Down-regulation of c-jun N-terminal kinase-activator protein-1 signaling pathway by Ginkgo biloba extract in human peripheral blood T cells

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

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

Ginkgo biloba for tinnitus

BACKGROUND

Tinnitus is a symptom defined as the perception of sound in the absence of an external source. In England alone there are an estimated ¾ million general practice consultations every year where the primary complaint is tinnitus, equating to a major burden on healthcare services. Clinical management strategies include education and advice, relaxation therapy, tinnitus retraining therapy (TRT), cognitive behavioural therapy (CBT), sound enrichment using ear-level sound generators or hearing aids, and drug therapies to manage co-morbid symptoms such as insomnia, anxiety or depression.  OBJECTIVES: To assess the effects of Ginkgo biloba for tinnitus in adults and children.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; CENTRAL (2022, Issue 6); Ovid MEDLINE; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 7 June 2022.

SELECTION CRITERIA

Randomised controlled trials (RCTs) recruiting adults and children with acute or chronic subjective tinnitus. We included studies where the intervention involved Ginkgo biloba and this was compared to placebo, no intervention, or education and information. Concurrent use of other medication or other treatment was acceptable if used equally in each group. Where an additional intervention was used equally in both groups, we analysed this as a separate comparison. The review included all courses of Ginkgo biloba, regardless of dose regimens or formulations, and for any duration of treatment.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were tinnitus symptom severity measured as a global score on a multi-item tinnitus questionnaire and serious adverse effects (bleeding, seizures). Our secondary outcomes were tinnitus loudness (change in subjective perception), tinnitus intrusiveness, generalised depression, generalised anxiety, health-related quality of life and other adverse effects (gastrointestinal upset, headache, allergic reaction). We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

This review included 12 studies (with a total of  1915 participants). Eleven studies compared the effects of Ginkgo biloba with placebo and one study compared the effects of Ginkgo biloba with hearing aids to hearing aids alone. All included studies were parallel-group RCTs. In general, risk of bias was high or unclear due to selection bias and poor reporting of allocation concealment and blinding of participants, personnel and outcome assessments. Due to heterogeneity in the outcomes measured and measurement methods used, only limited data pooling was possible.  Ginkgo biloba versus placebo When we pooled data from two studies for the primary outcome tinnitus symptom severity, we found that Ginkgo biloba may have little to no effect (Tinnitus Handicap Inventory scores) at three to six months compared to placebo, but the evidence is very uncertain (mean difference (MD) -1.35 (scale 0 to 100), 95% confidence interval (CI) -8.26 to 5.55; 2 studies; 85 participants) (very low-certainty). Ginkgo biloba may result in little to no difference in the risk of bleeding or seizures, with no serious adverse effects reported in either group (4 studies; 1154 participants; low-certainty). For the secondary outcomes, one study found that there may be little to no difference between the effects of Ginkgo biloba and placebo on tinnitus loudness measured with audiometric loudness matching at 12 weeks, but the evidence is very uncertain (MD -4.00 (scale -10 to 140 dB), 95% CI -13.33 to 5.33; 1 study; 73 participants) (very low-certainty). One study found that there may be little to no difference between the effects of Ginkgo biloba and placebo on health-related quality of life measured with the Glasgow Health Status Inventory at three months (MD -0.58 (scale 0 to 100), 95% CI -4.67 to 3.51; 1 study; 60 participants) (low-certainty). Ginkgo biloba may not increase the frequency of other adverse effects (gastrointestinal upset, headache, allergic reaction) at three months compared to placebo (risk ratio 0.91, 95% CI 0.52 to 1.60; 4 studies; 1175 participants) (low-certainty). None of the studies reported the other secondary outcomes of tinnitus intrusiveness or changes in depressive symptoms or depression, anxiety symptoms or generalised anxiety. Gingko biloba with concurrent intervention versus concurrent intervention only One study compared Ginkgo biloba with hearing aids to hearing aids only. It assessed the mean difference in the change in Tinnitus Handicap Inventory scores and tinnitus loudness using a 10-point visual analogue scale (VAS) at three months. The study did not report adverse effects, tinnitus intrusiveness, changes in depressive symptoms or depression, anxiety symptoms or generalised anxiety, or health-related quality of life. This was a single, very small study (22 participants) and for all outcomes the certainty of the evidence was very low. We were unable to draw meaningful conclusions from the numerical results.

AUTHORS' CONCLUSIONS

There is uncertainty about the benefits and harms of Ginkgo biloba for the treatment of tinnitus when compared to placebo. We were unable to draw meaningful conclusions regarding the benefits and harms of Ginkgo biloba when used with concurrent intervention (hearing aids). The certainty of the evidence for the reported outcomes, assessed using GRADE, ranged from low to very low. Future research into the effectiveness of Ginkgo biloba in patients with tinnitus should use rigorous methodology. Randomisation and blinding should be of the highest quality, given the subjective nature of tinnitus and the strong likelihood of a placebo response. The CONSORT statement should be used in the design and reporting of future studies. We also recommend the use of validated, patient-centred outcome measures for research in the field of tinnitus.

Traversing through half a century research timeline on Ginkgo biloba, in transforming a botanical rarity into an active functional food ingredient

Neurodegenerative diseases and various other chronic ailments have gradually transformed into public-health issues. Neurodegenerative disorders are a range of progressive neural abnormalities characterized by cellular dysfunctions, neuronal structure, and function loss. Among many chronic disorders, oxidative stress, inflammation, mitochondrial dysregulation, and cellular alterations in the human body are considered the most prevalent diagnostic symptoms. They have a profound impact on patients' health and wellbeing. The disease's poor curability, high healthcare costs, and lethality are the principal reasons for approaching and exploring the conventional treatment's phytotherapeutic alternatives. Ginkgo biloba (Maidenhair tree) is a well-known and widely used herbal plant in the Ginkgoaceae family. Its phytochemical constituents, Flavonoids, and terpenes, have been identified as the primary ingredients of Ginkgo biloba leaf extracts. It has been widely used due to its therapeutic properties, including its neuroprotective, anti-dementia, antioxidant, anti-inflammatory, vasoactive, anti-psychotic, anti-neoplastic, and anti-platelet activity. In recent decades, plenty of Ginkgo-derived substances has been researched and elucidated to have significant therapeutic effects in numerous disease models. This review aims to provide a thorough understanding of the botanical basis for Ginkgo biloba, its usage as herbal medicine, and its pivotal role in functional foods. Additionally, the clinical significance of Ginkgo biloba, as observed in various research works and clinical investigations, is also emphasized, facilitating a better understanding of their molecular basis and application in many chronic diseases.

Ginkgo Biloba Extract in Ophthalmic and Systemic Disease, With a Focus on Normal-Tension Glaucoma

Glaucoma is a neurodegenerative eye disease that results in retinal ganglion cell loss and ultimately loss of vision. Elevated intraocular pressure (IOP) is the most common known risk factor for retinal ganglion cell damage and visual field loss, and the only modifiable risk factor proven to reduce the development and progression of glaucoma. This has greatly influenced our approach and assessment in terms of diagnosis and treatment. However, as many as ≥50% of patients with progressive vision loss from primary open angle glaucoma without IOP elevation (≤22 mm Hg) have been reported in the United States and Canada; 90% in Japan and 80% in Korea. Extensive research is currently underway to identify the etiology of risk factors for glaucoma other than or in addition to elevated IOP (so-called "normal-tension" glaucoma; NTG) and use this knowledge to expand available treatment options. Currently, Food and Drug Administration-approved medications for glaucoma exclusively target elevated IOP, suggesting the need for additional approaches to treatment options beyond the current scope as the definition of glaucoma changes to encompass cellular and molecular mechanisms. This review focuses on alternative medical approaches, specifically Ginkgo Biloba extract, as a potential treatment option for normal-tension glaucoma.

The effect of Bacillus coagulans-fermented and nonfermented Ginkgo biloba on the immunity status of broiler chickens

To evaluate and compare the effects of Bacillus coagulans-fermented Ginkgo biloba (FG) and nonfermented Ginkgo biloba (NFG) on the immunity status of broiler chickens, 180 1-d-old female Arbor Acres chicks were divided into 3 groups and fed either a basal diet, a basal diet supplemented with 0.3% NFG, or a basal diet supplemented with 0.3% FG. Blood samples were taken on the seventh (before vaccination), 14th, 21st, 28th and 35th day for the assessment of serum IL-18 and interferon γ (IFN-γ) levels by ELISA. In addition, Newcastle disease antibody titer analysis was made via hemagglutination and hemagglutination inhibition test methods. On d 35, 6 chickens from each group were sacrificed and the thymus, liver, spleen, small intestine (jejunum segment), cecum, and bursa of Fabricius from each chicken were removed for analysis. RNA was isolated for defensin expression detection by real-time PCR (q-PCR). The results showed that serum IL-18 and IFN-γ levels decreased after treatment with NFG and FG compared with untreated control chickens. The ND antibody titers did not differ significantly between the 3 groups on the seventh, 14th, 21st and 28th day; however, on the 35th day, the ND antibody titers of the NFG and FG chickens were both significantly higher than those of control group chickens. Defensin RNA expression levels were inhibited by NFG; however, they were induced by FG. In conclusion, fermentation of Ginkgo biloba with Bacillus coagulans can promote the beneficial effect of Gingko biloba on the immunity status of broiler chickens.

Ginkgo biloba extract individually inhibits JNK activation and induces c-Jun degradation in human chondrocytes: potential therapeutics for osteoarthritis

Osteoarthritis (OA) is a common joint disorder with varying degrees of inflammation. The ideal anti-OA drug should have immunomodulatory effects while at the same time having limited or no toxicity. We examined the anti-inflammatory effects of Ginkgo biloba extract (EGb) in interleukin-1 (IL-1)-stimulated human chondrocytes. Chondrocytes were prepared from cartilage specimens taken from patients with osteoarthritis who had received total hip or total knee replacement. The concentrations of chemokines and the degree of cell migration were determined by ELISA and chemotaxis assays, respectively. The activation of inducible nitric oxide synthase (iNOS), mitogen-activated protein kinases (MAPKs), activator protein-1 (AP-1), and nuclear factor-kappaB (NF-κB) was determined by immunoblotting, immunohistochemistry, and electrophoretic mobility shift assay. We found that EGb inhibited IL-1-induced production of chemokines, which in turn resulted in attenuation of THP-1 cell migration toward EGb-treated cell culture medium. EGb also suppressed IL-1-stimulated iNOS expression and release of nitric oxide (NO). The EGb-mediated suppression of the iNOS-NO pathway correlated with the attenuation of activator protein-1 (AP-1) but not nuclear factor-kappaB (NF-κB) DNA-binding activity. Of the mitogen-activated protein kinases (MAPKs), EGb inhibited only c-Jun N-terminal kinase (JNK). Unexpectedly, EGb selectively caused degradation of c-Jun protein. Further investigation revealed that EGb-mediated c-Jun degradation was preceded by ubiquitination of c-Jun and could be prevented by the proteosome inhibitor MG-132. The results imply that EGb protects against chondrocyte degeneration by inhibiting JNK activation and inducing ubiquitination-dependent c-Jun degradation. Although additional research is needed, our results suggest that EGb is a potential therapeutic agent for the treatment of OA.

Antiapoptotic Effects of EGb 761

Ginkgo biloba extracts have long been used in Chinese traditional medicine for hundreds of years. The most significant extract obtained from Ginkgo biloba leaves has been EGb 761, a widely used phytopharmaceutical product in Europe. EGb 761 is a well-defined mixture of active compounds, which contains two main active substances: flavonoid glycosides (24-26%) and terpene lactones (6-8%). These compounds have shown antiapoptotic effects through the protection of mitochondrial membrane integrity, inhibition of mitochondrial cytochrome c release, enhancement of antiapoptotic protein transcription, and reduction of caspase transcription and DNA fragmentation. Other effects include the reduction of oxidative stress (which has been related to the occurrence of vascular, degenerative, and proliferative diseases), coupled to strong induction of phase II-detoxifying and cellular defense enzymes by Nrf2/ARE activation, in addition to the modulation of transcription factors, such as CREB, HIF-1 α , NF- κ B, AP-1, and p53, involved in the apoptosis process. This work reviews experimental results about the antiapoptotic effects induced by the standardized extract of Ginkgo biloba leaves (EGb 761).

Ginkgo bilobaExtract Prevents Ethanol Induced Dyslipidemia

Ginkgo biloba extract (EGB) functions as a natural substantial antioxidant and hypolipidemic. Chronic alcohol abuse leads to sustained dyslipidemia characterized by hyperlipidemia and lipid peroxidation. Thus, the present study investigates the effect of EGB on lipid disorders induced by ethanol in rats. Male Sprague-Dawley rats were fed with ethanol (2.4 g/kg), and pretreated with a daily dose of low or high EGB (48 or 96 mg/kg, respectively). During the experiment, serum was collected on day 30, 60, and 90. Serum lipid profile, including lipid peroxidation, was determined by colorimetric methods. Our data showed that ethanol intake resulted in a time-dependent increase in serum levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and malondialdehyde (MDA), and a decrease of the ratio of high-density lipoprotein cholesterol (HDL-C) against TC. EGB prophylactic medication (48 and 96 mg/kg), especially at the high dose, significantly increased HDL-C content, and normalized the abnormal lipid profile and peroxidation in comparison to ethanol-fed only rats. These results suggest that ethanol results in time-dependent hypercholesterolemia, hypertriglyceridemia and promotes serum lipid peroxidation. EGB pretreatment prevents hyperlipidemia and ameliorates lipid peroxidation induced by ethanol.

The effect of Ginkgo biloba extract on genotoxic damage in patients with differentiated thyroid carcinoma receiving thyroid remnant ablation with iodine-131

BACKGROUND

Radioiodine ((131)I) therapy is usually performed in patients with differentiated thyroid cancer (DTC). Although (131)I is generally considered safe, genotoxic damage has been demonstrated both in vivo and in vitro. The aim of the current study was to evaluate the effect of Ginkgo biloba extract (GBE) on the time-course of appearance, after (131)I therapy for DTC, of plasma factors with chromosome-damaging properties (so-called "clastogenic" factors [CFs]) and of micronuclei (MN) in lymphocytes.

METHODS

Twenty-three patients (median age 42 years, range 18-73) with DTC receiving (131)I activity (3.7 GBq) for thyroid remnant ablation were randomly assigned to receive GBE (120 mg/day for one month; n=10) or placebo (n=13) in a double-blind manner. Blood samples were taken at various intervals (from baseline to 90 days) after (131)I therapy. The frequency of MN in blood lymphocytes was determined, and CFs were assayed in plasma by a method that used MN increase in lymphocytes from an healthy donor as the endpoint of the assay.

RESULTS

MN in blood lymphocytes increased significantly after (131)I treatment in the placebo group, peaking at the 7th day (p=0.002) and slowly declining thereafter. In contrast, in similarly treated patients who were also treated with GBE both before and after (131)I treatment, a significant increase of blood lymphocyte MN level was not observed. In addition, only the placebo group showed a significant, progressive increase in CFs activity. This peaked at the 14th day (p=0.003 vs. baseline) and was still noted for the last plasma sample. The differences in the change in lymphocyte MN and CFs activity between the placebo and GBE-treated groups were significant (p<0.01 and p<0.05, respectively). Thyroid function tests, including serum thyroglobulin (Tg) and anti-Tg antibody levels, were never significantly different.

CONCLUSIONS

GBE may protect from possible oxidative and genotoxic damage associated with (131)I treatment in patients requiring (131)I therapy for thyroid cancer, without affecting the clinical outcome. Further studies with larger cohorts of patients are needed to confirm this report and verify the beneficial effect of GBE in patients requiring (131)I therapy, particularly for those in whom repeated treatments and high activities of (131)I are required.

Immunosuppressive effects and mechanisms of leflunomide in dengue virus infection of human dendritic cells

BACKGROUND

Dengue virus (DENV) infection is a serious public health issue without specific treatment. We examined the potential immunomodulatory effects of leflunomide, a dihydroorotate dehydrogenase inhibitor commonly prescribed for arthritis, in DENV-stimulated monocyte-derived dendritic cells (mo-DCs).

METHODS

mo-DCs were prepared from purified monocytes. Cytokine and chemokine concentrations were determined by enzyme-linked immunosorbent assay. Expression of cell surface markers or viral E protein was measured by flow cytometry. The activation of transcription factors and kinases was determined by electrophoretic mobility shift assays, Western blotting, or immunoprecipitation kinase assays. Chemotaxis assays were used to determine cell migration.

RESULTS

Leflunomide at therapeutic concentrations inhibited cytokine and chemokine production from DENV-infected mo-DCs. Leflunomide suppressed mo-DC maturation by downregulating the expression of both CD80 and CD86. In addition, leflunomide inhibited DENV-induced mo-DC migration and mo-DC response to chemoattractants CCL19 and CCL21. Inhibition of mo-DC migration was likely due to the suppression of CCR7 expression on mo-DCs. These events were associated with the suppression of nuclear factor kappa B and activator protein-1 signaling pathways by leflunomide.

CONCLUSIONS

Leflunomide preserves immunosuppressive effects, inhibiting activation of DENV-stimulated mo-DCs. Leflunomide may be helpful in the development of therapeutics for DENV infection.

10-Hydroxy-2-decenoic acid from Royal jelly: a potential medicine for RA

AIM OF THE STUDY

Rheumatoid arthritis synovial fibroblasts (RASFs) are known to produce matrix metalloproteinases (MMPs) and cause joint destruction. The purpose of this study is to develop a potential medicine for rheumatoid arthritis (RA).

MATERIALS AND METHODS

To this end, first, the MMPs inhibition factor was purified from an alkali-solubilized fraction of RJ (Apis mellifera) by C18 reverse-phase column chromatography and identified as 10-hydroxy-2-decenoic acid (10H2DA) by LTQ XL analysis. Next, Experimental test 10H2DA how to inhibited the activities of MMPs: with RASFs isolated from rheumatoid tissues by enzymatic digestion, cultures in monolayers were treated with 10H2DA (0.5mM, 1mM, and 2mM) or PBS for 2h followed by stimulation with TNF-alpha (10 ng/ml) for 2h, mRNA. Protein levels of MMP-1 and MMP-3 were measured by real-time PCR and enzyme-linked immunosorbent assay (ELISA), the DNA-binding activity of activator protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB) by electrophoretic mobility shift assay (EMSA), and the protein kinase activity of p38, ERK and JNK by kinase assay.

RESULTS

The molecular investigation revealed that the 10H2DA-mediated suppression was likely to occur through blocking p38 kinase and c-Jun N-terminal kinase-AP-1 signaling pathways. In contrast, 10H2DA had no effect on extracellular signal-regulated kinase activity, NF-kappaB DNA-binding activity and IkappaBalpha degradation.

CONCLUSION

These results suggest that 10H2DA may be of potential therapeutic value in inhibiting joint destruction in RA.

Dosage effects of EGb761 on hydrogen peroxide-induced cell death in SH-SY5Y cells

Standardized extract from the leaves of the Ginkgo biloba tree, labeled EGb761, is one of the most popular herbal supplements, taken for its multivalent properties. In this study, dosage effects of EGb761 on hydrogen peroxide (H(2)O(2))-induced apoptosis of human neuroblastoma SH-SY5Y cells were investigated. It was found that H(2)O(2)-induced apoptotic cell death in SH-SY5Y cells, which was revealed in DNA fragmentation, mitochondrial membrane potential depolarization, and activation of Akt, c-Jun N-terminal kinases (JNK) and caspase 3. Low doses of EGb761 (50-100 microg/ml) inhibited H(2)O(2)-induced cell apoptosis via inactivation of Akt, JNK and caspase 3 while high doses of EGb761 (250-500 microg/ml) enhanced H(2)O(2) toxicities via inactivation of Akt and enhancement of activation of JNK and caspase 3. Additional experiments revealed that H(2)O(2) decreased intracellular GSH content, which was also inhibited by low concentrations of EGb761 but enhanced after high concentrations of EGb761 treatment. This further suggests to us that dosage effects of EGb761 on apoptotic signaling proteins may be correlated with regulation of cell redox state. Therefore, treatment dosage may be one of the vital factors that determine the specific action of EGb761 on oxidative stress-induced cell apoptosis. To understand the mechanisms of dosage effects of EGb761 may have important clinical implications.

COX-2 and iNOS are critical in advanced glycation end product-activated chondrocytes in vitro

BACKGROUND

The advanced glycation end products (AGEs) accumulate in joints of osteoarthritis patients. This study aimed to investigate the roles of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) pathways in AGE-mediated cartilage damage.

MATERIALS AND METHODS

Methylglyoxal-modified albumin was used as the source of AGE. Porcine and human chondrocytes were prepared from the joint cartilage of pigs and osteoarthritis patients. The activation of COX-2, iNOS, nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and protein kinases was determined by Western blotting, kinase assay, electrophoretic mobility shift assay (EMSA) or transfection assay. Prostaglandin E(2) (PGE(2)) and NO concentrations were determined by enzyme-linked immunosorbent assay (ELISA) and Griess reaction respectively. The enzymatic activity of COX was determined by measuring the conversion of arachidonic acid to PGE(2). The release of sulphated glycosaminoglycan and the intensity of Safranin O staining were used to measure cartilage degradation.

RESULTS

AGE potently induced COX-2-PGE(2) and iNOS-NO activation in porcine and human chondrocytes. Meanwhile, the upstream molecules regulating COX-2/iNOS activation, such as AP-1, NF-kappaB, extracellular signal regulated protein kinase (ERK) and c-jun N-terminal kinase (JNK), were activated by AGE. Although AGE could not activate p38 directly, by measuring COX enzyme activity, the inhibition of p38 resulted in suppressing AGE-induced conversion of arachidonic acid to PGE(2). Furthermore, successful blockage of either COX-2 or NOS activity significantly reduced AGE-mediated proteoglycan release and cartilage degradation.

CONCLUSIONS

This study highlights the significance of COX-2 and iNOS pathways in AGE-mediated OA pathogenesis and their potential as therapeutic targets that are beyond pain killing for OA treatment.

Suppression of tissue necrosis factor-alpha or hydrogen peroxide-activated primary human T lymphocytes by Ginkgo biloba extract through down-regulation of activator protein-1 signal transduction

PURPOSE

It was unknown whether Ginkgo biloba extract has regulatory effects on human T lymphocytes activated by tissue necrosis factor-alpha (TNF-alpha), which has an important role on the progression of inflammatory atherosclerotic plaques. We evaluated the effects of G. biloba extract on activated human peripheral T lymphocytes, which were isolated from human whole blood.

METHODS

The human T lymphocytes were treated with 25-100 microg G. biloba extract for 2h first. Then they were activated by TNF-alpha and H(2)O(2) to investigate the modulatory effects of G. biloba extract on human T lymphocytes. Electrophoretic mobility shift assay, Western blot (Immunoblot) analysis and immunoprecipitation kinase assays were used.

RESULTS

The inhibition of activated human T lymphocyte specifically correlated with the down-regulation of AP-1 DNA-binding activities. G. biloba extract was unique in its ability to inhibit the activation of c-Jun NH2-terminal protein kinase.

CONCLUSIONS

G. biloba extract might have its novel therapeutic effects on inflammation-based atherosclerotic diseases.

Heme oxygenase-1 upregulated by Ginkgo biloba extract: Potential protection against ethanol-induced oxidative liver damage

Oxidative stress plays a pivotal role in the pathogenesis and progression of alcoholic liver disease (ALD) and HO-1 induction is suggested to protect hepatocytes from ethanol hepatotoxicity. Here, we present the data to explore the hepatoprotective effect and underlying mechanism(s) of Ginkgo biloba extract (EGB), a naturally occurring HO-1 inducer, against ethanol-induced oxidative damage. Ethanol-fed (2.4 g/kg) male rats were pretreated by EGB (48 or 96 mg/kg) for 90 days. Liver damage was evaluated by histopathology and serum aminotransferase assay. Hepatic redox parameters were measured by spectrophotometry. Heme oxygenase-1 (HO-1) expression was determined by RT-PCR and flow cytometry on mRNA and protein level, respectively. Our results showed that EGB, especially at high dose, ameliorated ethanol-induced macrovesicular steatosis and parenchymatous degeneration in hepatocytes, and decreased serum aminotransferases level. Furthermore, EGB reduced ethanol-derived glutathione depletion and lipid peroxidation, and inhibited the inactivation of superoxide dismutase, glutathione peroxidase and catalase, although EGB itself had no influence on such parameters. Importantly, EGB induced hepatic microsomal HO-1 on mRNA, protein expression and enzymatic activity, which is paralleled to the EGB-derived hepatoprotective effect. Hence, HO-1 upregulation by EGB may enhance the antioxidative capacity against the ethanol-induced oxidative stress and maintain the cellular redox balance.

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

Retinoic acid blocks pro-inflammatory cytokine-induced matrix metalloproteinase production by down-regulating JNK-AP-1 signaling in human chondrocytes

The development of osteoarthritis (OA) has recently been implicated as a result of immune-mediated damage of chondrocytes and their supporting matrixes. Pro-inflammatory cytokines like interleukin (IL)-1 and tumor necrosis factor alpha (TNF-alpha) play pivotal roles in immunopathogenesis of OA. Because vitamins preserving anti-oxidative effects are suggested to provide protection in OA patients from joint damage, in the present study, we examined the effects and mechanisms of all-trans retinoic acid (t-RA) in suppressing pro-inflammatory cytokine-induced matrix metalloproteinases (MMPs) production in human chondrocytes. Chondrocytes were prepared from cartilage specimens of OA patients receiving total hip or total knee replacement. The protein concentration was measured by ELISA, the mRNA expression by reverse transcriptase-polymerase chain reaction, the protein expression by Western blotting, the transcription factor DNA-binding activity by electrophoretic mobility shift assay and the protein kinase activity by kinase assay. We showed that both MMP-1 and MMP-13 mRNA expression, protein production and enzyme activity induced by either IL-1 or TNF-alpha were suppressed by t-RA or different retinoid derivatives. The molecular investigation revealed that the t-RA-mediated suppression was likely through blocking p38 kinase and c-Jun N-terminal kinase-activator protein-1 signaling pathways. In contrast, t-RA had no effect on extracellular signal-regulated kinase activity, nuclear factor (kappa)B (NF-(kappa)B) DNA-binding activity and I(kappa)B(alpha) degradation. Furthermore, we showed that t-RA could reduce IL-1-induced TNF-alpha production in chondrocytes. Our results suggest that vitamin A may protect OA patients from pro-inflammatory cytokine-mediated damage of chondrocytes and their supporting matrixes.

Central role of PKCdelta in glycoxidation-dependent apoptosis of human neurons

Accumulation of advanced glycation end products (AGEs) induces alterations in the intracellular redox balance, leading cells to functional injury. Current literature reports that intracellular signaling triggered by the interaction of AGEs with their specific receptors RAGEs depends on the cell type and the state of activation/stress. In this work, NT2 human neurons were exposed for 48 h to glycated fetal serum containing 750-3000 pmol/ml pentosidine; the treatment induced an increase in apoptosis rate linear with AGE concentration up to 1500 pmol/ml, but necrotic death was elicited with the highest AGE amount employed (3000 pmol/ml pentosidine). Pentosidine at 1500 pmol/ml, which was the concentration responsible for the highest apoptotic effect (40% of apoptotic neurons), was able to determine early generation of intracellular reactive oxygen species and increase in RAGE levels. Under these conditions, protein kinase C (PKC) delta activity was increased approximately 2-fold, and DNA binding activity of redox-sensitive transcription factor activator protein-1 (AP-1) was enhanced 2.5-fold. A relationship among oxidative stress, PKCdelta activity, AP-1 activation, and apoptosis was demonstrated by pretreating neurons with 500 muM vitamin E, with 20 mug/ml Ginkgo biloba extract, or with 3 muM Rottlerin, inhibitor of PKCdelta; these pretreatments were able to protect neurons from the glycoxidation-dependent effects.

The effects of Ginkgo biloba extract on lipopolysaccharide-induced inflammation in vitro and in vivo

PURPOSE

Ginkgo biloba extract (GBE) contains many different flavone glycosides and terpenoides. Several previous studies have demonstrated that GBE exhibits a wide variety of biological activities, including an antioxidant action, on which we focused our attention. The aim of the present study was to investigate the efficacy of GBE on endotoxin induced uveitis in rats. The anti-inflammatory potency of GBE in vivo was compared with that of prednisolone. In addition, we also investigated nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and the expression of iNOS in a mouse macrophage cell line (RAW 264.7) treated with GBE in vitro to clarify the anti-inflammatory effect.

METHODS

EIU was induced in male Lewis rats by a footpad injection of lipopolysaccharide (LPS). Immediately after the LPS inoculation, either 1, 10 or 100 microg of GBE were injected intravenously. 24hr later, the aqueous humor was collected from both eyes, and the number of infiltrating cells, protein concentration and NO level in the aqueous humor was determined. The RAW 264.7 cells were pretreated with various concentrations of GBE for 24hr and subsequently incubated with LPS for 24hr. Levels of NO, PGE2 and TNF-alpha were determined by enzyme-linked immunosorbent assay. The expression of iNOS protein was analyzed by Western blotting method.

RESULTS

GBE treatment in vivo decreased the concentrations of protein and NO in the aqueous humor of EIU rats. The anti-inflammatory effect of 1 mg GBE was as strong as that of same dose prednisolone. It also significantly reduced the concentration of PGE2, TNF-alpha and NO production in the medium of RAW 264.7 cells compared to that of the LPS group in vitro. The expression of iNOS protein in the 1000 microg ml(-1) of GBE treated cells decreased significantly.

CONCLUSION

The present results indicate GBE suppresses the inflammation of EIU by blocking the iNOS protein expression and its anti-inflammatory effect on eye is comparable with the effect of prednisolone used in similar doses.

Irbesartan inhibits human T-lymphocyte activation through downregulation of activator protein-1

1 Irbesartan is a promising antihypertensive drug with beneficial effects on atherosclerotic processes. In the progression of atherosclerosis, human T-lymphocytes play an important role, but it is not yet known how irbesartan modulates human T-lymphocytes activation. To gain insight into the mechanisms by which irbesartan acts, we investigated its effects on human T-lymphocytes. 2 Primary human T-lymphocytes were isolated from whole blood. Cytokines were determined by ELISA. Activator protein-1 (AP-1) and related protein activities were determined by electrophoretic mobility shift assays, kinase assays, Western blotting and transfection assays. 3 Irbesartan inhibited the production of both tumor necrosis factor-alpha and interferon-gamma by activated T-cells, especially at therapeutic concentrations. Further investigation at the molecular level indicated that the inhibition of activated human T-lymphocytes specifically correlated with the downregulation of AP-1 DNA-binding activity. In the Jurkat T-cell line, irbesartan also inhibited AP-1 transcriptional activity. Finally, we revealed that irbesartan is unique in its ability to inhibit the activation of both c-Jun NH2-terminal protein kinase and p38 MAPK. 4 Our studies show that irbesartan may modulate inflammation-based atherosclerotic diseases through a cell-mediated mechanism involving suppression of human T-lymphocytes activation via downregulation of AP-1 activity.