Targeted LC-MS/MS combined with multilocus DNA metabarcoding as a combinatory approach to determine the amount and the source of pyrrolizidine alkaloids contamination in popular cooking herbs, seeds, spices and leafy vegetables

ABSTRACT

Pyrrolizidine alkaloids (PAs) and their corresponding N-oxides (PANOs) are natural protoxins biosynthesised by many plant species and are responsible for occasional fatal intoxication outbreaks due to the consumption of contaminated food. However, only in rare cases has the origin of the contamination been determined. Although their presence has been studied in many matrices, occurrence data on popular widely used cooking herbs, seeds, spices and leafy vegetables is very scarce. Therefore, a systematic study on the occurrence of PA/PANOs contaminations in these popular herbal items, available on the Belgian market, was performed, by means of a validatedtargeted LC-MS/MS analysis, followed by multilocus DNA metabarcoding to track back the origin of the contamination for seven highly to moderately contaminated samples. Our results clearly indicate that 21% of the seed spices and 25% seed-based aromatic mixes contain an amount higher than 400 μg of the 30 summed targeted PAs and PANOs per kg, the value which is currently under discussion by the European member states to be set as a maximum threshold. For both the herbs and the herb-based mixes only 7% of analysed samples exceeded these levels. As a proof of concept, multilocus DNA metabarcoding was performed on six highly contaminated samples, belonging to each subtype matrix, containing high levels of heliotrine type of PA/PANOs. Each time the analysis demonstrated the presence of DNA from a plant species belonging to the plant genus Heliotropium. Moreover, a contaminated leafy vegetable sample, containing solely senecionine type PA/PANOs, contained DNA from Senecio vulgaris. Taken together, it can be stated that the proposed combinatory chemical and molecular techniques could be used to verify if a PA/PANO(s) contamination occurred in these popular cooking items and to pinpoint the origin the contamination, which is pivotal in the case of a detrimental intoxication or intoxication outbreak.

KEYWORDS:

• Pyrrolizidine alkaloids
• herbs
• spices
• aromatic mixes and frozen leafy vegetables
• UHPLC-MS/MS
• multilocus DNA metabarcoding

Acknowledgments

This research was funded by the Belgian Federal Public Service of Health, Food Chain Safety and Environment through the contract PASFOODEXTRA.

Declaration of interest statement

The authors do not declare any conflicts of interest.

Additional information

Funding

This work was supported by the FOD Volksgezondheid, Veiligheid van de Voedselketen en Leefmilieu [PASFOODEXTRA].