HPLC-UV
Fingerprint Profile of Phenolic Compounds Helps to Distinguish Black Cohosh
from Asian Actaea species
Reviewed: Bittner M, Schenk R, Springer A,
Melzig MF. Economical, plain, and rapid authentication of Actaea
racemosa L. (syn. Cimicifuga racemosa,
black cohosh) herbal raw material by resilient RP-PDA-HPLC and chemometric analysis.
Phytochem Anal. 2016;27(6):318-325.
Keywords: Actaea racemosa, black cohosh root and rhizome, adulteration, principal
component analysis, HPLC-UV
There have been a
number of reports1 of adulteration of black cohosh (Actaea racemosa, Ranunculaceae) root and rhizome raw
materials and extracts, mainly describing substitutions with ingredients made
from Asian Actaea species. When powdered or
extracted materials are present, chemical fingerprint analysis based on the
triterpene glycosides is most frequently used to authenticate the raw material.
The complexity of the triterpene-glycoside fingerprint and the occurrence of
different black cohosh chemotypes have made such authentication quite
challenging.
This group of
researchers, from two universities in Berlin, Germany, compared the phenolic
fingerprints obtained by high-performance liquid chromatography–ultraviolet
spectroscopy (HPLC-UV) of A. racemosa
(n=147), A. cimicifuga (n=13), A. cordifolia (n=10), A. simplex
(n=11), A. dahurica (n=3), and A. heracleifolia (n=3), and found that these species could
readily be distinguished by visual inspection of the chromatograms. The data
were also evaluated statistically using principal component analysis (PCA), and
the main contributors for species differentiation were found to be the
concentrations of cimicifugic acids A, D, and E. The main phenolics in
authentic black cohosh were identified as fukinolic acid and cimicifugic acids
A and B, with average concentrations of 3.03 mg/g, 1.56 mg/g, and 2.11 mg/g
powdered root, respectively. The findings correlate well with the data for
black cohosh published by Jiang et al.2; however, a comparison with
the fingerprints of the Asian species A. cimicifuga, A. dahurica, A. heracleifolia,
and A. simplex showed considerable
differences in the phenolic patterns published by the two groups. The HPLC-UV
method was applied to five commercial products from Germany, the United Kingdom
(n=2), Belgium, and Australia. Four products matched the authentic black cohosh
fingerprint, while the Belgian sample had the same phenolic pattern as A. cimicifuga.
Comment: The use of the phenolic compounds
as a means to distinguish Actaea species
has been proposed before,2,3 but this study has the largest number
of samples to date. The distinctive fingerprints obtained with this HPLC-UV
method is helpful to differentiate A. racemosa
from Actaea species growing in Asia. The use
of PCA to evaluate the results seems to be particularly helpful, since
intraspecific variations in the fingerprints can make an assessment based on
visual inspection challenging. The quantitative validation ensures that the
method is suitable for the evaluation of black cohosh crude raw materials.
However, the approach has not been evaluated on extracts, and unique
manufacturing processes may alter the phenolic composition in a way that the
reference materials need to be adjusted in order for the PCA to provide
accurate results. Maybe the authors can expand this work to include North
American Actaea species and additional samples of
A. dahurica and A.
heracleifolia. A minor shortcoming of the paper is the lack of the
exact name for each of the cimicifugic acids, so the reader of this paper has
to refer to other publications to determine which of the structures is cimicifugic
acid A, B, D, E, or F.
References
1.
Foster S. Exploring the
peripatetic maze of black cohosh adulteration: A review of the nomenclature,
distribution, chemistry, market status, analytical methods, and safety concerns
of this popular herb. HerbalGram. 2013;(98):32-51.
2. Jiang B, Ma C, Motley T, Kronenberg F, Kennelly EJ.
Phytochemical fingerprinting to thwart black cohosh adulteration: a 15 Actaea species analysis. Phytochem Anal.
2011;22(4):339-351.
3.
He K, Pauli GF, Zheng
B, et al. Cimicifuga species
identification by high performance liquid chromatography–photodiode array/mass
spectrometric/evaporative light scattering detection for quality control of
black cohosh products. J Chromatogr A.
2006;1112(1-2):241-254.
