The neuroprotective properties of the Ginkgo biloba leaf: a review of the possible relationship to platelet-activating factor (PAF)

Systematic Internet-Based Review of Complementary and Alternative Medicine for Glaucoma

OBJECTIVE

To identify the most popular forms of complementary and alternative medicine (CAM) for glaucoma on the Internet and to assess the quality of the most popular Web sites addressing CAM for glaucoma.

DESIGN

Systematic Internet-based search.

METHODS

Using a predefined search algorithm, Web sites most likely to receive hits from people searching the Internet for information on CAM therapies for glaucoma were identified.

MAIN OUTCOME MEASURES

Web sites were evaluated for quality based on the Sandvik score. Each Web site was also assessed for external validation based on listing on the Health on the Net (HON) Foundation Web site in accordance with their code of approval. Finally, the risk each Web site potentially posed to patients was assessed using a previously described scoring method.

RESULTS

Twenty-one Web sites were included in our study. Forty-four different CAM therapies were encountered; vitamin C supplements, forskolin, and diet and lifestyle modulation were the most common CAMs discussed. The mean Sandvik score for all Web sites was 9.4 (standard deviation, 2.6). Only one Web site was listed in the HON Foundation code of approval. Two of the 21 Web sites received the highest risk scores of 3 of a potential 4 points. None of the Web sites discouraged adhering to a clinician's advice. Fourteen of the 21 Web sites assessed provided commercial details promoting CAM, with the possibility of purchasing remedies or arranging consultations. Thirteen Web sites provided opinions and experiences without factual details.

CONCLUSIONS

Medical information conveyed over the Internet is of variable quality and is not subject to regulation. Many sources of information contain advice on therapies that have no evidence base and may put patients at risk. It is important that researchers and health care providers be aware of the content and quality of this information so as to offer advice to patients about the evidence and potential risks of CAM therapies. This can only be achieved by increasing awareness among ophthalmologists of the range of products and quality of information available for CAM therapies for glaucoma.

Ginkgo biloba extract EGb 761 and Wisconsin Ginseng delay sarcopenia in Caenorhabditis elegans

Previously we reported that the standardized Ginkgo biloba extract EGb 761 extended life span and increased stress resistance in Caenorhabditis elegans. In this study, pharmacological modulation of age-dependent muscle degeneration, or sarcopenia, was determined. Transgenic C. elegans strain (PD4251) expressing green fluorescent protein (GFP)-MYO-3, localized in body wall muscles and vulval muscle nuclei, were fed with EGb 761 or Wisconsin Ginseng, and muscle integrity was analyzed by quantification of GFP fluorescence. Both EGb 761 and Wisconsin Ginseng significantly delayed sarcopenia. Ginseng was more effective in worms of more advanced age, which is consistent with the ultrastructural changes observed by transmission electron microscopy. Furthermore, both agents ameliorated age-associated decline of locomotive behaviors including locomotion, body bend, and pharyngeal pumping. These results suggest that pharmacological extension of life span is a consequence of maintaining functional capacity of the tissue, and that C. elegans is a valid model system for testing therapeutic intervention for delaying the progress of sarcopenia.

The effect of Ginkgo biloba (EGb 761) on epileptic activity in rabbits

Different animal models are used to evaluate the process of epileptogenesis. In this investigation the kindling model of epilepsy was used. The epileptic focus was induced in Chinchilla rabbits by stimulation of the hippocampus with electric stimuli. We presumed that the extracts of Ginkgo biloba affect the formation of kindling epilepsy. Bioelectric activity of the brain was registered throughout the development of kindling with and without standardized extracts from dried ginkgo leaves (EGb 761). For each animal the following has been determined: the values of the minimum current strength necessary for the origination of threshold after-discharge (AD) - discharges appearing after the cessation of stimulation; duration of the threshold AD; number of stimulations necessary for the origination of full kindling; time latency for the development of full kindling; number of spontaneous epileptogenic discharges manifested in EEG two days following the formation of full kindling during 60-minute registration. The results show that the process of epileptogenesis was influenced by EGb 761. It has been established that if the animals received EGb 761, significantly weaker minimum current strength was necessary for the development of the epileptogenic focus and the AD were longer, while the number of necessary electrostimulations for the appearance of full kindling was less and the latency was shorter.

Screening of estrogenic and antiestrogenic activities from medicinal plants

The medicinal plant extracts commercially used in Asia were screened for their estrogenic and antiestrogenic activities in a recombinant yeast system featuring both a human estrogen receptor (ER) expression plasmid and a reporter plasmid. Pueraria lobata (flower) had the highest estrogenic relative potency (RP, 7.75×10(-3); RP of 17β-estradiol=1), followed by Amomum xanthioides (1.25×10(-3)). Next potent were a group consisting of Glycyrrhiza uralensis, Zingiber officinale, Rheum undulatum, Curcuma aromatica, Eriobotrya japonica, Sophora flavescens, Anemarrhena asphodeloides, Polygonum multiflorum, and Pueraria lobata (root) (ranging from 9.5×10(-4) to 1.0×10(-4)). Least potent were Prunus persica, Lycoppus lucidus, and Adenophora stricta (ranging from 9.0×10(-5) to 8.0×10(-5)). The extracts exerting antiestrogenic effects, Cinnamomum cassia and Prunus persica, had relative potencies of 1.14×10(-3) and 7.4×10(-4), respectively (RP of tamoxifen=1). The solvent fractions from selected estrogenic or antiestrogenic herbs had higher estrogenic relative potencies, with their RP ranging from 9.3×10(-1) to 2.7×10(-4) and from 8.2×10(-1) to 9.1×10(-3), respectively. These results support previous reports on the efficacy of Oriental medicinal plants used or not used as phytoestrogens for hormone replacement therapy.

Up-regulation of HIF-1alpha expression induced by ginkgolides in hypoxic neurons

Hypoxia-inducible factor-1 (HIF-1) is a master regulator of cellular and systemic oxygen homeostasis. Recently, we demonstrated that ginkgolides, the main constituents of the non-flavone fraction of the standardized Ginkgo biloba (Ginkgoaceae) extract EGb 761, have a significant protective role against chemical and physical hypoxia-induced injury in neurons and PC12 cells. Based on the findings and the function of HIF-1 as a master regulator of oxygen homeostasis, we speculate that the protective role of ginkgolides might be mediated by HIF-1. In this study, we therefore investigated the effects of ginkgolides on the expression of HIF-1alpha, the cell viability and the lactate dehydrogenase (LDH) release in the hypoxic cortical neuron. We demonstrated that ginkgolides significantly increase the expression of HIF-1alpha and the cell viability as well as decrease the release of LDH in the hypoxic neuron. The findings suggested that the neuroprotective role of ginkgolides against hypoxia-induced injury might be associated with its role to up-regulate the expression of HIF-1alpha in the hypoxic neurons.

Ginkgo biloba leave extract: biological, medicinal, and toxicological effects

Ginkgo biloba leave extract is among the most widely sold herbal dietary supplements in the United States. Its purported biological effects include: scavenging free radical; lowering oxidative stress; reducing neural damages, reducing platelets aggregation; anti-inflammation; anti-tumor activities; and anti-aging. Clinically, it has been prescribed to treat CNS disorders such as Alzheimer's disease and cognitive deficits. It exerts allergy and changes in bleeding time. While its mutagenicity or carcinogenic activity has not been reported, its components, quercetin, kaempferol and rutin have been shown to be genotoxic. There are no standards or guidelines regulating the constituent components of Ginkgo biloba leave extract nor are exposure limits imposed. Safety evaluation of Ginkgo biloba leave extract is being conducted by the U.S. National Toxicology Program.

Acute cognitive effects of standardised Ginkgo biloba extract complexed with phosphatidylserine

Recent data suggest that the complexation of standardised Ginkgo biloba extract (GBE) with soy-derived phospholipids enhances the bioavailability of GBE's active components. The current study therefore aimed to assess the comparative cognitive and mood effects of a low dose of GBE and products complexing the same extract with either phosphatidylserine or phosphatidylcholine. The study utilised a placebo-controlled, multi-dose, double-blind, balanced-crossover design. Twenty-eight healthy young participants received 120 mg GBE, 120 mg GBE complexed with phosphatidylserine (Virtiva), 120 mg GBE complexed with phosphatidylcholine and a matching placebo, on separate days 7 days apart. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery and Serial Subtraction tasks immediately prior to dosing and at 1, 2.5, 4 and 6 h thereafter. The primary outcome measures were the four aspects of cognitive performance, which have previously been derived by factor analysis of CDR subtests. Levels of terpenoids (bilobalide, ginkgolide A and ginkgolide B) were concomitantly assessed in plasma samples taken pre-dose and at 3 and 6.5 h post-dose.In keeping with previous research utilising the same methodology, 120 mg of GBE was not associated with markedly improved performance on the primary outcomes. However, administration of GBE complexed with phosphatidylserine resulted both in improved secondary memory performance and significantly increased speed of memory task performance across all of the post-dose testing sessions. Enhancement following GBE complexed with phosphatidylcholine was restricted to a modest improvement in secondary memory performance which was restricted to one post-dose time point. All three treatments were associated with improved calmness. There were no significant differences in post-dose levels of terpenoids between the Ginkgo containing treatments, although this latter finding may be attributable to methodological factors. Complexation with phosphatidylserine appears to potentiate the cognitive effects associated with a low dose of GBE. Further research is required to identify whether this effect is due to the complexation of the extracts, their mere combination, or the separate psychopharmacological actions of the two extracts.

Use of Herbal Supplements and Vitamins in Plastic Surgery: A Practical Review

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Explain what governmental regulations control the labeling and distribution of herbal supplements. 2. List the more commonly used supplements and their reported benefits. 3. List the possible postoperative complications from consumption of the more commonly used herbal supplements. 4. Explain the preoperative management of patients using herbal supplements. 5. Know additional resources to consult when unanswered questions arise.

BACKGROUND

The American public spends over $5 billion per year on herbal supplements, and approximately 20 percent of all Americans use prescription medications concurrently with herbal supplements. As the number of people who take alternative medicines rises, there is growing awareness among health care providers of the need to become educated and to educate their patients on the effects that such supplementation may have on their health. As plastic surgeons, we have an added responsibility to become informed because of potential adverse interactions with other medications and anesthesia in the elective surgical patient.

METHODS

Literature regarding commonly encountered herbal supplements and vitamins was reviewed and summarized to include reported indications for use and potential adverse effects and interactions specific to the perioperative patient.

RESULTS

Abundant literature exists regarding herbal supplementation, but very little scientific evidence exists to advocate the use of the majority of supplements available on the market. In addition, little is known about the positive and negative interactions that these supplements are capable of producing, and those interactions that are known are based on case reports.

CONCLUSIONS

With the lack of quality scientific studies to support the efficacy of most herbal products available and the limited regulation of these products by the government, health care providers are faced with a significant public health dilemma. This article provides a brief overview of information published on commonly encountered herbal supplements and vitamins taken by plastic surgery patients.

Advances in the treatment of Parkinson's disease

Parkinson's disease (PD) affects one in every 100 persons above the age of 65 years, making it the second most common neurodegenerative disease after Alzheimer's disease. PD is a disease of the central nervous system that leads to severe difficulties with body motions. The currently available therapies aim to improve the functional capacity of the patient for as long as possible; however they do not modify the progression of the neurodegenerative process. The need for newer and more effective agents is consequently receiving a great deal of attention and consequently being subjected to extensive research. This review concisely compiles the limitations of currently available therapies and the most recent research regarding neuroprotective agents, antioxidants, stem cell research, vaccines and various surgical techniques available and being developed for the management of PD.

Amyloid-beta-induced pathological behaviors are suppressed by Ginkgo biloba extract EGb 761 and ginkgolides in transgenic Caenorhabditis elegans

Amyloid-beta (Abeta) toxicity has been postulated to initiate synaptic loss and subsequent neuronal degeneration seen in Alzheimer's disease (AD). We previously demonstrated that the standardized Ginkgo biloba extract EGb 761, commonly used to enhance memory and by AD patients for dementia, inhibits Abeta-induced apoptosis in neuroblastoma cells. In this study, we use EGb 761 and its single constituents to associate Abeta species with Abeta-induced pathological behaviors in a model organism, Caenorhabditis elegans. We report that EGb 761 and one of its components, ginkgolide A, alleviates Abeta-induced pathological behaviors, including paralysis, and reduces chemotaxis behavior and 5-HT hypersensitivity in a transgenic C. elegans. We also show that EGb 761 inhibits Abeta oligomerization and Abeta deposits in the worms. Moreover, reducing oxidative stress is not the mechanism by which EGb 761 and ginkgolide A suppress Abeta-induced paralysis because the antioxidant L-ascorbic acid reduced intracellular levels of hydrogen peroxide to the same extent as EGb 761, but was not nearly as effective in suppressing paralysis in the transgenic C. elegans. These findings suggest that (1) EGb 761 suppresses Abeta-related pathological behaviors, (2) the protection against Abeta toxicity by EGb 761 is mediated primarily by modulating Abeta oligomeric species, and (3) ginkgolide A has therapeutic potential for prevention and treatment of AD.

Pentylenetetrazol-induced kindling seizure attenuated by Ginkgo biloba extract (EGb 761) in mice

Ginkgo biloba extract (EGb 761) has been used therapeutically for centuries. It has attracted great attention as agents for improving circulation, particularly cerebral circulation, which may lead to improved mental function. Many researches hypothesized on the role of the extract in the treatment of diseases involving free radicals and oxidative damage. In the present study, anticonvulsant and antioxidant effects of EGb 761 were investigated in pentylenetetrazol (PTZ)-kindled mice. Valproic acid (VA), a major antiepileptic drug, was also tested for comparison. EGb 761-treated mice displayed a significant attenuated response to PTZ on the test day (day 26) compared with saline-treated and VA-treated animals. Valproic acid significantly increased seizure latency. Pretreatments with EGb 761 significantly protected against PTZ-induced convulsive behaviors (seizure latency, seizure score). EGb 761 and VA significantly decreased PTZ-induced oxidative injury in brain tissue. EGb 761 was found to be the most effective in preventing PTZ-induced oxidative damage among both substances studied. The data obtained support our speculation that neuroprotective action of EGb 761 may correlate with its ability to inhibit not only excessive reactive oxygen species (ROS) formation but also seizure generation. Taken together, the results of the present study show that the effect of EGb 761 on ROS production contributes to their neuroprotective action. It might be concluded that the suppression of seizure-induced ROS generation may be involved in the mechanism of action of antiepileptic drugs.

Emerging role of polyphenolic compounds in the treatment of neurodegenerative diseases: a review of their intracellular targets

Aging is the major risk factor for neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. A large body of evidence indicates that oxidative stress is involved in the pathophysiology of these diseases. Oxidative stress can induce neuronal damages, modulate intracellular signaling, ultimately leading to neuronal death by apoptosis or necrosis. Thus antioxidants have been studied for their effectiveness in reducing these deleterious effects and neuronal death in many in vitro and in vivo studies. Increasing number of studies demonstrated the efficacy of polyphenolic antioxidants from fruits and vegetables to reduce or to block neuronal death occurring in the pathophysiology of these disorders. These studies revealed that other mechanisms than the antioxidant activities could be involved in the neuroprotective effect of these phenolic compounds. We will review some of these mechanisms and particular emphasis will be given to polyphenolic compounds from green tea, the Ginkgo biloba extract EGb 761, blueberries extracts, wine components and curcumin.

Effects of Ginkgo biloba administered after spatial learning on water maze and radial arm maze performance in young adult rats

Ginkgo biloba is reported to improve learning and memory in animals. However, many studies do not directly test the effects of Ginkgo on memory because the drug is administered during the learning phase of the experiments. In this study, we examined the effect of 10 mg/kg, 20 mg/kg, or 40 mg/kg G. biloba extract on spatial memory by administering the drug in the interval between training and testing. Rats were tested for long-term reference memory retention in the radial arm maze and in the Morris water maze during daily probe trials in which the hidden platform was removed. G. biloba had no effect on reference memory in either the water maze or radial arm maze. To test short-term working spatial memory using the radial arm maze, animals were removed after receiving the reward from 4 of the 8 arms and were returned to complete the maze 2 h later. While Ginkgo had no effect on working memory, over time animals exposed to Ginkgo learned task better than control animals. Thus, Ginkgo appears to enhance neither short-term working memory nor long-term reference memory, but it may promote learning of spatial information.

Alzheimer's disease, the nematode Caenorhabditis elegans, and ginkgo biloba leaf extract

Alzheimer's disease (AD) is affecting larger and larger proportions of our population as lifespan increases. Thus, the means to prevent or reduce the rate of this disorder is a high priority for medical research. A standardized extract of Ginkgo biloba leaves EGb 761 is a popular dietary supplement taken by the general public to enhance mental focus and by the elderly to delay onset of age-related loss of cognitive function. EGb 761 has been used for treatment of certain cerebral dysfunctions and dementias associated with aging and AD. Substantial evidence indicates that EGb 761 has neuroprotective effects. But, mechanisms of action of the components of the extract are, unfortunately, poorly understood. Research in my laboratory focuses on understanding mechanisms of action of the components of the herbal extract EGb 761 in protection against Alzheimer's disease. We have demonstrated that EGb 761 inhibited amyloid beta aggregation in vitro and attenuates reactive oxidative species (ROS) in a model organism - the round worm Caenorhabditis elegans. Furthermore, EGb 761 eased its toxicity in the transgenic C. elegans. We also found that only a certain size of the amyloid beta aggregates is toxic to the worms. These findings suggest that EGb 761 has a clear therapeutic potential for prevention and/or treatment of AD. A better understanding of the mechanisms of neuroprotection by EGb 761 will be important for designing therapeutic strategies, for basic understanding of the underlying neurodegenerative processes, and for a better understanding of the effectiveness and complexity of this herbal medicine.

Ginkgo biloba Use in Nursing Home Elderly with Epilepsy or Seizure Disorder

PURPOSE

Ginkgo biloba, among the most widely used herbs, possesses the capacity both to induce and to inhibit seizures. The purpose of this study was to describe the prevalence of ginkgo and other common herb prescribing in a sample of nursing home (NH) elderly diagnosed with epilepsy/seizure (Epi/Sz) disorder and to determine demographic, clinical, and functional factors associated with ginkgo use.

METHODS

This was a 1-year prevalence study of 68,403 NH residents living in 557 nursing facilities throughout the United States.

RESULTS

Overall, herb use in the NHs was very low (0.41%). Ginkgo was prescribed 162 times, more than any other herb. St. John's wort was prescribed 40 times; garlic, 29 times; and all others, <20 times, for a total of 307 herb orders. Among all residents with an herb order, ginkgo was prescribed for 61.9% of residents with an Epi/Sz diagnosis and 58.0% (p = 0.820) of residents without an Epi/Sz diagnosis. Dementia, educational level, and the interaction of age group with cognitive impairment were all significantly associated with herb use among Epi/Sz residents. Cognitive impairment and the interaction of Epi/Sz disorder with dementia were associated specifically with ginkgo use.

CONCLUSIONS

Ginkgo is the most frequently prescribed herb in this population in which >50% of all herb orders were written for ginkgo. The concern with ginkgo use among elderly with Epi/Sz is the lack of standardization that characterizes ginkgo products. In the absence of standardization, the likelihood is increased that ginkgo products may be adulterated with the Ginkgo biloba plant parts most commonly associated with seizure provocation.

Extract of Ginkgo biloba leaves reverses yohimbine-induced spatial working memory deficit in rats

Extract of Ginkgo biloba is used to alleviate age-related decline in cognitive function, which may be associated with the loss of catecholamines in the prefrontal cortex. The purpose of this study was to verify whether alpha-2 adrenergic activity is involved in the facilitative effects of extract of Ginkgo biloba on prefrontal cognitive function. Male Wistar rats were trained to reach criterion in the delayed alternation task (0, 25, and 50-s delay intervals). A pilot study found that 3 or 4 mg/kg of yohimbine (intraperitoneal) reduced the choice accuracy of the delayed alternation task in a dose and delay-dependent manner, without influencing motor ability or perseverative behaviour. Acute oral pre-treatment with doses of 50, 100, or 200 mg/kg (but not 25 mg/kg) of extract of Ginkgo biloba prevented the reduction in choice accuracy induced by 4 mg/kg yohimbine. These data suggest that the prefrontal cognition-enhancing effects of extract of Ginkgo biloba are related to its actions on alpha-2-adrenoceptors.

Does Ginkgo biloba Special Extract EGb??761?? Provide Additional Effects on Coagulation and Bleeding when Added to Acetylsalicylic Acid 500mg Daily?

OBJECTIVE

The aim of this study was to determine whether Ginkgo biloba special extract EGb 761 amplifies the known effects of acetylsalicylic acid (ASA) on platelet aggregation, bleeding time or other coagulation parameters in healthy subjects.

METHODS

In a double-blind, double-dummy procedure, 50 healthy male subjects (20-44 years) were randomly allocated in equal numbers to one of two possible treatment sequences, i.e. ASA followed by ASA + EGb 761 or ASA + EGb 761 followed by ASA. Each treatment lasted 7 days; the washout period between treatments was 3 weeks. Study medication was taken twice daily (ASA group: ASA 500 mg tablet + placebo-coated tablet in the morning and placebo tablet + placebo-coated tablet in the evening; ASA + EGb 761 group: ASA 500 mg tablet + EGb 761 120 mg-coated tablet in the morning and placebo tablet + EGb 761 120 mg-coated tablet in the evening), resulting in a daily dose of ASA 500 mg in the ASA group and 500 mg ASA + 240 mg EGb 761 in the ASA + EGb 761 group. Bleeding time, coagulation parameters and platelet activity in response to various agonists were determined. In addition, adverse events, laboratory variables and vital signs were measured. The primary variable bleeding time was assessed in confirmatory analysis, all other variables were evaluated descriptively. The coagulation variables were analysed by ANOVA under the crossover model.

RESULTS

ASA given alone clearly prolonged bleeding time. ASA and the combination of ASA + EGb 761 exerted quite similar effects on all coagulation parameters measured, including bleeding time (ASA alone: 4.1 min before therapy, 6.2 min after therapy; ASA + EGb 761: 4.2 min before therapy, 6.3 min after therapy; ratio of means: 1.01, 90% CI 0.86, 1.19) and agonist-induced platelet aggregation (collagen-induced platelet aggregation - ASA: 84.5% before therapy, 81.0% after therapy; ASA + EGb 761: 86.6% before therapy, 81.0% after therapy; ratio of means: 1.00, 90% CI 0.95, 1.05; adenosine diphosphate-induced platelet aggregation - ASA: 72.6% before therapy, 47.2% after therapy; ASA + EGb 761: 71.7% before therapy, 44.8% after therapy; ratio of means: 0.95, 90% CI 0.85, 1.06). Both treatments were well tolerated, and both the number and nature of adverse events in the two groups were similar.

CONCLUSIONS

Our findings suggest that co-administration of ASA and EGb 761 does not constitute a safety risk, including in an elderly patient population undergoing treatment with EGb 761.

Recent pharmacological studies on natural products in China

Natural products have been used as medicinal agents for many years. In addition, these compounds have also served as the starting points for semisynthetic analogs with improved properties. This review focuses on recent advances in the pharmacological studies on natural products mainly performed and published in China. Emphasis will be placed on those compounds that show the greatest promise clinically such as huperzine A (9-amino-13-ethylidene-11-methyl-4-azatricyclo[7.3.1.0(3.8)]trideca-3(8),6,11-trien-5-one), s-(-)-3-n-butylphthalide (s-(-)-3-butyl-1(3H)-isobenzofuranone), (-)-clausenamide (3-hydroxy-4-phenyl-5a-hydroxybenzyl-N-methyl-gamma-lactam) and Ginkgo biloba extract and its active components.

Radioprotection by plant products: present status and future prospects

The development of radioprotective agents has been the subject of intense research in view of their potential for use within a radiation environment, such as space exploration, radiotherapy and even nuclear war. However, no ideal, safe synthetic radioprotectors are available to date, so the search for alternative sources, including plants, has been on going for several decades. In Ayurveda, the traditional Indian system of medicine, several plants have been used to treat free radical-mediated ailments and, therefore, it is logical to expect that such plants may also render some protection against radiation damage. A systematic screening approach can provide leads to identifying potential new candidate drugs from plant sources, for mitigation of radiation injury. This article reviews some of the most promising plants, and their bioactive principles, that are widely used in traditional systems of medicine, and which have rendered significant radioprotection in both in vitro and in vivo model systems. Plants and their constituents with pharmacological activities that may be relevant to amelioration of radiation-mediated damage, including antiemetic, antiinflammatory, antioxidant, cell proliferative, wound healing and haemopoietic stimulatories are also discussed.

Liquid chromatography/electrospray tandem mass spectrometry of terpenoid lactones in Ginkgo biloba

Ginkgo biloba (ginkgo) is one of most frequently used botanical dietary supplements. The bioactive constituents include the terpenoid lactones consisting of bilobalide and the ginkgolides A, B, C and J. A new assay based on high-performance liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) was developed for the measurement of the terpenoid lactones in ginkgo products such as leaf powder and extracts. Initially, the MS/MS fragmentation pathways of ginkgolides were investigated to identify abundant fragment ions that might be useful for the sensitive and selective detection of ginkgolides and bilobalide during LC/MS/MS. Then, sample preparation and clean-up procedures were streamlined to maximize throughput by taking advantage of the selectivity of LC/MS/MS detection. Analyte recoveries exceeded 90%, the intra-assay and inter-assay relative standard deviations were <5%, the relative error was <8% and the limits of detection and quantification were 3.6-120 and 11-350 fmol, depending on the analyte that was injected on to the LC column. Therefore, this LC/MS/MS assay facilitated the rapid quantitative analysis of ginkgolides A, B, C and J and bilobalide in ginkgo dietary supplements with excellent recovery, reproducibity, accuracy and sensitivity.

Anti-stress effects of Ginkgo biloba and Panax ginseng: a comparative study

Stress is a global menace fortified by the advancement of industrialization. Failure of stress management is due to lack of proper evaluation of anti-stress products. We explored the anti-stress potential of the Ginkgo biloba (G. biloba, 30 mg/kg, p.o.) and compared it with that of Panax ginseng (P. ginseng, 100 mg/kg, p.o.) against acute stress (AS) and chronic stress (CS) models in rats. Immediately after AS and CS, the rats were sacrificed, and adrenal glands and stomach were dissected out for weight determination and scoring of the ulcer index (UI), respectively, as well as changes in biochemical parameters like plasma glucose (GL), triglycerides (TG), cholesterol (CL), creatine kinase (CK), and serum corticosterone (CORT) were also estimated. AS significantly increased UI, adrenal gland weight (AGW), GL, CK activity, and CORT, whereas G. biloba significantly reduced them. P. ginseng significantly reverted GL and CK activity. In CS, a significant increase was found in the UI, AGW, CK activity, and CORT with a decrease in the level of CL and TG. G. biloba did not produce any significant effect on CS-induced alterations. P. ginseng reduced the UI, AGW, plasma GL, TG, CK activity, and CORT level significantly. From the above study, G. biloba is more effective in AS, whereas for CS, P. ginseng will be a better option. Hence these extracts possess significant anti-stress properties and can be used for the treatment of stress-induced disorders.

Preparation of a tritiated ginkgolide

Ginkgolide B, a constituent of the tree Ginkgo biloba, was radiolabeled with the beta-emitter tritium ([(3)H]) in two steps from ginkgolide C. First, a triflate precursor was prepared utilizing the selective reactivity of 7-OH in ginkgolide C; the triflate was then reduced with sodium borotritide to yield tritiated ginkgolide B ([(3)H]GB) in good yield and high specific activity. The tritiated ginkgolide will be an important tool for studying neuromodulatory properties of ginkgolides.

Implications of herbal alternative medicine for electroconvulsive therapy

OBJECTIVES

To clarify the implications of herbal alternative medicine use during electroconvulsive therapy (ECT).

BACKGROUND

A substantial proportion of patients with mental disorders report frequent use of herbal alternative medicines. Our current understanding of the biology of such remedies suggests that they may have implications for ECT practice.

METHODS

We conducted electronic literature searches using Medline (via PubMed), Cochrane Database of Systematic Reviews, ACP Journal Club, PsychINFO, Database of Abstracts of Reviews of Effects, and Cochrane Central Register of Controlled Trials from their inception to April 2003. The search items were five selected herbal alternative medicines (Ginkgo biloba, ginseng, St. John's wort, valerian, kava-kava) in combination with the terms "drug interaction," "adverse effects," "side effects," "adverse drug reactions," "safety," and "toxicity." All data were included regardless of whether they were case reports, case series, clinical trials, or reviews.

RESULTS

Our literature review revealed several potential effects of herbal alternative medicines upon ECT outcome.

CONCLUSIONS

The growing use of herbal alternative medicine by patients with psychiatric illness may have implications for ECT practice. Our current knowledge is sparse and incomplete, however, indicating the need for more research.

Estrogenic activities of Ginkgo biloba extracts

Ginkgo biloba extracts (GBE) are extracted from the leaves of Ginkgo biloba tree. GBE contains 24% of phytoestrogens, which is kaempferol, quercetin, and isorhamnetin. It has been reported that phytoestrogens could be a part of SERMs (Selective estrogen receptor modulators) and possibly the alternative HRT (Hormone replacement therapy) for postmenopausal women. The goal of this study was to investigate the potencies of GBE and its major components (quercetin, kaempferol, isorhamnetin) for estrogenic effect, which confirms the capacity as an alternative HRP. It was found that GBE and its major components exerted a dual action on ER-alpha and ER-beta in competitive binding assay. The binding affinity of these chemicals to ER-beta was higher than to ER-alpha. In the E-screen assay, these chemicals induced cell proliferation in ER-positive MCF-7 cell, but not in ER-negative MDA-MB-231 cells. The cell proliferation induced by these chemicals was blocked by tamoxifen. Also, GBE and its major components induced pS2 and PR (progesterone receptor) transcription in MCF-7 cells. Therefore these results indicated that GBE and its major components had the weak estrogenic activities through the estrogen response pathway by an interaction with the ER. In conclusion, we provided the evidence of potential estrogenic activities of GBE, which could be useful as an alternative HRP. However, further studies are required to assess the physiological significance of GBE in animals and humans.

Ginkgo biloba normalises stress-elevated alterations in brain catecholamines, serotonin and plasma corticosterone levels

Stress and depression and associated mental health problems have increased tremendously in modern times. The search for effective and safe alternatives from natural sources especially plant products should, therefore, continue. Forced immobilization is one of the best explored models of stress in rats and the role of corticosterone, serotonin and catecholamines, i.e. norepinephrine (NE), dopamine (DA) is well documented. Numerous studies have shown that Ginkgo biloba has antioxidant and neuroprotective properties and utility in cerebrovascular insufficiency and impaired cerebral performance. We investigated the effect of G. biloba on whole brain catecholamine, serotonin and plasma corticosterone levels following 1, 2 and 4 h restraint stress using HPLC and also plasma corticosterone using luminescence spectrophotometry. G. biloba extract (14 mg/kg p.o.) restored restraint stress-induced elevation in whole brain levels of catecholamines (NE, DA), 5-HT and plasma corticosterone to near normal levels. Further studies are warranted to explore the clinical potential of this encouraging lead in the management of stress and to elucidate the mechanisms involved.

A surgeon’s guide to herbal supplements

The use of herbal supplements has steadily increased in the United States over the last decade. Despite the increased awareness of alternative therapies by the government and lay public, many physicians do not ask their patients about their use of these alternative medications. In addition, many physicians are unaware of the possible side effects that may occur when a patient consumes these substances. Considering a number of these supplements have been associated with adverse reactions in the perioperative period, it is important for a surgeon to understand all of the herbs a patient may be taking. The purpose of this article is to discuss the growing trend of herbal use among surgical patients and give the reader some background on the most commonly used herbs.

Electroencephalograph effects of single doses of Ginkgo biloba and Panax ginseng in healthy young volunteers

Both Ginkgo biloba and Panax ginseng exert a number of physiological effects and have been shown to modulate aspects of cognitive performance. Whilst a number of studies have examined ginkgo's effects on electroencephalograph (EEG) recordings, to date, none have investigated the EEG effects of ginseng. In this double-blind, placebo-controlled, balanced crossover experiment, the effects of single doses of G. biloba (360 mg GK501), P. ginseng (200 mg G115), and an identical placebo, on auditory-evoked potentials, contingent negative variation (CNV), and resting power within the delta, theta, alpha, and beta wavebands, were assessed in 15 healthy volunteers. Each participant was assessed on three separate occasions 4 h after consuming that day's treatment. The order of presentation of the treatments was dictated by a Latin square with 7 days between testing sessions. The results showed that ginseng led to a significant shortening of the latency of the P300 component of the evoked potential. Both ginseng and ginkgo also led to significant reductions in frontal 'eyes closed' theta and beta activity, with additional reduction for ginseng in the alpha waveband. These findings demonstrate for the first time that P. ginseng can directly modulate cerebroelectrical activity, and that these effects are more pronounced than those following G. biloba.

Protective effect of ginkgo biloba extract on endothelial cell against damage induced by oxidative stress

The viability of bovine aortic endothelial cells (BAECs) treated with 0.1 m H O was decreased by 39.8%, and 100 mg/l EGb761 increased the viability by 20.6%. Exposure BAECs to H O for 6 min resulted in a significant elevation in the intracellular free Ca. Pretreatment of BAECs with 10 mg/l and 100 mg/l EGb761 for 10 min showed a decrease in the intracellular free Ca, 4.5% and 20.6%, respectively. The apoptotic rate of BAECs measured by propidium iodide (PI) staining was (38.1 +/- 2%) after 18 h of treatment with H O. Pretreatment of BAECs with 100 mg/l EGb761 for 1 h reduced the apoptotic rate to 27 +/- 1%. In addition, there were about 5-7% of cells stained positive measured by TUNEL assay. When BAECs were exposed to 0.1 m H O for 18 h, the number of TUNEL-positive cells increased to 37-44%. When 10 mg/l EGb761 and 100 mg/l EGb761 were used, the TUNEL-positive cells decreased to 26.5 +/- 3.1% and 17.5 +/- 1.7%, respectively. Furthermore, EGb761 also inhibited caspase-3 activity induced by H O. It is concluded that EGb761 has protective effect on bovine vascular endothelial cells against damage induced by H O. Further studies are needed to clarify the mechanisms of action of EGb761.

A comparative study in rodents of standardized extracts of Bacopa monniera and Ginkgo biloba: anticholinesterase and cognitive enhancing activities

Bacopa monniera and Ginkgo biloba are well-known cognitive enhancers in Indian and Chinese traditional medicine systems. Standardized extracts of B. monniera and G. biloba were used to evaluate the antidementic and anticholinesterase activities in adult male Swiss mice. Antidementic activity was tested against scopolamine (3 mg/kg ip)-induced deficits in passive avoidance test. Three different extracts of B. monniera (30 mg/kg) and extract of G. biloba (15, 30 and 60 mg/kg) were administered postoperatively, daily for 7 days and 60 min after the last dose, i.e., on Day 7, first trial was conducted. In passive avoidance test, increased transfer latency time (TLT) and no transfer response (NTR) were taken as criteria for learning. TLT and NTR were significantly increased and decreased in second trial, 24 h after the first trial in control group and scopolamine-dementia group, respectively. The B. monniera- and G. biloba-treated groups produced significant increase in TLT and NTR on second trial (40-80%) after scopolamine treatment, thus, attenuating its antidementic effect. Both the extracts showed a dose (10-1000 microg)-dependent inhibitory effect on acetylcholinesterase (AChE) activity (in vitro), performed spectrophotometrically. IC(50) of G. biloba was 268.33 microg, whereas none of the extracts of B. monniera showed more than 50% inhibition. At a dose concentration of 30 and 60 mg/kg, extracts of G. biloba showed a cognitive enhancing property and, at the same time, a significant decrease in AChE-specific activity in both per se and scopolamine-dementia groups. These extracts possess a significant anticholinesterase and antidementic properties, which may be useful in the treatment of dementia.

Apoptosis of hepatoma cells SMMC-7721 induced by Ginkgo biloba seed polysaccharide

AIM: To study the apoptosis of hepatoma cells SMMC-7721 induced by polysaccharide isolated from Ginkgo biloba seed.

METHODS: Ginkgo biloba seed polysaccharide (GBSP) was isolated by ethanol fractionation of Ginkgo biloba seed and purified by Sephadex G-200 chromatography. The purity of GBSP was verified by reaction with iodine-potassium iodide and ninhydrin and confirmed by UV spectrophotometer, cellulose acetate membrane electrophoresis and Sepharose 4B gel filtration chromatography. The Scanning Electron Microscope (SEM) and Flow Cytometry (FCM) were used to examine the SMMC-7721 cells with and without GBSP treatment at 500 mg/mL for 36 h.

RESULTS: GBSP product obtained was of high purity with the average molecular weight of 1.86 × 10⁵. Quantitative analysis of SMMC-7721 cells in vitro with FCM showed that the percentages of G2-M cells without and with GBSP treatment were 17.01% ± 1.28% and 11.77% ± 1.50% (P < 0.05), the debris ratio of the cells were 0.46% ± 0.12% and 0.06% ± 0.06% (P < 0.01), and the apoptosis ratio of cells was 3.84% ± 0.55% and 9.13% ± 1.48% (P < 0.01) respectively. Following GBSP treatment, microvilli of SMMC-7721 cells appeared thinner and the number of spherical cells increased markedly. Most significantly, the apoptosis bodies were formed on and around the spherical cells treated with GBSP.

CONCLUSION: GBSP could potentially induce the apoptosis of SMMC-7721 cells.

Simultaneous determination of terpene lactones and flavonoid aglycones in Ginkgo biloba by high-performance liquid chromatography with evaporative light scattering detection

A gradient high performance liquid chromatographic method with evaporative light scattering detection (ELSD) for the simultaneous determination of ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, bilobalide, quercetin, kaempferol and isorhamnetin in Ginkgo biloba is described. Samples are analyzed by means of a reverse-phase column (Supelco Discovery C-18) using methanol (containing 0.05% TFA) and water (containing 5% methanol and 0.05% TFA) under gradient conditions as the mobile phase over 35 min. The evaporative light scattering detector (ELSD) used, is set at an evaporating temperature of 61 degrees C and compressed air pressure of 2.9 bar. The detection limits (S/N>3) of the compounds tested are 20-35 ng on the column. The exponential linear calibration curves are observed for all the compounds tested with r(2) more than 0.998. The reproducibility of the method was evaluated by analyzing three sets of controls on 3 consecutive days with RSD% and relative errors (RE%) less than 17.26 and 14.67%.

Ginkgolides: selective acetylations, translactonization, and biological evaluation

Protocols for selective acetylation of the hydroxyl groups of ginkgolide C have been developed. These acetylations have given rise to various ginkgolide C acetates and iso-ginkgolide C acetates, the latter having a rearranged skeleton resulting from translactonization. These acetyl derivatives, as well as ginkgolides A and B acetates have been investigated for their ability to bind to a cloned platelet-activating factor (PAF) receptor.

Acute administration of Ginkgo biloba extract (EGb 761) affords neuroprotection against permanent and transient focal cerebral ischemia in Sprague-Dawley rats

We examined the neuroprotective action of a standardized extract of Ginkgo biloba leaves (EGb 761) in permanent and transient middle cerebral artery (MCA) occlusion models in Sprague-Dawley rats. Forty-four animals were given either EGb 761 (50-200 mg/kg) or vehicle intraperitoneally, 1 hr before permanent MCA occlusion, to evaluate the dose-response effects. An additional 58 animals received EGb 761 (200 mg/kg) or vehicle, 0.5- 4 hr after permanent MCA occlusion, for establishing the therapeutic window. Delayed treatment was also employed in 110 animals treated with either EGb 761 (100-200 mg/kg) or vehicle at 2-3 hr following transient focal cerebral ischemia induced by MCA occlusion for 2 hr. Neurobehavioral scores were determined 22-24 hr after permanent MCA occlusion and either 3 or 7 days after transient MCA occlusion, and brain infarction volumes were measured upon sacrifice. Local cortical blood flow (LCBF) was serially measured in a subset of animals receiving EGb 761 (100-200 mg/kg) or vehicle, 0.5 hr and 2 hr after permanent and transient MCA occlusion, respectively. Relative to vehicle-treated controls, rats pretreated with EGb761 (100 and 200 mg/kg) had significantly reduced infarct volumes, by 36% and 49%, respectively, and improved sensory behavior (P < 0.05). Delayed treatment with EGb 761 also significantly reduced brain infarction, by 20-29% and 31%, when given up to 2 and 3 hr following transient and permanent MCA occlusion, respectively, whereas improved neurobehavioral scores were noted up to 2 hr after the onset of MCA occlusion (P < 0.05). LCBF was significantly improved in the ipsilateral cortex following the EGb 761 treatment, whereas a higher dose showed a more sustained effect. In conclusion, EGb 761 protected against transient and permanent focal cerebral ischemia and was effective after a prolonged reperfusion period even when therapy is delayed up to 2 hr. This neuroprotection may be at least partially attributed to the beneficial effects of selectively improved LCBF in the area at risk of infarction.

Comparative study of two Ginkgo biloba extracts on the phagocytic activity and DTH response of healthy mice

The phagocytic activity and delayed-type Hypersensitivity (DTH) response to dinitrofluorobenzene (DNFB) of healthy BALB/c mice treated orally (100 mg/kg/day for 7 days) using two Ginkgo biloba extracts were studied. The phytopharmaceuticals Gb 30 (Alban Muller International, France) and EGb 761 (Schwabe, Germany) administered orally stimulated the phagocytic activity of peritoneal and alveolar macrophages. Likewise, the DTH response was found to be increased only with Gb 30 treatment. These results suggest that Ginkgo biloba possesses immunological activity in addition to the biological activity reported. The different chemical concentration of the components of the Ginkgo biloba extracts mentioned above may be responsible for the differences in the observed findings.

Dietary flavonoids as potential neuroprotectants

There is an increasing awareness of the role of certain nutritional components, including dietary flavonoids found in fruit, vegetables and beverages, in the maintenance of health and prevention of chronic diseases. In this regard, recent studies highlight an exciting role with respect to their potential neuroprotective actions, in particular towards deficits commonly observed with aging, such as reduced performance of cognitive, memory and learning tasks. These neurological functions, and possible mechanisms involved in controlling them, can be influenced by supplementation of single dietary flavonoids, or as part of a flavonoid-rich preparation. With this, a renewed emphasis is aimed at further understanding their modes and sites of action. Moreover a common theme among many in vitro studies examining mechanisms of neuroprotection is the failure to include biologically relevant metabolites of the flavonoids known to enter the circulation, and thus most likely to be bioavailable to cells and tissues. This oversight will ultimately influence the mechanisms of action proposed to explain the neuroprotection observed in animals and human studies. As such, emerging findings suggest a variety of potential mechanisms of action of flavonoids and their bioavailable metabolites in cytoprotection against oxidative stress, which may be independent of conventional antioxidant reducing activities. Such mechanisms might involve their interaction with cell signalling cascades, their influence on gene expression and the down regulation of pathways leading to cell death.

Pharmacokinetics and bioavailability of herbal medicinal products

The use of herbs for treating various ailments dates back several centuries. Usually, herbal medicine has relied on tradition that may or may not be supported by empirical data. The belief that natural medicines are much safer than synthetic drugs has gained popularity in recent years and led to tremendous growth of phytopharmaceutical usage. Market driven information on natural products is widespread and has further fostered their use in daily life. In most countries there is no universal regulatory system that insures the safety and activity of phytopharmaceuticals. Evidence-based verification of the efficacy of HMPs (herbal medicinal products, botanicals) is still frequently lacking. However, in recent years, data on evaluation of the therapeutic and toxic activity of herbal medicinal products became available. The advances in analytical technology have led to discovery of many new active constituents and an ever-increasing list of putatively active constituents. Establishing the pharmacological basis for efficacy of HMPs is a constant challenge. Of particular interest is the question of bioavailability to assess to what degree and how fast compounds are absorbed after administration of HMPs. Of further interest is the elucidation of metabolic pathways (yielding potentially new active compounds), and the assessment of elimination routes and their kinetics. These data become an important issue to link data from pharmacological assays and clinical effects. Of interest are currently also interactions of herbal medicinal products with synthetically derived drug products. A better understanding of the pharmacokinetics and bioavailability of phytopharmaceuticals can also help in designing rational dosage regimens. In this review, pharmacokinetic and bioavailability studies that have been conducted for some of the more important or widely used phytopharmaceuticals are critically evaluated. Furthermore, various drug interactions are discussed which show that caution should be exercised when combining phytopharmaceuticals with chemically derived active pharmaceutical ingredients.

Enhanced maze performance and reduced oxidative stress by combined extracts of zingiber officinale and ginkgo biloba in the aged rat

Here we assessed the effects of i.g. administration of Zingicomb (ZC), a mixture of zingiber officinale and ginkgo biloba extracts, on learning and memory, and on indicators of oxidative stress in aged rats. Effects of ZC (1 and 10 mg/kg) were investigated in 22-24 months old Wistar rats using the Morris water maze, in which they show deficient performance as compared to 3 months old rats in the undrugged state (days 1 and 2). Treatment was administered on days 3 and 4 of training, then over 7 days with training discontinued, and again on days 5 and 6 when training was resumed. Thereafter chronic treatment was maintained over 5 months. 1 mg/kg ZC improved escape learning in the water maze. The two capital indicators of oxidative stress in brain homogenates, the amount of oxidized proteins (assessed as carbonyl group containing proteins) and lipid peroxidation, were significantly reduced in ZC treated animals. Thus, ZC, which had previously been shown to improve inhibitory avoidance learning and to have anxiolytic properties in adult animals, might also facilitate spatial learning in aged animals, and reduces indices of oxidative stress in brain tissue after chronic treatment.

The effect of Ginkgo biloba on memory in healthy male volunteers

The purpose of this study was to investigate possible effects of Ginkgo biloba, a widely used herbal extract, on memory. This study incorporated a double-blind, placebo-controlled design, which used 30 healthy male subjects in each of two groups. The treatment group received two 60-mg tablets of BioGinkgo (27/7) [corrected] daily for 5 days, while the placebo group received a placebo. On the fifth day, after a 2-h waiting period, all subjects were given the Sternberg Memory Scanning Test [Q. J. Exp. Psychol. 27 (1975) 1.], a reaction time control test, the vocabulary and digit span subtests of the WAIS-R [Wechsler D. Manual for the Wechsler adult intelligence scale - revised. New York: Psychological Corporation, 1981.], a reading span test [J. Verbal Learn. Verbal Behav. 19 (1980) 450.] and a prose recall test [Discourse Proc. 13 (1990) 387.]. Blood pressure, heart rate and side effects were also monitored throughout the study. Nonsignificant results were found on all interactions involving treatment group on all tests except the Sternberg Memory Scanning Test. The extract appeared to be safe but largely ineffective in enhancing memory.

K(Ca) channel-opening activity of Ginkgo Biloba extracts and ginsenosides in cultured endothelial cells

1. Extracts of Ginkgo biloba (EGb) and ginsenosides (GS) have been reported to induce vasorelaxation. In the present study, the role of K+ channels in the action of EGb and GS to activate nitric oxide synthase (NOS) activity was investigated in cultured endothelial cells. 2. Nitric oxide synthase activity of cultured endothelial cells detected by the reduced nicotinamide adenine dinucleotide phosphate (NADPH) histochemistry method was significantly increased after treatment with 20 microg/mL EGb or 40 microg/mL GS plus 10 mmol/L L-arginine. The effect was completely abolished by the addition of 0.5 micromol/L Nomega-nitro-L-arginine, an inhibitor of NOS, to the incubation medium and partially inhibited by 10 micromol/L tetraethylammonium (TEA), an inhibitor of Ca2+-activated K+ (KCa) channels. 3. Application of EGb to the intracellular surface of excised inside-out patches activated K+ channels in a concentration-dependent manner in the concentration range 1-100 microg/mL. Channel activity was also activated by application of GS at concentrations ranging from 1 to 300 microg/mL. The modulation of channel activity was inhibited by 0.5 mmol/L TEA but not by 0.5 mmol/L glibenclamide, an inhibitor of ATP-sensitive K+ channels. 4. Thus, in cultured endothelial cells, the increase in NOS activity induced by EGb or GS depends on the activity of KCa channels. These compounds may regulate nitric oxide release by changing the cell membrane potential in vascular endothelial cells.

A possible emerging role of phytochemicals in improving age-related neurological dysfunctions: a multiplicity of effects

It is rare to see a day pass in which we are not told through some popular medium that the population is becoming older. Along with this information comes the "new" revelation that as we enter the next millennium there will be increases in age-associated diseases (e.g., cancer, cardiovascular disease) including the most devastating of these, which involve the nervous system (e.g., Alzheimer's disease [AD] and Parkinson's disease [PD]). It is estimated that within the next 50 years approximately 30% of the population will be aged 65 years or older. Of those between 75 and 84 years of age, 6 million will exhibit some form of AD symptoms, and of those older than 85 years, over 12 million will have some form of dementia associated with AD. What appears more ominous is that many cognitive changes occur even in the absence of specific age-related neurodegenerative diseases. Common components thought to contribute to the manifestation of these disorders and normal age-related declines in brain performance are increased susceptibility to long-term effects of oxidative stress (OS) and inflammatory insults. Unless some means is found to reduce these age-related decrements in neuronal function, health care costs will continue to rise exponentially. Thus, it is extremely important to explore methods to retard or reverse age-related neuronal deficits as well as their subsequent, behavioral manifestations. Fortunately, the growth of knowledge in the biochemistry of cell viability has opened new avenues of research focused at identifying new therapeutic agents that could potentially disrupt the perpetual cycle of events involved in the decrements associated with these detrimental processes. In this regard, a new role in which certain dietary components may play important roles in alleviating certain disorders are beginning to receive increased attention, in particular those involving phytochemicals found in fruits and vegetables.

An examination of the efficacy of Ginkgo biloba extract EGb761 on the neuropsychologic functioning of cognitively intact older adults

OBJECTIVES

Few investigations have examined the effectiveness of Ginkgo biloba extract for enhancing cognitive abilities in individuals with no history of significant neurocognitive dysfunction. The purpose of this research was to examine the relatively short-term (i.e., 6 weeks) efficacy of Ginkgo biloba extract EGb 761 on the cognitive functioning of cognitively intact persons over the age of 55 years via a diverse battery of neuropsychologic tests and measures.

PARTICIPANTS

From the 48 cognitively intact participants between the ages of 55 and 86 years who initially enrolled in this study, 21 males and 19 females successfully completed the study's protocol and provided valid data sets.

DESIGN

A 6-week, double-blind, fixed-dose, placebo-controlled, parallel-group experimental design was utilized. Participants were randomly assigned to either a Ginkgo biloba extract EGb 761 (180 mg/d) or placebo control group. To evaluate participants' cognitive and behavioral functioning, series of neuropsychological tests were administered to them prior to the initiation of the Ginkgo biloba extract/placebo therapy (i.e., pretreatment baseline) and again, just prior to the termination of the treatment regimen (i.e., after 6 weeks).

RESULTS

Participants who received 180 mg of Ginkgo biloba extract EGb 761 daily for 6 weeks exhibited significantly more improvement on a task assessing speed of processing abilities (i.e., Stroop Color and Word Test color-naming task) by the end of treatment as compared to participants who received placebo. Trends favoring improved performances in the Ginkgo biloba group were also demonstrated in three of the four remaining tasks that involved a timed, speed of processing component, although they did not reach statistical significance. Furthermore, a significant relationship was found between the type of treatment (Ginkgo biloba extract or placebo) and participants' ratings of their overall abilities to remember. Specifically, more participants in the Ginkgo biloba extract group rated their overall abilities to remember by the end of treatment as "improved," as compared to the placebo group. In contrast, no significant differences were found between the Ginkgo biloba and placebo groups by treatment end on any of the four objective memory measures.

CONCLUSIONS

Taken together, the findings from standardized neuropsychologic assessment and a subjective, self-report questionnaire suggested that relatively short-term (i.e., 6 weeks) utilization of Ginkgo biloba extract EGb 761 may prove efficacious in enhancing certain neurocognitive functions/processes of cognitively intact older adults.

The Ginkgo biloba extract (EGb 761) protects and rescues hippocampal cells against nitric oxide-induced toxicity: involvement of its flavonoid constituents and protein kinase C

An excess of the free radical nitric oxide (NO) is viewed as a deleterious factor involved in various CNS disorders. Numerous studies have shown that the Ginkgo biloba extract EGb 761 is a NO scavenger with neuroprotective properties. However, the mechanisms underlying its neuroprotective ability remain to be fully established. Thus, we investigated the effect of different constituents of EGb 761, i.e., flavonoids and terpenoids, against toxicity induced by NO generators on cells of the hippocampus, a brain area particularly susceptible to neurodegenerative damage. Exposure of rat primary mixed hippocampal cell cultures to either sodium nitroprusside (SNP; 100 microM) or 3-morpholinosydnonimine resulted in both a decrease in cell survival and an increase in free radical accumulation. These SNP-induced events were blocked by either EGb 761 (10-100 microg/ml) or its flavonoid fraction CP 205 (25 microg/ml), as well as by inhibitors of protein kinase C (PKC; chelerythrine) and L-type calcium channels (nitrendipine). In contrast, the terpenoid constituents of EGb 761, known as bilobalide and ginkgolide B, as well as inhibitors of phospholipases A [3-[(4-octadecyl)benzoyl]acrylic acid (OBAA)] and C (U-73122), failed to display any significant effects. Moreover, EGb 761 (50 microm) CP 205 (25 microg/ml), and chelerythrine were also able to rescue hippocampal cells preexposed to SNP (up to 1 mM). Finally, EGb 761 (100 microg/ml) was shown to block the activation of PKC induced by SNP (100 microM). These data suggest that the protective and rescuing abilities of EGb 761 are not only attributable to the antioxidant properties of its flavonoid constituents but also via their ability to inhibit NO-stimulated PKC activity.

Platelet activating factor (PAF) antagonists on cytokine induction of iNOS and sPLA2 in immortalized astrocytes (DITNC)

Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) and its receptor are known to play important roles in modulating neuronal plasticity and inflammatory responses, particularly during neuronal injury. PAF receptors are widespread in different brain regions and are present on the cell surface as well as in intracellular membrane compartments. Astrocytes are immune active cells and are responsive to cytokines, which stimulate signaling cascades leading to transcriptional activation of genes and protein synthesis. Our recent studies indicate the ability of cytokines, e.g., tumor necrosis factor-alpha (TNFalpha), interleukin-1beta (IL-1beta) and interferon-gamma (IFNgamma), to induce the inducible nitric oxide (iNOS) and secretory phospholipase A2 (sPLA2) genes in immortalized astrocytes (DITNC) (Li et al., J. Interferon and Cytokine Res. 19: 121-127. 1999). The main objective for this study is to examine the effects of PAF antagonists on cytokine induction of iNOS and sPLA2 in these cells. Results show that BN50730, a synthetic PAF antagonist, but not BN52021, a natural PAF antagonist (ginkolide B) can dose-dependently inhibit cytokine induction of NO production and sPLA2 release. Inhibition of NO production by BN50730 corroborated well with the decrease in iNOS protein and mRNA levels as well as binding of NF-kappaB STAT- 1 to DNA, suggesting that BN50730 action is upstream of the transcriptional process. These results are in agreement with the role of intracellular PAF in regulating the cytokine signaling cascade in astrocytes and further suggest the possible use of BN50730 as a therapeutic agent for suppressing the inflammatory pathways elicited by cytokines.

Identification of kaempferol as a monoamine oxidase inhibitor and potential Neuroprotectant in extracts of Ginkgo biloba leaves

The effects of Ginkgo biloba leaf extract on rat brain or livermonoamine oxidase (MAO)-A and -B activity, biogenic amine concentration in nervous tissue, N-methyl-D-aspartate (NMDA)- and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4)-induced neurotoxicity and antioxidant activity was investigated to determine the effects of the extract on monoamine catabolism and neuroprotection. Ginkgo biloba leaf extract was shown to produce in-vitro inhibition of rat brain MAO-A and -B. The Ginkgo biloba extract was chromatographed on a reverse-phase HPLC system and two of the components isolated were shown to be MAO inhibitors (MAOIs). These MAOIs were identified by high-resolution mass spectrometry as kaempferol and isorhamnetin. Pure kaempferol and a number of related flavonoids were examined as MAOIs in-vitro. Kaempferol, apigenin and chrysin proved to be potent MAOIs, but produced more pronounced inhibition of MAO-A than MAO-B. IC50 (50% inhibition concentration) values for the ability of these three flavones to inhibit MAO-A were 7 x 10(-7), 1 x 10(-6) and 2 x 10(-6) M, respectively. Ginkgo biloba leaf extract and kaempferol were found to have no effect ex-vivo on rat or mouse brain MAO or on concentrations of dopamine, noradrenaline, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid. Kaempferol was shown to protect against NMDA-induced neuronal toxicity in-vitro in rat cortical cultures, but did not prevent DSP-4-induced noradrenergic neurotoxicity in an in-vivo model. Both Ginkgo biloba extract and kaempferol were demonstrated to be antioxidants in a lipid-peroxidation assay. This data indicates that the MAO-inhibiting activity of Ginkgo biloba extract is primarily due to the presence of kaempferol. Ginkgo biloba extract has properties indicative of potential neuroprotective ability.

Neuroprotection: is it already applicable to glaucoma therapy?

Many categories of both natural and synthetic compounds have been reported to have neuroprotective activity. These include not only antioxidants, N-methyl-D-aspartate receptor antagonists, inhibitors of glutamate release, calcium channel blockers, polyamine antagonists, and nitric oxide synthase inhibitors, but cannabinoids, aspirin, melatonin, and vitamin B-12. The lack of availability of specific neuroprotectant compounds in the United States and the lack of clinical trials examining the benefits of neuroprotective agents for glaucoma currently limit the use of these agents. This article provides a short overview of the concept of neuroprotection as it applies to glaucoma and suggests the possibility of neuroprotective activity that might be provided by compounds that are presently easily available.

Protective and rescuing abilities of IGF-I and some putative free radical scavengers against beta-amyloid-inducing toxicity in neurons

beta-Amyloid (A beta) peptides are most likely involved in the neurodegenerative process occurring in Alzheimer's Disease (AD) and are enriched in senile plaques. The mechanisms of A beta toxicity are not clear but likely involve free radicals and apoptosis. Much interest is currently aiming at developing effective approaches to block A beta toxicity in order to slow down disease progression. In that context, we are particularly interested in studying the role of insulin-like growth factors, particularly IGF-I and purported free radical scavengers including a Gingko biloba extract (EGb761) as blocker of A beta toxicity in a simple in vitro model of hippocampal primary cultures. We observed that both IGF-I and EGb761 are unique in that they are able not only to protect but even to rescue neurons against A beta toxicity. These results are summarized here and possible mechanisms of action are discussed to explain the protective properties of these two classes of agents.