A Combination of HPLC Fingerprints and the Agnuside/Casticin
Ratio Serves as a Useful Tool to Evaluate the Qualities of Chaste Berry
Preparations
Reviewed: Fukahori M, Kobayashi S, Naraki Y, et al. Quality
evaluation of medicinal products and health foods containing chaste berry (Vitex agnus-castus) in
Japanese, European and American markets. Chem Pharm Bull (Tokyo).
2014;62(4):379-385.
Twenty-four
commercial chaste tree (Vitex agnus-castus,
Lamiaceae) berry products were purchased from a Japanese online shopping site and
an American online shopping site and analyzed by HPLC-UV. The commercial samples were
separated into medicinal products (n = 7) and health food products (n = 17).*
Seventeen chaste
tree extracts were separated using a C18 column and the peak areas of 26
individual compounds (although only p-hydroxybenzoic
acid, isoorientin, agnuside, and casticin were actually identified) were
measured at 275 nm. The profiles of the seven medicinal products were similar
to the fingerprint of the authenticated crude drug (i.e., dried berry). The
health food products* had more variable profiles, with one product lacking ten out
of the 26 peaks. One medicinal product and five health food products contained
less than the minimum requirements of agnuside (0.05%) and casticin (0.08%)
specified for the crude drug and the powdered crude drug in the United States Pharmacopeia1,2 (used as a reference criteria; the
products were not necessarily required to meet USP standards unless labeled as
doing so).
As
an additional indicator of authentic chaste tree, the agnuside/casticin ratio
was calculated for authentic chaste tree berries (agnuside/casticin [a/c]
ratio: 0.75) and for those of the possible adulterants V.
negundo
(leaf and berry a/c ratios: 288.0 and 63.3, respectively), V.
rotundifolia (berry a/c ratio: 0.3), and V.
trifolia
(berry a/c ratio: 2.8). The a/c ratios varied between 0.4 and 4.1 for medicinal
products. In contrast, the ratios were more elevated in health foods, with eight
products having a ratio of ten or higher. The highest a/c ratio of 35 was found
in a product from the United States. The authors hypothesize that such high
agnuside content can be obtained only by using the leaf or the fruit of V.
negundo or
by adding a significant amount of semi-purified agnuside to the original
preparation.
*According
to the authors, commercial chaste tree products that comply with compositions
in compliance with the community herbal monograph on Vitex
agnus-castus3 are considered medicinal products; all
other samples were categorized as health food products.
Comment:
Going along with the trend seen in the previously reviewed publications, this
paper presents yet another fingerprinting method for the authentication of a
botanical ingredient. The reported HPLC-UV chromatogram from authentic chaste tree
can be used as a basis for comparison with a commercial chaste tree powder in a
QC setting. Since the authors have authenticated material of Vitex spp. that are alleged adulterants, the addition of the
HPLC-UV fingerprints of these species would have been helpful. The use of the
agnuside/casticin ratio alone to detect adulteration of chaste tree is limited,
since it is unclear what the natural variability of the ratio is in chaste tree
berries (the authors' number is based on the analysis of one sample of
authenticated material only), and since some of the potential adulterants
(e.g., V. rotundifolia, V. trifolia)
have a similar ratio. Nevertheless, chaste tree materials with an
agnuside/casticin ratio of ten or higher seem to have a high likelihood of being
adulterated
References
1.
United States
Pharmacopeial Convention. Chaste tree. In: USP
37-NF 32. Rockville, MD: United States
Pharmacopeial Convention; 2014.
2.
United States
Pharmacopeial Convention. Powdered chaste tree. In: USP 37-NF 32. Rockville, MD: United States
Pharmacopeial Convention; 2014.
3.
EMA Committee on
Herbal Medicinal Products (HMPC). Community herbal monograph on Vitex agnus-castus L., fructus. London, UK: European
Medicines Agency; November 25, 2010. Available at: http://www.ema.europa.eu/docs/en_GB/document_library/Herbal_-_Community_herbal_monograph/2011/01/WC500101541.pdf. Accessed October 29, 2014.
