Investigation into the Authenticity St. John’s wort Herbal Medicine and Dietary Supplement Products

Reviewed: Booker A, Agapouda A, Frommenwiler DA, Scotti F, Reich E, Heinrich M. St. John’s wort (Hypericum perforatum) products – an assessment of their authenticity and quality. Phytomedicine. 2018;40:158-164.

Keywords: Adulteration, amaranth, brilliant blue FCF, chemometrics, food dye, ¹H NMR, HPTLC, Hypericum perforatum, PCA, St. John’s wort, sunset yellow FCF, tartrazine

A number of issues surrounding the authenticity of St. John’s wort (Hypericum perforatum, Hypericaceae; SJW) dietary supplements have been raised in the past.¹ In this study, 47 finished SJW products were purchased from the internet, pharmacies, and stores, mainly in Central London, but also Germany and the United States. The products were labeled to contain either plant extract (24), ground aerial parts of the plant (17), or claimed to be made of a mixture of plant extract and crude ground material (6). One of the goals of the investigation was to determine if contents in products sold and registered in the European regulatory category known as traditional herbal medicinal products (traditional herbal use registration, THR) were more likely to correspond to the expected quality than those marketed as dietary supplements (food supplements in Europe), the latter regulatory category requiring a lower level of quality control. A total of nine products registered as THR and 38 dietary supplements were included in this study. Also included were four crude St. John’s wort raw material samples from cultivations in China, and two botanical reference materials, also acquired in China.

The samples were analyzed by proton nuclear magnetic resonance (¹H NMR) spectroscopy with chemometric analysis, and high-performance thin-layer chromatography (HPTLC). For HPTLC, the samples were analyzed using the conditions outlined in the United States Pharmacopeia,² and the method for food dyes previously reported by Frommenwiler et al.³ The results from the HPTLC analysis provided evidence of adulteration with food dyes (tartrazine, amaranth, brilliant blue, sunset yellow) in nine samples. A number of samples showed an additional yellow colored band at R_f: 0.49 compared to the reference standard, a registered and quantified product. This additional band, tentatively identified as either avicularin (quercetin-3-O-arabinofuranoside) or guaijaverin (quercetin-3-O-arabinopyranoside) based on mass spectrometric data, was also present in the four cultivated and two reference materials from China, indicating that these materials from China represent a different chemotype of SJW.

The chemometric evaluation of the ¹H NMR data allowed distinguishing products containing SJW extracts from those made with crude powdered plant material. The products adulterated with food dyes clustered with the crude powdered SJW samples, independent of the presence of avicularin/guaijaverin.

One of the dietary supplements was analyzed with and without food dyes by visible spectrophotometry for the concentration of total hypericins according to the method outlined in the European Pharmacopoeia.⁴ The addition of food dyes in proportions determined by Frommenwiler et al.³ led to a 3.36-fold increase in the “hypericin” concentration. This adulteration may therefore lead unsuspecting buyers into purchasing a product of perceived higher quality.

Adulteration with food dyes was detected in nine (23.7%) of the 38 products sold as dietary supplements, while all of the products in the THR category were devoid of these colorants. One THR product exhibited the band of avicularin/guaijaverin, suggesting SJW of Asian origin. Avicularin/guaijaverin was present in 13 (34.2%) of the samples in the dietary supplement category.

Comment: This investigation confirms the SJW dietary supplement quality issues summarized in the St. John’s wort Botanical Adulterants Bulletin.¹ The publication also provides the answer to the question if the additional band observed in the HPTLC traces of materials from China is due to Hypericum species other than H. perforatum, or if it is due to the existence of a different chemotype of SJW growing in China. While the data support existence of a different chemotype, appropriate means to rule out adulteration with other Hypericum species need to be in place in a quality control laboratory. The implementation of the HPTLC methods as published earlier by Frommenwiler et al.³ provides an adequate test to detect the addition of undeclared food dyes, and to distinguish among SJW from European and Asian origin.

References

1.     McCutcheon A. Adulteration of Hypericum perforatum. Austin, TX: ABC-AHP-NPNCR Botanical Adulterants Program; 2017. Botanical Adulterants Bulletin.

2.     St. John's wort, St. John's wort powder, and St. John's wort powdered extract. In: United States Pharmacopoeia 36 and National Formulary 31. Rockville, MD: United States Pharmacopeial Convention, 2013.

3.     Frommenwiler DA, Sudberg S, Sharaf MHM, Bzhelyansky A, Lucas B, Reich E. St. John’s wort versus counterfeit St. John’s wort: An HPTLC study. J AOAC Int. 2016;99(5):1204-1212.

4.     Hyperici herba, and Hyperici herba extractum siccum quantificatum. In: European Pharmacopoeia 8.0, Volume 2.  Strasbourg, France: European Directorate for the Quality of Medicine and Healthcare; 2014:1391.