Pyrrolizidine alkaloids (PAs) are toxins exclusively biosynthesized by plants. They are typical plant secondary metabolites against herbivores, e.g. for Senecio genus they represent the major defense compounds. It has been estimated that about 6000 species worldwide may contain PAs, many of these plants are common weeds.
The interest of the scientific community and legislators in these compounds owes itself to their high toxicity and biological activity.
It has been shown that PAs-containing weeds contaminate botanical raw materials used for the production of herbal products. The investigation showed, that the occurrence of these alkaloids is due to the co-harvesting or as recently found by up-taking from the soil. The PAs-content in vegetal raw material and theirs extract depends on a large number of factors (species, plant organ, harvest method and extraction procedures) and cannot be generalized.
Because the content of alkaloids may result from contamination with very few plants, appropriate control on vegetal raw material cannot be assured even by a well develop sampling methods. Therefore the appropriate control could be performed on herbal preparations that are representative of the plant material batch, used for the production, in its entirety and for the capability of the manufacturing process to purge or concentrate the alkaloids in the final product.
This presentation gives an overview about the occurrence of the PAs in the herbal ingredients, identifies the origin of the contamination, the rule of extraction process and the impact of the new legal limit for PAs.