DNA analysis offers authentication for true black cohosh

21 Nov 2012

A new method based on specific markers in DNA can ‘consistently’ distinguish black cohosh (Actaea racemosa) from closely related species that may be accidental or deliberate adulterants in herbal dietary supplements.

New York-based scientists subsequently applied their DNA test to 36 dietary supplements, and found that nine contained Asian Actaea species (A. cimicifuga, A. dahurica, and A. simplex).

“We have developed a DNA-based assay that can unambiguously identify black cohosh DNA sequences in dietary supplements,” wrote David Baker from Stony Brook University Medical Center, and Dennis Stevenson and Damon Little from the New York Botanical Garden in the Journal of AOAC International.

“The two matK nucleotide positions that are targeted by the assay consistently distinguish black cohosh from other Actaea species.

“Species that can be easily confused with, or disguised as, black cohosh are being marketed to consumers.

These plants may pose great risk to patients who inadvertently ingest them.

Considerable adulteration of North American black cohosh

Commenting independently on the new analysis, Mark Blumenthal, founder & executive director at the American Botanical Council (ABC), said: “DNA analysis is an important and welcome addition to the tools that laboratories can utilize to make definitive determination of the identity of botanical raw materials.

“And, with respect to identifying black cohosh, DNA now joins appropriate physical examination, and HPTLC and LC-MS chemical methods for determining identity.

“This is important, as we know that there may be a considerable amount of adulteration of North American black cohosh (Actaea racemosa, syn. Cimicifuga racemosa) with several lower-cost species of Asian Actaea. Although these Asian species are in the same genus as North American black cohosh, they are not botanically or chemically identical.

“The DNA method can help to confirm the authentication of true black cohosh material using chemical methods and/or to detect the presence of other Actaea species.

Caveat

Blumenthal added, however, that the application of DNA methods is limited to relatively unprocessed botanical material because heating (e.g., when drying), improper storage, and solvents used in the extraction process can destroy DNA.

“Thus DNA technology is not applicable to most black cohosh extracts or finished products made with extracts.

“In such cases, authentication and detection of adulterants would still have to rely on chemical methods or on complete control of the supply chain from field/forest to manufacturer.”

Source: Journal of AOAC International