Enantioselective analysis of the pesticide imazamox after in vitro permeability study in Caco-2 cells.

Imazamox (IMX), a chiral herbicide used in cereals and oilseed crops to control weeds, is commonly sold as a racemic mixture. Its enantiomers, being chiral compounds, may exhibit unique properties when exposed to chiral environments. While IMX enantiomers have been reported to degrade differently in soil and be toxic to some species, their effects on human systems remain poorly understood. This study utilized Caco-2 (human colon adenocarcinoma cell line) cells to assess the in vitro permeability of a racemic mixture of IMX and its isolated enantiomers. Additionally, the study aimed to evaluate whether the metabolite imazamox-O-desmethyl (IMX-D) forms during the permeability process. An enantioselective chromatographic method was developed, fully validated, and the apparent permeability values were obtained. The apparent permeability of rac-IMX, (+)-IMX, and (-)-IMX was determined to be 4.15 × 10-5 , 5.78 × 10-5 , and 7.33 × 10-5  cm s-1 , respectively. These findings suggest that IMX exhibits high intestinal permeability, with an enantioselective absorption for (-)-IMX as compared to (+)-IMX. Finally, the permeability study in Caco-2 cells revealed that the metabolite IMX-D was not generated.

Temperature-responsive comprehensive two-dimensional liquid chromatography coupled to high resolution mass spectrometry for the elucidation of the oxidative degradation processes of chemicals of environmental concern.

This study explores the possibilities offered by temperature-responsive liquid chromatography (TRLC) based comprehensive 2-dimensional liquid chromatography in combination with reversed-phase liquid chromatography (RPLC) for the analysis of degradation products formed upon oxidative treatment of persistent organic pollutants, in this case exemplified through carbamazepine (CBZ). The TRLC×RPLC combination offers the possibility to overcome peak overlap and incomplete separation encountered in 1D approaches, while the transfer of the purely aqueous mobile phase leads to refocusing of all analytes on the second dimension column. Consequently, this allows for about method-development free and hence, easier LC×LC. The study focuses on the oxidative degradation of CBZ, a compound of environmental concern due to its persistence in water bodies. The TRLC×RPLC combination effectively separates and identifies CBZ and its degradation products, while offering improved selectivity over the individual TRLC or RPLC separations. This allows gathering more understanding of the degradation cascade and allows real-time monitoring of the appearance and disappearance of various degradation products. The compatibility with high-resolution mass spectrometry is last shown, enabling identification of 21 CBZ-related products, nine of which were not previously reported in CBZ degradation studies. The approach's simplicity, optimization-free aspects, and ease of use make it a promising tool for the analysis of degradation pathways in environmental contaminants.

Enantioselective in vitro metabolism of the herbicide diclofop-methyl: Prediction of toxicokinetic parameters and reaction phenotyping.

Human exposure to contaminants of emerging concern, like pesticides, has increased in the past decades. Diclofop-methyl (DFM) is a chiral herbicide that is employed as a racemic mixture (rac-DFM) in soybean and other crops against wild oats. Studies have shown that DFM has enantioselective action (higher for R-DFM), degradation (faster for S-DFM), and metabolism, producing diclofop (DF) which is also a pesticide. Although toxic effects have been reported for DFM, information regarding how DFM affects humans is lacking, especially when its chirality is concerned. In this study, the in vitro metabolism of rac-DFM and its isolated enantiomers was assessed by using a human model based on human liver microsomes. The kinetic model and parameters were obtained, and the hepatic clearance (CLH) and hepatic extraction ratio (EH) were estimated. Enzyme phenotyping was carried out by employing carboxylesterase isoforms (CES 1 and CES 2). DFM was metabolized through positive homotropic cooperativity with slight preference for (-)-DFM metabolism to (-)-DF. CLH and EH were above 19.60 mL min-1 kg-1 and 98 % for all the monitored reactions, respectively, and CES 1 was the main enzyme underlying the metabolism. These findings point out that liver contributes to DFM metabolism, which is fast, resulting in nearly complete conversion to DF after exposition to DFM.

Iron oxide nanoparticle phytotoxicity to the aquatic plant Lemna minor: effect on reactive oxygen species (ROS) production and chlorophyll a/chlorophyll b ratio.

Although iron oxide occurs naturally in the environment, iron oxide nanoparticles have distinct mobility, reactivity, and toxicity, which can harm the human health and nature. This scenario has motivated the investigation of the toxic effects of iron oxide nanoparticles (akaganeite predominance + hematite) on the aquatic plant Lemna minor. First, nanoparticles were synthesized and characterized; then, different iron oxide NP concentrations were added to Lemna minor culture. After 7 days, all the Lemna minor leaves died, irrespective of the added NP concentration. The iron oxide NP impact on the plant was evaluated based on malondialdehyde (MDA) production from thiobarbituric acid reactive substances (TBARS), which was dose-dependent; i.e., lipid peroxidation in the plant increased with rising iron oxide NP concentration. The chlorophyll content decreased at high iron oxide NP concentrations, which disrupted the light absorption mechanism. Fe accumulation in Lemna minor roots also occurred, which can harm nutrient uptake. Therefore, the iron oxide NP toxic impact on plants and related ecosystems requires further studies in order to prevent environmental damage.