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German Government Limits Ginkgolic Acid Levels.
In Germany the standardized extracts of Ginkgo biloba L., Ginkgoaceae, leaf are approved by Commission E for increased peripheral circulation and related cognitive benefits. The approved Commission E monograph for Ginkgo biloba leaf dry extract notes several parameters for the quality of the extract: the drug (herb)/extract ratio must be from 35-67:1, averaging 50:1; the extract must be characterized by 22-27 percent flavonone glycosides and 5-7 percent terpene lactones, with specified ranges of ginkgolides A, B, and C as well as a specified range of bilobalide.

The monograph also notes that the level of ginkgolic acids must be below 5 parts per million (ppm).

In the preparation of ginkgo biloba leaf extracts by some manufacturers, ginkgolic acids are normally kept to a minimum level. This is done because they are chemicals classified as alkylphenols of the urushiol type, related to compounds in poison ivy (Rhus toxicodendron, [Small ex Rydb.] Greene, Anacardiaceae), and are associated with contact allergic responses, especially dermatitis. Ginkgolic acids are found in relatively high concentrations in the seed cover of Ginkgo biloba but are also found in lower concentrations in ginkgo leaf. Their presence in the leaves is the reason why some authorities consider ginkgo leaves unsuitable for use in herbal teas (Thiele, 1997).

In May 1997, the German Institute for Drugs and Medicinal Products (BfArM) sent a letter to manufacturers of Ginkgo biloba leaf extracts and other ginkgo preparations regarding the levels of ginkgolic acid in these products.

The communication stated that, based on the present level of knowledge, the BfArM considers it necessary to reduce the content of ginkgolic acid in finished ginkgo preparations to a maximum level of 5 ppm.

In a letter to the leading producer of Ginkgo biloba standardized extract in Germany, the Dr. Willmar Schwabe Co. of Karlsruhe, Dr. A. Thiele of BfArM wrote that if proof of the 5 ppm maximum level cannot be documented, "the registration for these pharmaceuticals will be canceled since in this case, there is the well-founded suspicion that the pharmaceuticals -- when used in accordance with the instructions [in the Commission E monographs] -- produce damaging effects which exceed a justifiable degree according to the knowledge of medical science." (Thiele, 1997)

"The Ginkgo biloba extract produced by Schwabe, known in the pharmaceutical industry as Egb 761, does not contain more than the maximum amount of ginkgolic acids, because these compounds are eliminated during manufacture of the extract. All of our products thus comply with the positive Monograph I [i.e., the approved Commission E monograph], as well as the draft monograph of the WHO [World Health Organization], so that no action is necessary from our side." (Busse, 1997)

It is not clear how this new regulatory enforcement action will affect other ginkgo products sold in Germany. After Schwabe's Tebonin(R), the second best-selling ginkgo extract is Kaveri(R), marketed by Lichtwer Pharma GmbH of Berlin, which reduces ginkgloic acids below 5 ppm in the manufacturing process. Reduction or minimization of ginkgolic acid content is not an industry or regulatory issue in the U.S. at this time. There does not appear to be any significant reports of adverse reactions to ginkgo extracts related to ginkgolic acid content.


Busse, W. 1997. Personal communication to M. Blumenthal, Aug. 18.

Thiele, A. 1997. Averting of drug-induced risks, grade II: pharmaceuticals containing Ginkgo biloba leaves. Communication to Dr. Willmar Schwabe, GmbH & Co., May 27.

Article copyright American Botanical Council.


By Mark Blumenthal