Effects of Ginkgo biloba extract on cell proliferation and cytotoxicity in human hepatocellular carcinoma cells

Ginkgo biloba extract mediates HT22 cell proliferation and migration after oxygen-glucose deprivation/reoxygenation via regulating RhoA-ROCK2 signalling pathway

Vascular dementia (VD) is a neurocognitive disorder resulting from cerebral vascular disorders, leading to the demise of neurons and cognitive deficits, posing significant health concerns globally. Derived from Ginkgo biloba leaves, EGb761 is a potent bioactive compound widely recognized for its benefits in treating cerebrovascular diseases. Previous studies have demonstrated that the administration of EGb761 to VD rats enhances the proliferation, differentiation, and migration of neurons, effectively alleviating cognitive dysfunction. However, the specific mechanisms by which EGb761 exerts its remedial influence on VD persist in ambiguity. This investigation utilized an integrated approach incorporating network pharmacology with experimental procedures on HT-22 mouse hippocampal neuronal cells amidst oxygen-glucose deprivation and reoxygenation (OGD/R) to delve into certain repercussions of EGb761 on cell proliferation and migration. Results revealed that ras homolog family member A (RHOA) and B-cell lymphoma 2 (BCL-2) are potential targets of Ginkgo biloba leaves. Target genes are mainly enriched in pathways including those involved in growth hormone synthesis, secretion and action and the neurotrophin signalling pathway. Cellular experiments further demonstrated that the application of EGb761 notably enhanced the viability, proliferation, and migration of HT22 cells subjected to OGD/R through RhoA-ROCK2 pathway. In conclusion, our findings indicated that EGb761 significantly enhances neuronal proliferation and migration following OGD/R injury by targeting the RhoA-ROCK2 signalling pathway, thus offering valuable insights into its potential as a treatment for VD.

Chitosan Nanoparticles-Preparation, Characterization and Their Combination with Ginkgo biloba Extract in Preliminary In Vitro Studies

Nanoparticles (NPs), due to their size, have a key position in nanotechnology as a spectrum of solutions in medicine. NPs improve the ability of active substances to penetrate various routes: transdermal, but also digestive (active endocytosis), respiratory and injection. Chitosan, an N-deacetylated derivative of chitin, is a natural biodegradable cationic polymer with antioxidant, anti-inflammatory and antimicrobial properties. Cross-linked chitosan is an excellent matrix for the production of nanoparticles containing active substances, e.g., the Ginkgo biloba extract (GBE). Chitosan nanoparticles with the Ginkgo biloba extract (GBE) were obtained by ion gelation using TPP as a cross-linking agent. The obtained product was characterized in terms of morphology and size based on SEM and Zeta Sizer analyses as well as an effective encapsulation of GBE in nanoparticles-FTIR-ATR and UV-Vis analyses. The kinetics of release of the active substance in water and physiological saline were checked. Biological studies were carried out on normal and cancer cell lines to check the cytotoxic effect of GBE, chitosan nanoparticles and a combination of the chitosan nanoparticles with GBE. The obtained nanoparticles contained and released GBE encapsulated in research media. Pure NPs, GBE and a combination of NPs and the extract showed cytotoxicity against tumor cells, with no cytotoxicity against the physiological cell line.

Therapeutic Versus Preventative Use of Ginkgo biloba Extract (EGb 761) against Indomethacin-Induced Gastric Ulcer in Mice

The main bioactive constituents in the standardized Ginkgo biloba leaf extract (EGb 761) are the terpene lactones and flavonoid glycosides. EGb 761’s antioxidant and anti-inflammatory properties have previously been demonstrated. Indomethacin-induced gastric ulcers have a multifactorial etiology and represent a major restriction to its therapeutic utility. The underlying ulcerogenic process involves oxidative and inflammatory biomolecular insults. This study was performed to explore the curative and preventative benefits of EGb 761 in experimentally-induced ulcers. To develop gastric ulcers in mice, indomethacin (40 mg/kg) was administered orally. EGb 761 (200 mg/kg) was given by gavage for 7 days before (preventative) and after (therapeutic) indomethacin administration. The histological alterations and macroscopic mucosal lesions were assessed. In gastric tissue homogenates, malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), and inflammatory cytokines were measured. The expressions of cyclooxygenase-2 (COX-2), cytokines, and proliferating cell nuclear antigen (PCNA) in the stomach mucosa were also investigated. The ulcer index, histological alterations, gastric oxidants, and inflammatory biomarkers were all significantly increased by indomethacin. In stomach specimens, it increased COX-2 and PCNA expression. EGb 761 treatments, both prophylactic and therapeutic, resulted in significant reductions in ulcer lesions, nitrosative and oxidative damage, and inflammatory markers, along with the lowering of COX-2 and PCNA expressions. Furthermore, in the fight against stomach ulcers, EGb 761 treatment was found to be more efficient than prevention.

RNA splicing: a dual-edged sword for hepatocellular carcinoma

RNA splicing is the fundamental process that brings diversity at the transcriptome and proteome levels. The spliceosome complex regulates minor and major processes of RNA splicing. Aberrant regulation is often associated with different diseases, including diabetes, stroke, hypertension, and cancer. In the majority of cancers, dysregulated alternative RNA splicing (ARS) events directly affect tumor progression, invasiveness, and often lead to poor survival of the patients. Alike the rest of the gastrointestinal malignancies, in hepatocellular carcinoma (HCC), which alone contributes to ~ 75% of the liver cancers, a large number of ARS events have been observed, including intron retention, exon skipping, presence of alternative 3'-splice site (3'SS), and alternative 5'-splice site (5'SS). These events are reported in spliceosome and non-spliceosome complexes genes. Molecules such as MCL1, Bcl-X, and BCL2 in different isoforms can behave as anti-apoptotic or pro-apoptotic, making the spliceosome complex a dual-edged sword. The anti-apoptotic isoforms of such molecules bring in resistance to chemotherapy or cornerstone drugs. However, in contrast, multiple malignant tumors, including HCC that target the pro-apoptotic favoring isoforms/variants favor apoptotic induction and make chemotherapy effective. Herein, we discuss different splicing events, aberrations, and antisense oligonucleotides (ASOs) in modulating RNA splicing in HCC tumorigenesis with a possible therapeutic outcome.

A critical review of Ginkgolic acid in Ginkgo biloba leaves extract (EGb). Toxicity, technologies to remove the ginkgolic acids and its promising bioactivities

Ginkgo biloba leaves extract (EGb) is high in bioactive components (over 170), which are used in food additives, medicine, cosmetics, health products, and other sectors. Nonetheless, ginkgolic acids (GAs) in...

Development of Potential Antitumor Agents from the Scaffolds of Plant-Derived Terpenoid Lactones

Naturally occurring terpenoid lactones and their synthetic derivatives have attracted increasing interest for their promising antitumor activity and potential utilization in the discovery and design of new antitumor agents. In the present perspective article, selected plant-derived five-membered γ-lactones and six-membered δ-lactones that occur with terpenoid scaffolds are reviewed, with their structures, cancer cell line cytotoxicity and in vivo antitumor activity, structure-activity relationships, mechanism of action, and the potential for developing cancer chemotherapeutic agents discussed in each case. The compounds presented include artemisinin (ART, 1), parthenolide (PTL, 2), thapsigargin (TPG, 3), andrographolide (AGL, 4), ginkgolide B (GKL B, 5), jolkinolide B (JKL B, 6), nagilactone E (NGL E, 7), triptolide (TPL, 8), bruceantin (BRC, 9), dichapetalin A (DCT A, 10), and limonin (LMN, 11), and their naturally occurring analogues and synthetic derivatives. It is hoped that this contribution will be supportive of the future development of additional efficacious anticancer agents derived from natural products.

Cytotoxic effect of Ginkgo biloba kernel extract on HCT116 and A2058 cancer cell lines

While the pharmacology of Ginkgo biloba leaf extract has been studied extensively, little is known about the pharmacological potential of Ginkgo biloba seeds, although they contain similar active ingredients that are responsible for the therapeutic effects of the leaf extract. In this study we used 70%-methanol Ginkgo biloba kernel extract, quantified its bioactive constituents and tested their cytotoxic effect on two cancer cell lines, A2058 and HCT116, and the non-tumor cell line McCoy-Plovdiv. We studied the biological effect of the extract by real-time analysis in the xCELLigence system, WST-1 assay and LIVE/DEAD viability assay. We show that the extract significantly perturbed the viability of cancer cells in a concentration- and time-dependent manner. In contrast, non-cancerous McCoy-Plovdiv cells sustained their proliferation potential even at high concentrations of the extract. Therefore, we propose that the active constituents of the Ginkgo biloba endosperm extract may interact additively or synergistically to protect against cancer.

Ginkgolide B inhibits lung cancer cells promotion via beclin-1-dependent autophagy

BACKGROUND

Ginkgolide B (GKB) is a major active component of the extracts of Ginkgo biloba leaves, and it has been used as an anti-cancer agent. However, it is unknown whether GKB has the therapeutic effects on lung cancer. Here, we studied the effects of GKB on lung cancer cells.

METHODS

The effects of GKB on lung cancer cell proliferation and invasion were analyzed by cell counting kit (CCK-8) and cell invasion assays, respectively. Apoptosis was detected by flow cytometry. Western blot analysis was used to confirm the expression of autophagy-associated proteins in GKB-treated cells. Immunofluorescence analysis was used to analyze the level of light chain 3B (LC3B).

RESULTS

Treatment with GKB time-dependently inhibited the proliferation and decreased the invasive capacity of A549 and H1975 cells. GKB induced apoptosis of these cells, but there was no significant effect on apoptosis compared to the control treatment. GKB-induced inhibition of cell proliferation and GKB-induced cell death were due to autophagy rather than apoptosis. GKB-induced autophagy of lung cancer cells was dependent on beclin-1, and autophagy-induced inhibition of the NLRP3 inflammasome contributed to the anti-tumor effect of GKB.

CONCLUSIONS

GKB-mediated autophagy of lung cancer cells is beclin-1-dependent and results in inhibition of the NLRP3 inflammasome. Therefore, GKB might be a potential therapeutic candidate for the treatment of lung cancer.

Phyotochemical candidates repurposing for cancer therapy and their molecular mechanisms

Though limited success through chemotherapy, radiotherapy and surgery has been obtained for efficient cancer therapy for modern decades, cancers are still considered high burden to human health worldwide to date. Recently repurposing drugs are attractive with lower cost and shorter time compared to classical drug discovery, just as Metformin from Galega officinalis, originally approved for treating Type 2 diabetes by FDA, is globally valued at millions of US dollars for cancer therapy. As most previous reviews focused on FDA approved drugs and synthetic agents, current review discussed the anticancer potential of phytochemicals originally approved for treatment of cardiovascular diseases, diabetes, infectious diarrhea, depression and malaria with their molecular mechanisms and efficacies and suggested future research perspectives.

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.

Ginkgo biloba induces different gene expression signatures and oncogenic pathways in malignant and non-malignant cells of the liver

Ginkgo biloba (EGb761) is a widely used botanical drug. Several reports indicate that EGb761 confers preventive as well as anti-tumorigenic properties in a variety of tumors, including hepatocellular carcinoma (HCC). We here evaluate functional effects and molecular alterations induced by EGb761 in hepatoma cells and non-malignant hepatocytes. Hepatoma cell lines, primary human HCC cells and immortalized human hepatocytes (IH) were exposed to various concentrations (0–1000 μg/ml) of EGb761. Apoptosis and proliferation were evaluated after 72h of EGb761 exposure. Response to oxidative stress, tumorigenic properties and molecular changes were further investigated. While anti-oxidant effects were detected in all cell lines, EGb761 promoted anti-proliferative and pro-apoptotic effects mainly in hepatoma cells. Consistently, EGb761 treatment caused a significant reduction in colony and sphere forming ability in hepatoma cells and no mentionable changes in IH. Transcriptomic changes involved oxidative stress response as well as key oncogenic pathways resembling Nrf2- and mTOR signaling pathway. Taken together, EGb761 induces differential effects in non-transformed and cancer cells. While treatment confers protective effects in non-malignant cells, EGb761 significantly impairs tumorigenic properties in cancer cells by affecting key oncogenic pathways. Results provide the rational for clinical testing of EGb761 in preventive and therapeutic strategies in human liver diseases.

Ginkgolic acids induce HepG2 cell death via a combination of apoptosis, autophagy and the mitochondrial pathway

Ginkgolic acids may induce malignant cell death via the B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax)/Bcl-2 apoptosis pathway. Concurrently, apoptosis, autophagy and mitochondrial dysfunction may also be involved in bringing about this endpoint. The anticancer effect of Ginkgolic acids (GAs) was investigated using the HepG2 cell line. The median lethal dose of the GAs of the HepG2 was measured via an MTT assay, the dose-response curves were evaluated and changes in cell morphology were monitored by microscopy. Autophagy in HepG2 cells was down regulated using 3-methyladenine (3-MA) or Beclin-1-specific small interfering RNA (siRNA) and the expression of apoptosis associated proteins caspase-3, Bax/Bcl-2, and the autophagy-associated protein 5 and microtubule-associated protein 1A/1B-light chain 3 in the GA-treated HepG2 cells were all measured by western blot analysis. The level of apoptosis in the GA-treated cells was also assessed using terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) assay, and the mitochondrial membrane potential (Δψ_m) was detected by immunofluorescence. The results of the MTT and TUNEL assays indicated that the proliferation of HepG2 cells treated with GAs was significantly reduced compared with the control group, and the rate of the inhibition was dose-dependent. Western blot analysis indicated that treatment with the Gas induced apoptosis and autophagy in the HepG2 cells. The Δψ_m of the GA-treated HepG2 cells was decreased compared with the control, as monitored by immunofluorescence. However, upon the administration of 3-MA or Beclin-1-specific siRNAs (inhibitors of the autophagy), the expression levels of the apoptosis- and autophagy-associated proteins were decreased. In conclusion, the results of the present study indicated that GAs are potent anticancer agents that function through a combination of the apoptosis, autophagy and mitochondrial pathways.

Ginkgo biloba extract EGb 761-induced upregulation of LincRNA-p21 inhibits colorectal cancer metastasis by associating with EZH2

EGb 761, the standard ginkgo biloba extract, is frequently prescribed in traditional Chinese medicine. Currently, there is no research focusing on its role in human colorectal cancer progression. In our study, we determined the anti-metastatic effect of EGb 761 on colorectal cancer cells and further explored the potential underlying regulatory mechanism. The cell migration and invasion assay indicated that EGb 761 treatment of colorectal cancer cells induced inhibition of cell migration and invasion ability in a concentration-dependent manner. To further explore the underlying regulatory mechanisms that may account for these findings, we performed quantitative real-time PCR (RT-qPCR), western blotting and immunoprecipitation analysis. The results showed that EGb 761 induced upregulation of LincRNA-p21 expression in a dose- and time-dependent manner. Overexpression of LincRNA-p21 also suppressed colorectal cancer cell metastasis. Furthermore, EGb 761 as well as LincRNA-p21 inhibited the expression of extracellular matrix protein, fibronectin. More importantly, RNA immunoprecipitation (RIP) and Chromatin immunoprecipitation (ChIP) assays showed that LincRNA-p21 directly interacted with EZH2, and this interaction suppressed the expression of fibronectin. Finally, the gain and loss function assay revealed that EGb 761 inhibited migration, invasion and fibronctin expression by the LincRNA-p21/EZH2 pathway in colorectal cancer cells. Hence, EGb 761 may be a promising treatment regimen for colorectal cancer and restoration of LincRNA-p21 levels may be helpful for enhancing the anti-cancer effect of EGb 761.

Evaluation of anti-inflammatory and gastric anti-ulcer activity of Phyllanthus niruri L. (Euphorbiaceae) leaves in experimental rats

BACKGROUND

The medicinal plants signify a massive basin of potential phytoconstituents that could be valuable as a substitute to allopathic drugs or considered as an analogue in drug development. Phyllanthus niruri L. (Euphorbiaceae) is generally used in traditional medicine to treat ulcer and inflammation. In this project we investigated the methanolic extract of leaves of Phyllanthus niruri for anti-inflammatory and anti-ulcer activity.

METHODS

The anti-inflammatory activity of methanol extract of Phyllanthus niruri leaves was evaluated at the doses of 100, 200 and 400 mg/kg, p.o. while using ibuprofen (20 mg/kg, p.o) as the standard drug. The animals used were Swiss albino rats. Inflammation was induced by injecting 0.1 ml carrageenan (1% w/v) into the left hind paw. Paw tissues from the different groups were examined for inflammatory cell infiltration. On the other hand, antiulcer activity of methanolic extract of P. niruri leaves at the doses of 100, 200 and 400 mg/kg, p.o. were examined against ethanol-acid induced gastric mucosal injury in the Swiss albino rats - keeping omeprazole (20 mg/kg, p.o.) as reference. The rats were dissected and the stomachs were macroscopically examined to identify hemorrhagic lesions in the glandular mucosa.

RESULTS

P. niruri significantly (p < 0.01) decreased carrageenan-induced paw edema; it exhibited a reduction of 46.80%, 55.32% and 69.14% at doses of 100, 200 and 400 mg/kg, respectively. These findings were further supported by the histological study. The methanolic extract also disclosed good protective effect against ethanol-acid induced gastric mucosal injury in the rats. Administration of the extract's doses (100, 200 and 400 mg/kg) demonstrated a significant (p < 0.01) reduction in the ethanol- acid induced gastric erosion in all the experimental groups when compared to the control. The methanolic extract at the higher dose (400 mg/kg) resulted in better inhibition of ethanol-acid induced gastric ulcer as compare to omeprazole (20 mg/kg). Histological studies of the gastric wall revealed that toxic control rats revealed mucosal degeneration, ulceration and migration of numerous inflammatory cells throughout the section. On the other hand, MEPN treatment groups showed significant regeneration of mucosal layer and significantly prevented the formation of hemorrhage and edema.

CONCLUSIONS

The investigation suggests that methanolic extract of P. niruri leaf possess anti-inflammatory activity and promotes ulcer protection as ascertained by regeneration of mucosal layer and substantial prevention of the formation of hemorrhage and edema.

Review of Ginkgo biloba-induced toxicity, from experimental studies to human case reports

Ginkgo biloba seeds and leaves have been used as a traditional herbal remedy for thousands of years, and its leaf extract has been consumed as a botanical dietary supplement for decades. Ginkgo biloba extract is a complex mixture with numerous components, including flavonol glycosides and terpene lactones, and is one of the most widely sold botanical dietary supplements worldwide. Concerns about potential health risks for the general population have been raised because of the widespread human exposure to Ginkgo biloba and its potential toxic and carcinogenic activities in rodents. The National Toxicology Program conducted 2-year gavage studies on one Ginkgo biloba leaf extract and concluded that there was clear evidence of carcinogenic activity of this extract in mice based on an increased incidence of hepatocellular carcinoma and hepatoblastoma. Recently, Ginkgo biloba leaf extract has been classified as a possible human carcinogen (Group 2B) by the International Agency for Research on Cancer. This review presents updated information on the toxicological effects from experimental studies both in vitro and in vivo to human case reports (caused by ginkgo seeds or leaves), and also summarizes the negative results from relatively large clinical trials.

Ginkgo biloba extract in combination with sorafenib is clinically safe and tolerable in advanced hepatocellular carcinoma patients

BACKGROUND

Sorafenib is the only therapy shown to improve overall survival in advanced hepatocellular carcinoma (HCC). However, the clinical efficacy of sorafenib is limited. Combination therapy targeting multiple signaling pathways may improve outcomes. Ginkgo biloba extract (GBE) has exhibited antitumor activity in multiple human cancers.

HYPOTHESIS/PURPOSE

This study was designed to evaluate the tolerability and effectiveness of GBE combined with sorafenib in patients with advanced HCC.

STUDY DESIGN

Patients with advanced HCC were treated with increasing doses of GBE in combination with sorafenib.

METHODS

We first determined the maximum tolerated dose (MTD) of GBE, then the patients were treated with GBE at the MTD to evaluate its safety and efficacy. 27 patients were enrolled in the first part of our study and treated with sorafenib 400mg twice daily (BID) and increasing doses (cohort 1: 60mg, cohort 2: 120mg, cohort 3: 240mg, cohort 4: 360mg) of GBE once daily (QD). An additional group of 32 new patients next to the 27 described before were accrued for the second part of our study, and all these 32 patients were eligible for the evaluation of toxicity and efficacy.

RESULTS

No patient in cohort 1 and 2 experienced a dose-limiting toxicity (DLT). One of the ten patients in cohort 3 experienced a DLT. DLT occurred in two of the three initial patients in cohort 4. Cohort 3 (GBE 240mg QD plus sorafenib 400mg BID) was considered to be the MTD. Three patients had a partial response, 21 had stable disease, and 8 had progressive disease. The median times to progression and overall survival were 2.5 and 11.6 months, respectively. Compared with previous study, the toxicities of the combination therapy were similar with those observed in sorafenib monotherapy, GBE in combination with sorafenib slightly improved OS.

CONCLUSIONS

The combination of GBE (240mg QD) and standard dose sorafenib (400mg BID) is safe and tolerable among patients with advanced HCC. Early signs of antitumor activity may warrant further development of this combination.

Traditional Chinese medicine in the prevention and treatment of cancer and cancer metastasis

Traditional Chinese medicine (TCM) has been a major part of healthcare in China, and has extensively affected medicine and healthcare in surrounding countries over a long period of time. In the fight against cancer, certain anticancer remedies using herbs or herbal formulas derived from TCM have been developed for the management of malignancies. Furthermore, there are clinical trials registered for the use of herbal remedies in cancer management. Herbal medicine has been used as part of combined therapies to reduce the side-effects of chemotherapy, including bone marrow suppression, nausea and vomiting. Herbal remedies have also been used as chemopreventive therapies to treat precancerous conditions in order to reduce the incidence of cancer in high-risk populations. Emerging evidence has revealed that herbal remedies can regulate the proliferation, apoptosis, adhesion and migration of cancer cells. In addition to this direct effect upon cancer cells, a number of herbal remedies have been identified to suppress angiogenesis and therefore reduce tumour growth. The inhibition of tumour growth may also be due to modifications of the host immune system by the herbal treatment. However, the precise mechanisms underlying the therapeutic effects of herbal remedies remain poorly understood and are yet to be fully elucidated. The present study aims to summarize the current literature and clinical trial results of herbal remedies for cancer treatment, with a particular focus on the recent findings and development of the Yangzheng Xiaoji capsule.

Apoptosis induced by Ginkgo biloba (EGb761) in melanoma cells is Mcl-1-dependent

Melanoma is an aggressive skin cancer. Unfortunately, there is currently no chemotherapeutic agent available to significantly prolong the survival of the most patients with metastatic melanomas. Here we report that the Ginkgo biloba extract (EGb761), one of the most widely sold herbal supplements in the world, potently induces apoptosis in human melanoma cells by disturbing the balance between pro- and anti-apoptosis Bcl-2 family proteins. Treatment with EGb761 induced varying degrees of apoptosis in melanoma cell lines but not in melanocytes. Induction of apoptosis was caspase-dependent and appeared to be mediated by the mitochondrial pathway, in that it was associated with reduction in mitochondrial membrane potential and activation of Bax and Bak. Although EGb761 did not cause significant change in the expression levels of the BH3-only Bcl-2 family proteins Bim, Puma, Noxa, and Bad, it significantly downregulated Mcl-1 in sensitive but not resistant melanoma cells, suggesting a major role of Mcl-1 in regulating apoptosis of melanoma cells induced by EGb761. Indeed, siRNA knockdown of Mcl-1 enhanced EGb761-induced apoptosis, which was associated with increased activation of Bax and Bak. Taken together, these results demonstrate that EGb761 kills melanoma cells through the mitochondrial apoptotic pathway, and that Mcl-1 is a major regulator of sensitivity of melanoma cells to apoptosis induced by EGb761. Therefore, EGb761 with or without in combination with targeting Mcl-1 may be a useful strategy in the treatment of melanoma.

Ginkgo biloba extract decreases non-small cell lung cancer cell migration by downregulating metastasis-associated factor heat-shock protein 27

Heat-shock proteins (HSPs) are molecular chaperones that protect proteins from damage. HSP27 expression is associated with cancer transformation and invasion. Ginkgo biloba extract (EGb761), the most widely sold herbal supplement, has antiangiogenic effects and induces tumor apoptosis. Data regarding the effect of EGb761 on HSP expression is limited, particularly in cancer. HSP27 expression in paired tumors and normal lung tissues of 64 patients with non-small cell lung cancer (NSCLC) were detected by real-time PCR, western blotting, and immunohistochemistry. NSCLC cell lines (A549/H441) were used to examine the migratory abilities in vitro. NSCLC tissue showed higher HSP27 expression than normal lung tissue. Kaplan–Meier survival analysis showed that NSCLC patients with low HSP27 expression ratio (<1) had significantly longer survival time than those with a high expression ratio (>1) (p = 0.04). EGb761 inhibited HSP27 expression and migratory ability of A549/H441 cells, which is the same as HSP27-siRNA transfection effect. Moreover, EGb761 treatment activated the AKT and p38 pathways and did not affect the expression of PI3K, ERK, and JNK pathways. HSP27 is a poor prognostic indicator of NSCLC. EGb761 can decrease the migration ability of A549/H441 by inhibiting HSP27 expression most likely through AKT and p38 MAPK pathways activation.

Mitochondria protection with ginkgolide B-loaded polymeric nanocapsules prevents diethylnitrosamine-induced hepatocarcinoma in rats

Aim: Hepatocellular carcinoma (HCC) has no successful pharmacotherapeutic remedy. The aim of this study was to ascertain whether ginkgolide B (GB)-loaded polymeric nanocapsules can prevent diethylnitrosamine (DEN)-induced HCC in rats. Materials & methods: GB was fabricated in two types of nanocapsules of which one was polyethylene glycol coated (N1GB) and the other was uncoated (N2GB). These nanocapsules were orally gavaged during DEN-induced HCC development in rats. Results: Nanocapsulation of GB enabled aqueous suspension and slow time-dependent release of the compound. Anticarcinogenic potential of N2GB was reflected by its ability in the management of DEN-induced reactive oxygen species generation, mitochondrial dysfunction, p53, NF-κB, inducible nitric oxide synthase, COX-2 and VEGF expressions, and induction of apoptosis in cancer cells in the rat liver. Conclusion: Positive zeta-potential on N2GB surface might have offered higher hepatic accumulation of GB, especially at the electron-dense organelle mitochondria. Mitochondria protection against DEN-induced oxidative damage ensured HCC prevention.

Original submitted 27 June 2012; Revised submitted 4 December 2012; Published online 7 June 2013

Antiproliferative effect of the Ginkgo biloba extract is associated with the enhancement of cytochrome P450 1B1 expression in estrogen receptor-negative breast cancer cells

Ginkgo biloba is a dioecious tree and its extract is a complex mixture that has been used for thousands of years to treat a variety of ailments in traditional Chinese medicine. The aim of this study was to present our observations on the inhibitory effects of different Ginkgo biloba extracts on human breast cancer cell proliferation and growth. Our results demonstrated that treatment of MCF-7 and MDA-MB-231 human breast cancer cells with Ginkgo biloba leaves and ginkgo fruit extract inhibited cell proliferation. It was also observed that this inhibition was accompanied by the enhancement of cytochrome P450 (CYP) 1B1 expression in MDA-MB-231 cells. In addition, treatment with ginkgo fruit extract resulted in a higher CYP1B1 expression in MDA-MB-231 cells compared to treatment with the Ginkgo biloba leaves extract. Our results suggested that the inhibitory effects of the Ginkgo biloba extract on estrogen receptor-negative breast cancer proliferation and the induction of CYP1B1 expression may be exerted through an alternative pathway, independent of the estrogen receptor or the aryl hydrocarbon receptor pathway.

Ginkgolic acid inhibits HIV protease activity and HIV infection in vitro

BACKGROUND

Several HIV protease mutations, which are resistant to clinical HIV protease inhibitors (PIs), have been identified. There is a great need for second-generation PIs with different chemical structures and/or with an alternative mode of inhibition. Ginkgolic acid is a natural herbal substance and a major component of the lipid fraction in the nutshells of the Ginkgo biloba tree. The objective of this study was to determine whether ginkgolic acid could inhibit HIV protease activity in a cell free system and HIV infection in human cells.

MATERIAL/METHODS

Purified ginkgolic acid and recombinant HIV-1 HXB2 KIIA protease were used for the HIV protease activity assay. Human peripheral blood mononuclear cells (PBMCs) were used for HIV infection (HIV-1SF162 virus), determined by a p24gag ELISA. Cytotoxicity was also determined.

RESULTS

Ginkgolic acid (31.2 µg/ml) inhibited HIV protease activity by 60%, compared with the negative control, and the effect was concentration-dependent. In addition, ginkgolic acid treatment (50 and 100 µg/ml) effectively inhibited the HIV infection at day 7 in a concentration-dependent manner. Ginkgolic acid at a concentration of up to 150 µg/ml demonstrated very limited cytotoxicity.

CONCLUSIONS

Ginkgolic acid effectively inhibits HIV protease activity in a cell free system and HIV infection in PBMCs without significant cytotoxicity. Ginkgolic acid may inhibit HIV protease through different mechanisms than current FDA-approved HIV PI drugs. These properties of ginkgolic acid make it a promising therapy for HIV infection, especially as the clinical problem of viral resistance to HIV PIs continues to grow.

The immunology of traumatic brain injury: a prime target for Alzheimer's disease prevention

A global health problem, traumatic brain injury (TBI) is especially prevalent in the current era of ongoing world military conflicts. Its pathological hallmark is one or more primary injury foci, followed by a spread to initially normal brain areas via cascades of inflammatory cytokines and chemokines resulting in an amplification of the original tissue injury by microglia and other central nervous system immune cells. In some cases this may predispose individuals to later development of Alzheimer’s disease (AD). The inflammatory-based progression of TBI has been shown to be active in humans for up to 17 years post TBI. Unfortunately, all neuroprotective drug trials have failed, and specific treatments remain less than efficacious. These poor results might be explained by too much of a scientific focus on neurons without addressing the functions of microglia in the brain, which are at the center of proinflammatory cytokine generation. To address this issue, we provide a survey of the TBI-related brain immunological mechanisms that may promote progression to AD. We discuss these immune and microglia-based inflammatory mechanisms involved in the progression of post-trauma brain damage to AD. Flavonoid-based strategies to oppose the antigen-presenting cell-like inflammatory phenotype of microglia will also be reviewed. The goal is to provide a rationale for investigations of inflammatory response following TBI which may represent a pathological link to AD. In the end, a better understanding of neuroinflammation could open therapeutic avenues for abrogation of secondary cell death and behavioral symptoms that may mediate the progression of TBI to later AD.

The effects of a plant proteinase inhibitor from Enterolobium contortisiliquum on human tumor cell lines

Supplementary to the efficient inhibition of trypsin, chymotrypsin, plasma kallikrein, and plasmin already described by the EcTI inhibitor from Enterolobium contortisiliquum, it also blocks human neutrophil elastase (K(iapp)=4.3 nM) and prevents phorbol ester (PMA)-stimulated activation of matrix metalloproteinase (MMP)-2 probably via interference with membrane-type 1 (MT1)-MMP. Moreover, plasminogen-induced activation of proMMP-9 and processing of active MMP-2 was also inhibited. Furthermore, the effect of EcTI on the human cancer cell lines HCT116 and HT29 (colorectal), SkBr-3 and MCF-7 (breast), K562 and THP-1 (leukemia), as well as on human primary fibroblasts and human mesenchymal stem cells (hMSCs) was studied. EcTI inhibited in a concentration range of 1.0-2.5 μM rather specifically tumor cell viability without targeting primary fibroblasts and hMSCs. Taken together, our data indicate that the polyspecific proteinase inhibitor EcTI prevents proMMP activation and is cytotoxic against tumor cells without affecting normal tissue remodeling fibroblasts or regenerative hMSCs being an important tool in the studies of tumor cell development and dissemination.

The chemopreventive effect of Ginkgo biloba and Silybum marianum extracts on hepatocarcinogenesis in rats

Background/objective

This study was designed to evaluate the potential chemopreventive activities of Ginkgo biloba extract (EGb) and Silybum marianum extract (silymarin) against hepatocarcinogenesis induced by N-nitrosodiethylamine (NDEA) in rats.

Methods

Rats were divided into 6 groups. Group 1 served as normal control rats. Group 2 animals were intragastrically administrated NDEA at a dose of 10 mg/kg five times a week for 12 weeks to induce hepatocellular carcinoma (HCC). Groups 3 and 4 animals were pretreated with silymarin and EGb respectively. Groups 5 and 6 animals were posttreated with silymarin and EGb respectively. The investigated parameters in serum are alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyltransferase (GGT) and vascular endothelial growth factor (VEGF). The investigated parameters in liver tissue are malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and comet assay parameters.

Results

In NDEA group, MDA level was elevated with subsequent decrease in GSH level and SOD, GPx and GR activities. In addition, NDEA group revealed a significant increase in serum ALT, AST and GGT activities and VEGF level. Furthermore, NDEA administrated animals showed a marked increase in comet assay parameters. These biochemical alterations induced by NDEA were confirmed by the histopathological examination of rat livers intoxicated with NDEA that showed an obvious cellular damage and well differentiated HCC.

In contrast, silymarin+NDEA treated groups (3&5) and EGb+NDEA treated groups (4&6) showed a significant decrease in MDA level and a significant increase in GSH content and SOD, GPx and GR activities compared to NDEA group. Silymarin and EGb also beneficially down-regulated the increase in serum ALT, AST, GGT activities and VEGF level induced by NDEA. In addition, silymarin and EGb significantly decreased comet assay parameters. Histopathological examination of rat livers treated with either silymarin or EGb exhibited an improvement in the liver architecture compared to NDEA group.

Conclusions

The obtained findings suggested that silymarin and EGb may have beneficial chemopreventive roles against hepatocarcinogenesis through their antioxidant, antiangiogenic and antigenotoxic activities.

Effects of Ginkgo biloba constituents on fruit-infesting behavior of codling moth (Cydia pomonella) in apples

Codling moth, Cydia pomonella (L.), is a cosmopolitan pest of apple, potentially causing severe damage to the fruit. Currently used methods of combating this insect do not warrant full success or are harmful to the environment. The use of plant-derived semiochemicals for manipulation with fruit-infesting behavior is one of the new avenues for controlling this pest. Here, we explore the potential of Ginkgo biloba and its synthetic metabolites for preventing apple feeding and infestation by neonate larvae of C. pomonella. Experiments with crude extracts indicated that deterrent constituents of ginkgo are present among alkylphenols, terpene trilactones, and flavonol glycosides. Further experiments with ginkgo synthetic metabolites of medical importance, ginkgolic acids, kaempferol, quercetin, isorhamnetin, ginkgolides, and bilobalide, indicated that three out of these chemicals have feeding deterrent properties. Ginkgolic acid 15:0 prevented fruit infestation at concentrations as low as 1 mg/mL, bilobalide had deterrent effects at 0.1 mg/mL and higher concentrations, and ginkgolide B at 10 mg/mL. On the other hand, kaempferol and quercetin promoted fruit infestation by codling moth neonates. Ginkgolic acids 13:0, 15:1, and 17:1, isorhamnetin, and ginkgolides A and C had no effects on fruit infestation-related behavior. Our research is the first report showing that ginkgo constituents influence fruit infestation behavior and have potential applications in fruit protection.

EGb761, a Ginkgo biloba extract, is effective against atherosclerosis in vitro, and in a rat model of type 2 diabetes

BACKGROUND

EGb761, a standardized Ginkgo biloba extract, has antioxidant and antiplatelet aggregation and thus might protect against atherosclerosis. However, molecular and functional properties of EGb761 and its major subcomponents have not been well characterized. We investigated the effect of EGb761 and its major subcomponents (bilobalide, kaemferol, and quercetin) on preventing atherosclerosis in vitro, and in a rat model of type 2 diabetes.

METHODS AND RESULTS

EGb761 (100 and 200 mg/kg) or normal saline (control) were administered to Otsuka Long-Evans Tokushima Fatty rats, an obese insulin-resistant rat model, for 6 weeks (from 3 weeks before to 3 weeks after carotid artery injury). Immunohistochemical staining was performed to investigate cell proliferation and apoptosis in the injured arteries. Cell migration, caspase-3 activity and DNA fragmentation, monocyte adhesion, and ICAM-1/VCAM-1 levels were explored in vitro. Treatment with EGb761 dose-dependently reduced intima-media ratio, proliferation of vascular smooth muscle cells (VSMCs) and induced greater apoptosis than the controls. Proliferation and migration of VSMCs in vitro were also decreased by the treatment of EGb761. Glucose homeostasis and circulating adiponectin levels were improved, and plasma hsCRP concentrations were decreased in the treatment groups. Caspase-3 activity and DNA fragmentation increased while monocyte adhesion and ICAM-1/VCAM-1 levels decreased significantly. Among subcomponents of EGb761, kaemferol and quercetin reduced VSMC migration and increased caspase activity.

CONCLUSIONS

EGb761 has a protective role in the development of atherosclerosis and is a potential therapeutic agent for preventing atherosclerosis.

Ginkgo biloba extract EGb 761 exerts anti-angiogenic effects via activation of tyrosine phosphatases

The standardised Ginkgo biloba extract EGb 761 (Dr. Willmar Schwabe Pharmaceuticals, Karlsruhe, Germany) is one of the most widely used herbal remedies. Indications for this extract range from dementia to peripheral vascular disease, based on well-documented vascular effects. Surprisingly, the actions of EGb 761 on angiogenesis as a function of vascular cells have not been investigated to date. The anti-cancer activity of EGb 761 in vitro and epidemiological data showing reduced risk for ovarian cancer in regular users have prompted us to investigate this issue. We show an anti-angiogenic profile of EGb 761 in vitro (inhibited proliferation, migration and tube formation of endothelial cells) and in vivo in the chicken chorio-allantoic membrane (CAM) assay. An analysis of the underlying mechanisms indicates inhibition of growth factor-induced extracellular signal-regulated kinase (ERK) phosphorylation by EGb 761. Inhibitory effects of EGb 761 on ERK as well as of the upstream kinases map-erk-kinase (MEK) and rapidly growing fibrosarcoma (Raf)-1 could be completely reversed by pre-treatment with sodium vanadate (inhibitor of tyrosine phosphatases). Sodium vanadate also reversed the EGb 761-induced inhibition of endothelial cell migration. Focusing on tyrosine phosphatases upstream of the Raf-MEK-ERK cascade, we identified the tyrosine phosphatase Src homology-2 domain-containing phosphatase 1 (SHP-1) as one target of EGb 761. SHP-1 was rapidly activated by EGb 761, and silencing SHP-1 (siRNA) abrogated reduction of endothelial proliferation by EGb 761. In summary, we identify EGb 761 as a potent anti-angiogenic drug. The underlying mechanism is the activation of protein tyrosine phosphatases, leading to inhibition of the Raf-MEK-ERK pathway. These findings provide a rational basis for using EGb 761 for an additional therapeutic indication: anti-angiogenesis-based tumour prevention and adjuvant therapy.

Ginkgo biloba extract EGb 761 has anti-inflammatory properties and ameliorates colitis in mice by driving effector T cell apoptosis

Ulcerative colitis is a dynamic, chronic inflammatory condition of the colon associated with an increased colon cancer risk. Ginkgo biloba is a putative antioxidant and has been used for thousands of years to treat a variety of ailments. The aim of this study was to test whether the standardized G.biloba extract, EGb 761, is an antioxidant that can be used to prevent and treat colitis in mice. Here, we show that EGb 761 suppresses the activation of macrophages and can be used to both prevent and treat mouse colitis. Markers of inflammation (iNOS, Cox-2 and tumor necrosis factor-alpha) and inflammatory stress (p53 and p53-phospho-serine 15) are also downregulated by EGb 761. Furthermore, we show that EGb 761 reduces the numbers of CD4+/CD25-/Foxp3- effector T cells in the colon. Interestingly, EGb 761 drives CD4+ effector T cell apoptosis in vitro and in vivo, providing a mechanistic explanation to the reduction in numbers of this cell type in the colon. This current study is in agreement with previous studies supporting a use of EGb 761 as a complementary and alternative strategy to abate colitis and associated colon cancer.

Protective effects of Ginkgo biloba against rat liver carcinogenesis

Ginkgo biloba (EGb) has been proposed as a promising candidate for cancer chemoprevention and has shown protective effects on the liver against chemically induced oxidative injury and fibrosis. The potential beneficial effects of EGb were investigated in two rat liver carcinogenesis bioassays induced by diethylnitrosamine (DEN). In a short-term study for anti-initiating screening, male Wistar rats were fed a basal diet or supplemented diet with 500 or 1000 ppm EGb and initiated 14 days later with a single dose of DEN (100 mg/kg i.p.). The respective groups were killed 24h or 2 weeks after DEN-initiation. Liver samples were collected for the analysis of proliferating cell nuclear antigen (PCNA), transforming growth factor alpha (TGF-alpha), p53, apoptosis and induction of single hepatocytes and minifoci positive for the enzyme glutathione S-transferase P-form (GST-P). In a medium-term study for anti-promoting screening, the animals received a single dose of DEN (200 mg/kg i.p.) and, 2 weeks later, were fed a basal diet or supplemented diet with 500 or 1000 ppm EGb for 6 weeks. All animals underwent 70% partial hepatectomy (PH) at week 3 and killed at week 8. Liver samples were collected to analyze development of preneoplastic foci of altered hepatocytes (FAH) expressing GST-P. In the short-term study, pretreatment of rats with 1000 ppm EGb significantly reduced the rates of cell proliferation, apoptosis and p53, TGF-alpha immunoreactivity and the number of GST-P-positive hepatocytes. In the medium-term study, EGb treatment during the post-initiation stage failed to reduce the development of DEN-induced GST-P-positive foci. Thus, EGb presented inhibitory actions during initiation but not promotion of rat liver carcinogenesis induced by DEN.

Ginkgo Biloba Extract (EGb 761) Protects Against Cisplatin-Induced Ototoxicity in Rats

HYPOTHESIS

A standardized Ginkgo biloba extract, EGb 761, may have protective effect against cisplatin-induced ototoxicity in rats.

BACKGROUND

Cisplatin-induced ototoxicity is a major dose-limiting side effect in anticancer chemotherapy. Cisplatin-induced ototoxicity has been correlated to depletion of the cochlear antioxidant system and increased lipid peroxidation. EGb 761 contains potent antioxidants capable of scavenging free radicals, inhibiting nitric oxide synthesis, reducing lipid peroxidation, and protecting against apoptosis. The purpose of this study was to investigate the effect of EGb 761 on cisplatin-induced ototoxicity in rats.

METHODS

Male Wistar rats were divided into four groups and were treated as follows: 1) vehicle control; 2) cisplatin (13 mg/kg, intraperitoneally) plus vehicle; 3) EGb 761 (200 mg/kg, intraperitoneally); and 4) EGb 761 plus cisplatin. Auditory brainstem responses (ABRs) were measured pretreatment and 72 hours posttreatment, and threshold shifts were analyzed. Endocochlear potentials (EPs) were also obtained at 72 hours posttreatment. Cochleae were harvested and processed for scanning electron microscopy after completion of auditory testing.

RESULTS

Cisplatin-treated rats showed significant ABR threshold shifts across all frequencies (click, and 2-, 4-, 8-, 16-, and 32-kHz tones) compared with each of the other groups (p < 0.001). Rats treated with EGb 761 plus cisplatin did not show significant ABR threshold shifts (p > 0.05). Similarly, the EPs of cisplatin-treated rats were decreased significantly approximately 50% in comparison with the other groups (p < 0.001). The EPs of EGb 761 plus cisplatin-treated rats were decreased less than 20% compared with vehicle control group or the EGb 761 only group (p < 0.01). The scanning electron microscopy observation indicated severe outer hair cell loss in the basal turn of cochleae of cisplatin-treated rats, whereas outer hair cells remained intact in the rats treated with EGb 761 plus cisplatin.

CONCLUSION

These results demonstrate that EGb 761 protects against cisplatin-induced ototoxicity.

Ginkgo biloba and ovarian cancer prevention: Epidemiological and biological evidence

There is considerable interest in herbal therapies for cancer prevention but often with little scientific evidence to support their use. In this study, we examined epidemiological data regarding effects of commonly used herbal supplements on risk for ovarian cancer and sought supporting biological evidence. 4.2% of 721 controls compared to 1.6% of 668 cases regularly used Ginkgo biloba for an estimated relative risk (and 95% confidence interval) of 0.41 (0.20,0.84) (p=0.01); and the effect was most apparent in women with non-mucinous types of ovarian cancer, RR=0.33 (0.15,0.74) (p=0.007). In vitro experiments with normal and ovarian cancer cells showed that Ginkgo extract and its components, quercetin and ginkgolide A and B, have significant anti-proliferative effects ( approximately 40%) in serous ovarian cancer cells, but little effect in mucinous (RMUG-L) cells. For the ginkgolides, the inhibitory effect appeared to be cell cycle blockage at G0/G1 to S phase. This combined epidemiological and biological data provide supportive evidence for further studies of the chemopreventive or therapeutic effects of Ginkgo and ginkgolides on ovarian cancer.

Study of the efficacy and mechanism of ALA-mediated photodynamic therapy on human hepatocellular carcinoma cell

OBJECTIVES

To examine the efficacy and mechanism of delta- or 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) on a human hepatocellular carcinoma cell line.

MATERIALS AND METHODS

The optimal uptake of photosensitizer ALA in HepG2 (p53 wild) cells was investigated by means of spectrometric measurement. Cell viability was determined by trypan blue exclusion assay. Morphological apoptotic changes in HepG2 cells before and after ALA-mediated PDT were determined by microscopic examination. Detection of apoptotic bodies was examined by DAPI staining. The changes in p53 expression were revealed by the immunostaining method.

RESULTS

ALA/protoporphyrin IX (PpIX) was mainly located in the cytoplasm of HepG2 cells. The maximal cellular uptake occurred after 18 h in vitro incubation. The photocytotoxic assay showed that ALA PDT induced 80% killing at 2 mM drug dose and 2 J/cm2 light intensity. Up to 70% of cells showed membrane blebbing and positive DAPI staining, indicating that ALA-PDT-mediated cell death was predominantly via apoptosis. In addition, p53 was upregulated after treatment, implying that p53 might evoke apoptotic cell death.

CONCLUSIONS

HepG2 cell line is sensitive to ALA-mediated PDT. ALA-PDT induces apoptosis in the HepG2 cell line that may be mediated by a p53-dependent pathway.

Ginkgolide A contributes to the potentiation of acetaminophen toxicity by Ginkgo biloba extract in primary cultures of rat hepatocytes

The present cell culture study investigated the effect of Ginkgo biloba extract pretreatment on acetaminophen toxicity and assessed the role of ginkgolide A and cytochrome P450 3A (CYP3A) in hepatocytes isolated from adult male Long-Evans rats provided ad libitum with a standard diet. Acetaminophen (7.5-25 mM for 24 h) conferred hepatocyte toxicity, as determined by the lactate dehydrogenase (LDH) assay. G. biloba extract alone increased LDH leakage in hepatocytes at concentrations > or =75 mug/ml and > or =750 mug/ml after a 72 h and 24 h treatment period, respectively. G. biloba extract (25 or 50 mug/ml once every 24 h for 72 h) potentiated LDH leakage by acetaminophen (10 mM for 24 h; added at 48 h after initiation of extract pretreatment). The effect was confirmed by a decrease in [(14)C]-leucine incorporation. At the level present in a modulating concentration (50 mug/ml) of the extract, ginkgolide A (0.55 mug/ml), which increased CYP3A23 mRNA levels and CYP3A-mediated enzyme activity, accounted for part but not all of the potentiating effect of the extract on acetaminophen toxicity. This occurred as a result of CYP3A induction by ginkgolide A because triacetyloleandomycin (TAO), a specific inhibitor of CYP3A catalytic activity, completely blocked the effect of ginkgolide A. Ginkgolide B, ginkgolide C, ginkgolide J, quercetin, kaempferol, isorhamnetin, and isorhamnetin-3-O-rutinoside did not alter the extent of LDH leakage by acetaminophen. In summary, G. biloba pretreatment potentiated acetaminophen toxicity in cultured rat hepatocytes and ginkgolide A contributed to this novel effect of the extract by inducing CYP3A.

Study of PMS777, a new type of acetylcholinesterase inhibitor, in human HepG2 cells. Comparison with tacrine and galanthamine on oxidative stress and mitochondrial impairment

Acetylcholinesterase inhibitors are commonly used as cognitive enhancers for dementia in aged people. Among them, tacrine (THA) but not galanthamine, was shown to exhibit hepatotoxicity which reduces its clinical use. PMS777, both a PAF antagonist and a new potent acetylcholinesterase inhibitor was recently demonstrated to reverse scopolamine-induced amnesia in mice without toxicity. In the present study, the effects of THA, galanthamine and PMS777 were compared in HepG2 cells on the oxidative parameters involved in the reported hepatotoxicity of THA. THA (> or = 10 microM) induced an oxidative stress as shown by elevated ROS and MDA production and by a decrease in GSH level. Moreover, mitochondrial membrane potential and redox status were decreased. At low concentrations (< or =10 microM), there was no significant disturbance. None of the oxidative stress markers was affected by PMS777 up to the maximum concentration tested and it is suggested that PMS777 is not cytotoxic for HepG2 cells. Galanthamine was also without cytotoxicity. Our results suggest that the toxic effect of THA above 10 microM may be caused by drug-induced mitochondrial energization impairment and destabilisation of membrane phospholipids associated with an oxidative stress. In contrast by preventing these dysfunctions, PMS777 could be safer than THA.

An adjunctive preventive treatment for cancer: Ultraviolet light and ginkgo biloba, together with other antioxidants, are a safe and powerful, but largely ignored, treatment option for the prevention of cancer

Cancer has surpassed heart disease as the leading cause of death in the United States. The mortality rate for cancer is high (roughly 42%), and it increases dramatically with increasing age, especially in patients between the ages of 40 and 60 years old. Currently, the efforts at cancer prevention have been minimal. The drugs developed so far are expensive and have serious side effects. There are at least 18 vitamin D-sensitive cancers. Ultraviolet light, and specifically ultraviolet B (UVB), could reduce cancer by the limited exposure of suitable skin areas to UVB of an intensity and duration insufficient to produce skin cancer. An irrational fear of skin cancer is preventing this idea from being implemented. Though skin cancer incidence is significant, mortality from skin cancer is relatively rare. Roughly 1,000,000 Americans will be affected by skin cancer but only 10,000 deaths are expected in 2005 (a 1% mortality rate). Skin cancer is easily detected and often cured by excisional biopsy alone. Current practice among practicing clinicians is to use a prescription drug substitute for UV light, calcitriol (1-25 dihydroxycholcalciferol). However, high levels of (calcitriol) are dangerous, and there is no consensus on just what a high dose or a safe dose is. Apart from skin cancer, UV light exposure possesses few risks. Additionally, a number of botanical agents such as ginkgo biloba, vitamins E and C, carotenoids, selenium and proanthocyanidins can prevent the risk of skin cancer. Ginkgo biloba also possess the following additional cancer chemopreventive qualities: (1) promoting apoptosis of cancer cells; (2) an anti-clastogenic effect on chromosomes by repairing and reconstituting broken and damaged chromosomes; (3) a powerful therapeutic effect on the treatment of fibrosis-related cancer; (4) a therapeutic effect on free radical-induced cancer; (5) a therapeutic effect on the treatment of cancer incident to the result of numerous carcinogens; (6) a therapeutic effect on preventing free radical-induced cancer; (7) an enhancing effect on radiation therapy in the treatment of cancer; and (8) a therapeutic effect on reducing the size of cancer tumors. Ginkgo biloba is widely-used and has few adverse effects. The proposed preventive treatment for cancer consists of short intermittent exposure of the least sensitive areas of the body to sunlight and/or artificial ultraviolet light. The routine testing of plasma vitamin D levels help monitor the effectiveness of the treatment and periodic checkups with a dermatologist help monitor the safety.

Differential effect of PMS777, a new type of acetylcholinesterase inhibitor, and galanthamine on oxidative injury induced in human neuroblastoma SK-N-SH cells

In the search for highly selective and potent cholinesterase inhibitors (AChEI) being able to improve oxidative injury, PMS777, a tetrahydrofuran derivative, was designed as a novel dual PAF and acetylcholinesterase inhibitor. The aim of this study was to investigate the modulatory effects of PMS777 and galanthamine, another AChEI, on the oxidative injury induced in neuronal cells. The SK-N-SH cells stimulated with LPS+IL-(1beta) were selected to investigate the direct inhibitory effect of PMS777 and galanthamine. LPS+IL-(1beta) induced oxidative injury as assessed by ROS production (29%), GSH depletion (11%) and loss of mitochondrial activity (22%). GSH depletion was never decreased by either drug. In contrast, ROS production and mitochondrial activity were totally prevented by addition of PMS777 but not galanthamine. PMS777 also inhibits butylcholinesterase and it shows selectivity for acetylcholinesterase. Thus, this PAF antagonist inaugurates a new type of AChEI, able to fight oxidative injury. Therefore, PMS777 could be of interest on patients with cognitive impairments and inflammatory damage, as in AD.

The protozoan Tetrahymena as a bioindicator to screen bioactive substances

Tetrahymena thermophila has been used as a "swimming receptor" to study its chemotaxis in the presence of various bioactive substances from herbal plants. Chemotaxis of this ciliated protozoan is, in part, controlled by a cyclic GMP-dependent protein kinase (PKG), which can adjust ciliary beating. In this paper, the effects of Ginkgo biloba extract (GBE) and its main functional constituents, terpene lactones, flavonol glycosides and aglycones, on the chemotaxis and PKG activity of ciliates, were systematically investigated. GBE and its constituents exerted significant inhibition of chemotaxis and PKG activity in cells of T. thermophila. The minimal concentrations to completely inhibit chemotaxis of T. thermophila were 12, 25, 50, 100, 300, 400, 400, 500 microM, 2 mg/ml for isorhamnetin, kaempferol, quercetin, myricetin, isoquercitrin, quercetin-3-beta-d-galactoside, rutin, quercitrin, and GBE, respectively. The IC(50) values for PKG were 14, 17, 20, 25, 186, 78 microM, 0.157 mg/ml for isorhamnetin, kaempferol, quercetin, myricetin, isoquercitrin, rutin and GBE, respectively. The results indicate that the chemotaxis inhibition by GBE and its constituents and their effects on PKG are similar. This suggests that T. thermophila may be a potential experimental organism for screening other bioactive substances.