Ecotoxicity evaluation of tetramethrin and analysis in agrochemical formulations using chiral electrokinetic chromatography

Simultaneous enantiomeric separation of linagliptin and clopidogrel by capillary electrophoresis for the individual, combined, and enantiomeric ecotoxicity evaluation on Pseudokirchneriella subcapitata

An analytical methodology was developed in this work enabling the simultaneous enantioseparation of linagliptin and clopidogrel by Capillary Electrophoresis (CE). The use of 10.4 mg/mL carboxymethyl-β-CD (CM-β-CD) as chiral selector in 25 mM phosphate buffer (pH 7.0), at 25 °C and a separation voltage of 30 kV, made possible the chiral separation in 7.4 min, with resolution values of 3.9 and 2.7 for linagliptin and clopidogrel enantiomers, respectively. The analytical characteristics of the developed methodology were evaluated in terms of linearity, precision, trueness, LODs and LOQs, and found adequate for the enantiomeric determination of both drugs. The method was applied to study the stability under abiotic and biotic conditions and the ecotoxicity of both drugs on Pseudokirchneriella subcapitata at individual, combined, and enantiomeric level. Both studies were carried out for each enantiomer of linagliptin, racemic linagliptin, S-clopidogrel, racemic clopidogrel, a mixture of the active enantiomers (R-linagliptin and S-clopidogrel), and a mixture of both racemates. Results obtained showed that individual solutions of S-linagliptin, R-linagliptin, S-clopidogrel, RS-linagliptin, and a mixture of the active enantiomers of both compounds, were stable under abiotic and biotic conditions, regardless of the incubation time; however, the concentration of racemic clopidogrel after 96 h of incubation showed a decay which ranged from 18 to 24 % under abiotic and biotic conditions, respectively. Experimental determination of ecotoxicological parameters demonstrated that all compounds studied (individual enantiomers, racemates, the combination of active enantiomers, and racemic mixtures) are highly toxic to algae. In mixtures, different degrees of antagonisms and synergism were observed.

Enantioseparation and ecotoxicity evaluation of ibrutinib by Electrokinetic Chromatography using single and dual systems

In this work, two chiral methods enabling the separation of ibrutinib enantiomers were developed by Electrokinetic Chromatography. A cyclodextrin (CD) or a mixture of the CD and a chiral ionic liquid (CIL) was used as chiral selector. Using the single CD system, seven neutral and six anionic CDs were tested in a formate buffer at pH 3.0 working in positive and negative polarity, respectively. The use of sulfated-γ-CD (S-γ-CD) and negative polarity originated the best results considering analysis time and enantioresolution. The optimization of the experimental conditions allowed obtaining the separation of ibrutinib enantiomers in an analysis time of 4.2 min with an enantioresolution value of 1.5. The effect of the addition of fifteen CILs on the enantioresolution was evaluated showing that both analysis time and enantioresolution were generally increased. A mixture of S-γ-CD and [TMA][L-Lys] was selected which provided the separation of ibrutinib enantiomers in 8.1 min with an enantioresolution value of 3.3 under the same experimental conditions as in the case of using the single CD system. The enantiomeric impurity (S-ibrutinib) was the first-migrating isomer when using the single CD and the combined CD/CIL systems, as corresponds to the most desirable situation. Both chiral methods allowed the detection of the enantiomeric impurity up to a 0.1% as established by the International Council on Harmonization. After establishing the analytical characteristics of both chiral methodologies developed, they were applied to the enantiomeric determination of ibrutinib in a pharmaceutical formulation for hospital use marketed as pure enantiomer (R-ibrutinib) and to evaluate the stability and ecotoxicity of racemic ibrutinib and R-ibrutinib on Daphnia magna. The developed methodologies enabled, for the first time, the rapid chiral quantitation of ibrutinib in abiotic and biotic matrices.

Systematic Stereoselectivity Evaluations of Tetramethrin Enantiomers: Stereoselective Cytotoxicity, Metabolism, and Environmental Fate in Earthworms, Soils, Vegetables, and Fruits

Tetramethrin is a widely applied type I chiral pyrethroid insecticide that exists as a mixture of four isomers. In the present study, its stereoselective cytotoxicity, bioaccumulation, degradation, and metabolism were investigated for the first time at the enantiomeric level in detail by using a sensitive chiral high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) method. Results showed that among rac-tetramethrin and its four enantiomers, the trans (+)-1R,3R-tetramethrin had the strongest inhibition effect on the PC12 cells. In the earthworm exposure trial, the concentration of trans (-)-1S,3S-tetramethrin was 0.94-8.92 times in earthworms (cultivated in natural soil) and 1.67-5.01 times (cultivated in artificial soil) higher than trans (+)-1R,3R-tetramethrin, respectively. In the greenhouse experiment, the trans (+)-1R,3R-tetramethrin and cis (+)-1R,3S-tetramethrin were preferentially degraded. Furthermore, for rat liver microsome in vitro incubation, the maximum metabolism rate of cis (-)-1S,3R-tetramethrin was 1.50 times higher than its antipodes. Altogether, the aim of this study was to provide a scientific and reasonable reference for the possibility of developing a single enantiomer to replace the application of rac-tetramethrin, which could possess better bioactivity and lower ecotoxicity, and thus permit more reliable and accurate environmental monitoring and risk assessment.