Ibuprofen exposure in Lemna gibba L.: Evaluation of growth and phytotoxic indicators, detection of ibuprofen and identification of its metabolites in plant and in the medium

Ibuprofen (IBU) is detected worldwide in water bodies due to the incomplete removal by wastewatertreatments. Contrasting results have been reported on the toxicity of IBU on aquatic biomonitor plantssuch as duckweed, and no data about IBU detection and metabolism in plants has been reported. Inthis work, the effects of 1 mg L-1IBU on Lemna gibba L. were monitored in an 8-day laboratory test.In particular, an increase in frond number (+12%) and multiplication rate (+10%) while no variationsin photosynthetic pigment content were observed. Moreover, UPLC-HRMS analysis of the presence ofIBU and its metabolites in plants and in the growth medium was performed. The results showed that,besides IBU, 11 IBU metabolites were detected in plants. Among the IBU metabolites, hydroxyl- anddihydroxyl-IBU were found, whereas carboxyl-IBU was undetectable. Interestingly, some IBU metaboliteswere detected in the plant growth solution at the end of the IBU treatment, while no IBU products werefound in the IBU solution without plants, suggesting a role for L. gibba in IBU metabolism. The findings ofthis work represent an important step for a better evaluation of the effects of IBU and its metabolites induckweed, with notable implications for the eco-toxicological assessment of IBU in the aquatic ecosystem.