New York Attorney General (NY AG) Eric Schneiderman issued cease-and-desist letters to 13 manufacturers of devil’s claw dietary supplements in September, claiming the products are adulterated or misbranded based on DNA barcode analysis conducted by the New York Botanical Garden.

That analysis concluded the devil’s claw supplements tested contained a cheaper related species that is considered “less desirable” than what was listed on labels.
However, the non-profit American Botanical Council (ABC), Austin, TX, said the NY AG’s investigation reached an incorrect conclusion based on its “too-narrow interpretation of botanical classifications.”

In botanical classification and nomenclature, devil’s claw is usually known scientifically by its Latin name, Harpagophytum procumbens, where Harpagophytum is the genus of the plant and procumbens refers to the species of the plant, ABC explained. The DNA-barcoding tests commissioned by the NY AG showed that some herbal supplements actually contained Harpagophytum zeyheri, a slightly different form of devil’s claw (i.e., a different, but very closely related species). In effect, they are like two siblings, ABC noted.

“Both species of devil’s claw have a similar chemical profile,” said Thomas Brendler, a medicinal plant expert and editor of the African Herbal Pharmacopeia, a compilation of technical information of various African medicinal plants, including their botany, growing conditions, range of habitat, chemistry and traditional and modern medicinal activities and uses.
“While both species differ marginally in shape and chemical composition, both are considered equally effective,” he added.

According to various government-recognized medicine evaluation bodies and pharmacopeias, the two species of devil’s claw are considered interchangeable for the purpose of their use for their medicinal actions. These organizations include the European Medicines Agency, the European Pharmacopoeia and the unofficial ESCOP (European Scientific Cooperative for Phytotherapy), a pan-European consortium of medicinal plant experts. Also listing both species as interchangeable is the proposed monograph “Harpagophytum species root” in the U.S. Pharmacopeia’s Herbal Medicines Compendium.

Mr. Brendler added that many, possibly most, devil’s claw extracts in the world market are based on mixtures of the two species, as are devil’s claw herbal teas and dried powdered root materials used in supplements and other products. Both species of devil’s claw have been on the market in the U.S. since the 1980s, he noted.

Devil’s claw occurs in the desert regions of southern Africa and its bitter root has historically been used to treat a wide range of ailments and, prominently, as an anti-inflammatory and digestive. Major clinical uses in modern phytotherapy (herbal medicine) focus on its anti-inflammatory effects in the treatment of joint diseases and back pain.

According to data ABC used for its annual herb market report, devil’s claw is a relatively low-selling herb in the U.S. In 2014, devil’s claw ranked 162nd in sales in the U.S. mainstream retail market and 150th in the natural and health foods channel. Total estimated sales of devil’s claw dietary supplements in the U.S. range from approximately $250,000 to up to $500,000.

Mr. Schneiderman contended that federal regulation requires manufacturers to identify plant species using the common name standardized in the trade publication, Herbs of Commerce. That publication defines the common name “devil’s claw” as procumbens, he said. While use of the common name is all that is required by law, most product labels for the supplements tested by the New York Botanical Garden also explicitly referred to the ingredient by its scientific name, procumbens.