The value of plant collections in ethnopharmacology: a case study of an 85-year-old black cohosh (Actaea racemosa L.) sample.

Ethnopharmacological collections of plants used in traditional medical systems are a valuable but often underappreciated resource for scientific investigation. These collections contain many samples of plants currently employed in herbal and pharmaceutical medicine, and questions on stability and storage life can be examined using these historic collections as vouchers. A sample of black cohosh (Actaea racemosa L.), collected in 1919 by the physician and plant explorer Henry Hurd Rusby, was recently identified in the collections of The New York Botanical Garden and analyzed for its triterpene glycosidic and phenolic constituents qualitatively and quantitatively by high-performance liquid chromatography-photodiode array detector (HPLC-PDA) and liquid chromatography-mass spectrophotometry (LC-MS). A comparison of the triterpene glycosidic and phenolic constituents of the 85-year-old plant sample with those of a modern collection of Actaea racemosa showed the similarity of the two samples, confirming the stability of the older sample, despite its curation over the years under a variety of conditions. Quantitative analyses indicated that both plant samples have similar amounts of the four major triterpene glycosides, but the total amount of the six major phenolic constituents measured in the 85-year-old plant material is lower than the amount measured in the modern plant material. Methanol extracts of the two plant materials were tested for their antioxidant activity, and both extracts showed similar antioxidant activity.