Target screening of plant secondary metabolites in river waters by liquid chromatography coupled to high-resolution mass spectrometry (LC–HRMS)

Abstract

Background Substantial efforts have been made to monitor potentially hazardous anthropogenic contaminants in surface waters while for plant secondary metabolites (PSMs) almost no data on occurrence in the water cycle are available. These metabolites enter river waters through various pathways such as leaching, surface run-off and rain sewers or input of litter from vegetation and might add to the biological activity of the chemical mixture. To reduce this data gap, we conducted a LC–HRMS target screening in river waters from two different catchments for 150 plant metabolites which were selected from a larger database considering their expected abundance in the vegetation, their potential mobility, persistence and toxicity in the water cycle and commercial availability of standards. Results The screening revealed the presence of 12 out of 150 possibly toxic PSMs including coumarins (bergapten, scopoletin, fraxidin, esculetin and psoralen), a flavonoid (formononetin) and alkaloids (lycorine and narciclasine). The compounds narciclasine and lycorine were detected at concentrations up to 3 µg/L while esculetin and fraxidin occurred at concentrations above 1 µg/L. Nine compounds occurred at concentrations above 0.1 µg/L, the Threshold for Toxicological Concern (TTC) for non-genotoxic and non-endocrine disrupting chemicals in drinking water. Conclusions Our study provides an overview of potentially biologically active PSMs in surface waters and recommends their consideration in monitoring and risk assessment of water resources. This is currently hampered by a lack of effect data including toxicity to aquatic organisms, endocrine disruption and genotoxicity and demands for involvement of these compounds in biotesting.

Occurrence of Emerging Contaminants of Plant Origin in River Waters from Vejle, Denmark

“…Piperine, a piperidine alkaloid, was detected in samples from the rivers Kvak Moellebaek and Vejle in concentrations up to 18.1 ng/L. It was also previously reported in river waters from Germany at concentration up to 338 ng/L (Nanusha et al 2020b). Piperine is a major component of Piper species (e.g.…”

“…Some target compounds were annotated several times due to picking multiple peaks at a single precursor ion mass with given retention time Table S4 in SI-2. Chemical structure for some of the detected target compounds (not reported previously by (Nanusha et al 2020a;Nanusha et al 2020b)).…”

“…2.5 Target screening 2.5.1 Qualitative target screening About 160 target compounds have been prioritized for their likelihood to occur in surface waters, their toxicity and commercial availability for screening of water samples as described by (Nanusha et al 2020a;Nanusha et al 2020b). The LC-HRMS raw data were converted to mzML format using ProteoWizard (version 2.1.0) (Holman et al 2014).…”

“…The study also pointed out the impact of rain intensity on the leaching and run-off of phytochemicals into receiving surface waters (Nanusha et al 2020a). Another study identi ed the toxic alkaloids lycorine and narciclasine and the photosensitive furanocoumarins bergapten and psoralen in river waters at maximum concentrations of 3 µg/L and 0.5 µg/L, respectively (Nanusha et al 2020b). The occurrence of estrogenic iso avones (e.g.…”

“…Phytochemicals (toxins) have been studied in food and feed for decades, but little attention has been paid to their occurrence in the environment (Hoerger et al 2009a;Fletcher and Netzel 2020;Jensen et al 2009;Clauson-Kaas et al 2016). Only recently rst results on the occurrence of naturally occurring compounds in water and soil have been reported (Hama and Strobel 2019;Hoerger et al 2009b;Günthardt et al 2020;Hama and Strobel 2020;Nanusha et al 2020a;Nanusha et al 2020b). Despite the large variety of natural compounds that might be leached to surface waters, only few compounds have been reported in surface water.…”