Proof of efficacy of the Ginkgo biloba special extract EGb 761 in outpatients suffering from mild to moderate primary degenerative dementia of the Alzheimer type or multi-infarct dementia

Ferroptosis, Pyroptosis, and Cuproptosis in Alzheimer's Disease

Alzheimer's disease (AD), the most common type of dementia, is a neurodegenerative disorder characterized by progressive cognitive dysfunction. Epidemiological investigation has demonstrated that, after cardiovascular and cerebrovascular diseases, tumors, and other causes, AD has become a major health issue affecting elderly individuals, with its mortality rate acutely increasing each year. Regulatory cell death is the active and orderly death of genetically determined cells, which is ubiquitous in the development of living organisms and is crucial to the regulation of life homeostasis. With extensive research on regulatory cell death in AD, increasing evidence has revealed that ferroptosis, pyroptosis, and cuproptosis are closely related to the occurrence, development, and prognosis of AD. This paper will review the molecular mechanisms of ferroptosis, pyroptosis, and cuproptosis and their regulatory roles in AD to explore potential therapeutic targets for the treatment of AD.

Nootropic Herbs, Shrubs, and Trees as Potential Cognitive Enhancers

Plant-based nootropics are a diverse group of natural drugs that can improve cognitive abilities through various physiological mechanisms, especially in cases where these functions are weakened or impaired. In many cases, the nootropics enhance erythrocyte plasticity and inhibit aggregation, which improves the blood's rheological properties and increases its flow to the brain. Many of these formulations possess antioxidant activity that protects brain tissue from neurotoxicity and improves the brain's oxygen supply. They can induce the synthesis of neuronal proteins, nucleic acids, and phospholipids for constructing and repairing neurohormonal membranes. These natural compounds can potentially be present in a great variety of herbs, shrubs, and even some trees and vines. The plant species reviewed here were selected based on the availability of verifiable experimental data and clinical trials investigating potential nootropic effects. Original research articles, relevant animal studies, meta-analyses, systematic reviews, and clinical trials were included in this review. Selected representatives of this heterogeneous group included Bacopa monnieri (L.) Wettst., Centella asiatica (L.) Urban, Eleutherococcus senticosus (Rupr. & Maxim.) Maxim., Ginkgo biloba L., Lepidium meyenii Walp., Panax ginseng C.A. Meyer, Paullinia cupana Kunth, Rhodiola rosea L., Schisandra chinensis (Turcz.) Baill., and Withania somnifera (L.) Dunal. The species are depicted and described, together with their active components and nootropic effects, and evidence of their efficacy is presented. The study provides brief descriptions of the representative species, their occurrence, history, and the chemical composition of the principle medicinal compounds, with uses, indications, experimental treatments, dosages, possible side effects, and contraindications. Most plant nootropics must be taken at optimal doses for extended periods before measurable improvement occurs, but they are generally very well tolerated. Their psychoactive properties are not produced by a single molecule but by a synergistic combination of several compounds. The available data suggest that including extracts from these plants in medicinal products to treat cognitive disorders can have substantial potential therapeutic benefits.

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

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

Shenmayizhi Formula Combined with Ginkgo Extract Tablets for the Treatment of Vascular Dementia: A Randomized, Double-Blind, Controlled Trial

Shenmayizhi formula (SMYZF) has been shown to have an effect on vascular dementia (VaD) in previous studies. The aim of this study was to evaluate whether a combination of SMYZF with Ginkgo extract tablets improves mild-to-moderate VaD. In this 12-week, randomized, double-blind, controlled study, we randomly assigned 196 patients with VaD (aged 50-85 years) to either the SMYZF group (n = 98) or the Ginkgo group (n = 98). All patients received Ginkgo extract tablets as a basic treatment, while the SMYZF group also received SMYZF treatment. We evaluated the participants at baseline and after 12 weeks of the intervention for the following: the Mini-Mental State Examination (MMSE), National Institutes of Health Stroke Scale (NIHSS), activities of daily living (ADL), Chinese Medicine Symptom Scale (CM-SS) scores, serum endothelin-1 (ET-1), nitric oxide (NO), vascular endothelial growth factor (VEGF), von Willebrand factor (vWF), neuron-specific enolase (NSE), brain-derived neurotrophic factor (BDNF), and homocysteine (Hcy) serum levels. Both interventions significantly increased MMSE scores and decreased NIHSS, ADL, and CM-SS scores. The SMYZF group showed greater improvement in MMSE, NIHSS, and CM-SS scores. Both groups showed a significant decrease in serum ET-1 and an increase in serum VEGF. Furthermore, serum NO increased, and vWF decreased significantly in the SMYZF group. Changes in serum ET-1 and NO were greater in the SMYZF group. Both groups showed a significant increase in serum BDNF and a decrease in serum NSE and Hcy. Improvement in serum NSE and BDNF was greater in the SMYZF group. SMYZF combined with Ginkgo extract tablets improved vascular endothelial and cognitive functions, as well as the syndromes diagnosed based on the traditional Chinese medicine in patients with VaD.

Mitochondria- and Oxidative Stress-Targeting Substances in Cognitive Decline-Related Disorders: From Molecular Mechanisms to Clinical Evidence

Alzheimer's disease (AD) is the most common form of dementia affecting people mainly in their sixth decade of life and at a higher age. It is an extensively studied neurodegenerative disorder yet incurable to date. While its main postmortem brain hallmarks are the presence of amyloid-β plaques and hyperphosphorylated tau tangles, the onset of the disease seems to be largely correlated to mitochondrial dysfunction, an early event in the disease pathogenesis. AD is characterized by flawed energy metabolism in the brain and excessive oxidative stress, processes that involve less adenosine triphosphate (ATP) and more reactive oxygen species (ROS) production respectively. Mitochondria are at the center of both these processes as they are responsible for energy and ROS generation through mainly oxidative phosphorylation. Standardized Ginkgo biloba extract (GBE), resveratrol, and phytoestrogens as well as the neurosteroid allopregnanolone have shown not only some mitochondria-modulating properties but also significant antioxidant potential in in vitro and in vivo studies. According to our review of the literature, GBE, resveratrol, allopregnanolone, and phytoestrogens showed promising effects on mitochondria in a descending evidence order and, notably, this order pattern is in line with the existing clinical evidence level for each entity. In this review, the effects of these four entities are discussed with special focus on their mitochondria-modulating effects and their mitochondria-improving and antioxidant properties across the spectrum of cognitive decline-related disorders. Evidence from preclinical and clinical studies on their mechanisms of action are summarized and highlighted.

Influence of Mineral Supplementation on the Results from Analysis of Flavonol Glycoside Content in Ginkgo biloba Dietary Supplements

Flavonoids are a major component of Ginkgo biloba extract (GBE). Several studies have investigated chelate formation and the redox reaction between flavonoids and metal ions; however, the effect of mineral supplements on the results from the analysis of the flavonol glycoside content in products containing GBE dietary supplement remains unknown. In this study, the effects of commonly used mineral supplements on the recovery of quercetin from GBE-containing dietary supplements were investigated using conventional methods of flavonol glycoside determination. Mineral supplements containing Zn (II), Mn (II), and Fe (II) did not affect quercetin recovery, whereas Cu (II) and Fe (III) significantly reduced recovery (P<0.05). Quercetin oxidation was prevented by adding an antioxidant to the diluent (extraction solvent). Among the tested synthetic antioxidants, tert-butyl hydroquinone (TBHQ) promoted the greatest increase in quercetin recovery. The flavonol glycoside content of commercially available GBE-containing dietary supplements was analyzed using a conventional diluent or a diluent containing 20 mg/mL TBHQ. The amount of quercetin recovered from products containing Cu (II) was found to decrease with increasing hydrolysis duration and the duration in the final test solution state using the conventional diluent, while the TBHQ-containing diluent yielded consistent quercetin contents (P<0.05). These findings suggest that quercetin, a major aglycone of GBE flavonol glycosides, can be oxidized by Cu (II) and Fe (III) during the analytical process and, therefore, the total flavonol glycoside content may be underestimated. The addition of TBHQ to the diluent can improve the accuracy and reproducibility of flavonol glycoside content analysis in GBE-containing dietary products supplemented with minerals.

The use of ginkgo biloba in the treatment of dementia

Aims and Method

To assess and update the available data on use of ginkgo to treat dementia. A Medline search as conducted for the period January 1985 to October 2000. The search included other aspects of the usage of ginkgo, such as side-effects, mechanism of action and drug interactions.

Results

Most of the trials using ginkgo were to treat cerebral insufficiency. Only five trials could be identified that used ginkgo to treat dementia. There are no trials comparing ginkgo to cholinesterase inhibitors such as donepezil.

Clinical Implications

Ginkgo is generally well-tolerated and appears to ease the symptoms of dementia. Although it has been suggested that the effect is comparable to donepezil, confirmation from controlled studies is required.

Long-term pre-treatment of antioxidant Ginkgo biloba extract EGb-761 attenuates cerebral-ischemia-induced neuronal damage in aged mice

Antioxidant activity has been attributed to the neuroprotective effects of Ginkgo biloba extract EGb-761 on brain disorders including ischemic stroke. It is suggested that oxidative stress implicates in neuron injuries during aging. However, whether or not EGb-761 could be used to treat age-related cerebral ischemia is unclear. In the present study, we directly studied the protective effects of EGb-761 in brain ischemia in the mice with different age. As expected, the recovery from brain damages was impaired in aged mice (24 months) in an animal model of middle cerebral artery occlusion (MCAO). Notably, a 12-month pretreatment of EGb-761 significantly ameliorated the ischemic injury of aged mice in a dose-dependent manner. The decreased stroke severity by EGb-761 was suggested by the reduced infarct volumes and brain edema, accompanied by alleviated oxidative stress. Additionally, we further explored the potential involvement of extra-cellular signal-regulated kinase (ERK) activation by MCAO in aged mice. ERK activation after MCAO was diminished by EGb-761, and this reduction may be mediated through an upregulation of phosphatase PP2A by EGb-761. These observations collectively support that natural antioxidant EGb-761 could be potentially exploited as an effective approach in treating neurological injury during aging.

Ginkgo biloba extract mitigates liver fibrosis and apoptosis by regulating p38 MAPK, NF-κB/IκBα, and Bcl-2/Bax signaling

Background

Liver fibrosis is the consequence of diverse liver injuries and can eventually develop into liver cirrhosis. Ginkgo biloba extract (GBE) is an extract from dried ginkgo leaves that has many pharmacological effects because of its various ingredients and has been shown to be hepatoprotective.

Purpose and methods

Aimed to investigate the underlying protective mechanisms of GBE on carbon tetrachloride (CCl₄)-induced liver fibrosis in rats. Male Sprague Dawley rats were randomly divided into four groups: control group (C), model group (M), low-dose group (L), and high-dose group (H). Liver fibrosis was induced by CCl₄ groups M, L, and H: group C was administered saline. In addition, GBE at different doses was used to treat groups L and H.

Results

The results of hematoxylin and eosin staining, Masson’s trichrome staining, a liver function index, and a liver fibrosis index showed that GBE application noticeably mitigated fibrosis and improved the function of the liver. The western blotting and immunohistochemistry analyses indicated that GBE reduced liver fibrosis not only by inhibiting p38 MAPK and NF-κBp65 via inhibition of IκBα degradation but also by inhibiting hepatocyte apoptosis via downregulation of Bax, upregulation of Bcl-2, and subsequent inhibition of caspase-3 activation. Inflammation-associated factors and hepatic stellate cell (HSC)-activation markers further demonstrated that GBE could effectively inhibit HSC activation and inflammation as a result of its regulation of p38 MAPK and nuclear factor-kappa B/IκBα signaling.

Conclusion

Our findings indicated a novel role for GBE in the treatment of liver fibrosis. The potential mechanisms may be associated with the following signaling pathways: 1) the p38 MAPK and nuclear factor-kappa B/IκBα signaling pathways (inhibiting inflammation and HSCs activation) and 2) the Bcl-2/Bax signaling pathway (inhibiting the apoptosis of hepatocytes).

Drug and Exercise Treatment of Alzheimer Disease and Mild Cognitive Impairment: A Systematic Review and Meta-Analysis of Effects on Cognition in Randomized Controlled Trials

OBJECTIVE

Demographic changes are increasing the pressure to improve therapeutic strategies against cognitive decline in Alzheimer disease (AD) and mild cognitive impairment (MCI). Besides drug treatment, physical activity seems to be a promising intervention target as epidemiological and clinical studies suggest beneficial effects of exercise training on cognition. Using comparable inclusion and exclusion criteria, we analyzed the efficacy of drug therapy (cholinesterase inhibitors, memantine, and Ginkgo biloba) and exercise interventions for improving cognition in AD and MCI populations.

METHODS

We searched The Cochrane Library, EBSCO, OVID, Web of Science, and U.S Food and Drug Administration data from inception through October 30, 2013. Randomized controlled trials in which at least one treatment arm consisted of an exercise or a pharmacological intervention for AD or MCI patients, and which had either a non-exposed control condition or a control condition that received another intervention. Treatment discontinuation rates and Standardized Mean Change score using Raw score standardization (SMCR) of cognitive performance were calculated.

RESULTS

Discontinuation rates varied substantially and ranged between 0% and 49% with a median of 18%. Significantly increased discontinuation rates were found for galantamine and rivastigmine as compared to placebo in AD studies. Drug treatments resulted in a small pooled effect on cognition (SMCR: 0.23, 95% CI: 0.20 to 0.25) in AD studies (N = 45, 18,434 patients) and no effect in any of the MCI studies (N = 5, 3,693 patients; SMCR: 0.03, 95% CI: 0.00 to 0.005). Exercise interventions had a moderate to strong pooled effect size (SMCR: 0.83, 95% CI: 0.59 to 1.07) in AD studies (N = 4, 119 patients), and a small effect size (SMCR: 0.20, 95% CI: 0.11 to 0.28) in MCI (N = 6, 443 patients).

CONCLUSIONS

Drug treatments have a small but significant impact on cognitive functioning in AD and exercise has the potential to improve cognition in AD and MCI. Head-to-head trials with sufficient statistical power are necessary to directly compare efficacy, safety, and acceptability. Combining these two approaches might further increase the efficacy of each individual intervention.

IDENTIFIER

PROSPERO (2013:CRD42013003910).

Rationale and design of a multicenter, phase 2 clinical trial to investigate the efficacy of traditional Chinese medicine SaiLuoTong in vascular dementia

BACKGROUND

Vascular dementia (VaD) is the second most prevalent type of dementia among the aged, for whom limited pharmacologic options are available so far. SaiLuoTong capsule is a modern traditional Chinese medicine formula, which has been demonstrated to improve cognition of VaD by the reports of animal experiments and preliminary clinical trial. However, evaluation of this therapy in randomized multicenter trials is needed. In this article, we present the rationale and design of the SaiLuoTong in Vascular Dementia Study.

METHODS

This phase 2 clinical trial of SaiLuoTong among patients with mild-to-moderate VaD is a 26-week, multicenter, randomized, double-blind, placebo-controlled study with a subsequent 26-week, open-label extension. After a 4-week placebo run-in period, participants are centrally randomized (1:1:1) to 3 groups: group A receives SaiLuoTong 360 mg per day for 52 weeks; group B receives SaiLuoTong 240 mg per day for 52 weeks; group C (the control group) are further randomly assigned to 2 groups in a 1:1 ratio and receives placebo during the double-blind phase, then SaiLuoTong 360 mg per day or SaiLuoTong 240 mg per day during the extension phase. The primary outcome measures include the VaD assessment scale cognitive subscale and the Alzheimer Disease Cooperative Study-clinical global impression of change. Safety measures include body weight, vital signs, electrocardiography, laboratory tests, and records of adverse events. Assuming an attrition rate of 20%, at least 372 patients are required to obtain a statistical power of 80%.

RESULTS

The first patient was enrolled into the study in April 2012 and the completion of the study is expected in September 2014.

CONCLUSIONS

The rigorous methodology of the study will hopefully move forward the scientific evaluation of traditional Chinese medicine in treatment of VaD. The results of the present study will provide high-quality evidence on the effect of SaiLuoTong in patients with VaD and has the potential to establish a novel therapeutic approach for this disorder.

A Systematic Review on Natural Medicines for the Prevention and Treatment of Alzheimer's Disease with Meta-Analyses of Intervention Effect of Ginkgo

We performed a systematic review to evaluate the efficacy of natural medicines for the treatment of Alzheimer's disease (AD) in randomized controlled trials (RCTs). Disease-specific and intervention terms were searched in MEDLINE, EMBASE, the Cochrane Library and PsycINFO to identify RCTs for the AD intervention of natural medicines, and searched for literatures in English language. The RCTs compared natural medicines and either placebo or orthodox medication in AD patients. The quality of literature was evaluated by Jadad's score and the Cochrane assessing tool to reduce the risk of bias. Meta-analysis and the heterogeneity of results across the trials were performed. Out of the literatures, 21 clinical reports were included in this review that satisfied the particular selection criteria. Apart from Ginkgo, other treatments we came across had minimal benefits and/or the methodological quality of the available trials was poor. The meta-analyses showed that Ginkgo had better outcomes than the placebo, with the standardized mean difference (SMD) between Ginkgo and the placebo on cognition being -1.62 (95% CI: -2.69 to -0.56) and on activities of daily living being -1.55 (95% CI: -2.55 to -0.55), with the existence of significant heterogeneity across studies. The meta-analysis for assessing the prevention effect of Ginkgo against AD suggested that risk ratio (RR) is 1.06 (95% CI: 0.92 to 1.22) between Gingko and the placebo, with no significant heterogeneity across studies (test for heterogeneity, p = 0.49). Our results suggest that Ginkgo may help established AD patients with cognitive symptoms but cannot prevent the neurodegenerative progression of the disease.

Herbal medicine in the treatment of Alzheimer's disease

Alzheimer's disease (AD) is characterized by profound memory loss sufficient to interfere with social and occupational functioning. It is the most common form of dementia, affecting more than 20 million people worldwide. AD is characterized by an insidious loss of memory, associated functional decline, and behavioral disturbances. Patients may live for more than a decade after they are diagnosed with AD, making it the leading cause of disability in the elderly. The incidence of AD ranges from 1 to 4 percent of the population per year, rising from its lowest level at ages 65 to 70 years to rates that may approach 6 percent for those over the age of 85 years. The first neurotransmitter defect discovered in AD involved acetylcholine (ACh). As cholinergic function is required for short-term memory, the cholinergic deficit in AD was also believed to be responsible for much of the short-term memory deficit. Clinical drug trials in patients with AD have focused on drugs that augment levels of ACh in the brain to compensate for the loss of cholinergic function. These drugs have included ACh precursors, muscarinic agonists, nicotinic agonists, and acetylcholinesterase inhibitors. The most highly developed and successful approaches to date have employed acetylcholinestrase inhibition. Although some Food and Drug Administration-approved drugs are available for the treatment of Alzheimer's disease, the outcomes are often unsatisfactory, and there is a place for alternative medicine, in particular, herbal medicine. This paper reviews the clinical effects of a number of commonly used types of herbal medicines for the treatment of AD.

Complementary and alternative medical approaches to treating adult neurogenic communication disorders: a review

PURPOSE

This paper reviews studies investigating the effectiveness of treating adult neurogenic communication disorders with complementary and alternative medicines (CAM). CAM is gradually experiencing recognition as a viable treatment approach for a variety of disorders by practitioners and patients. Some patients are using CAM as an adjunct to traditional rehabilitation. Additionally, speech-language pathologists are increasingly using CAM in treating communication disorders.

METHOD

This review provides a description of various CAM techniques including acupuncture, hypnosis, relaxation training, dreamwork, biofeedback and homeopathy/herbal medicine. Investigations exploring the effectiveness of each of these approaches as they have been applied to aphasia, motor speech disorders, and cognitive impairments are discussed.

RESULTS AND CONCLUSIONS

Little scientific inquiry into the effectiveness of CAM in the treatment of aphasia, motor speech disorders, and cognitive impairments has occurred. Many of the reviewed studies demonstrate inconsistent results; use limited sample sizes; do not include quantitative measures of cognitive, linguistic or motor speech skills; and are poorly reported. This review suggests that further exploration of this area is required before any strong conclusions regarding effectiveness and efficacy of these techniques can be made.

Plants used in Chinese and Indian traditional medicine for improvement of memory and cognitive function

In traditional practices of Ayurvedic and Chinese medicine, numerous plants have been used to treat cognitive disorders, including neurodegenerative diseases such as Alzheimer's disease (AD). An ethnopharmacological approach has provided leads to identifying potential new drugs from plant sources, including those for cognitive disorders. Many drugs currently available in Western medicine were originally isolated from plants, or are derived from templates of compounds isolated from plants. Some anticholinesterase (anti-ChE) alkaloids isolated from plants have been investigated for their potential in the treatment of AD, and are now in clinical use. Galantamine, isolated from several plants including Lycoris radiata Herb., which was used in traditional Chinese medicine (TCM), is licensed in the United Kingdom for the treatment of mild to moderate AD. Various other plant species have shown pharmacological activities relevant to the treatment of cognitive disorders, indicating potential for therapeutic use in disorders such as AD. This article reviews some of the plants and their active constituents that have been used in traditional Ayurvedic medicine and TCM for their reputed cognitive-enhancing or antiageing effects. Plants and their constituents with pharmacological activities that may be relevant for the treatment of cognitive disorders, including enhancement of cholinergic function in the central nervous system (CNS), anti-inflammatory and antioxidant activities, are discussed.

In-vitro activity of S. lavandulaefolia (Spanish sage) relevant to treatment of Alzheimer's disease

Salvia lavandulaefolia Vahl. (Spanish sage) essential oil and individual monoterpenoid constituents have been shown to inhibit the enzyme acetylcholinesterase in-vitro and in-vivo. This activity is relevant to the treatment of Alzheimer's disease, since anticholinesterase drugs are currently the only drugs available to treat Alzheimer's disease. Other activities relevant to Alzheimer's disease include antioxidant, anti-inflammatory and estrogenic effects. Results of in-vitro tests for these activities are reported here for S. lavandulaefolia extracts, the essential oil and its major constituents. Antioxidant activity (inhibition of bovine brain liposome peroxidation) was found in the EtOH extract of the dried herb (5 mg mL(-1)) and the monoterpenoids (0.1 M) alpha- and beta-pinene and 1,8-cineole. Thujone and geraniol had lower antioxidant effects, while camphor had no antioxidant effects. Possible anti-inflammatory activity (eicosanoid inhibition in rat leucocytes) was found in the EtOH extract (50 microg mL(-1)) and was shown by the monoterpenoids alpha-pinene and geraniol (0.2 mM), but not 1,8-cineole, thujone or camphor. Possible estrogenic activity (via induction of beta-galactosidase activity in yeast cells) was found in the essential oil (0.01 mg mL(-1)) and the monoterpenoid geraniol (0.1-2 mM). 1,8-Cineole, alpha- and beta-pinene and thujone did not exhibit estrogenic activity in this analysis. These results demonstrate that S. lavandulaefolia, its essential oil and some chemical constituents have properties relevant to the treatment of Alzheimer's disease and provide further data supporting the value of carrying out clinical studies in patients with Alzheimer's disease using this plant species.

Effect of the Ginkgo biloba extract, EGb 761, on memory formation in day-old chicks

Previous studies indicate that the Ginkgo biloba extract, EGb 761, has a facilitative effect on deficient memory. The temporal parameters of this effect, however, have not been clearly defined or distinguished from the effect on normal memory. The aim in the current study was to investigate the effects of EGb 761 on memory using a well-controlled animal model. Day-old chicks were trained on either a weakly or strongly reinforced version of a passive avoidance task. Long-term memory formation of the weakly reinforced version of the task was improved significantly by EGb 761 (3 mg/ml) when administered between 10 and 30 min after training. However, the same dose of EGb 761 impaired retention when administered prior to strongly reinforced training. These data provide convincing evidence that posttraining administration of EGb 761 initiates long-term memory in chicks with only short-term memory, but that the same dose-administered pretraining can be deleterious for normal retention. This dual effect has important implications for the clinical use of Ginkgo biloba extracts.

Prevention of neuronal cell damage induced by oxidative stress in-vitro: effect of different Ginkgo biloba extracts

The effect of two different Ginkgo biloba extracts (GB1 and GB4) was studied in-vitro on cultured neurons exposed to oxidative stress caused by H2O2(50 micromol L(-1)) and FeSO4(100 micromol L(-1)). Only about 50% of the neurons were still viable at the end of the experiment (8 h) in control conditions, while the two extracts dose dependently increased the number of viable cells, in the concentration range 10-200 microg mL(-1). The two Ginkgo biloba extracts differed in their effect on hydroxyl-radical-scavenging capacity: GB1 and GB4 had an IC50 (50% inhibiting concentration) value of 78 microg mL(-1) and 186 microg mL(-1), respectively. However, both extracts inhibited apoptosis in cortical neurons after oxidative stress in-vitro. These observations make one suppose that different preparations of Ginkgo biloba have quantitatively different actions and outline the importance of the contribution of apoptosis prevention toward their neuroprotective action.

Facilitative effects of EGb 761 on olfactory recognition in young and aged rats

The aim of the present study was to evaluate the effects of chronic and acute treatment by the Gingko biloba extract, EGb 761 (IPSEN, France) on olfactory short-term memory in rats, using a spontaneous recognition procedure. The effects of a daily EGb 761 treatment (30 or 60 mg/kg) over a period of 30 days (Experiment 1) were evaluated in young male rats. Those of a single injection of EGb 761 were assessed either in young male rats at 60 or 120 mg/kg (Experiment 2) or in aged female rats at 60 mg/kg (Experiment 3). Results showed that, at the highest dose (60 mg/kg), chronic EGb 761 treatment enhanced the recognition performances, allowing recognition at delays at which control animals did not show any recognition. Acute treatment enhanced recognition at both doses tested. The results of the third experiment showed that EGb 761 had an overall enhancement effect on the performances of aged rats. In summary, our results provide evidence for a short-term memory enhancement effect of EGb 761 in both young and aged rats.

Potential role for Ginkgo biloba extract in the treatment of glaucoma

Glaucoma is becoming recognized as a condition for which not only elevated intraocular pressure, but also non-pressure-dependent risk factors are responsible. New avenues of treatment into which investigations are being initiated include agents which could possibly improve blood flow to the eye and neuroprotective drugs. Only calcium channel blockers are presently available for such treatment in glaucoma, and these have not been widely adopted, in contrast to clinical trials involving a number of neuroprotectants in other neurologic disorders. Ginkgo biloba extract is freely available and has several biological actions which combine to make it a potentially important agent in the treatment of glaucoma: improvement of central and peripheral blood flow, reduction of vasospasm, reduction of serum viscosity, antioxidant activity, platelet activating factor inhibitory activity, inhibition of apoptosis, and inhibition of excitotoxicity. The effect of Ginkgo biloba extract as a potential antiglaucoma therapy deserves intensive scrutiny.

Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents)

This review highlights the current advances in knowledge about the safety, efficacy, quality control, marketing and regulatory aspects of botanical medicines. Phytotherapeutic agents are standardized herbal preparations consisting of complex mixtures of one or more plants which contain as active ingredients plant parts or plant material in the crude or processed state. A marked growth in the worldwide phytotherapeutic market has occurred over the last 15 years. For the European and USA markets alone, this will reach about $7 billion and $5 billion per annum, respectively, in 1999, and has thus attracted the interest of most large pharmaceutical companies. Insufficient data exist for most plants to guarantee their quality, efficacy and safety. The idea that herbal drugs are safe and free from side effects is false. Plants contain hundreds of constituents and some of them are very toxic, such as the most cytotoxic anti-cancer plant-derived drugs, digitalis and the pyrrolizidine alkaloids, etc. However, the adverse effects of phytotherapeutic agents are less frequent compared with synthetic drugs, but well-controlled clinical trials have now confirmed that such effects really exist. Several regulatory models for herbal medicines are currently available including prescription drugs, over-the-counter substances, traditional medicines and dietary supplements. Harmonization and improvement in the processes of regulation is needed, and the general tendency is to perpetuate the German Commission E experience, which combines scientific studies and traditional knowledge (monographs). Finally, the trend in the domestication, production and biotechnological studies and genetic improvement of medicinal plants, instead of the use of plants harvested in the wild, will offer great advantages, since it will be possible to obtain uniform and high quality raw materials which are fundamental to the efficacy and safety of herbal drugs.