EU Regulation 396/2005: Pesticide Residue Testing and the Critical Role of QuEChERS Evaporation in Food Safety

<div><div><p><strong>Researchers led by </strong><a target="_blank" rel="noopener noreferrer" href="https://kudova.group.uochb.cz/en"><strong>Eva Kudová</strong></a><strong> from IOCB Prague and Jitka Viktorová from UCT Prague have identified new androstane-based steroid derivatives that can significantly improve the effectiveness of existing antibiotics against multidrug-resistant </strong><i><strong>Staphylococcus aureus</strong></i><strong>.</strong></p></div></div><div><p>The team screened dozens of natural steroidal hormones and synthetic derivatives to see whether they could block bacterial efflux pumps – mechanisms that bacteria use to eject antibiotics and survive treatment. Two compounds emerged as particularly promising: they inhibited efflux pumps and lowered the effective doses of antibiotics such as ciprofloxacin and erythromycin.</p><p>Further analysis showed that one of the compounds also suppressed genes linked to bacterial virulence. Another key finding is that the most active molecules are non-toxic to human immune cells and showed no detectable endocrine activity, suggesting a favorable safety profile.</p><p>These findings support the idea that rationally designed steroid-based molecules could act as antibiotic adjuvants, helping existing drugs overcome bacterial resistance.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/IOCB_Prague_Steroidal_hormones_and_neurosteroids_novel_therapeutic_strategies_in_bacterial_infections_8e5d2a7b48.jpg" alt="IOCB Prague: Steroidal hormones and neurosteroids – novel therapeutic strategies in bacterial infections" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_IOCB_Prague_Steroidal_hormones_and_neurosteroids_novel_therapeutic_strategies_in_bacterial_infections_8e5d2a7b48.jpg 222w," sizes="100vw" width="1258" height="886"></p><blockquote><h4><strong>Original Article</strong></h4><h4><a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S0223523426001613?via%3Dihub"><strong>Steroidal hormones and neurosteroids - novel therapeutic strategies in bacterial infections: Design, synthesis, and biological evaluation</strong></a></h4><p>Daniela Brdová, Bára Křížkovská, Jan Špaček, Zdeněk Míchal, Eva Jablonská, Ondřej Strnad, Hana Chodounská, Eszter Szánti-Pintér, Marina Morozovová, Václav Hanžl, Jan Tkadlec, Martijn Riool, Jan Lipov, Jitka Viktorová, Eva Kudová&nbsp;</p><p><i><strong>Eur. J. Med. Chem., 2026, 308, 118716</strong></i></p><p><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1016/j.ejmech.2026.118716">https://doi.org/10.1016/j.ejmech.2026.118716</a></p><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/"><strong>CC-BY 4.0</strong></a></h6></blockquote><h4><strong>Abstract</strong></h4><p>The global rise of antibiotic resistance necessitates novel therapeutic strategies for infectious diseases. Inhibition of bacterial efflux pumps, which contribute to multidrug resistance, represents a promising approach to restore or even increase the efficacy of existing antibiotics. Using fluorescence-based ethidium bromide accumulation, broth microdilution, and checkerboard assays, we evaluated 26 endogenous steroidal hormones and neurosteroids, along with 30 synthetic derivatives, for their ability to enhance antibiotic susceptibility in multidrug-resistant <i>Staphylococcus aureus</i>. Structure-activity relationship analysis identified compounds <strong>13</strong> and <strong>16</strong> as lead candidates, exhibiting strong efflux pump inhibition and marked reductions in the minimum inhibitory concentrations of ciprofloxacin and erythromycin. Both compounds showed additive effects in checkerboard assays. Modifications at C-3 (polar substitution) and C-17 (3α,5β-stereochemistry and nonpolar substitution) were essential for potent efflux inhibition and sensitization, although these modifications were not additive when combined. Transcriptome analysis further revealed that compound <strong>13</strong> significantly downregulated <i>S. aureus</i> virulence-associated genes when administered alone or in combination with antibiotics. Cytotoxicity assessment in human peripheral blood mononuclear cells and receptor transactivation assays for estrogen, androgen, and progesterone receptors indicated that the most active derivatives were non-toxic and lacked detectable endocrine activity, suggesting a favorable safety profile. Overall, these findings support the concept that rationally designed andostane-based steroidal scaffolds can function as competitive bacterial efflux pump inhibitors and serve as potential antibiotic adjuvants to mitigate efflux-mediated resistance.</p><h4><strong>Instrumentation</strong></h4><h5><strong>Structural characterization</strong></h5><ul><li><strong>AVANCE III 400 MHz NMR spectrometer</strong> (Bruker)</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=3&amp;search=LTQ+Orbitrap+XL"><strong>LTQ Orbitrap XL HRMS</strong></a> (Thermo Fisher Scientific, ESI)</li></ul></div>

Steroidal hormones and neurosteroids – novel therapeutic strategies in bacterial infections

<p><strong>Metformin is currently the first-line oral drug of choice for the treatment of type 2 diabetes. It reduces glucose production in the liver, improves tissue sensitivity to insulin, and does not cause weight gain or hypoglycemia, which sets it apart from some other antidiabetic drugs. Moreover, its long-term beneficial effects on the risk of cardiovascular complications and mortality in people with type 2 diabetes have been well established. Researchers from the Institute of Physiology CAS (IPHYS) have identified a new group of blood metabolites that could help physicians objectively monitor whether patients with type 2 diabetes are taking their metformin as prescribed.</strong></p><h4><strong>New biomarkers for metformin use</strong></h4><p>A team led by Tomáš Čajka from the Laboratory of Translational Metabolism at IPHYS analyzed plasma samples from <strong>637 patients with type 2 diabetes treated with metformin</strong> and <strong>143 non-diabetic controls</strong> using advanced metabolomics and lipidomics. Among 614 detected metabolites, they identified five from the group of <strong>N-lactoyl-amino acids </strong>(e.g. N‑lactoyl-phenylalanine), which had previously been seen as unknown signals due to missing reference spectra in databases. The levels of these metabolites in the blood closely reflected the plasma concentrations of metformin. In patients with the highest metformin exposure, the concentrations of these metabolites were up to 7.2 times higher than in controls.</p><h4><strong>A sensitive “fingerprint” of the drug’s effect</strong></h4><p>N-Lactoyl-amino acids are formed in cells by combining lactate and amino acids, thus reflecting the metformin-induced changes in cellular energy metabolism. “<i>Importantly, even though they occur in plasma only at nanomolar concentrations, they reliably distinguish patients who take metformin regularly from those who take it irregularly or not at all</i>,” emphasizes T. Čajka.</p><h4><strong>Metabolomics in practice and international collaboration</strong></h4><p>The study also provides a detailed description of broader metabolic changes in type 2 diabetes, including increases in lactate, organic acids, and branched-chain amino acids, as well as extensive remodelling of the lipid profile. In addition to T. Čajka’s team, collaborators from the Institute for <strong>Clinical and Experimental Medicine in Prague</strong> and the <strong>West Coast Metabolomics Center</strong> (University of California, Davis) also participated in the study.</p><p>The results demonstrate that advanced metabolomics approaches developed at IPHYS within the <strong>CarDia project</strong> can find highly practical applications both in clinical studies and in personalized monitoring of treatment in patients with diabetes.</p><blockquote><h4><strong>The original article</strong></h4><h4><a target="_blank" rel="noopener noreferrer" href="https://ascpt.onlinelibrary.wiley.com/doi/10.1002/cpt.70205"><strong>Untargeted Metabolomics Identifies N-Lactoyl-Amino Acids as Dose-Responsive Plasma Biomarkers of Metformin Adherence in Type 2 Diabetes</strong></a></h4><p>Tomas Cajka, Jiri Hricko, Lucie Rudl Kulhava, Michaela Paucova, Michaela Novakova, Veronika Hola, Stanislava Rakusanova, Oliver Fiehn, Vojtech Skop, Ivana Lankova, Iva Miskova, Terezie Pelikanova, Martin Haluzik</p><p>Clin Pharmacol Ther, 119: 1057-1069</p><p><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1002/cpt.70205">https://doi.org/10.1002/cpt.70205</a></p><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/"><strong>CC-BY 4.0</strong></a></h6></blockquote><h4><strong>Abstract</strong></h4><p>Metformin is the most widely prescribed antidiabetic drug, yet adherence remains difficult to objectively assess. Using untargeted metabolomics and lipidomics, we analyzed plasma from 637 patients with type 2 diabetes (T2D) with confirmed metformin use and 143 nondiabetic controls, annotating 614 metabolites. Patients were stratified by plasma metformin into sub-therapeutic, therapeutic, and supra-therapeutic groups, and associations were evaluated by multiple linear regression and composite metabolite ranking. Five previously unannotated features were structurally identified as N-lactoyl-amino acids, whose levels correlated strongly with plasma metformin (ρ = 0.42–0.55, P &lt; 0.0001) and increased up to 7.2-fold in the supra-therapeutic group (&gt; 2000 ng/mL). While N-lactoyl-amino acids were consistently detected in the nanomolar range, they still displayed robust and dose-dependent associations with metformin. Broader metabolic changes in T2D included elevated lactate, organic acids, and branched-chain amino acids, together with reduced urea cycle metabolites. Lipidomics showed increases in saturated triacylglycerols and diacylglycerols and decreases in cholesteryl esters, sphingomyelins, and phospholipids. These findings establish N-lactoyl-amino acids as robust, dose-responsive plasma biomarkers of metformin exposure. Despite being up to four orders of magnitude less abundant than their amino acid precursors, they sensitively reflect mitochondrial lactate overflow and pharmacodynamic adaptation, offering objective assessment of adherence.</p>

New blood biomarkers reveal how faithfully diabetes patients take metformin

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The Czech Academy of Sciences (CAS) was established by Act No. 283/1992 Coll. as the Czech successor of the former Czechoslovak Academy of Sciences. It is set up as a complex of 54 public research institutions.

Czech Academy of Sciences

The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague) is a leading scientific institution in the Czech Republic, recognized internationally. Its primary mission is basic research in the fields of chemical biology and medicinal chemistry, organic and material oriented chemistry, chemistry of natural compounds, biochemistry and molecular biology, physical chemistry, theoretical chemistry, and analytical chemistry. 

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences

Organomation, founded in 1959, designs and manufactures high-quality nitrogen evaporators and extraction systems. Known for innovation and durability, their lab instruments are used globally for efficient sample preparation with strong customer support.

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KNAUER Sepapure Laboratory Filtration

Sepapure laboratory filtration includes syringe filters, membranes, and filter units for clean, precise, and reproducible results.

<p><strong>The Sepapure® Laboratory Filtration range provides a comprehensive solution for laboratory sample filtration, focusing on purity, precision, and reproducibility.</strong></p><p>The portfolio includes:</p><ul><li><strong>syringe filters</strong></li><li><strong>membrane disc filters</strong></li><li><strong>filter units</strong></li><li><strong>filter holders</strong></li></ul><p>These products are designed to ensure <strong>maximum sample recovery, minimal loss, and broad compatibility</strong> across analytical, pharmaceutical, and routine laboratory applications.</p><h4><span><strong>Key Features</strong></span></h4><ul><li>High filtration purity and reproducibility</li><li>Minimal sample loss</li><li>Color-coded identification</li><li>Wide range of membrane materials</li><li>Broad application compatibility</li><li>Pressure resistance (&gt;6 bar)</li><li>Eco-friendly reusable solutions</li></ul><h3><span><strong>Product Variants</strong></span></h3><h4><span><strong>Sepapure® Syringe Filters</strong></span></h4><ul><li>Color-coded and labeled</li><li>Integrated polypropylene prefilter</li><li>Low hold-up volume → minimal sample loss</li><li>High pressure resistance (&gt;6 bar)</li><li>Wide application compatibility</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Sepapure_Laboratory_Filtration_5_00f6e96bbe.jpg" alt="KNAUER: Sepapure® Syringe Filters" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Sepapure_Laboratory_Filtration_5_00f6e96bbe.jpg 245w," sizes="100vw" width="1216" height="196"></p><h4><span><strong>Sepapure® Membrane Disc Filters</strong></span></h4><ul><li>Various membrane materials</li><li>Efficient separation for complex samples</li><li>High filtrate purity</li><li>Suitable for lab and research use</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Sepapure_Laboratory_Filtration_3_1e207905e0.jpg" alt="KNAUER: Sepapure® Membrane Disc Filters" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Sepapure_Laboratory_Filtration_3_1e207905e0.jpg 156w," sizes="100vw" width="1000" height="1000"></p><h4><span><strong>Filter Units (Glass Vacuum Units)</strong></span></h4><ul><li>Glass vacuum filtration systems</li><li>Available volumes: 1000 mL and 2000 mL</li><li>Ground glass or rubber joints</li><li>Compatible with membrane filters</li><li>High chemical resistance and durability</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Sepapure_Laboratory_Filtration_2_86cf0cc5f8.jpg" alt="KNAUER: Filter Units (Glass Vacuum Units)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Sepapure_Laboratory_Filtration_2_86cf0cc5f8.jpg 156w," sizes="100vw" width="1000" height="1000"></p><h4><span><strong>Filter Holders</strong></span></h4><ul><li>Reusable and durable</li><li>Eco-friendly (waste reduction)</li><li>Versatile applications</li><li>High mechanical stability</li></ul><h4><span><strong>Typical Applications</strong></span></h4><ul><li>Sample preparation for HPLC/LC-MS</li><li>Mobile phase filtration</li><li>Environmental analysis</li><li>Pharmaceutical QC</li><li>Biochemical and clinical workflows</li></ul>

KNAUER Vials & Caps

KNAUER vials and caps for HPLC/UHPLC with high chemical resistance, multiple closure types, and optimized solutions for precise sample handling.

<p><strong>The KNAUER Vials &amp; Caps range provides a complete solution for sample preparation in HPLC/UHPLC analysis, where precision, purity, and sample integrity are critical.</strong></p><p>Selecting the correct vial and cap combination directly impacts:</p><ul><li><strong>result reproducibility</strong></li><li><strong>contamination prevention</strong></li><li><strong>minimization of evaporation</strong></li><li><strong>autosampler performance</strong></li></ul><p>KNAUER offers a wide variety of configurations including:</p><ul><li>glass types (clear / amber)</li><li>closure types (screw, crimp, snap)</li><li>septa (pre-slit / non pre-slit)</li><li>accessories (µ-inserts for small volumes)</li></ul><h3><span><strong>Product Variants</strong></span></h3><h4><span><strong>Sample Vials</strong></span></h4><ul><li><strong>Neck types:</strong><ul><li>screw neck</li><li>crimp neck</li><li>snap ring</li></ul></li><li><strong>Materials:</strong><ul><li>clear glass</li><li>amber glass (UV protection)</li></ul></li><li>High chemical resistance</li><li>Compatible with micro-inserts</li></ul><h4><span><strong>Caps</strong></span></h4><ul><li>Compatible with all vial types</li><li><strong>Options:</strong><ul><li>pre-slit septa</li><li>solid septa</li></ul></li><li>Optimized sealing</li><li>Suitable for automated and manual sampling</li></ul><h3><span><strong>Vial Selection Guide</strong></span></h3><h4><span><strong>Glass Color</strong></span></h4><ul><li><strong>Amber glass</strong><ul><li>UV protection</li><li>ideal for <strong>light-sensitive compounds (vitamins, steroids, pharmaceuticals)</strong></li></ul></li><li><strong>Clear glass</strong><ul><li>maximum visibility</li><li>ideal for <strong>routine applications</strong></li></ul></li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Vials_and_Caps_glass_color_bd1238185e.jpg" alt="KNAUER: Vials &amp; Caps - Glass color" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Vials_and_Caps_glass_color_bd1238185e.jpg 155w," sizes="100vw" width="435" height="437"></p><h4><span><strong>Closure Types</strong></span></h4><ul><li><strong>Screw Neck</strong><ul><li>resealable</li><li>ideal for <strong>volatile samples and storage</strong></li></ul></li><li><strong>Crimp Neck</strong><ul><li>tightest seal</li><li>ideal for <strong>highly volatile samples</strong></li></ul></li><li><strong>Snap Ring</strong><ul><li>tool-free handling</li><li>suitable for <strong>short-term use</strong></li></ul></li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Vials_and_Caps_closure_type_c6c7a61418.jpg" alt="KNAUER: Vials &amp; Caps - Closure type" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Vials_and_Caps_closure_type_c6c7a61418.jpg 245w," sizes="100vw" width="978" height="389"></p><h4><span><strong>Septum Types</strong></span></h4><ul><li><strong>Pre-slit septum</strong><ul><li>easier needle penetration</li><li>ideal for <strong>autosamplers</strong></li><li>prevents vacuum formation</li></ul></li><li><strong>Non pre-slit septum</strong><ul><li>tighter seal</li><li>ideal for <strong>storage and evaporation control</strong></li></ul></li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Vials_and_Caps_septum_type_0b6afde0e9.jpg" alt="KNAUER: Vials &amp; Caps - Septum type" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Vials_and_Caps_septum_type_0b6afde0e9.jpg 245w," sizes="100vw" width="551" height="343"></p><h4><span><strong>µ-Inserts (Small Volumes)</strong></span></h4><ul><li>Reduce sample volume requirements</li><li>Maximize recovery</li><li>Ideal for valuable or limited samples</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Vials_and_Caps_3_b697f0f41b.webp" alt="KNAUER: Vials &amp; Caps - Micro inserts" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Vials_and_Caps_3_b697f0f41b.webp 239w," sizes="100vw" width="1000" height="653"></p>

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