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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Thermo Scientific Dionex IonPac AS15 IC Columns

Determine trace-level concentrations of inorganic anions and low-molecular-weight organic acids in high-purity water matrices with the Thermo Scientific Dionex IonPac AS15 Capillary, Analytical & Guard Columns.

<p><strong>Determine trace-level concentrations of inorganic anions and low-molecular-weight organic acids in high-purity water matrices with the Thermo Scientific™ Dionex™ IonPac™ AS15 Capillary, Analytical &amp; Guard Columns. Specifically designed for analysis of trace anions in high-purity water matrices used by the semiconductor and power generation industries, the column delivers high sensitivity and superior resolution of early-eluting anions (e.g., fluoride, glycolate, acetate, and formate). The column is optimized for selective at an operating temperature of 30°C, and it is ideal for use with large-loop injections.</strong></p><h5><strong>Available in Multiple Formats</strong></h5><ul><li>Dionex IonPac AS15-5μm (3x150mm) column for high efficiency, fast analysis (15 min)</li><li>Dionex IonPac AS15-9μm (2x250mm, 4x250mm, and 0.4x250mm) columns for higher-capacity applications</li><li>Dionex IonPac AS15 capillary column (0.4x250mm) delivers the performance of the standard bore version but requires only 1% of the eluent flow rate, which helps reduce operating costs</li></ul><h5><strong>For Best Performance</strong></h5><ul><li>Use the Thermo Scientific™ Dionex™ IonPac™ AC15 Concentrator column for ultratrace (part per trillion) analyses</li><li>Use a Dionex eluent generator for simplified eluent preparation</li><li>Use the Thermo Scientific™ Dionex™ Anion Self-Regenerating Suppressor (ASRS™ 300) or the Thermo Scientific™ Dionex™ Anion Capillary Electrolytic Suppressor (ACES™ 300) with the Dionex IonPac AS15 column for eluent suppression</li></ul><h4><strong>Specifications</strong></h4><ul><li><strong>Anion Exchange Capacity:</strong> 225 μeq</li><li><strong>Crosslinking: </strong>55% DVB</li><li><strong>Column Capacity:</strong> 225 μeq</li><li><strong>Column Chemistry:</strong> Hydroxide</li><li><strong>For Use With (Application):</strong> Anion Exchange</li><li><strong>Ion Exchange Group: </strong>Alkanol Quaternary Ammonium Ion</li><li><strong>Max. Pressure:</strong> 4000 psi (275 bar)</li><li><strong>Solvent Compatibility:</strong> pH 0 to 14, 0 to 100% HPLC Solvents</li><li><strong>Stationary phase:</strong> IonPac AS15</li><li><strong>Format:</strong> Standard Bore</li><li><strong>Packing Material: </strong>Ethylvinylbenzene/Divinylbenzene</li></ul>

Thermo Scientific Dionex IonPac AS16 IC Columns

Measure trace perchlorate and other highly polarizable anions quickly and accurately in a variety of water matrices with the Thermo Scientific Dionex IonPac AS16 IC Columns.

<p><strong>Measure trace perchlorate and other highly polarizable anions quickly and accurately in a variety of water matrices with the Thermo Scientific™ Dionex™ IonPac™ AS16 IC Columns . This column simplifies the determination of polarizable anions, including thiosulfate, iodide, thiocyanate, and perchlorate using an isocratic hydroxide eluent. It is ideally suited for determination of trace perchlorate in drinking water in accordance with U.S. EPA Methods 314.0 and 314.1 (Primary Method).</strong></p><h5><strong>Designed for Simple, Sensitive Analysis</strong></h5><ul><li>Easily measure trace concentrations of perchlorate in drinking water, surface water, and ground water matrices using a large-loop injection</li><li>Separate hydrophobic anions (iodide, thiocyanate, and thiosulfate) in less than 20 min</li><li>Ideal for polyvalent anions, including polyphosphates and polycarboxylates</li><li>Ultralow hydrophobicity allows fast analysis of polarizable anions</li><li>Can be used in the second dimension of the 2D-IC method for the analysis of trace perchlorate (sub ppb) in drinking water</li></ul><h5><strong>Available in Multiple Formats</strong></h5><ul><li>Standard bore (4x250mm) and microbore (2x250mm) formats</li></ul><h4><strong>Specifications</strong></h4><ul><li><strong>Anion Exchange Capacity:</strong> 170 μeq</li><li><strong>Crosslinking: </strong>55% DVB</li><li><strong>Column Capacity:</strong> 170 μeq</li><li><strong>Column Chemistry:</strong> Hydroxide</li><li><strong>For Use With (Application):</strong> Anion Exchange</li><li><strong>Ion Exchange Group: </strong>Alkanol Quaternary Ammonium Ion</li><li><strong>Max. Pressure:</strong> 4000 psi (275 bar)</li><li><strong>Solvent Compatibility:</strong> pH 0 to 14, 0 to 100% HPLC Solvents</li><li><strong>Stationary phase:</strong> IonPac AS16</li><li><strong>Format:</strong> Standard Bore</li><li><strong>Packing Material: </strong>Ethylvinylbenzene/Divinylbenzene</li></ul>

Thermo Scientific Dionex IonPac AS17-C IC Columns

Quickly determine common inorganic anions in high-purity water matrices with the Thermo Scientific Dionex IonPac AS17-C column. 

<p><strong>Quickly determine common inorganic anions in high-purity water matrices with the Thermo Scientific™ Dionex IonPac AS17-C column. This low-capacity column is optimized for fast gradient separation of inorganic anions in simple sample matrices. It is also ideal for fast gradient separation of sulfur species, including sulfite, sulfate, and thiosulfate. The Dionex IonPac AS17C column is the recommended replacement for all Dionex IonPac AS17 column anion applications.</strong></p><h5><strong>Make Gradient Separations as Easy as Isocratic Runs</strong></h5><p>The Dionex IonPac AS17-C column is designed to be used in conjunction with the Dionex Eluent Generator. The Dionex Eluent Generator automatically produces potassium hydroxide eluents from water, making gradient separations as easy as isocratic runs. Using the Dionex Eluent Generator under gradient conditions, common inorganic anions can easily be separated in a variety of sample matrices including high purity water, drinking water, wastewater, process streams, and scrubber solutions.</p><h5><strong>Achieve Superior Chromatographic Performance</strong></h5><ul><li>Fast gradient separation of inorganic anions in high purity water matrices</li><li>Easy suppression of hydroxide eluent to a very low background with the Thermo Scientific™ Dionex™ Anion Self-Regenerating Suppressor (ASRS™ 300) for trace level determinations (including fluoride) even with a large loop injection</li><li>Superior retention and quantification of fluoride, acetate, propionate, and formate</li><li>Meets performance requirements specified in U.S. EPA Method 300.0 (A)</li><li>Operates at ambient or elevated temperatures</li><li>Column selectivity is optimized for operating temperature of 30°C to ensure reproducible results</li><li>Compatible with Reagent-Free™ Ion Chromatography (RFIC™) systems</li><li>Compatible with organic solvents to enhance analyte solubility, modify column selectivity, or for effective column clean-up</li></ul><p><strong>Note:</strong><i> The Thermo Scientific™ Dionex™ IonPac™ AS18 column is the recommended hydroxide-selective column for determination of common anions in diverse sample matrices.</i></p><h4><strong>Specifications</strong></h4><ul><li><strong>Anion Exchange Capacity:</strong> 30 μeq</li><li><strong>Crosslinking: </strong>55% DVB</li><li><strong>Column Capacity:</strong> 30 μeq</li><li><strong>Column Chemistry:</strong> Hydroxide</li><li><strong>For Use With (Application):</strong> Anion Exchange</li><li><strong>Ion Exchange Group: </strong>Alkanol Quaternary Ammonium Ion</li><li><strong>Max. Pressure:</strong> 4000 psi (275 bar)</li><li><strong>Solvent Compatibility:</strong> pH 0 to 14, 0 to 100% HPLC Solvents</li><li><strong>Stationary phase:</strong> IonPac AS17-C</li><li><strong>Format:</strong> Standard Bore</li><li><strong>Packing Material: </strong>Ethylvinylbenzene/Divinylbenzene</li></ul>

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New blood biomarkers reveal how faithfully diabetes patients take metformin

Steroidal hormones and neurosteroids – novel therapeutic strategies in bacterial infections

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