiovascular Diseases

Ginkgo biloba is one of the oldest living tree species that has been referred to as a living fossil. Extract from Ginkgo biloba leaves (GBE) is among the most commonly used herbal drugs and is popularized for its alleged tonic effect and possible curative and restorative properties. There is an increasing evidence of the potential role of GBE in treating cardiovascular diseases. We examined the history of GBE usage and reviewed the literature on its effects on the cardiovascular system. In the extensive studies involving cell cultures and animal models, GBE has been shown to exert its action through diverse mechanisms. GBE has been reported to have antioxidatant properties, to modify vasomotor function, to reduce adhesion of blood cells to endothelium, to inhibit activation of platelets and smooth muscle cells, to affect ion channels, and to alter signal transduction. In addition, relevant clinical trials with CBE are being carried out, particularly in the treatment of arterial and venous insufficiency and in the prevention of thrombosis. Finally, the controversial clinical findings and the possible adverse interactions between GBE and other drugs are discussed. This review underscores the potential benefits of Ginkgo biloba in cardiovascular diseases, highlights the gaps in our current research, and suggests the necessity for more rigorous systematic investigation of cardiovascular properties of CBE.

36kDa Glycoprotein isolated from Rhus verniciflua Stokes fruit has a protective activity to glucose/glucose oxidase-induced apoptosis in NIH/3T3 cells

The present study was carried out to investigate the antioxidative and antiapoptotic activities of 36 kDa RVS glycoprotein isolated from Rhus verniciflua Stokes fruits (RVS) in NIH/3T3 cells in vitro. The results showed that the RVS glycoprotein has scavenging activities of free radicals and hydroxyl radicals, and protects from glucose/glucose oxidase (G/GO)-induced cellular damage in NIH/3T3 cells dose-dependently. For example, cell viability was 43.5% in the G/GO treatment alone, whereas it was 93.8% in the co-treatment with RVS glycoprotein (200 microg/ml). We also demonstrated that RVS glycoprotein inhibits activities of the nuclear factor-kappa B (NF-kappaB) and activator protein-1 (AP-1) induced by G/GO, and prevents from G/GO-induced apoptosis in the NIH/3T3 cells. In this regard, the results in this study indicated that RVS glycoprotein has a strong antioxidative activity and an antiapoptotic effect through the modulation activities of NF-kappaB and AP-1in NIH/3T3 cells.

Ginkgo biloba extract inhibits tumor necrosis factor-alpha-induced reactive oxygen species generation, transcription factor activation, and cell adhesion molecule expression in human aortic endothelial cells

OBJECTIVE

This study was conducted to examination whether Ginkgo biloba extract (GBE), a Chinese herb with antioxidant activity, could reduce cytokine-induced monocyte/human aortic endothelial cell (HAEC) interaction, a pivotal early event in atherogenesis.

METHODS AND RESULTS

Pretreatment of HAECs with GBE (50 and 100 microg/mL for 18 hours) significantly suppressed cellular binding between the human monocytic cell line U937 and tumor necrosis factor-alpha (TNF-alpha)-stimulated HAECs by using in vitro binding assay (68.7% and 60.1% inhibitions, respectively). Cell enzyme-linked immunosorbent assay and immunoblot analysis showed that GBE (50 microg/mL for 18 hours) significantly attenuated TNF-alpha-induced cell surface and total protein expression of vascular cellular adhesion molecule-1 and intracellular adhesion molecule-1 (63.5% and 69.2%, respectively; P<0.05). However, pretreatment with probucol (5 micromol/L for 18 hours) reduced the expression of vascular cellular adhesion molecule-1 but not intracellular adhesion molecule-1. Preincubation of HAECs with GBE or probucol significantly reduced intracellular reactive oxygen species formation induced by TNF-alpha (76.8% and 68.2% inhibitions, respectively; P<0.05). Electrophoretic mobility shift assay demonstrated that both GBE and probucol inhibited transcription factor nuclear factor-kappaB activation in TNF-alpha-stimulated HAECs (55.2% and 65.6% inhibitions, respectively) but only GBE could inhibit the TNF-alpha-stimulated activator protein 1 activation (45.1% inhibition, P<0.05).

CONCLUSIONS

GBE could reduce cytokine-stimulated endothelial adhesiveness by downregulating intracellular reactive oxygen species formation, nuclear factor-kappaB and activator protein 1 activation, and adhesion molecule expression in HAECs, supporting the notion that the natural compound Ginkgo biloba may have potential implications in clinical atherosclerosis disease.

Natural products as targeted modulators of the nuclear factor-kappaB pathway

The use of plant extracts to alleviate inflammatory diseases is centuries old and continues to this day. This review assesses the current understanding of the use of such plants and natural products isolated from them in terms of their action against the ubiquitous transcription factor, nuclear factor kappa B (NF-kappaB). As an activator of many pro-inflammatory cytokines and inflammatory processes the modulation of the NF-kappaB transduction pathway is a principal target to alleviate the symptoms of such diseases as arthritis, inflammatory bowel disease and asthma. Two pathways of NF-kappaB activation will first be summarised, leading to the IKK (IkappaB kinase) complex, that subsequently initiates phosphorylation of the NF-kappaB inhibitory protein (IKB). Natural products and some extracts are reviewed and assessed for their activity and potency as NF-kappaB inhibitors. A large number of compounds are currently known as NF-kappaB modulators and include the isoprenoids, most notably kaurene diterpenoids and members of the sesquiterpene lactones class, several phenolics including curcumin and flavonoids such as silybin. Additional data on cellular toxicity are also highlighted as an exclusion principle for pursuing such compounds in clinical development. In addition, where enough data exists some conclusions on structure-activity relationship are provided.

Interaction between cultured endothelial cells and macrophages: in vitro model for studying flavonoids in redox-dependent gene expression

This article focused on two methods to measure the activity of NF-kB. Both methods evalute "post-IkB phosphorylation" stages in the NF-kB activation cascade. In fact, EMSA performed with nuclear extracts provides an information only on NF-kB nuclear translocation and its ability to bind kB-DNA sequences. Likewise, the reporter gene assay is limited to assessing NF-kB-dependent gene expression no matter the mechanism that originally activated NF-kB. Nevertheless, the latter assay represents a more physiological and more reproducible way of measuring NF-kB activity in mammalian cells than the EMSA does. In order to obtain further insights into NF-kB signal transduction pathways, investigating IkB degradation and phosphorylation are recommended. The cloning and characterization of IkB kinases provided new testing possibilities based on measure of their activity.

Cardiac myocytes exposed to anoxia-reoxygenation promote neutrophil transendothelial migration

The goal of the present study was to assess whether cardiac myocytes exposed to anoxia-reoxygenation (A/R) could generate a chemotactic gradient for polymorphonuclear neutrophil (PMN) transendothelial migration. Exposure of neonatal mouse cardiac myocytes to A/R induced an oxidant stress in the myocytes. Supernatants obtained from A/R-conditioned myocytes promoted mouse PMN migration across mouse myocardial endothelial cell monolayers. This increase in PMN transendothelial migration could be prevented if catalase or a platelet-activating factor (PAF) antagonist was added to the supernatants before assay. Supernatants from A/R-conditioned myocytes activated endothelial cells by inducing an intracellular oxidant stress. The oxidant stress and PMN transendothelial migration induced by supernatants from A/R-conditioned myocytes were substantially reduced when endothelial cells derived from manganese superoxide dismutase overexpressing mice were used in the assays. Supernatants from A/R-conditioned myocytes also increased endothelial cell surface levels of E-selectin and intercellular adhesion molecule-1. Our results indicate that cardiac myocytes exposed to A/R can generate a chemotactic gradient, presumably due to production and release of stable oxidants and PAF. The ability of supernatants from A/R-conditioned myocytes to promote PMN transendothelial migration was largely dependent on induction of an oxidant stress in endothelial cells. In addition, these supernatants also induced a proadhesive phenotype in the endothelial cells.