Why substitute herbs don't work.
About a decade ago, the price of goldenseal (Hydrastis canadensis) shot up from historic levels of around 13 dollars a pound to more than 100 dollars a pound, prompting a closer look at the sustainability of goldenseal supplies. Subsequently, the U.S. Fish and Wildlife Service added goldenseal to its list of restricted items.
After goldenseal was listed, some in the herb community began to suggest potential herbal substitutes for goldenseal. Substitute suggestions included berberine-rich herbs, such as Oregon grape root (Mahonia aquifolium); Chinese goldthread (Coptis chinensis, also known by its Chinese name, huang lian); and a small plant found in forests in the Northeastern United States, American goldthread (Coptis trifolia, also known as C. groenlandica).
The use of American goldthread was dismissed by many familiar with the plant. Although the plant is fairly common, the root is too difficult to harvest. It is literally a “gold thread,” and any attempt to harvest it from the wild would not produce a significant supply, and was certain to create a new conservation crisis for goldthread.
All of the plants mentioned above contain significant amounts of the alkaloid berberine, which is responsible for the bitter flavor and bright-yellow color of their respective roots. In the end, Chinese goldthread seemed like the best possible choice. However, as supplies of Chinese goldthread dwindled in China, some suggested that goldenseal might be a suitable substitute for it. Instead, scientists have begun to look to growing supplies of both plants.
A recent study published in the journal Chinese Medicine looked at the comparative chemistry of goldenseal, Chinese goldthread and its North American counterpart, American goldthread. All three species are members of the buttercup family (Ranunculaceae). As expected, all three plants were shown to contain the alkaloid berberine.
The chemical analysis also quantified the alkaloids copistine, palmatine and hydrastine, all of which may contribute to expected medicinal effects. The results showed that goldenseal contains the most berberine. All three species contain copistine, with American goldthread containing the most. The alkaloid hydrastine was confirmed to be unique to goldenseal and palmatine unique to Chinese goldthread.
Most medicinal plants contain varying levels of compounds that are responsible for the health benefits consumers expect from herbs. Given the complexity and variability in chemistry from one species to another, it often is difficult to find a substitute that fits the chemical profile of other plants. This is the case with goldenseal, particularly in light of studies that show the alkaloids in goldenseal work synergistically.
Given the wide-ranging chemistry of the three plants included in this study, the authors concluded that neither goldenseal nor American goldthread contain all of the alkaloids found in Chinese goldthread. Therefore, goldenseal is not a suitable substitute for Chinese goldthread, and vice versa.
The solution to developing a sustainable supply is the commercially cultivated sources of the herbs. Significant progress has been made in North America to supply cultivated goldenseal to the market and Chinese goldthread also is being grown commercially in China.
The Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES) is an international treaty that regulates the trade of such items as tiger skins and elephant tusks. In the past 15 years, there has also been more emphasis on monitoring trade in medicinal plants. Items listed in CITES Appendix 1 are illegal in international trade. Appendix II-listed items (like goldenseal) are monitored to “ensure their survival.”
Kamath, S., Skeels M, and Pai. A. “Significant differences in alkaloid content of Coptis chinensis (Huanglian), from its related American species.” Chinese Medicine 4(1):17; August 24, 2009.
Steven Foster is an expert on medicinal plants.
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