PCR-based Assays for the Authentication of Black Cohosh Products

Black Cohosh (Actaea racemosa L.) is one of the highest selling medicinal plants, ranking as the eighth best seller in the US in 2005. However, this popularity has been damaged by links to cases of hepatotoxicity and other significant health implications. The investigation of these reports has not been able to confirm that Black Cohosh plant material is responsible. This has led to the suspicion that some cases of adverse reactions may result from substitution or adulteration with Asian species of Actaea, rather than to A. racemosa (1). This context demonstrates the requirement for correct identification of A. racemosa in Black Cohosh products.

We report the development of the PlantID assay for Actaea species; a DNA-based assay capable of discriminating A. racemosa from potential adulterant species, particularly those associated with hepatotoxicity. A group of cohosh species were chosen on the basis of their widespread growth, commercial availability and/or knowledge of use as an adulterant of Black Cohosh preparations. DNA sequences for each species were aligned to identify hotspots of sequence variation. Species-specific primers were then designed to these regions and optimised for qPCR and multiplex PCR. The product from each reaction was designed to differ in size to enable their resolution by capillary electrophoresis; fluorescent labels attached to each forward primer allow detection of each fragment. The profile of peaks generated is indicative of each species present in the sample.

References: 1 Jordan S A, Cunninghan DG & Marles RJ.(2010) Toxicology and Applied Pharmacology 243: 198–216.