Herbal remedies are used by an estimated 12% of the adult population in the United States. Ginkbo biloba is one of the most widely used herbs, with sales last year of more than $90 million. Ginkbo has traditionally been thought to improve circulation, particularly to the brain, and it has been used both to increase cognition and to improve peripheral circulation. Recent clinical trial indicating improve cognition in patients with early stage Alzheimer's Disease should increase ginkgo's use among older adults. Use, however, may not be without risk. The medical literature contains several case reports of an association between ginkgo use and severe risk. The medical literature contains several case reports of an association between ginkgo use and severe hemorrhage, and studies in both human subjects and animals confirm that certain fractions of ginkgo impair normal coagulation. Clinical reports suggest an interaction between ginkgo and such prescribed anticoagulants as aspirin and warfarin, while animal studies show3 an interaction with the anti- thrombotic drug ticlopidine. In the case of aspirin the interaction may result from combining direct effects on platelet aggregation, but with the other drugs an interaction at the level of cytochrome P450 system is likely. The goal of this proposal is to investigate is to investigate whether ginkgo may interact with such prescribed anticoagulants as warfarin and ticlopidine at the level of the cytochrome P450 system. Additional studies will determine which fractions of ginkgo are responsible for it anti- platelet effects and how these fractions relate to ginkgo's non-specific antioxidant effects, which may believe are responsible for ginkgo's benefit. Such fractions will also be assayed for their capacity to prevent apoptosis induced in embryonic rat nerve cells by oxidative stress. The project will also address the issue of the consistency of herbal products, which our preliminary studies suggest varies from product to product as well as from to batch of the same product. By addressing the issues of herbal product consistency and using laboratory models to define chemical and biological mechanisms of potential clinical significance, this proposal offers a paradigm for the multi-disciplinary study of commonly used herbal products.
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| von Moltke, Lisa L; Weemhoff, James L; Bedir, Erdal et al. (2004) Inhibition of human cytochromes P450 by components of Ginkgo biloba. J Pharm Pharmacol 56:1039-44 |
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