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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SIELC Samplify Automated sampling system

Samplify Is a device which allows unattended sampling of a reaction mixture or bioprocess or continue in line flow by taking small amount of liquid from the monitoring mixture and collecting it in a vial or a 96 wells plate

<p><strong>Samplify™ Is a device which allows unattended sampling of a reaction mixture or bioprocess or continue in line flow by taking small amount of liquid from the monitoring mixture and collecting it in a vial or a 96 wells plate. It also allows to dilute the sample with assigned dilution ratio and can provide reaction quenching to preserve the sample state at time of sampling. It has two main components: an autosampler and a probe. The Samplify™ &nbsp;controlled and setup by a PC software.</strong></p><h3><strong>Description</strong></h3><p>It is a common task in the lab to <strong>periodically sample a reactor</strong> or a fermenter to <strong>obtain information about reaction kinetic, completion and have a tangible representation of intermediate states of a dynamic process</strong>. This usually done manually with pipettes or syringes, using stopwatch to measure time and requires to be in the lab during the entire process.</p><p><strong>With Samplify it can be done in automated mode.</strong> When an automated sampling process is used it increases accuracy, safety, and productivity. It reduces potential samples cross contamination, and exposure of the reaction mixture to oxygen or moisture, when anaerobic or moisture free conditions are required.</p><ul><li>Based on a proprietary alpha/beta mechanical configuration, <strong>Alltesta Miniature Autosampler</strong> and patent pending sample probe offers affordable and reliable <strong>automation</strong> <strong>for many analytical and liquid-handling applications</strong>.&nbsp;</li><li>Small <strong>controllable volume of sample</strong> can be programmed and precisely removed from the <strong>enclosed or open system</strong>. The sample will then be transferred to a vial with inert solvent with measured volume to create a <strong>controllable dilution factor</strong>.</li><li><strong>A quench solution can be automatically preloaded</strong> in each vial to provide termination of reaction or biological process, and preserve sample content in the time of probing.</li><li>In order to effectively mix samples with diluents or quenching reagents a <strong>shaking capability</strong> of the autosampler tray can be initiated after each sample cycle.</li><li><strong>PC based software</strong> allows quick, but flexible, setup of the sampling experiment. Several <strong>preloaded methods</strong> can be quickly adapted to a particular needs of the user.</li><li>For temperature sensitive samples the entire autosampler can be placed in the <strong>temperature controlled</strong> environment.</li><li>The device <strong>small size</strong> allow to place it close to the reactor and use <strong>short connection lines</strong> to minimize dispersion. Also a small cooler can be used to keep samples in cold conditions after they are collected.</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/SIELC_SIELC_Samplify_Automated_sampling_system_937b70e8d2.jpg" alt="SIELC: SIELC Samplify™ Automated sampling system." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_SIELC_SIELC_Samplify_Automated_sampling_system_937b70e8d2.jpg 245w," sizes="100vw" width="1346" height="663"></p><h3><strong>Specifications</strong></h3><h4><strong>Samplify™ Autosampler:</strong></h4><ul><li><strong>Syringe volume: </strong>4.0 mL</li><li><strong>Pressure: </strong>up to 250 psi</li><li><strong>Valve configuration: </strong>7×6</li><li><strong>Power Requirements:</strong> 24 VDC</li><li><strong>Current Requirements:</strong> Up to 1.0 A</li><li><strong>Dimensions (WHL):</strong> 160 x 145 x 195 mm / 6.3 x 5.71 x 7.68 in</li><li><strong>Weight:</strong> &nbsp;3 kg / 6.6 lb</li><li><strong>Inlets/Outlets:</strong> Thread 10-32 UNF compression type</li><li><strong>Materials in contact with liquid:</strong> SS316, PTFE, PEEK</li><li><strong>Tray capacity: </strong>48 vials 1.8 mL volume or 96 wells plate</li><li><strong>Communication:</strong> USB virtual serial port</li></ul><h4><strong>Samplify™ Probe:</strong></h4><ul><li><strong>Connection</strong>: requires Alltesta-Samplify autosampler</li><li><strong>Dimensions:</strong> 1 x 1 inch, DIA ¼ inch. Immersion length up to 6 inch</li><li><strong>Materials in contact with liquid: </strong>Stainless Steel 316 (316L), PEEK &amp; PTFE</li><li><strong>Variable sample volume: </strong>from 5 to 500 µL</li><li><strong>Max. working pressure:</strong> 120 psi (8 bar)</li><li><strong>Max. working temperature:</strong> &nbsp;200 °C</li></ul><h3><strong>Software</strong></h3><p><strong>The Samplify can be controlled:</strong></p><ul><li><strong>directly through your software via serial commands</strong> (Alltesta™ protocol available upon request, please contact us at support@sielc.com),</li><li><strong>remotely through our cloud so</strong>ftware (autosampler.cloud),</li><li><strong>directly via our Samplify PC software</strong>, allowing to fully control all the parameters of the sampling operations</li></ul><h3><strong>Available Custom Options</strong></h3><p>Metal-free version of the syringe pump includes no metal contact pump head.</p>

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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