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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Waters Atlantis Silica HILIC HPLC Columns

Waters Atlantis HILIC Silica columns are used in combination with high organic mobile phases (>80% ACN) to provide retention of analytes that are too polar 

Atlantis HILIC Silica columns are used in combination with high organic mobile phases (&gt;80% acetonitrile) to provide retention of analytes that are simply too polar to be retained by reverse-phase chromatography. HILIC separation mechanisms provide orthogonal analyte selectivity compared to traditional chromatographic reversed-phase approaches.Due to their hydrophilic nature combined with their net positive charge at acidic pH, retention and separation of very basic polar analytes are extremely difficult using reversed-phase chromatography. The HILIC technology is able to resolve these challenging separation problems. This is what makes the Atlantis Silica HILIC Column the ideal lab equipment for use in metabolism, drug discovery, and combinatorial chemistries.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Waters_Atlantis_d_C18_HPLC_Columns_d7a741df9f.jpg" alt="Waters: Atlantis Silica HILIC HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Waters_Atlantis_d_C18_HPLC_Columns_d7a741df9f.jpg 234w," sizes="100vw" width="660" height="440"><h4>Specifications</h4><ul><li>Chemistry: HILIC</li><li>Separation Mode: Hydrophilic Interaction (HILIC)</li><li>Particle Substrate: Silica</li><li>pH Range Min: 1 pH</li><li>pH Range Max: 5 pH</li><li>Maximum Pressure: 6000 psi (415 Bar)</li><li>Endcapped: No</li><li>Silanol Activity: High</li><li>Particle Shape: Spherical</li><li>Pore Size: 100 Å</li><li>System: HPLC</li><li>USP Classification: L3</li></ul><h4>The Waters Atlantis Silica HILIC HPLC Column is also available as:</h4><h5>Waters Atlantis Silica HILIC HPLC Column&nbsp;with eConnect Column Tag</h5><ul><li>This column comes equipped with an electronic eConnect column tag containing unique column-specific information. These NFC-enabled device-tagged columns were developed to automatically identify, track and digitally trace column use history. eConnect columns can be used on any HPLC, but its advantages are unlocked when used with the Waters Alliance iS System running Empower software.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Waters_X_Bridge_BEH_C18_Column_with_e_Connect_Column_Tag_c056302ec7.jpeg" alt="Waters: Atlantis Silica HILIC HPLC Column with eConnect Column Tag" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Waters_X_Bridge_BEH_C18_Column_with_e_Connect_Column_Tag_c056302ec7.jpeg 234w," sizes="100vw" width="660" height="440"><h3>Atlantis Columns</h3><h4>Reversed-phase and HILIC HPLC Columns for superior polar compound retention</h4>Polar analytes are difficult to retain using traditional reversed-phase (RP) chromatography as they often elute in the void volume of the column. You can solve this challenge today with Atlantis Columns, which retain and separate polar analytes under reversed phase and HILIC conditions and provide quick, accurate, and reproducible quantification with increased retention and sensitivity.Available in T3, dC18, and the unbonded HILIC chemistries, the Waters Atlantis Column family provides exceptional performance, versatility, retention, and chromatographic stability for polar compounds and balanced retention for broad analyte mixtures.&nbsp;<h4>Overview</h4><ul><li>Retains and separates small, water-soluble polar organic compounds</li><li>Compatible with 100% aqueous mobile phases</li><li>Improves detection limits, method reproducibility, and robustness by eliminating ion-pairing reagents</li><li>Long column lifetimes using low-pH mobile phases</li><li>Fully scalable in 3, 5, and 10 μm particle sizes</li><li>Recommended Use: For the reproducible retention and separation of a broad range of polar and non-polar compounds.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Waters_Atlantis_HPLC_Columns_6651612161.jpg" alt="Waters: Atlantis HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Waters_Atlantis_HPLC_Columns_6651612161.jpg 234w," sizes="100vw" width="1024" height="682">

Waters SunFire Silica HPLC Columns

Waters SunFire Prep Silica columns are general purpose columns used under normal phase conditions.

SunFire Prep Silica columns are general purpose columns used under normal phase conditions.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Waters_Atlantis_d_C18_HPLC_Columns_d7a741df9f.jpg" alt="Waters: SunFire Silica HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Waters_Atlantis_d_C18_HPLC_Columns_d7a741df9f.jpg 234w," sizes="100vw" width="660" height="440"><h4>Specifications</h4><ul><li>Chemistry: Silica</li><li>Separation Mode: Normal Phase</li><li>Particle Substrate: Silica</li><li>pH Range Min: 2 pH</li><li>pH Range Max: 8 pH</li><li>Maximum Pressure: 6000 psi (415 Bar)</li><li>Endcapped: No</li><li>Silanol Activity: High</li><li>Particle Shape: Spherical</li><li>Pore Size: 100 Å</li><li>System: HPLC</li><li>USP Classification: L3</li></ul><h3>SunFire Columns</h3><h4>Superior mass loading at low pH</h4>High efficiency at a low pH can be challenging. Waters SunFire HPLC Columns, available in analytical and preparative dimensions, help you do just that with state-of-the-art bonded silica designed for high mass loading, excellent low pH stability, superior peak shapes, and high efficiency.SunFire Analytical Columns are available in 2.5 µm to 10 µm particle sizes across two reversed-phase column chemistries, C18 and C8, sure to meet your silica-based HPLC column requirements. For preparative applications, in addition to the C18 and C8 chemistries, SunFire silica is offered in 5 and 10 µm particle sizes for preparative normal-phase purification.<h4>Overview</h4><ul><li>Exceptional loading capacity for both analytical and preparative columns</li><li>Excellent low pH stability for longer lifetimes</li><li>Superior peak shapes for faster and easier integration</li><li>Low mass spectral (MS) bleed, for enhanced analyte MS signal</li><li>Seamless scalability from analytical to optimum bed density (OBD) preparative columns</li><li>Recommended Use: For increased mass loading with excellent column stability.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Waters_Sun_Fire_Columns_3f48bd770c/Waters-SunFire-Columns.jpg" alt="Waters: SunFire Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Waters_Sun_Fire_Columns_3f48bd770c/thumbnail_Waters-SunFire-Columns.jpg 242w," sizes="100vw" width="900" height="580">

Waters Nova-Pak Silica HPLC Columns

Nova-Pak HR Silica columns are silica-based, semi-preparative and preparative columns that are based on 6 µm particle technology.

Nova-Pak HR Silica columns are silica-based, semi-preparative and preparative columns that are based on 6 µm particle technology. Compared to a 5 µm column, Nova-Pak HR columns offer higher resolution, more efficient separations, and faster chromatography.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Waters_Atlantis_d_C18_HPLC_Columns_d7a741df9f.jpg" alt="Waters: Nova-Pak Silica HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Waters_Atlantis_d_C18_HPLC_Columns_d7a741df9f.jpg 234w," sizes="100vw" width="660" height="440"><h4>Specifications</h4><ul><li>Chemistry: Silica</li><li>Separation Mode: Normal Phase</li><li>Particle Substrate: Silica</li><li>pH Range Min: 2 pH</li><li>pH Range Max: 8 pH</li><li>Maximum Pressure: 6000 psi (415 Bar)</li><li>Endcapped: No</li><li>Silanol Activity: Low</li><li>Particle Shape: Spherical</li><li>Pore Size: 60 Å</li><li>System: HPLC</li><li>USP Classification: L3</li></ul><h3>Nova-Pak Columns</h3><h4>Scale-up from analytical to prep, simplified</h4>Reducing solvent consumption while maintaining resolution for complex mixtures is important, but that’s a challenge with larger particle sizes. With the smaller particle sizes and shorter column lengths in Nova-Pak Columns, those problems are a thing of the past. The bonded phases of Nova-Pak Columns are available in 4 µm and 6 µm particle sizes, offering high resolution and faster, more efficient chromatography over columns packed with larger particle sizes.Nova-Pak Analytical Columns with 4 µm particle size packing offer a range of length options with 75, 100, 150, and 300 mm length steel columns. The semi-preparative Prep Nova-Pak HR Columns are packed with 6 µm particle size packings for unparalleled separation possibilities. The high-efficiency packing of Prep Nova-Pak HR Columns provides faster separations with less solvent for the added advantage of more concentrated fractions—reducing your preparative chromatography cost. To ensure batch-to-batch reproducibility, all Nova-Pak C18, C8, Cyano and Phenyl Columns are packed according to stringent quality control (QC) procedures in Waters cGMP manufacturing facility.<h4>Overview</h4><ul><li>Reduces solvent consumption while maintaining resolution for complex mixtures</li><li>Packed to stringent QC procedures to ensure batch-to-batch reproducibility</li><li>Chemistries include C18, C8, Cyano, and Phenyl stationary phases</li><li>Available in 4 µm analytical and 6 µm semi-preparative particle sizes</li><li>Recommended Use: For higher resolution and faster chromatography.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Waters_Nova_Pak_Columns_fad066ad02/Waters-Nova-Pak-Columns.jpg" alt="Waters: Nova-Pak Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Waters_Nova_Pak_Columns_fad066ad02/thumbnail_Waters-Nova-Pak-Columns.jpg 245w," sizes="100vw" width="900" height="392">

Products from category Si HPLC columns focused on LC columns distributed by Waters Corporation (Europe) - page 1

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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