Ginkgo Herbal Supplements Vary Widely In Content

"Consumers seldom can be sure exactly what they are buying," says chemistry professor Chen Wai, Ph.D., lead researcher for the study, which was published in the science journal Analytical Chemistry, published by the American Chemical Society.

"The large variation of active ingredients found in Ginkgo biloba products could be a problem for the consumers," the researchers write in the journal article.

Ginkgo products are based on herbal extracts from the leaves of the Ginkgo biloba tree, also known as the maidenhair tree, which first appeared on Earth during the time of the dinosaurs about 200 million years ago. Widely marketed as a way of improving mental alertness and slowing the development of Alzheimer's disease, Ginkgo supplements are among the top selling herbal products in both Europe and the U.S. and have long been a staple of Chinese herbalists.

Chemical substances known as ginkgolides and bilobalide, found in the leaves of the tree, are believed to be the most pharmacologically active compounds, say the researchers. However, they point out, as is the case with many herbal products, the active ingredients are usually present in only trace amounts along with large quantities of other compounds. Determining the amount of ginkgolides and bilobalide in Ginkgo products generally is a time-consuming and tedious process, which has added to the difficulty of establishing efficient quality control programs for the products, claim the researchers.

"The lack of simple and reliable separation and analytical processes for herbal products is probably a major cause of the quality-related problems found in the herbal medicine market today," according to the researchers.

The process developed by Wai and colleague Qingyong Lang could help solve that problem by reducing the time required to separate the active ingredients from hours to just a few minutes. It essentially involves boiling the leaves of the tree, or Ginkgo extract products, to separate the ginkgolides and bilobalide and then using a common analytical instrument called a gas chromatograph to measure the compounds.

"Compared to other reported methods for ginkgolide separation, this method can significantly reduce the operation time," say the researchers. "The principle of this analytical method may also be applied to other medicinal herbs," they add.