Igor Alexandrovich Rodin

The chemical identification of indigoid dyes in archeological textiles remains a significant analytical challenge due to the diversity of indigoid components, their susceptibility to post-deposition degradation, and the risk of further transformation during sample preparation. Seventeen samples of early medieval textiles from the ancient city of Deraheib (Sudan) were studied. Tryptanthrin—an indoloquinazoline alkaloid previously documented only in model solutions—was identified in archeological textiles for the first time, providing a new qualitative marker of indigo-type dyeing that may persist when the original dye has undergone substantial degradation. Two variants of the methanolic hydrochloric acid treatment step—ultrasonication without heating versus boiling in a water bath at 100 °C—and the replacement of dimethylformamide with acetonitrile in the third extraction stage were systematically compared.

Electron beam irradiation, extensively used for suppressing a wide range of pathogens contaminating food products, pharmaceuticals and biological raw materials, inevitably damages the surrounding proteins, stripping the product of its essential nutritional and functional properties. This issue can be addressed by adjusting the electron beam irradiation dose, bearing in mind the concentration of proteins in the product since it can affect the rate of radiation-induced modifications in proteins. The study investigates the impact of 7.5 MeV electron-beam irradiation on modifications in bovine serum albumin (BSA) molecules in 0.9% NaCl solution in the concentration range of 0.5–70 mg/mL, encompassing a wide range of protein concentrations in food products, pharmaceuticals and biological raw materials. Conformational changes and aggregation of BSA were evaluated using UV–Vis spectrophotometry at λ = 350 nm. Peptide bond rupture in protein native structures was assessed by performing HPLC-MS/MS analysis after trypsin hydrolysis using three selected peptides located in different domains of the BSA amino acid sequence. It was found that the rate of radiation-induced modifications increased with an increase in the irradiation dose but decreased markedly as BSA concentration increased. While at the BSA concentration of 0.5 mg/mL over 87% of BSA molecules underwent peptide bond rupture under irradiation with a dose of 5 kGy, a two-fold increase in the BSA concentration and irradiation dose enabled bond rupture in only 20% of BSA molecules. Our experimental approach resulting in the development of the dose and concentration model allows us to quantify the degree of radiation-induced protein modifications depending on the irradiation dose and protein concentration in food products, pharmaceuticals and biological raw materials.

The interaction between proteins and salts in aqueous solutions represents a compelling scientific problem in both biophysical and medical research. One manifestation of the interaction in the bovine serum albumin (BSA)–NaCl–H₂O system is the formation of ordered patterns upon droplet drying. In our experiments, the topographic features of the deposited particles as well as their elemental composition were studied using optical microscopy and scanning electron microscopy (SEM). In this work, we experimentally investigated the stepwise change in the characteristic structures of the precipitate with an increase in the BSA concentration from 0.005 to 35 mg/mL. The formation of discrete BSA–NaCl ring deposits near the droplet edge and around crystallization centers in the interior at BSA concentrations of 0.05–1 mg/mL proved particularly interesting. We demonstrated the sequence of ring structure formation: the process primarily begins with the formation of BSA aggregates arranged in sectors around the circumference, which in turn serve as nucleation sites for NaCl crystallization. We propose a qualitative conceptual–phenomenological interpretation of the observed experimental effects. Concentration-dependent patterns in the emergence and development of other patterns (such as spikes, fractal structures, and chrysanthemum-like formations) were established. These results expand our understanding of protein behavior in aqueous-salt solutions. This can be used in medical diagnostics as biomarkers. The characteristic patterns presented in the work can serve as a useful experimental basis for further studies of the impact of physicochemical factors on proteins and other biopolymers.

Antimicrobial resistance is a major threat to modern society and healthcare, as it severely compromises the efficacy of standard antibiotic treatments. To meet the ever-increasing demand for novel antimicrobial drugs, it is crucial to develop new strategies for screening antimicrobial compounds and improve existing high-throughput techniques. Reporter systems that employ specific genetic markers are powerful tools not only for detecting antimicrobial activity of the substance being studied, but also for identifying the potential mechanism of its action. Among other metabolic pathways, RNA biosynthesis machinery is considered a promising molecular target as it remains underutilized in current antimicrobial therapy and therefore is rarely exposed to drug pressure. However, there is no suitable biomarker for identifying compounds that inhibit the transcription in Gram-negative bacteria. Combining bioinformatic search and RT-qPCR experimental validation, we have established the overexpression of the spermidine synthase gene (speE) as a biomarker associated with impaired transcription in Escherichia coli. Monitoring the expression level of speE in antibiotic-treated cells enables reliable detection of compounds that inhibit bacterial RNA-polymerase, such as rifampicin and fidaxomicin. Moreover, our screening system was successfully applied in practice to analyze chromatography fractions from fermentation broth of antibiotic producers, with compounds of the rifamycin family being identified as hits and isolated. The proposed method has the potential to be used in sequential screening procedures to reveal active antimicrobial compounds that inhibit bacterial transcription process, giving the world novel antimicrobials with minimal risk of resistance development.

The design of multifunctional theranostic nanomaterials, including the application of J-aggregates as photothermal (PTT) and photodynamic (PDT) therapy agents, is in high demand.

In recent years, a scenario involving milk contamination by biotransformation products of the veterinary drug Emidonol has received widespread publicity. Emidonol is intended for use in cattle under pathological conditions accompanied by hypoxia. The drug dissociates into two antihypoxants—meldonium, a metabolic modulator prohibited in sports, and emoxypine, which also has antioxidant properties. A small‐scale pilot study involved three volunteers consuming a single 900‐mL dose of unpasteurized cow's milk collected on the last (15th) day of treatment with the drug. The mean estimated urinary concentration of emoxypine peaked between 7‐ and 8.5‐h postadministration (1360 ± 240 ng/mL), elimination time being approximately 50–54 h. The mean estimated urinary concentration of meldonium peaked between 5.8‐ and 9.0‐h postadministration and was 322 ± 68 ng/mL, elimination time being approximately 35–45 h. The simultaneous presence of emoxypine and meldonium in urine samples may be indicative of the consumption of Emidonol‐contaminated milk, which may facilitate the identification of cases of unintended doping in sport.

Three positional isomers of 1,10-phenanthroline-2,9-dicarboxamides were synthesized. The coordination chemistry of these diamides has been studied, and the photophysical properties of their complex compounds have been investigated.

Objectives: Vitamin K homologues are essential to human health, and their concentrations in biological samples serve as valuable diagnostic biomarkers. This study was aimed to develop a method for determining vitamins K1 (phylloquinone, VK1) and K2 (menaquinone, MK-4) in human serum. The proposed method was validated and applied to the serum of a cohort of 20 Russian individuals. Methods: High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was used to analyse the content of VK1 and MK-4 in serum. Atmospheric pressure chemical ionisation (APCI) in negative mode was applied to ionise VK1 and MK-4. Protein precipitation and solid-phase extraction (SPE) on polystyrene-divinylbenzene resin were combined to isolate and preconcentrate the analytes from serum. Results: The HPLC-MSMS method was developed and validated for the determination of vitamins VK1 and MK-4 in human serum. The method demonstrated a lower limit of quantification (LLOQ) of 0.05 μg/L, with more than 71 % recoveries and precision within 17 %. To demonstrate the applicability of the method to real samples, serum from 20 healthy adults was analyzed. VK1 was detected in four individuals (0.094–0.96 μg/L), whereas MK-4 concentrations were below 0.22 μg/L in all cases. Conclusions: The validated HPLC-MS/MS workflow provides a reliable and sensitive approach for the quantification of VK1 and MK-4 in minimal serum volumes. The method demonstrates robustness, reproducibility, and suitability for large-scale analytical applications. The proposed LC-MS/MS protocol successfully applied to native human serum samples, illustrating its applicability for future clinical and biochemical studies involving vitamin K.

Food irradiation is increasingly used to extend shelf life and control pests and diseases. Monitoring post-treatment doses typically relies on expensive, laborious instruments and may miss low doses. We previously proposed a chemical fingerprinting method that estimates dose based on indicator reaction rates, but this approach was tested only on freshly irradiated samples. In this study, we investigated the feasibility of determining the order of magnitude of dose in irradiated raw potato tubers after several days of storage. A completely randomized experimental design was used. Water extracts of potatoes were assayed in oxidation–reduction and aggregation reactions in 96-well plates; reaction rates were tracked by absorbance and fluorescence and analyzed chemometrically. We could distinguish dose orders of magnitude (0, 100, 1000 Gy) after 0, 2, and 6 days of storage at 4 °C. The accuracy of dose recognition on day 6 was at least 97% by using SoftMax regression (SR) or linear discriminant analysis (LDA); irradiated and non-irradiated samples were confidently distinguished using partial least square–discriminant analysis (PLS-DA). The reaction-based method of dose assessment is simple, rapid, and does not require sophisticated equipment.