Chiral Inversion of 2-Arylpropionic Acid Enantiomers under Anaerobic Conditions

Stereoselective behavior of naproxen chiral enantiomers in promoting horizontal transfer of antibiotic resistance genes

Antibiotic resistance poses a global threat to public health, with recent studies highlighting the role of non-antibiotic pharmaceuticals in the transmission of antibiotic resistance genes (ARGs). This study provides insights into the comprehensive profile, horizontal gene transfer potential, hosts, and public health risks associated with antibiotic resistomes in river ecosystems exposed to chiral naproxen (NAP). Our findings demonstrate that NAP stress selectively enriches ARGs and mobile genetic elements (MGEs), thereby bolstering bacterial resistance to specific antibiotics. Importantly, the spatial variation of NAP chiral enantiomers influences the enantioselective response of bacterial communities to antibiotics. While (S)-NAP and (R)-NAP exhibit differing degrees of horizontal transfer potential, (S/R)-NAP notably facilitates microbial aggregation and DNA transport via type IV secretion system (T4SS)-related functional genes, promoting the conjugation of sul1. Moreover, (S/R)-NAP promotes the horizontal transfer of ARGs by stimulating ROS production and altering cell membrane permeability. Chiral NAP exposure induces pathogens to acquire ARGs and accelerates the proliferation of Burkholderia. ARG-Rank analysis indicates that the health risk posed by (R)-NAP exposure surpasses that of (S)-NAP, with the highest risk observed when both enantiomers are present. This study elucidates the horizontal transfer and transmission mechanisms of ARGs under chiral NAP stress, underscoring the potential health hazards associated with NAP chiral enantiomers.

Enantioselective Toxicity of Ibuprofen to Earthworms: Unraveling the Effect and Mechanism on Enhanced Toxicity of S-Ibuprofen Over R-Ibuprofen

With the global implementation of wastewater reuse, accurately assessing the soil ecological risk of chiral pollutants from wastewater necessitates a comprehensive understanding of their enantioselective toxicity to soil animals. Ibuprofen (IBU) is the most prevalent chiral pharmaceutical in municipal wastewater. However, its enantioselective toxicity toward soil animals and the underlying mechanism remain largely unknown. In this study, the toxicity of IBU enantiomers, S-IBU and R-IBU, to earthworms was evaluated at environmentally relevant concentrations (10 and 100 μg/L), simulating wastewater reuse for irrigation. The results demonstrated that IBU adversely affects the growth, reproduction, regeneration, defense systems, and metabolic processes of earthworms, with S-IBU exhibiting stronger toxic effects than R-IBU. The bioavailability assessment revealed that S-IBU was more readily absorbed by earthworms and converted to its enantiomer within earthworms than R-IBU. This is consistent with molecular docking results showing that S-IBU had stronger affinities for functional proteins associated with xenobiotic transport and transformation. The findings of this study highlight that S-IBU poses a higher risk than R-IBU to soil organisms under wastewater reuse scenarios and that the chirality of chemical pollutants in wastewater deserves more attention when implementing wastewater reuse. In addition, our study underscores that the differences in bioavailability and bioactivity may account for the enantioselective toxicity of chiral pollutants.

Designing Powerful Biindole-Based Inherently Chiral Selectors: Enhancing Enantiodiscrimination by Core Functionalization with Additional Coordination Elements

Among inherently chiral selectors of axial stereogenicity, usually resulting in very good enantiodiscrimination performances, the biindole-based family has the additional advantage of very easy functionalization of the two nitrogen atoms with a variety of substituents with desirable properties. Aiming to evaluate the possibility of exploiting such feature to enhance the enantiodiscrimination ability of the archetype structure, a series of three inherently chiral monomers were designed and synthesized, characterised by a 2,2'-biindole atropisomeric core conjugated to bithiophene wings enabling fast and regular electrooligomerization, and functionalised at the nitrogen atoms with an ethyl, a methoxyethyl, or a hydroxyethyl substituent. Nitrogen alkylation was also exploited to obtain for the first time the chemical resolution of the biindole selectors without employing chiral HPLC. The enantiodiscrimination ability of the selector series was comparatively evaluated in proof-of-concept chiral voltammetry experiments with a "benchmark" chiral ferrocenyl probe as well as with chiral non-steroidal anti-inflammatory drugs naproxen and ketoprofen. The large enantiomer potential differences for all probes increased in the ethyl < methoxyethyl ≪ hydroxyethyl sequence of selector substituents, supporting our assumption on the beneficial role of an additional coordination element. The powerful hydroxyethyl selector was also applied to ketoprofen in a commercial drug matrix.