Challenges in Determining Species Identity of Medicinal Plants: the Case of Euphrasia

The chemically complex nature of botanically-derived ingredients calls for unique quality control processes by suppliers, manufacturers, and producers of herbal products. One of the regulatory requirements in industrialized nations is the appropriate testing for identity and authenticity of botanical materials used in consumer products. Nevertheless, there have been numerous recent cases of accidental or intentional adulteration. Intentional adulteration (economically motivated adulteration, EMA) is where raw materials are intentionally substituted or diluted with undisclosed lower-quality ingredients for financial gain of the seller. Examples are being compiled and published by an independent consortium consisting of the American Botanical Council (ABC), the American Herbal Pharmacopoeia (AHP), and the National Center for Natural Product Research (NCNPR) at the University of Mississippi as part of the ABC-AHP-NCNPR Botanical Adulterants Prevention Program.

However, assigning the correct identity is not always straightforward. A particularly challenging material is eyebright (Euphrasia spp.), where a number of species have been used interchangeably. Euphrasia officinalis, which is the species name given to medicinally used eyebright, is considered an unresolved taxonomic entry by many experts. Species assignment is further complicated by the fact that morphological and genetic species delineation is challenging due to the ease of hybridization and the occurrence of mixed pollination (insect- and self-pollination), favoring taxon diversification and differentiation. Chemical and genetic analysis of 15 commercial eyebright samples showed highly variable chemical compositions, and that substitution with materials from the genus Odontites is common.

No conflict of interest has been declared by the author(s).