Our researchers study the transfer of Pyrrolizidine alkaloids from weeds to crop

IES researchers carry on work in order to characterise the transfer of pyrrolizidine alkaloids (PAs) from weeds containing these compounds to crops. As mentioned before, the concentration of PAs in various products (drugs, teas, food supplements) is regulated by EC Regulation 2020/2040. Consequently, growers and processors of medicinal and aromatic plants are looking for ways to reduce the concentration of these compounds in products at all stages of production and processing.

Crops studied:

  • German chamomile (Matricaria recutita)
  • Mint (Mentha x piperita)
  • Parsley (Petroselinum crispum L)

Weeds studied:

  • Field forget-me-not (Myosotis arvensis L.)
  • Small bugloss (Anchusa arvensis (L.) M. Bieb.)
  • Common bugloss (Anchusa officinalis)
  • Groundsel (Senecio vulgaris L.)

We have started a large-scale experiment to draw first conclusions on how the PA transfer takes place. In the first phase of the study, we sowed or planted crops in containers and either planted PA-containing weeds next to them or dug in residues of PA-containing weeds next to them. The residues were dug in with the aim to understand whether and how PAs enter and remain in the soil, and whether PAs can also enter and remain in the crop plants via contamination from soil. The experimental containers are buried in the ground in an open field, ensuring that the soil processes in the containers are as similar to those in real agricultural conditions as possible.

In parallel to the container experiment in the field, we collected weed samples and analysed them using liquid chromatography-mass spectrometry (LC-MS) to gain insight into the PA profiles of the studied weeds.


Field forget-me-not. Photo: IES
Common bugloss and german chamomile. Photo: IES
Small bugloss, dried. Photo: IES
Small bugloss, dried and crushed. Photo: IES
Extracts of the studied weeds before transfer to LC-MS vials. Photo: IES

When the agronomist gives the green light for harvesting the potted crop, the part of the plant that is destined for production is taken off. In the case of chamomile, for example, the heads are plucked in several passes (used for dried herb production) and then the entire aerial part of the plant is cut off (used for essential oil production). These parts of the plant are dried, crushed and powdered to produce an extract that potentially contains the  PA compounds that we are looking for. The extract is then analysed using liquid chromatography-mass spectrometry (LC-MS) method. All chamomile samples have now been collected and analysed. Mint and parsley samples are planned to be collected by the end of September.

German chamomile flower heads after harvesting. Photo:IES
German chamomile heads, dried. Photo: IES
German chamomile heads, crushed. Photo: IES
German chamomile extracted, filled into LC-MS vials. Photo: IES

Later, soil samples will be analysed in a similar way to determine whether and how much PA compounds are transferred to the soil during weed growth.

Sample collection, preparation and analysis are carried out by our colleague Emīls Francis, a 2nd year student of the Master’s degree programme in Chemistry at the University of Latvia, under the supervision of Dr Ilva Nakurte, Head of the Analytical Chemistry Laboratory at the Institute for Environmental Solutions. Part of the research will be included in Emīl’s Master’s thesis, which will be defended next year. He admits that his new responsibilities in the research project are very different from his previous work in a quality control laboratory. “I have had a great experience and professional development!”, says Emīls, smilingly describing his first months in the research project.

IES researcher Emīls Francis. Photo: IES

Information on the research regarding PA transfer will be compiled in a scientific publication.

The research is carried out within the project “Transfer of pyrrolizidine alkaloids from weeds to soil and medicinal plants (No lzp-2022/1-0543)”. The project is funded by the Fundamental and Applied Research Programme of the Latvian Council of Science

More information on the project HERE.