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

<div><div>Researchers led by <a target="_blank" rel="noopener noreferrer" href="https://kudova.group.uochb.cz/en">Eva Kudová</a> 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 Staphylococcus aureus.</div></div><div>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.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.These findings support the idea that rationally designed steroid-based molecules could act as antibiotic adjuvants, helping existing drugs overcome bacterial resistance.<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"><blockquote><h4>Original Article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S0223523426001613?via%3Dihub">Steroidal hormones and neurosteroids - novel therapeutic strategies in bacterial infections: Design, synthesis, and biological evaluation</a></h4>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;Eur. J. Med. Chem., 2026, 308, 118716<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><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote><h4>Abstract</h4>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 Staphylococcus aureus. Structure-activity relationship analysis identified compounds 13 and 16 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 13 significantly downregulated S. aureus 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.<h4>Instrumentation</h4><h5>Structural characterization</h5><ul><li>AVANCE III 400 MHz NMR spectrometer (Bruker)</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=3&amp;search=LTQ+Orbitrap+XL">LTQ Orbitrap XL HRMS</a> (Thermo Fisher Scientific, ESI)</li></ul></div>

Steroidal hormones and neurosteroids – novel therapeutic strategies in bacterial infections

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.<h4>New biomarkers for metformin use</h4>A team led by Tomáš Čajka from the Laboratory of Translational Metabolism at IPHYS analyzed plasma samples from 637 patients with type 2 diabetes treated with metformin and 143 non-diabetic controls using advanced metabolomics and lipidomics. Among 614 detected metabolites, they identified five from the group of N-lactoyl-amino acids (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.<h4>A sensitive “fingerprint” of the drug’s effect</h4>N-Lactoyl-amino acids are formed in cells by combining lactate and amino acids, thus reflecting the metformin-induced changes in cellular energy metabolism. “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,” emphasizes T. Čajka.<h4>Metabolomics in practice and international collaboration</h4>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 Clinical and Experimental Medicine in Prague and the West Coast Metabolomics Center (University of California, Davis) also participated in the study.The results demonstrate that advanced metabolomics approaches developed at IPHYS within the CarDia project can find highly practical applications both in clinical studies and in personalized monitoring of treatment in patients with diabetes.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://ascpt.onlinelibrary.wiley.com/doi/10.1002/cpt.70205">Untargeted Metabolomics Identifies N-Lactoyl-Amino Acids as Dose-Responsive Plasma Biomarkers of Metformin Adherence in Type 2 Diabetes</a></h4>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 HaluzikClin Pharmacol Ther, 119: 1057-1069<a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1002/cpt.70205">https://doi.org/10.1002/cpt.70205</a><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote><h4>Abstract</h4>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.

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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Villa Labeco ITP-CZE EA 202M electrophoretic analyser

For the analysis of ionic substances in water, agriculture, food, and clinical materials. The modular design of the Villa Labeco ITP-CZE EA 202M analyzer allows its use with multiple electrophoretic modes.

The modular arrangement of this analyser enables its application with several electrophoretic modes of operation e.g.<ul><li>isotachophoresis (ITP)</li><li>capillary zone electrophoresis (CZE)</li><li>or the highly efficient combination of ITP – CZE</li></ul>Users can choose to work with traditional columns (employing contact conductivity detectors) or alternatively take advantage of our updated columns which employ contactless conductivity detectors (less sensitivity and a higher price but with increased lifetimes).Columns for the first and second dimension are named ‘pre-separation' and ‘analytical' columns respectively. Pre-separation columns employ FEP capillaries (i.d 0.8 mm) and are available in several lengths (see Acessories). Each analytical column is equipped with an adapter (SMA or 2 mm JM) for connection with optical fibres to the UV detection facility. The standard package includes an in-built UV detector with 4 wavelengths, however a variable wavelength or DAD UV detector can be purchased as an optional extra.The standard and most basic version of the instrument is equipped with an ITP injection valve, 2 columns and modules for manual filling of electrolytes.<h4>Standard Package:</h4><ul><li>Preseparation column with contact conductivity detectors employing FEP capillaries</li><li>Analytical column with contact conductivity (FEP capillary) detector</li><li>Variable column lengths: 85 mm PC CLD, 90 mm PC CD and AC CD, 140mm AC CLD, 160 – 200 mm PC CD and AC CD</li><li>Max. voltage: 15kV</li><li>Max. current: 500 mA</li><li>UV detector: 200, 220, 254, 280 nm</li><li>ITP injection valve: 30 μl</li><li>Variable injection volume via microsyringe facility: up to 100 μl</li><li>Dimensions: 400 x 685 x 390 mm (w x h x d)</li><li>Weight: 25 kg</li><li>Power supply: 230, 50 Hz, 100 W</li></ul><h4>Optional Accessories:</h4><ul><li>Preseparation column with contactless conductivity detectors employing FEP capillaries</li><li>Analytical column with contactless detector (FEP or quartz capillary).</li><li>UV VIS detector (190 - 600 nm): optional</li><li>DAD detector: optional</li><li>CZE and micro-preparative injection valve: optional</li><li>Education columns: clear column housing for educational purposes as zones can be directly visualised during separation</li></ul>

Villa Labeco ITP-CZE EA 303 A electrophoretic analyser

New Electrophoretic Analyser EA303A is a fully automatic 2-column analyzer that enables to perform the electrophoretic analysis in ITP, ITP-ITP and ITP-CZE mode. The modular design provides simple and user friendly changing of the columns.

New Electrophoretic Analyser EA303A is a fully automatic 2-column analyzer that enables to perform the electrophoretic analysis in ITP, ITP-ITP and ITP-CZE mode. The modular design provides simple and user friendly changing of the columns to optimize analysis and quick change the type of analysis. Both (preseparation and analytical) columns are equipped with the conductometric contact or contactless detectors. The analytical column is possible (via optical cables) to connect to UV, DAD or LIF detector. The capillary in the preseparation column is made from FEP with the inner diameter 0.8 mm and in the analytical column from FEP or quartz with the inner diameter 0.3 mm.&nbsp;<h4>Compare to previous type EA202A</h4><ul><li>Much smaller dimensions (only 1 box + autosampler)</li><li>Substantially reduce consumption of buffers</li><li>Originally designed much more versatile sample injection system</li><li>More reliable liquid connections</li><li>New principle improve reliability of checking of the level of the buffers in the reservoirs</li><li>Up-date software enables faster and more evaluating of the data</li></ul><h4>Technical Specifications</h4><ul data-start="124" data-end="432"><li data-start="124" data-end="162">Dimensions: 410 × 290 × 670 mm</li><li data-start="163" data-end="184">Weight: 28 kg</li><li data-start="185" data-end="218">Current Range: 0 – 500 µA</li><li data-start="219" data-end="251">Voltage Range: 0 – 15 kV</li><li data-start="252" data-end="311">Autosampler: Spark Marathon or Triathlon – 99 vials</li><li data-start="312" data-end="389">Sample Volume: 20 µL (standard), other options available upon request</li><li data-start="390" data-end="432">Power Supply: 230 V, 50 Hz, 150 VA</li></ul>

Villa Labeco ITP-CZE EA 102 electrophoretic analyser

Villa Labeco ITP-CZE EA 102 analyser is a more sophisticated and electronically reliable up-grade from the EA 100 and EA 101. From the analytical point of view, this analyser is identical to the EA 202M.

Villa Labeco ITP-CZE EA 102 analyser is a more sophisticated and electronically reliable up-grade from the EA 100 and EA 101. From the analytical point of view, this analyser is identical to the <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1716">EA 202M </a>but with the advantage that it has a smaller foot-print (dimensions (w x h x d): 275 x 620 x 256 mm). It is also possible to use both contact and contactless conductivity column detectors with this analyser and the whole unit is controlled by up-graded, easy to operate Windows software. However, in comparison to the EA 202M, an automation up-grade is not possible.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Villa_Labeco_ITP_CZE_EA_102_19af05a38d.jpg" alt="Villa Labeco ITP-CZE EA 102." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Villa_Labeco_ITP_CZE_EA_102_19af05a38d.jpg 174w," sizes="100vw" width="1147" height="1029">The analyser is on offer at a SPECIALLY REDUCED PRICE. Due to this low price, we highly recommend this analyser for use as an education tool in Universities and to this end we have a special ‘education column' available.

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