The new document, authored by Stefan Gafner, PhD, chief science officer of the American Botanical Council (ABC) and technical director of BAPP, assesses the usefulness of 78 laboratory analytical methods to authenticate ginkgo leaf extract and/or detect ginkgo leaf extract adulteration.
“Finding a suitable analytical method to authenticate ginkgo leaf extracts is time-consuming at least in part because of the large number of methods available in the peer-reviewed literature, national pharmacopeias, and other official compendia,” said Dr Gafner.
“Not many botanical ingredients have been subject to such a vast body of analytical work dedicated to its quality control. We hope that this is where the ginkgo laboratory guidance document can be of value to the international medicinal plant community since it provides an overview of relevant, reliable, and fit-for-purpose methods in a single document.”
Sizing up the issue
According to ABC’s 2020 Herb Market Report (HerbalGram 131), ginkgo leaf extract dietary supplements have been consistently among the 25 top-selling herbal supplements in the US, with over $33 million in sales in the combined natural and mass-market channels. The extracts are typically used in formulations to improve cognitive and mental performance. They are also used for circulatory issues such as peripheral arterial occlusive disease, and for vertigo and tinnitus.
There are numerous reports in the scientific literature over the past two decades of adulteration of ginkgo leaf extract ingredients and finished consumer products. Such adulteration generally involves the addition of undeclared flavonol-rich ingredients or highly purified flavonoids (e.g., quercetin or rutin) from lower-cost sources, most commonly extracts or purified fractions of the flowers and leaves of Japanese sophora (Styphnolobium japonicum, syn. Sophora japonica).
Of the 501 samples analyzed in these 27 papers, 242 (48%) were considered to be adulterated according to criteria established by the authors of each of these publications, suggesting that ginkgo leaf extract adulteration is widespread.
Undeclared added materials typically are rich in rutin and/or quercetin in order to increase the extract content of flavonol glycosides to 24%, the minimum amount specified on the labels of most commercial dietary supplements to meet the same standardization requirement as the extract EGb761 by Dr. Willmar Schwabe GmbH & Co. KG, Karlsruhe, Germany, considered the pioneering and most clinically tested ginkgo leaf extract in the world. Since both rutin and quercetin are also found in ginkgo leaves, the detection of adulteration of commercial ginkgo materials can be challenging.
“Standardized ginkgo leaf extract is one of the most clinically researched phytomedicinal products in the world,” said Mark Blumenthal, founder and executive director of ABC and founder and director of BAPP. “Many consumers purchase ginkgo products and are sometimes recommended to use them by their health care practitioner in the hope that these products will deliver a clinically documented health benefit. However, if the product contains an intentionally adulterated extract, it is not likely that it will produce the health benefits observed in published clinical trials.
“Adulteration of ginkgo, or of any herb product, is a great disservice to the millions of people who wish to improve or maintain their health naturally.”
The ginkgo leaf extract is the 13th publication in the series of lab guidance documents and the 73rd peer-reviewed publication published by BAPP. For more information, please click HERE.