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Molecules

Molecules is a leading international, peer-reviewed, open access journal of chemistry published semimonthly online by MDPI.
Indexed in PubMed | Quartile Ranking JCR - Q2 (Biochemistry and Molecular Biology | Chemistry, Multidisciplinary)

All Articles (63,000)

Nitrofurans are banned veterinary medicinal products due to their carcinogenic and mutagenic properties; however, their protein-bound metabolites (AOZ, AMOZ, AHD, SEM, and DNSAH) may persist in food-producing animals, particularly in eggs. Reliable confirmatory methods are therefore essential for residue monitoring under the stringent requirements of Commission Implementing Regulation (EU) 2021/808. This study reports the development and validation of a sensitive and selective LC–MS/MS method combining acid hydrolysis, 2-nitrobenzaldehyde derivatization, and QuEChERS extraction for the determination of nitrofuran metabolites in eggs. Chromatographic separation was carried out using a phenyl-hexyl column, and detection using a tandem mass spectrometer, supported by isotope-labeled internal standards, ensured robust identification and quantification. Linearity was satisfactory over the investigated concentration range (R2 > 0.99), with recoveries between 82 and 109%. The method’s precision was acceptable, with repeatability RSD values below 10% and within-laboratory reproducibility RSD values below 22%. Matrix effects were effectively controlled, remaining within ±20% following internal standard normalization. Decision limits (CCα) ranged from 0.29 to 0.37 µg/kg, well below the EU reference point for action of 0.5 µg/kg. The method’s performance was further confirmed through participation in an accredited proficiency test scheme. Overall, the validated method provides a reliable analytical tool for routine official control laboratories, enabling the sensitive confirmatory detection of banned nitrofuran residues in eggs and supporting food safety and regulatory compliance.

17 February 2026

(a) Analyte peak of AOZ (positive mode) in negative control [black—quantifier transition; blue and green—quantifier transitions]. (b) Analyte peak for AOZ (positive mode) spiked at 0.2 μg/kg. (c) Analyte peak of DNSAH (negative mode) in negative control [black-quantifier transition; blue and green–quantifier transitions]. (d) Analyte peak for DNSAH (negative mode) spiked at 0.2 μg/kg. Notes: Quantifier transition: used to determine analyte concentration. Qualifier transitions: used to confirm analyte identity. X-axis: retention time (min), Y-axis: relative response. In the upper side of the picture and in the lower side of the picture, the chromatogram of the internal standard is shown.

ywqN encodes a protein with an unassigned function that shares partial 3D homology with B. subtilis YhdA, Pseudomonas putida ChrR, and Escherichia coli YieF, which are NADP(H)/FMN-dependent oxidoreductases that catalyze the reduction of diverse chemical pollutants, including Cr(VI). Here, we report that a recombinant His6-YwqN protein displays marginal chromate reductase activity but is capable of reducing synthetic azo dyes. Remarkably, His6-YwqN exhibits a potent quinone reductase activity, catalyzing the reduction of menadione (MD) and 1,4-naphthoquinone (NQ). The individual and combined roles of YwqN and YhdA in protecting B. subtilis from ROS-promoting agents were further tested. Sensitization to the oxidizing agent H2O2 required the simultaneous loss of both YwqN and YhdA. In contrast, strains deficient in ywqN, either alone or in combination with yhdA, exhibited similar but higher susceptibilities to the superoxide-generating agent MD compared with the WT strain. These results indicate that YwqN and YhdA contribute to protection against the deleterious effects of ROS in B. subtilis. Further results revealed that while YwqN, but not YhdA, prevented MD-induced mutagenesis, both proteins synergistically prevented RifR mutations induced by H2O2. Furthermore, overexpression of YwqN suppressed the hypermutagenesis phenotype of a B. subtilis strain deficient in the prevention/repair oxidized guanine (GO) system, which is prone to accumulate 8-oxoGs. In summary, YwqN counteracts the cytotoxic and genotoxic effects promoted by ROS in B. subtilis and represents a potential tool for the remediation of soils and effluents contaminated with carcinogenic azo dyes.

17 February 2026

Sequence homology comparison of bacterial quinone reductases. Amino acid sequence alignment comparing YwqN from B. subtilis with the well-characterized quinone reductases YhdA from B. subtilis and YieF from E. coli. The dashed blue box indicates the FMN cofactor-binding site, and the dashed red box encloses the conserved motifs that characterize the NAD(P)H-dh2 family, including quinone reductases. Conserved residues are highlighted in bold; dark boxed residues indicate identical residues, and gray boxed residues indicate similar residues. Secondary structure information for BsuYwqN is depicted above the sequences, showing a typical flavodoxin-like topology.

Phospodiesterase 4 (PDE4) has long been an attractive target not only for the anti-inflammatory therapy in respiratory diseases, but also for other pathologies such as psoriatic arthritis and atopic dermatitis. In this study, we report the synthesis of 5-acetyl-2-ethyl-6-phenyl-3(2H)-pyridazinones differently substituted at position 4 with a variety of aryl/alkylamines, which act as potent PDE4B1 inhibitors in the low nanomolar range. The selectivity toward PDE4A4, PDE4D3 and HARBS, as well as the ability to inhibit TNFα production in human whole blood (hWB), was also evaluated for the most potent products, resulting in a small cluster of compounds with an interesting profile and two selected products (3a and 3k) have been in depth investigated with additional in vitro tests on metabolism and in vivo studies. Finally, molecular docking and minimization of the ligand-enzyme complexes were carried out.

17 February 2026

PDE4 inhibitors on the market: Roflumilast, Apremilast, Crisaborole and Ibudilast.

The aim of this study was to investigate the chemical composition and biological activity of extracts obtained from vegetative cranberry biomass generated during plantation rejuvenation. This biomass, composed mainly of young shoots removed during routine agricultural maintenance, represents a readily available and currently underutilized by-product of commercial cranberry (Vaccinium macrocarpon Aiton) cultivation. Extraction optimization was performed using response surface methodology (RSM), which enabled both the assessment of the effects of process variables and the identification of conditions ensuring maximal extraction efficiency. The optimal parameters were determined to be 40% ethanol, a temperature of 60 °C, and an extraction time of 49.44 min, and these conditions were further validated through an additional triplicate extraction. The resulting extract exhibited a high antioxidant activity (429–490 mg Trolox equivalents per gram) and was rich in phenolic compounds, particularly quercetin glycoside derivatives. The chemical profile and bioactivity of the extract highlight the considerable potential of cranberry pruning biomass as an alternative, sustainable source of high-value phytochemicals. Its valorization may support the development of environmentally friendly extraction technologies and contribute to closing the resource loop within agricultural production systems.

17 February 2026

Graphical representation of the relationship between the tested variables. (A–C) illustrate the effect of the variables on polyphenol recovery, whereas (D–F) present the effect of the factors on the recovery of antioxidants reacting with DPPH.

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Molecules - ISSN 1420-3049