Pyrrolizidine Alkaloids and Dietary Supplements. Are Your Products At Risk?
Background
Pyrrolizidine alkaloids are a wide group of natural toxins produced as secondary metabolites by a number of plant species from Asteraceae, Boraginaceae, and Fabaceae families. Over 500 different pyrrolizidine alkaloids and their N-oxides are known to date. Pyrrolizidine alkaloids were shown to be hepatotoxic and genotoxic. Toxicity may differ between various sub-classes and is associated with their chemical structure (pyrrolizidine alkaloids with 1,2-unsaturated being of the highest toxicological concern). Presence of these compounds in the food chain represents a potential health risk to consumers and must be avoided with alkaloid concentrations kept as low as is reasonably achievable.
Pyrrolizidine Alkaloids in Dietary Supplements
Contamination of herbal dietary supplements, herbal medicines and teas with pyrrolizidine alkaloids is typically associated with co-harvesting of alkaloid-containing weeds or accidental and in some cases deliberate inclusion of such plant materials in the herbal ingredients. Alternatively, cross-contamination of crops that do not produce pyrrolizidine alkaloids in the field via uptake of these toxins from soil may occur. Soil contamination occurs by toxin transfer from both rotting and living donor plants. Reduction or elimination of the presence of pyrrolizidine alkaloids in herbal ingredients and finished products is a challenging task that requires integration of mitigation measures both at the cultivation/harvesting stage and during processing of raw materials. In addition to effective mitigation strategies, reliable analytical methods allowing selective and sensitive determination of these compounds are the key tool in ensuring safety of products containing herbal ingredients.
Analysis of Pyrrolizidine Alkaloids
Following the extraction of alkaloids from homogeneous and representative test material with acidified water, organic solvents or their mixtures, pyrrolizidine alkaloids are usually determined with the use of chromatographic separation techniques coupled with various detection methods. The use of high performance liquid chromatography (HPLC) or ultra-high performance liquid chromatography (UHPLC), thin layer chromatography (TLC) and gas chromatography (GC) has been described. Considering relatively low target concentrations and high complexity of matrices of interest, liquid chromatography-mass spectrometry has become the primary tool for quantification of pyrrolizidine alkaloids in plant materials, herbal dietary supplements and foods. Workflows based on LC coupled to state of the art triple quadrupole tandem mass spectrometers enable determination down to low part per billion levels.
New EU Regulation
On July 1st 2022, new EU Regulation 2020/2040 becomes effective that sets the maximum limits for lower bound sum of 21 pyrrolizidine alkaloids and their N-oxides, including 14 additional alkaloids that may analytically interfere (co-elute) in certain herbal dietary supplements, herbs, and other relevant matrices.
Our Method
Eurofins Food Chemistry Testing of Madison, WI has introduced an UHPLC-MS/MS method for the determination of 30 pyrrolizidine alkaloids and respective N-oxides, which also covers additional 14 compounds and allows determination in compliance with the new EU regulation. The method was validated in a wide range of relevant matrices including spices, herbs, herbal dietary supplements, tea and honey.