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April 2005

Effects of Ginkgo biloba on mental functioning in healthy volunteers.

BACKGROUND: There has been a lack of investigations examining the effects of Ginkgo biloba extract EGb 761 on mental functions and quality of life in healthy subjects with no cognitive impairment. Thus, the objective of the present study was to evaluate the relatively short-term (i.e., 4 weeks) effects of EGb 761 on mental functioning and quality of life in healthy volunteers. METHODS: The trial was conducted as a 4-week, randomized, double-blind, placebo-controlled, parallel-group, monocentric study. Sixty six healthy volunteers aged between 50 and 65 years without age-associated cognitive impairment were randomized, 32 into the placebo and 34 into the EGb 761-treatment group (240 mg, t.i.d.). Safety and compliance were monitored after 1, 2, 3 and 4 weeks. Primary outcome measures in this study are the subjects’ judgment of their own mental health (MH), their general health (GH) and their quality of life (QoL) operationalized on the basis of three different visual analog scales (VAS). Secondary outcome measures are 15 tests and experimental procedures based on a neurobiologically based classification or taxonomy of functions. RESULTS: Intergroup differences in self-estimated mental health as well as self-estimated quality of life were significant in favor of EGb 761. No intergroup differences were found in self-estimated general health. Secondary outcomes supporting the notion of superiority of the active drug were found for both motor performance and emotional evaluation. This study did not reveal evidence of unknown drug-induced side effects or intolerance. No serious adverse events were observed during the study. CONCLUSIONS: Both questions treated in this study, efficacy and safety, are important from a medical perspective because many persons take the agent studied in an effort to enhance their mental functioning and general well-being. The findings of this study support the adequacy of intake of EGb 761 to improve the functions indicated previously.

Arch Med Res. 2003 Sep-Oct;34(5):373-81

The effects of Ginkgo biloba extract (LI 1370) supplementation and discontinuation on activities of daily living and mood in free living older volunteers.

The aim of the study was to investigate the effects of continuing treatment with Ginkgo biloba extract (GBE) 120 mg/day on the activities of daily living (ADLs) and mood in healthy older volunteers who had immediately previously participated in a survey of the effects of a 4 month treatment with the drug.Following a prior postal survey investigating the effects of 4 months supplementation with GBE on ADLs and various aspects of mood and sleep, 1,570 volunteers continued onto a 6 month follow-up postal survey. Subjects selected their own treatment option for the follow-up survey, which effectively created four groups: a continuation group who received GBE in the initial 4 month study and during the 6 month follow-up (GBE-GBE), a discontinuation group who received GBE in the initial study but not during the follow-up (GBE-NT), a new treatment group who did not receive GBE in the initial 4 month study but who did receive GBE during the 6 month follow-up (NT-GBE), and a no treatment group who received no treatment in either survey (NT-NT). At the end of the 6 month follow-up period each subject completed a line analogue rating scale (LARS) and a self-rating activities of daily living scale (SR-ADL).There were signi fi cant differences in the mean overall LARS and SR-ADL scores between the four treatment combination groups at the end of the follow-up period. A factor analysis of the LARS revealed two factors, ‘mood’ and ‘alertness’. When scores from each of the treatment groups were examined over the whole 10 month period it was evident that the ratings of overall competence in the SR-ADL and both factors of the LARS were diminished on cessation of treatment with GBE, and improved when GBE treatment was initiated. The magnitude of the improvements on all scales was related to the overall duration of GBE supplementation.Signi fi cant differences between the groups of subjects treated with GBE for different periods of time (4-10 months) suggests that the extract has a demonstrable effect in improving mood and the self-assessed performance of the tasks of everyday living.

Phytother Res. 2004 Jul;18(7):531-7

Studies on molecular mechanisms of Ginkgo biloba extract.

In the past decade, interest by the general public in the use of herbal dietary supplements has risen exponentially. As throughout history, individuals are now turning to the use of “natural” therapies for the prevention, treatment and cure of almost every ailment and aging malady imaginable. often without substantial proof of safety or efficacy. One of the most popular herbal supplements is Ginkgo biloba extract, taken for its perceived “memory enhancing” properties. Given the inordinate popularity, growing use, and substantial number of pharmaceutical products containing G. biloba, coupled with demands for product safety and “hard evidence,” science has followed this trend closely with an ever-expanding body of pharmacological and clinical data on such preparations. Claims that standardized G. biloba extract (EGb 761) can modulate the cellular environment of an organism under both physiological and stress conditions may be attributed to its multivalent or totipotent properties, and can now be substantiated by the availability of modern molecular techniques. As opposed to pharmacologically manufactured or synthetic drugs, which provide a single target for a single receptor as the mechanism of action, EGb 761 is able to up- or down-regulate signaling pathways, gene transcription, cellular metabolism, etc., and thus assist in the regulation of the general physiological status of the cell and/or organism in response to stressors posed by both intracellular and extracellular conditions. Presumably, this is one of the biggest advantages of using natural products for the prevention and treatment of infirmity, as well as the maintenance of health in an organism.

Appl Microbiol Biotechnol. 2004 May;64(4):465-72

Effects of bilobalide on cerebral amino acid neurotransmission.

Bilobalide is one of many active constituents found in EGb 761 (definition see editorial), which is extracted from Ginkgo biloba leaves. Whilst there is good, sound evidence that bilobalide exhibits neuroprotective actions in a variety of model systems, there is currently no consensus on its mechanism of action. This present communication summarises the results we have obtained with this compound on excitatory amino acid neurotransmission in the central nervous system using both neurochemical and electrophysiological techniques. Bilobalide was shown to reduce glutamate and aspartate release elicited by both high potassium-containing artificial cerebrospinal fluid (aCSF) or veratridine from mouse cortical slices. In addition, bilobalide had a very potent effect (IC (50) 2.7 microM) on glutamate release elicited by hypoxia/hypoglycaemia-induced release from
rat cortical slices. Electrophysio-logically, bilobalide also decreased the frequency of gamma-amino-butyric acid (GABA) uptake inhibitor-induced depolarisations in mouse cortical slices, an effect probably mediated by a decrease in glutamate release. No definitive conclusions can be reached concerning the mechanism of action of bilobalide, but an ability to decrease excitotoxic amino acid release, particularly glutamate, would suggest that this is a probable mechanism to account for its neuroprotective properties.

Pharmacopsychiatry. 2003 Jun;36 Suppl 1:S84-8

Improved haemorrheological properties by Ginkgo biloba extract (Egb 761) in type 2 diabetes mellitus complicated with retinopathy.

BACKGROUND & AIMS: Abnormal haemorrheological property changes in erythrocyte deformability, plasma and blood viscosity, and blood viscoelasticity may play very important roles in the development of microangiopathies in diabetes mellitus (DM). In this study, we demonstrate the improvement in abnormal haemorrheological parameters in DM with ingestion of Ginkgo biloba extract 761 (Egb 761). METHODS: Haemorrheo-logical parameters before and 3 months after Egb 761 oral ingestion were determined in 25 type 2 DM patients with retinopathy. These parameters included lipid peroxidation stress of erythrocytes, erythrocyte deformability, plasma and blood viscosity, blood viscoelasticity, and retinal capillary blood flow velocity. RESULTS: After taking Egb 761 orally for 3 months, the blood viscosity was significantly reduced at different shear rates, by 0.44 +/- 0.10 (gamma = 400), 0.52 +/- 0.09 (gamma = 150) and 2.88 +/- 0.57 (gamma = 5). Viscoelasticity was significantly reduced in diabetic patients by 3.08 +/- 0.78 (0.1 Hz). The level of erythrocyte malondialdehyde (MDA) was reduced by 30%; however, the deformability of erythrocyte was increased by 20%. And lastly, retinal capillary blood flow rate was increased from 3.23 +/- 0.12 to 3.67 +/- 0.24 cm min(-1). CONCLUSION: In this preliminary clinical study, 3 months of oral administration of Egb 761 significantly reduced MDA levels of erythrocytes membranes, decreased fibrinogen levels, promoted erythrocytes deformability, and improved blood viscosity and viscoelasticity, which may facilitate blood perfusion. Furthermore, it effectively improved retinal capillary blood flow rate in type 2 diabetic patients with retinopathy.

Clin Nutr. 2004 Aug;23(4):615-2