Ginkgo Biloba Research Today is a free monthly online journal that collates and summarizes the latest research about Ginkgo Biloba, including details on ginkgo biloba, herbal remedies, side effects, benefits.

Structure-activity analysis of ginkgolide binding in the glycine receptor pore.

Heads JA, Hawthorne RL, Lynagh T, Lynch JW

School of Biomedical Sciences, University of Queensland, Brisbane, QLD, Australia.

Ginkgolides, active constituents of Ginkgo biloba extracts, potently block the glycine receptor chloride channel (GlyR). Ginkgolides A, B, C and J are structurally similar, varying only by the presence or absence of oxygens at their R1 and R2 positions. The aim of this study was to understand how variable ginkgolide groups bind to pore-lining 2' and 6' residues in the alpha1 GlyR. Ginkgolide potency was not affected by G2'A or G2'S mutations, suggesting 2' residues are not important for ginkgolide coordination. Analysis of the alpha1(T6'S) GlyR suggests that ginkgolides bind to this receptor via hydrogen bonds between T6'S and ginkgolide R1 hydroxyls. The abolition of block by the T6'A and T6'V mutations but not by the T6'S mutation implies the existence a second transmembrane domain alpha-helical kink formed by hydrogen bonding between 6' threonine and serine sidechains and backbone carbonyl oxygens. We also found that ginkgolide A binds in different orientations in the closed and open states of a mutant GlyR, possibly reflecting its enhanced flexibility relative to other ginkgolides. Together these results indicate that small variations in ginkgolide structure or pore structure can lead to drastic potency variations. This property may be exploited to create improved pharmacological probes for discriminating among anionic Cys-loop receptor isoforms with 6' structural variations.

Published 1 May 2008 in J Neurochem, 105(4): 1418-27.
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Articles on Ginkgo Biloba published 1 May 2008:

Microtubules in early development of the megagametophyte of Ginkgo biloba.   J Plant Res.

Food storage tissue in the seeds of gymnosperms is female gametophyte (megagametophyte) that develops before fertilization, whereas, in seeds of angiosperms, food is stored as endosperm initiated by double fertilization. The megagametophyte is haploid, and endosperm is usually triploid, at least initially. Despite differences in origin, ploidy level, and developmental trigger, the early events of female gametophyte development in ginkgo are very similar to nuclear endosperm development in the ... [Abstract] [Full-text]

Articles on Ginkgo Biloba published 30 April 2008:

Treatment options in Alzheimer's disease: maximizing benefit, managing expectations.   Dement Geriatr Cogn Disord, 25(5): 408-22.

Alzheimer's disease (AD) is becoming an increasingly heavy burden on the society of developed countries, and physicians now face the challenge of providing efficient treatment regimens to an ever-higher number of individuals affected by the disease. Currently approved anti-AD therapies - the cholinesterase inhibitors and the N-methyl-D-aspartate receptor antagonist memantine - offer modest symptomatic relief, which can be enhanced using combination therapy with both classes of drugs. ... [Abstract] [Full-text]

Ginkgo biloba extract improves coronary artery circulation in patients with coronary artery disease: contribution of plasma nitric oxide and endothelin-1.   Phytother Res, 22(6): 734-739.

In patients with coronary artery disease (CAD), coronary blood flow is usually impaired due to imbalanced vasoactive substances such as nitric oxide (NO) and endothelin-1 (ET-1). The study was designed to test the effects of Ginkgo biloba extract (GBE) on the distal left anterior descending coronary artery (LAD) blood flow and plasma NO and ET-1 levels. Eighty CAD patients were randomly assigned to GBE (n = 42) and control (n = 38) groups. The LAD blood flow was assessed non-invasively using ... [Abstract] [Full-text]

Articles on Ginkgo Biloba published 22 April 2008:

Application of FDA adverse event report data to the surveillance of dietary botanical supplements.   Ann Pharmacother, 42(5): 653-60.

BACKGROUND: Concerns have been raised about the sufficiency of dietary botanical supplement (DBS) surveillance in the US. The Food and Drug Administration's Center for Food Safety and Applied Nutrition's Adverse Event Reporting System (CAERS) represents one of the few existing surveillance mechanisms, but it has not been well characterized with respect to DBS adverse effects. OBJECTIVE: To characterize data on DBSs associated with adverse event reports submitted to CAERS. METHODS: We requested ... [Abstract] [Full-text]

Articles on Ginkgo Biloba published 21 April 2008:

Fingerprint profile of Ginkgo biloba nutritional supplements by LC/ESI-MS/MS.   Phytochemistry, 69(7): 1555-64.

Ginkgo biloba is one of the most popular herb nutrition supplements, with terpene lactones and flavonoids being the two major active components. A fingerprint profile method was developed using a capillary HPLC/MS method which can identify more than 70 components from the G. biloba product. The method allows the flavonoids and terpene lactones to be detected simultaneously and information of both the parent ion and its fragmentation can be obtained in just one HPLC/MS run. Targeted ... [Abstract] [Full-text]

Articles on Ginkgo Biloba published 18 April 2008:

Induction of cytochrome P450s by terpene trilactones and flavonoids of the Ginkgo biloba extract EGb 761 in rats.   Xenobiotica, 38(5): 465-81.

1. Ginkgo biloba is one of the most popular herbal medicines worldwide due to its memory-enhancing and cognition-improving effects. The current study was designed to investigate the effects of five major constituents (bilobalide, ginkgolide A, B, quercetin, and kaempferol) in the standardized G. biloba extract EGb 761 on various cytochrome P450s (CYPs) in rats. 2. The activity of CYP450 was measured by the quantification of six metabolites from multiple cytochrome P450 probe substrates using a ... [Abstract] [Full-text]

Limitations of Using a Single Postdose Midazolam Concentration to Predict CYP3A-Mediated Drug Interactions.   J Clin Pharmacol.

Midazolam is a common probe used to predict CYP3A activity, but multiple blood samples are necessary to determine midazolam's area under the concentration-time curve (AUC). As such, single sampling strategies have been examined. The purpose of this study was to assess the ability of single midazolam concentrations to predict midazolam AUC in the presence and absence of CYP3A modulation by Ginkgo biloba extract (GBE). Subjects received oral midazolam 8 mg before and after 28 days of GBE ... [Abstract] [Full-text]

Articles on Ginkgo Biloba published 17 April 2008:

In vitro inhibition of CYP3A4 metabolism and P-glycoprotein-mediated transport by trade herbal products.   Basic Clin Pharmacol Toxicol, 102(5): 466-75.

Extracts of six commonly used commercially available herbal products, St. John's wort, common valerian, common sage, Ginkgo biloba, Echinacea purpurea and horse chestnut were investigated for their in vitro inhibitory potential of CYP3A4 mediated metabolism and P-glycoprotein efflux transport activity. C-DNA baculovirus expressed CYP3A4 and Caco-2 cells were used. Ketoconazole and verapamil were applied as positive control inhibitors, respectively. A validated high-performance liquid ... [Abstract] [Full-text]

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