Quantitative analysis of cycloartane glycosides in black cohosh rhizomes and dietary supplements by RRLC-ELSD and RRLC-qTOF-MS

Actaea racemosa L. (syn.: Cimicifuga racemosa (L.) Nutt.), commonly known as black cohosh, is a perennial herb growing in temperate regions of the Northern hemisphere [1]. The centre of its distribution is in the Southeastern United States, where Native North Americans used the rhizome of black cohosh for the treatment of rheumatism and menstrual disorders [1,2]. In the present study, a fast and reproducible RRLC-ELSD method for the quantitative analysis of 17 cycloartane glycosides and the aglycone cimigenol in black cohosh rhizomes and dietary supplements has been developed. Separation of the 18 triterpenes was achieved within 16min using reversed phase material and a gradient elution system consisting of water, acetonitrile and methanol as mobile phase. The method was validated for accuracy (recovery rates from 96.79 to 102.86%), repeatability (R.S.D.? 6.94%), precision (intra-day variation? 5.98%, inter-day variation? 3.74%) and sensitivity. Detection limits of 2.50–3.75µg/mL and quantification limits of 7.50–10.00µg/mL were determined. Calibration curves were set in a range from 5–1000µg/mL, with R²>0.998 for all constituents investigated. Peak purity analysis and peak assignment were accomplished by means of RRLC-qTOF-MS and in comparison with reference compounds. Thereby three different sources (ESI, APCI and APPI) were applied and studied for their ionisation potential in regard to the respective cycloartane derivatives. One of the isolated black cohosh constituents, 24-O-acetylhydroshengmanol-3-O-α-L-arabinopyranoside, could be identified as new natural compound.

References: 1. Britton, N., Brown, A. (1913) An illustrated flora of the Northern United States, Canada and the British Possessions -Vol. II. Charles Scribner's Sons. New York.

2. Hardy, M. (2000)J. Am. Pharmaceut. Assoc. 40:234–242.