Evaluation of the accumulation and toxicity of pharmaceuticals in lettuce plants

• Author(s): Leitão, Inês Isabel Barata
• Date: 2021
• Persistent ID: http://hdl.handle.net/10400.5/22877
• Origin: Repositório da UTL
• Subject(s): Acetaminophen; Carbamazepine; Metformin; oxidative stress; proteomics
• Document Type: Doctoral thesis
• Language: English
• Advisor(s): Martins, Maria Luísa Louro; Mourato, Miguel; Oliveira, Maria da Conceição André
• Contributor(s): Repositório da Universidade de Lisboa

Description

Doutoramento em Engenharia do Ambiente / Instituto Superior de Agronomia. Universidade de Lisboa

Pharmaceutical products (considered emerging contaminants) are a growing source of environmental contaminants, mainly due to their high daily use by the population. The main objective of this work was to study the absorption of pharmaceuticals and their main effects on lettuce metabolism. The experimental tests were carried out in hydroponic culture, contaminating lettuce plants with three selected pharmaceuticals, carbamazepine (CBZ), metformin (MTF) and acetaminophen (ACT). Three concentrations (0.1, 1 and 5 mg L-1), of each pharmaceutical were tested as well as three different time points (1, 8 and 15 days). CBZ and ACT uptake was measured in roots and leaves, and it was possible to observe that both pharmaceuticals were absorbed by roots and translocated to the leaves. MTF quantification was not carried out, yet the effects resulting from its presence in growth medium were analysed. Plants subjected to the highest concentrations of CBZ (5 mg L-1) showed visible symptoms of toxicity, such as a reduction in leaf and root biomass, as well as a decrease in root length. The main results point to different responses according to the pharmaceutical applied. The three contaminants showed to increase the concentrations of stress indicators (hydrogen peroxide and malondialdehyde). Consequently, the enzymes involved in the detoxification of reactive oxygen species showed different patterns over time and according to the applied concentration. The ability to tolerate different concentrations of CBZ, ACT and MTF reflects the global antioxidant response of lettuce. In general, these mechanisms showed to be more effective in contaminations with ACT and MTF than with CBZ. Proteomic analysis allowed a detailed study of different proteins involved in detoxification processes and cellular regulation processes. CBZ proved to be the contaminant that most influenced proteins abundance in roots, comparing to control, while in the leaves, this trend was observed in contamination with ACT