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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Watrex SPR-200 Solvent saver

Watrex SPR-200 Solvent Recycler is designed to save up to 90% of mobile phase during isocratic HPLC.

This Solvent Recycler saves up to 90% of mobile phase by redirection of the pure solvent to the solvent reservoir during the isocratic HPLC. The stand alone device is powered by 5 V DC from power adapter or from computer USB port. Working parameters (Threshold and Delay) are easily set on the display using a membrane keyboard.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Watrex_Watrex_SPR_200_Solvent_saver_I_Nputs_694d991f2c.jpg" alt="Watrex: Watrex SPR-200 Solvent saver - INputs">The SPR-220™ Solvent Recycler continuously monitors the output signal of the chromatography detector and displays its current value on the built-in display. A highresolution analog-to-digital converter provides data for further evaluation in the built-in processor. If the input signal level exceeds a preset value (Threshold), the SPR-200 will redirect the flow to the waste.When the signal drops, the solvent recycler waits for the transport delay and then switches the mobile phase back to the reservoir. An autosampler injection marker connected to the SPR-200 ZERO input can be used to zero the input signal at the time of injection.<h3>FEATURES</h3><ul><li>Stand alone operation</li><li>Detachable valve</li><li>Possibility of manual Waste/Recycle switching</li></ul><h3>TECHNICAL SPECIFICATION</h3><ul><li>Detector compatibility: compatible with any HPLC detector</li><li>Connection: 1/16″ O.D. tubing, 1/4″-28 flat bottom fittings</li><li>Maximum pressure: 30 p.s.i./0,2 MPa</li><li>Wetted material: PEEK, PTFE</li><li>Input range: +/- 1 V or +/- 100 mV, user selectable</li><li>Computer connection: μUSB</li><li>TTL/contact closure input: configurable (ZERO, start, valve position)</li><li>Power: 5V DC/&lt;100 mA (power supply or computer USB port)</li><li>User interface: large character LCD alphanumeric display + membrane keypad</li></ul><h3>Ordering information:</h3><h5>PN/Component:</h5><ul><li>SPR200-001 SPR-200 Solvent Recycler, PEEK version (Price 1 250 € ex VAT)</li><li>SPR200-002 SPR-200 Solvent Recycler, PTFE version (Price 1 250 € ex VAT)</li></ul>You can also visit this product on the <a target="_blank" rel="noopener noreferrer" href="https://watrex.com/?s=SPR-200+Solvent&amp;post_type=product&amp;dgwt_wcas=1?utm_source=labrulez&amp;utm_medium=propagace&amp;utm_campaign=labrulez_produkty">Watrex website</a>.

Watrex LSS-205 Liquid Sensing System

Liquid Sensing System LSS-205 is a universal sensing system for monitoring the level of your chromatographic system liquids.

Universal sensing system for monitoring the level of your chromatographic system liquids. The daily task in the chromatographic laboratory is the manipulation of mobil phases. The operator must check the supply of solvents at the inlet of the device and regular monitor the condition of the waste solvent container. The LSS-205 greatly simplifies these tasks.<blockquote>Price: 578<bdi>&nbsp;€ ex VAT</bdi></blockquote>LSS-205 is a universal accessory for any (chromatographic) system. The level sensors used in the LSS-205 system are contactless, do not require immersion in liquid, and are installed on the outer shell of a non-metallic solvent container. The method of mounting the sensor allows placement on a container of virtually any shape and size.The LSS-205 central unit is ready to process the signal from up to five liquid sensors, which can be individually set to trigger an alarm in the event of a missing or present liquid. The error status of the individual sensors is indicated optically directly on the central unit and the alarm can be accompanied by an acoustic signal. An external loud siren suitable for a noisy environment is available as an option to the central unit.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Watrex_LSS_205_Liquid_Sensing_System_33_0fd5d29a02/Watrex-LSS-205-Liquid-Sensing-System-33.jpg" alt="Watrex LSS-205 Liquid Sensing System"><h3>FEATURES</h3><ul><li>Simple operation</li><li>Flexible in application</li><li>Multiple connection option</li><li>Starter kit contents: central unit, one sensor, light bar, power supply</li><li>Color touch panel control</li></ul><h3>TECHNICAL SPECIFICATION</h3><ul><li>Power supply: 5V DC (wall mount power supply or USB port of PC)</li><li>Number of liquid sensors: 1 – 5</li><li>Alarm condition: individually adjustable for each sensor (off, missing liquid, liquid present)</li><li>Internal alarm indication: high intensity LED for each sensor</li><li>Internal acoustic alarm: 80dB, common for all sensors</li><li>External optical signaling: connector on the central unit</li><li>External acoustic alarm: optional 105 dB external horn</li><li>Alarm signal for external devices: logic (open collector), relay switching contact</li><li>Computer connection: micro USB connector, simple text communication protocol</li><li>Firmware update: possible in field</li><li>Dimension: 130x80x30 mm</li><li>Weight: 250 g</li><li>Sensor dimensions: 50x30x15 mm</li><li>Sensor connection cable: 2 m length</li><li>Sensor mounting: plastic holder with flexible silicon tube (length 700 mm, other lengths on request)</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Watrex_LSS_205_Liquid_Sensing_System_6_7b35aadbb7/Watrex-LSS-205-Liquid-Sensing-System-6.jpg" alt="Watrex LSS-205 Liquid Sensing System - level sensor"><h3>Ordering information:</h3><h5>PN/Component:</h5><ul><li>40-0728 Starter Kit (incl. 1 sensor + light)</li><li>40-0738 LSS-205 Additional Sensor</li><li>40-0841 LSS-205 Additional 2 Sensors</li><li>40-0842 LSS-205 Additional 3 Sensors</li><li>40-0843 LSS-205 Additional 4 Sensors</li><li>40-0838 LSS-205 External Alarm Horn</li></ul>You can also visit this product on the <a target="_blank" rel="noopener noreferrer" href="https://watrex.com/obchod/chromatography/dedicated-instruments/lss-205-starter-kit/?utm_source=labrulez&amp;utm_medium=propagace&amp;utm_campaign=labrulez_produkty">Watrex website</a>.

Watrex UFO Solvent Recycler

UFO Solvent Recycler saves up to 90% of mobile phase by redirection of the pure solvent to the solvent reservoir during the isocratic HPLC.

This compact device saves up to 90% of mobile phase by redirection of the pure solvent to the solvent reservoir during the isocratic HPLC. The device is powered by 5 V DC from computer USB port or power adapter. Working parameters (Threshold and Delay) are set using user friendly software.<blockquote>Price: 635<bdi>&nbsp;€ ex VAT</bdi></blockquote>The UFO Solvent Recycler continuously monitors the output signal of the chromatography detector and displays its current value in the application on computer. A high-resolution analog-to-digital converter provides data for further evaluation in the built-in processor.If the input signal level exceeds a preset value (Threshold), the UFO recycler will redirect the flow to the waste. When the signal drops, the solvent recycler waits for the transport delay and then switches the mobile phase back to the reservoir. An autosampler injection marker connected to the UFO recycler START input can be used to zero the input signal at the time of injection.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UFO_schema_6a4cdc0ed4/UFO_schema.png" alt="Watrex: Principle and process of mobile phase recycling during isocratic HPLC using the UFO system"><h3>FEATURES</h3><ul><li>Very compact design</li><li>Simple operation</li></ul><h3>TECHNICAL SPECIFICATION</h3><ul><li>Detector compatibility: compatible with any HPLC detector</li><li>Connection: 1/16″ O.D. tubing, 1/4″-28 flat bottom fittings</li><li>Maximum pressure: 30 p.s.i./0,2 MPa</li><li>Wetted material: PEEK, PTFE</li><li>Input range: +/- 1 V or +/- 100 mV, user selectable</li><li>Computer connection: USB-A</li><li>TTL/contact closure input: configurable (ZERO, start, valve position)</li><li>Power: 5V DC/&lt;100 mA (power supply or computer USB port)</li><li>User interface: PC Windows based software</li></ul><h3>Ordering information:</h3><h5>PN/Component:</h5><ul><li><a target="_blank" rel="noopener noreferrer" href="https://watrex.com/obchod/chromatography/dedicated-instruments/ufo-solvent-recycler-peek-version/?utm_source=labrulez&amp;utm_medium=propagace&amp;utm_campaign=labrulez_produkty">UFO000-001</a> UFO™ Solvent Recycler , PEEK version</li><li><a target="_blank" rel="noopener noreferrer" href="https://watrex.com/obchod/chromatography/dedicated-instruments/ufo-solvent-recycler-ptfe-version/?utm_source=labrulez&amp;utm_medium=propagace&amp;utm_campaign=labrulez_produkty">UFO000-002</a> UFO™ Solvent Recycler , PTFE version</li></ul>

Watrex PCRS-300 Post-column derivatization

The PCRS-300 post-column reaction system is a combination of a precision low-pulse high-pressure pump and thermostat in one unit.

Compact system for post-column derivatization consisting of low-pulse reagent pump with selector valve and tempered reaction chamber for reaction coil.<blockquote>Price: 5 033<bdi>&nbsp;€ ex VAT</bdi></blockquote>A selector valve at the inlet of the pump allows choice between reagent and flushing solvent. The system is controlled through color touch panel placed on the front of main unit.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Watrex_PCRS_300_3_d3a79a1a57/Watrex-PCRS-300-3.jpg" alt="Watrex: Schematic of the Watrex PCRS-300 low-pulse pump system for post-column derivatisation"><h3>FEATURES</h3><ul><li>Very low pulse reagent delivery</li><li>Excellent temperature stability</li><li>Heating up to 150°C</li><li>Number of reagent coil options</li><li>Thermal fuse against overheating</li><li>Color touch panel control</li></ul><h3>TECHNICAL SPECIFICATION</h3><ul><li>Wetted materials: PEEK, PTFE, HDPE, ruby, sapphire</li><li>Flow rate range: 0,01 – 9,99 ml/min</li><li>Flow rate accuracy: &lt; 2%</li><li>Temperature range: up to 150 °C</li><li>Temperature stability: &lt; +/- 0,1 °C</li><li>Liquid connections: Inlet – 1/8″, 1/4″-28 flat bottom; Outlet – 1/16″, UNF 10-32</li><li>Connections: USB, TTL I/O control (ready out, shutdown in)</li><li>Control: build-in color touch panel</li><li>Dimensions: 310 x 270 x 170 mm (WxDxH, main unit)</li><li>Power requirements: 19-20V DC/4,7A</li></ul><h3>Ordering information:</h3><h5>PN/Component:</h5><ul><li>PCRS300-001 Post Column Reaction System</li><li>PCRS300-002 Reaction coil select from 250µl - 2000µl in Stainless Steel</li><li>PCRS300-003 Reaction coil select from 500µl - 1000µl in PEEK</li><li>PCRS300-004 Reaction coil select from 500µl - 1000µl in PTFE</li><li>PCRS300-999 Reaction coil , customized</li></ul>You can also visit this product on the <a target="_blank" rel="noopener noreferrer" href="https://watrex.com/obchod/chromatography/dedicated-instruments/pcrs-300-post-column-reaction-system-2/?utm_source=labrulez&amp;utm_medium=propagace&amp;utm_campaign=labrulez_produkty">Watrex website</a>.

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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