Quantitative Estimation of Triterpenoids and Formononetin in Rhizomes of Black Cohosh (A. racemosa) and Dietary Supplements that Claim to Contain A. racemosa by Reversed Phase Ultra-Performance Liquid Chromatography and Evaporative Light Scattering Detection

Actaea racemosa (Black cohosh) is one of the most extensively studied herbal products, and is used as an herbal dietary supplement for the alleviation of menopausal symptoms [1]. The rhizomes/roots used in black cohosh products are often collected from the wild; correct identification is therefore crucial. Actein, 23-epi-26-deoxyactein (syn. 27-deoxyactein), acetylshengmanol 3-O-xyloside, cimigenol 3-O-arabinoside, and cimigenol 3-O-xyloside represent the major triterpene glycosides found in black cohosh [1]. Black cohosh has been described by previous studies to contain a phytoestrogen, formononetin. A UPLC-ELSD method has been developed for the analysis of major triterpenoids and formononetin in Actaea racemosa samples. The best results were obtained with Acquity UPLC™ BEH C₁₈ (100 mm × 2.1 mm, i.d., 1.7 µm) column system using an isocratic elution with a mobile phase consisting of water and acetonitrile:methanol (7:3) at a constant flow rate of 0.3 mL/min. Owing to their low UV absorption, the triterpene saponins were detected by evaporative light scattering. Within 5.5 minutes three main glycosides [cimiracemoside (2), 26-deoxyactein (3) and actein (4)] and the isoflavonoid formononentin (1), could be separated, with detection limits of 5, 5, 10 and 0.1 µg/mL, respectively. The method was successfully used to analyze different Actaea recemosa market products, as well as to distinguish between other A. species. For the products containing black cohosh and in rhizomes of black cohosh, there was a significant variability in the amounts of the selected triterpene glycosides and formononetin was not detected. Acknowledgements: This research is funded in part by “Science Based Authentication of Dietary Supplements” Funded by the Food and Drug Administration grant number 2 U01 FD 002071-07 and the United States Department of Agriculture, Agricultural Research Service Specific Cooperative Agreement Number 58-6408-06-067. References: [1] He K, et al., (2006) J. Chromatography A 1112 (1–2): 241–254.

Fig. 1 UPLC Chromatograms of a mixture of standard (A), rhizomes of A. racemosa (B) and Dietary Supplement (C)