Alleged St. John’s Wort Adulteration

Information on the adulteration of a St. John’s wort (Hypericum perforatum, Hypericaceae) extract was provided to the Botanical Adulterants Program by NOW Foods (Bloomingdale, IL). Analysis of the commercial extract by high-performance liquid chromatography-ultraviolet/visible (HPLC-UV/Vis) spectrometry showed two main peaks corresponding to the synthetic dyes brilliant blue FCF (for coloring food) and sunset yellow FCF. The identification of the adulterants was based on HPLC-UV/TOFMS analysis and comparison of the observed spectra with literature values. Brilliant blue absorbs in a similar visible range as hypericin; therefore, adulterated St. John’s wort materials analyzed by UV/Vis spectrometry will provide erroneously high hypericin contents. The adulterants are easily detected using HPLC-UV/Vis analysis when measuring at wavelengths of 500 and 590 nm.

Comment: According to Roy Upton, founder, executive director, and editor of the American Herbal Pharmacopoeia, the occurrence of St. John’s wort’s containing synthetic dyes in the market has been known for many years, but there haven’t been any recent reports of such fraudulent activity (oral communication, December 19, 2014). As with other UV/Vis methods to measure the contents of marker compounds (e.g., total anthocyanins in bilberry extract, or total proanthocyanidins in cranberry), the suppliers of the adulterated materials take advantage of the lack in specificity of the UV/Vis method to deceive the buyers of the botanical ingredient. Dyes are also reported as common adulterants of bilberry extracts.

Note: The evidence for the above-reported cases of adulteration are based on internal data gathered by the companies but has not been independently verified by a third-party analytical laboratory.