ESR7 Vaidotas Kisielius

Project: Spatial and temporal variation in the production and release of glycosidic natural toxins in nonagricultural terrestrials

Principal supervisor: Dr. Lars Holm Rasmussen

Intro to project:

In this project it is hypothesized that a release of harmful plant toxins to water resources is a frequent but largely unknown phenomenon (a knowledge gap). Based on the physicochemical properties of natural toxic compounds and on the prevalence of the plants that biosynthesize them, carcinogenic terpene glycosides from genus Pteridium and carcinogenic/hepatotoxic pyrrolizidine alkaloids from genus Petasites were investigated.

The methods and analytical standards needed to investigate the bioactive terpene glycosides from the genus Pteridium were created. For the first time the toxic compounds caudatoside and ptesculentoside have been detected in surface waters (up to 5.3 µg/l of the total compounds). It has been estimated that water with the highest reported concentration, if used for drinking, would violate the tolerable level of carcinogens by 2650 times. Another part of this study reported up to 0.53 μg/l of the total pyrrolizidine alkaloids in surface water and up to 0.23 μg/l in shallow groundwater wells. The levels of pyrrolizidine alkaloids in waters were compared with the tolerable levels of the same compounds established for food. It has been concluded that 2 l of the well water reported in this thesis would violate the safety limit for an average healthy human being.

This study detected 2 types of toxic plant compounds in water bodies out of 2 options carefully selected for targeted investigation. Even though the exact waters in which the compounds were detected were not utilised for drinking, the results can have far-reaching implications. Pteridium is the fifth most abundant plant genus in the world. As indirect result of anthropogenic activities, it is expanding, and large monocultures can be often encountered adjacently to water resources. The other genus – Petasites – require high moisture and proliferate very close to freshwater resources. Besides, it is known that 3% of all flowering plants contain at least 1 pyrrolizidine alkaloid, and many more produce other structurally similar water-soluble, persistent and toxic compounds.