Suspected Toxic Chemical Colchicine is Not Found in Ginkgo
Scientists say Research Methods, Assumptions, and Conclusions are Flawed
AUSTIN, Texas, Aug. 30 -- Research that incorrectly suggests that colchicine has been detected in a ginkgo dietary supplement is flawed and erroneous, according to the American Botanical Council (ABC). The controversial study, published Chemical Research in Toxicology August 20, 2001, claims that pregnant women who consume ginkgo extracts (Ginkgo biloba) may run the risk of accumulating the natural chemical colchicine (see below) in their placentas, thereby causing potential harm to the fetuses.
ABC has determined that the original research study and resulting paper is seriously flawed and that the resulting false alarms generated about ginkgo are groundless and unwarranted.
"Ginkgo does not contain colchicine and there is no credible scientific evidence that it does," said ABC founder and Executive Director, Mark Blumenthal. "Furthermore, the levels of colchicine claimed to have been found in the placental samples would likely have been lethal, if accurately reported."
Regarding the question of the absence of colchicine in ginkgo, Blumenthal confirmed this information with Norman R. Farnsworth, Ph.D., Distinguished Research Professor of Pharmacognosy and Senior University Scholar at the College of Pharmacy at the University of Illinois at Chicago. Prof. Farnsworth was emphatic that colchicine is not a constituent of ginkgo.
At ABC's request, Prof. Farnsworth conducted a comprehensive search of the scientific literature for any research paper that might support the possibility that colchicine occurs in ginkgo. According to the NAPRALERT database at the University of Illinois (the world's largest computer database on scientific articles on herbs, their chemistry, pharmacology, toxicology and clinical studies), no scientific evidence in the published literature supports the suggestion that colchicine is an ingredient in ginkgo.
Prof. Farnsworth shared the results of his search with Blumenthal on Aug.10:
"The NAPRALERT database of the world literature on natural products revealed that colchicine has been reported in 91 species of the Lily family (Liliaceae), comprising 28 genera. It also occurs in one species of the Araceae (Arisaema curvatum) and is reported in one species of the Asteraceae (Compositae), i.e., Saussurea sacra. Based on biogenetic considerations, colchicine should never be found outside of the Monocotyledoneae (e.g., Araceae, Liliaceae) and thus the report of its occurrence in Saussurea sacra (Asteraceae) is an anomaly that has not been duplicated by other reports on the chemistry of this species. Thus, colchicine has never been reported as a normal constituent of Ginkgo biloba nor would it be expected or predicted to be present."
Farnsworth also questioned the scientific validity of the study and the editorial process it underwent to be published. "Anyone who thinks that colchicine can be found naturally in ginkgo is not qualified to be a peer reviewer of this paper," he said, referring to the editorial process for scientific journals in which papers are reviewed by independent experts to determine their scientific merit and the accuracy of their conclusions prior to publication.
"Ginkgo is probably the world's best well-researched herbal product," said Blumenthal. "There are more than 120 clinical studies on ginkgo documenting its safety and efficacy for a variety of uses, from improving circulation to reducing cognitive disorders in the elderly. If ginkgo contained a toxic compound like colchicine, scientists would have known this a long time ago."
Blumenthal also noted that when the story was published, the world's foremost researcher and producer of ginkgo extract, based in Germany, conducted special tests on three separate samples of ginkgo leaf and three additional samples of ginkgo extract. Chemical analysis designed specifically for the presence of colchicine found absolutely no trace.
The American Herbal Products Association (AHPA) and the National Nutritional Foods Association (NNFA) conducted independent analysis of leading ginkgo supplements sold in the U.S. Reports released today confirmed the absence of colchicine. The Council for Responsible Nutrition (CRN) also released its own findings that showed no traces of colchicine in ginkgo according to an independent third-party testing laboratory.
ABC also questions the accuracy of reports of the colchicine levels in the women's placental blood. ABC Advisory Board member Jerry Cott, Ph.D., formerly the head of the Psychopharmacology Research Program at the National Institutes of Mental Health, indicated that the probability that the reported levels of colchicine were accurate is highly questionable. Dr. Cott suggested that the levels of colchicine reported in the study were so high they could be considered lethal. "With such high levels of colchicine, neither the women nor the fetuses should have been able to survive," he said.
Colchicine is a biologically active alkaloid found in several species of plants including the autumn crocus (Colchicum autumnale). Colchicine has been used in conventional medicine as a treatment for gout. Other medical uses are minimal due to its toxicity. The plant is considered toxic although it has been used in traditional medicine since the days of the Greek physician Hippocrates, some 2,500 years ago.
Founded in 1988 in Austin, Texas, the American Botanical Council is the leading independent non-profit research and education organization that educates the public on the responsible and scientific use of medicinal plants. Its peer-reviewed quarterly journal HerbalGram has been published since 1983 as a reliable and authoritative source of herb and medicinal plant research, regulatory and market issues, native plant conservation and other general interest aspects of herb use. Information for consumers and healthcare professionals about herbal medicine may be found on the organization's website http://www.herbalgram.org.
Notes to this release:
The information in this release is based on the original research article that appeared in the American Chemical Society's journal Chemical Research in Toxicology by Petty et al., Identification of Colchicine from Placental Blood from Patients Using Herbal Medicines, published August 20, 2001 and was posted on the website in advance of publication:
A second article discussing the Petty et al. paper appeared a week earlier on Monday, August 13, 2001 in Chemical & Engineering News (Borman S. Toxin Reported in Supplements. C&EN. August 13, 2001;79(33):33-34.). This story also reported concerns from two prominent scientists about the flaws in the study: Joseph Betz, Ph.D., Vice-President for Scientific and Technical Affairs at AHPA and formerly with the Food and Drug Administration, and John Cardellina, Ph.D., Director of Botanical Science and Regulatory Affairs at CRN, formerly with National Cancer Institute.