Objectives. The work set out to investigate the antioxidant activity of phenolic antioxidants synthesized by the authors (3,5-di-tert-butyl4-hydroxybenzyl alcohol, bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, bis(3,5-di-tert-butyl-4-hydroxybenzyl)glutarate, bis(3,5di-tert-butyl-4-hydroxybenzyl)adipate) in virgin high-density polyethylene and to compare this result with the antioxidant activity of industrially used stabilizers (Agidol-2, Agidol-23, Synox-1010).

Methods. The antioxidants were synthesized using developed methods described in previous works. The polyethylene films used in the study were produced by hot-pressing with the addition of the antioxidants under investigation at concentrations of 0.25, 0.5, and 1.0 wt %. Polymer samples containing antioxidants were subjected to accelerated oxidation at 100°C for 120 h. The degree of oxidation was monitored using the carbonyl index via infrared (IR) spectroscopy. IR analysis of the samples was carried out after 24, 52, 80, 100, and 120 h.

Results. This paper presents the results of a study on the antioxidant activity of commercial and author-synthesized phenolic antioxidants in virgin polyethylene at antioxidant concentrations of 0.25, 0.5, and 1.0 wt %. Among the industrial samples, Agidol-2 was found to be the most effective, demonstrating a significant antioxidant effect that begins at a concentration of 0.5 wt %. The protective effect of Agidol-23 begins at a concentration of at least 1.0 wt %; by the end of the experiment, darkening of the film is observed. The antioxidant Synox-1010 in polyethylene films, which is shown to migrate from the depth of the film to the surface, consequently cannot be recommended for use in polyethylene films and thin-walled products. As compared to industrial analogs, the antioxidants synthesized by the authors are shown to be more effective. The most effective of these is 3,5-di-tert-butyl4-hydroxybenzyl alcohol at a concentration of 1.0 wt %. However, ester antioxidants based on it can be used at lower concentrations while maintaining the same effectiveness.

Conclusions. The developed antioxidants, comprising 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, bis(3,5-di-tert-butyl-4-hydroxybenzyl)glutamate, and bis(3,5-di-tert-butyl-4-hydroxybenzyl)adipate, are shown to exhibit higher antioxidant activity as compared to the commercial antioxidants Agidol-2 and Agidol-23.

Objectives. This study set out to develop approaches for creating new photodynamic agents that incorporate a tumor-targeting ligand and a photoactive photosensitizer component within their structure. The work continues a series of investigations into the influence of the chemical structure of photosensitizers and type of conjugation with the targeting moiety on the antitumor efficacy of photodynamic therapy. The work proposed the design and synthesis of a new conjugate based on meso -aryl-substituted porphyrin and erlotinib, a low-molecular-weight tyrosine kinase inhibitor, which ensures selective delivery of the photosensitizer to the tumor.

Methods. In order to obtain the target compound, erlotinib was modified, the porphyrin was synthesized, and the conjugate of these two components was prepared using a click reaction. The compounds were characterized by[1] H and[13] C nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry.

Results. The target water-soluble conjugate of meso -arylporphyrin and erlotinib was obtained and characterized. Its biological activity was studied against conditionally normal (Normal Kidney Epithelial, NKE) and tumor (MCF-7, MDA-MB-231, A431) cell lines. The target conjugate demonstrated photoinduced activity in the submicromolar range and low dark toxicity. A relatively high dark-to-light toxicity ratio (~30 times) was shown for the conjugate.

Conclusions. The proposed design of a photodynamic agent based on the obtained conjugate of meso-arylporphyrin and erlotinib may facilitate progress in addressing the challenge of targeted photosensitizer delivery for use in photodynamic therapy.

Objectives. The work set out to analyze plant sources with the highest squalene content growing in the Russian Federation: Styrian pumpkin seeds, wheat sprouts, corn grains, grape seeds, Amaranthus caudatus seeds, Emperor amaranth seeds, Voronezhsky amaranth seeds, Kines amaranth seeds, Giant amaranth seeds. In order to evaluate the squalene content in the raw materials and identify the most promising sources, oil extraction and subsequent isolation of the unsaponifiable fraction from plant raw materials was carried out.

Methods. Oil extraction from plant raw materials was carried out by means of a Soxhlet apparatus with subsequent saponification of the obtained fraction and purification with n -hexane. Quantitative determination of squalene was carried out by high-performance liquid chromatography with diode array detection. The concentration of squalene in the test solutions was determined according to the calibration graph.

Results. After extracting oil from the plant material using a Soxhlet apparatus, the content of the oil was determined. The quantitative content of squalene was determined from the unsaponifiable fraction obtained from each oil sample in order to identify the species and variety of plant material that is the richest in squalene.

Conclusions. While the highest oil content was found in Styrian pumpkin seeds (35%) and grape seeds (10%), these extracts had a low (less than 1%) squalene content. A similarly low content was observed in corn grains and wheat sprouts. Among the studied amaranth varieties, a comparable oil content was found (6–8%), with the lowest value obtained in the Voronezhsky amaranth seeds (6.1%) and the maximum in the Kines amaranth seeds (7.9%). The squalene content in different types of amaranth seeds varied from 0.13 to 0.21%, of which the maximum value belongs to the Emperor amaranth seeds. This trend was observed both in the oil and in the unsaponifiable fraction. This makes this seed variety a promising source for commercial extraction of squalene.

Objectives. Porphyrins are known to selectively accumulate in tumor cells and exhibit photosensitizing properties. However, the use of free-base porphyrins is accompanied by side effects due to the slow elimination of such drugs from the body and long-term skin phototoxicity. One approach to solving this problem is to obtain metal complexes of porphyrins offering reduced phototoxicity. Gallium metal complexes of porphyrins are additionally known for their antimicrobial activity, which expands the range of their applications. In this connection, the work set out to synthesize gallium metal complexes of porphyrins as potential photosensitizers for use in antitumor and antimicrobial photodynamic therapy (PTD) applications.

Methods. Strategies for the synthesis of metal complexes of derivatives of natural porphyrins with gallium were implemented. The structures of the obtained compounds were obtained by mass spectrometry, ultraviolet spectroscopy, and X-ray photoelectron spectroscopy. The resulting compounds were isolated and purified by thin-layer chromatography, column chromatography, dialysis, and recrystallization.

Results. Strategies were developed for the synthesis of gallium metal complexes of etioporphyrin II, protoporphyrin IX dimethyl ether, and Dimegin for potential use in PTD. Based on the structural analysis of the obtained compounds using a combination of physicochemical methods, the elemental composition and chemical state of the atoms were identified to confirm the formation of metal complexes with gallium. Natural porphyrins and their derivatives, in particular etioporphyrin II, protoporphyrin IX, and Dimegin, were confirmed to have been successfully metalated with gallium at high yields. The high chelating ability of derivatives of natural porphyrins was demonstrated.

Conclusions. The resulting compounds are potential photosensitizers for antimicrobial and antitumor photodynamic therapy.

Objectives. The aim of this work is to investigate the corrosion resistance of ultrafine-grained magnesium alloy Mg–1%Zn–0.2%Ca processed by severe plastic deformation (SPD) methods, namely equal channel angular pressing combined with extrusion (ECAP-Ex) and circular simple shear extrusion (CSSE). In order to use such materials in the development of biocompatible implants, it becomes necessary to control their degradation rate.

Methods. To form an ultrafine-grained (UFG) structure, equal-channel angular pressing combined with extrusion (ECAP+Ex) and circular shear extrusion (CSSE) methods were used. Structural studies were conducted using X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In order to confirm the reliability of this material for use in biodegradable medical implants, a gravimetric corrosion resistance study was carried out at 36.6°C over a long period (month).

Results. The use of ECAP-Ex processing led to the formation of an ultrafine-grained (UFG) structure in the alloy having a grain size of about 1 μm and the appearance of nanotwins, as well as the formation of highly dispersed Ca₂Mg₆Zn₃ nanoparticles 10 nm in a size with a volume fraction of 1%. The corrosion rate of the UFG samples was 3.8 mm/year. Following additional annealing at 175°C, the UFG alloy demonstrated a decrease in the corrosion rate to 0.9 mm/year as compared with coarse grained homogenized sample (4.8 mm/year). By way of comparison, the CSSE processing resulted in grain size reduction to 1 μm and a corrosion rate of 1.3 mm/year.

Conclusions. The study demonstrates that combining equal-channel angular pressing ECAP+ Ex and subsequent annealing at 175°C is an effective method for improving corrosion properties of the Mg–1%Zn–0.2%Ca alloy. By reducing the corrosion rate to 0.9 mm/year, the alloy becomes promising for medical applications such as biodegradable implants.

Objectives. The work set out to obtain materials based on calcium titanate via cold sintering process (CSP) using magnesium sulfate hydrate as an activating additive and study the phase composition, microstructure, integral structural characteristics, and dielectric properties of the obtained materials depending on the activating additive fraction and the CSP temperature.

Methods. CaTiO₃-based materials with additions of MgSO₄·6H₂O (5–15 mol %) having an open porosity of at least 10% were obtained via CSP using uniaxial compression at a pressure of 220 MPa, temperatures from 300 to 400°C, and isothermal holding for 1 h.

Results. A formation mechanism of the material under the specified conditions is proposed, including stages involving a predominance of dissolution–precipitation and solid-phase diffusion mechanisms. With the addition of 5–10 mol % of MgSO₄·6H₂O, the dielectric loss tangent tanδ is ~0.01, while the relative permittivity ε_r is 38–52 at frequencies from 500 kHz to 2 MHz. Increasing the CSP time to 2 h at 400°C leads to an increase in ε_r to 50. Subsequent calcination in air at 900°C for 3 h leads to an increase in ε_r to 62 and a decrease in tanδ to 0.004. The decrease in the ε_r value of all the obtained materials as compared to pure CaTiO₃ (ε_r = 150–170) is due to high open porosity values (at least 10%).

Conclusions. A calcium titanate–based material via CSP can be produced using magnesium sulfate hydrate as an activating additive. CSP gives a porous material with high frequency stability, ε_r = 38–62, and tanδ ~ 10⁻² –10⁻³ . Due to their high open porosity, the resulting materials are promising for use as frameworks for composite capacitor materials.

Objectives . Oligomeric hyaluronans are pivotal molecules in pharmaceutics. Their efficiency and safety critically depend on their precise molecular weight distribution and stability. Current size-exclusion chromatography (SEC) methods for hyaluronan molecular weight assessment, which are primarily tailored for higher molecular weight samples, are often not applicable for oligomeric fractions, particularly within the 11–50 kDa range. These methods often lack the requisite resolution and reproducibility for robust degradation assessment and effective product quality control. The study set out to develop and optimize a highly efficient and precise chromatographic method for the accurate stability assessment of oligomeric hyaluronans within this critical molecular weight range.

Methods. To establish a robust analytical methodology, a systematic evaluation of the applicability of refractive index (RI) and ultraviolet-visible (UV/Vis) detectors was carried out. For the UV/Vis detector, the optimal wavelength for ensuring maximal signal-to-noise ratio and high specificity was empirically determined to be 214 nm. The careful selection of optimal mobile phase composition and chromatographic column type was critical for achieving effective separation of oligomers and minimizing nonspecific interactions. Standard chromatographic parameters, including flow rate, analyte concentration, injection volume, and column temperature, were additionally optimized to ensure high efficiency, reproducibility, and prevention of system overload.

Results. During the optimization process, it was found that a UV/Vis detector wavelength setting of 214 nm, which demonstrates significantly higher sensitivity and selectivity for oligomeric hyaluronans as compared to the RI detector, is the most suitable for analysis. The developed method ensured full baseline separation of all investigated oligomers within the 11–50 kDa molecular weight range. The optimized conditions demonstrated high separation efficiency with a coefficient of variation of less than 0.5% for retention times and less than 2.0% for peak areas, thereby confirming the excellent reproducibility of the method and absence of system overload.

Conclusions. The developed and validated size-exclusion liquid chromatography (SEC) method is a highly accurate, reliable, reproducible, and sensitive tool for assessing the stability of oligomeric hyaluronans. As well as significantly streamlining and enhancing the efficiency of quality control for oligomeric hyaluronan products, this methodology opens new avenues for in-depth investigation into their degradation mechanisms, thereby contributing to the improved quality and safety of hyaluronan-based pharmaceutical products.

Objectives. In recent years, the issue of food contamination with substances on the World Anti-Doping Agency (WADA) Prohibited List has become particularly pressing. Meldonium, prohibited in sport under Article S4.4, may be unintentionally consumed by athletes via the use of the veterinary drug Emidonol^® , approved by the Federal Service for Veterinary and Phytosanitary Surveillance ( Rosselkhoznadzor ), in farm animals. Two studies have already been published on the determination of meldonium in meat samples contaminated with the veterinary drug. However, its concentrations in urine samples obtained from volunteers following heat treatment and consumption of such meat have not yet been determined, nor has the duration of its urinary excretion been studied, both factors being important for rigorous anti-doping control. The present study therefore set out to quantitatively evaluate meldonium in samples of raw meat obtained from calves slaughtered on the 15th ( n = 3) and 30th ( n = 3) days following a course of Emidonol® injections, as well as to study the kinetics of its excretion in urine following the single consumption of 350 g of meat contaminated with it.

Methods. Raw meat samples were prepared using methanol–water extraction followed by acetonitrile protein precipitation, while urine samples were prepared using the dilute-and-shoot approach. High-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) under electrospray ionization conditions with positive ion detection (ESI+) was used for analysis. Meldonium was identified in selective reaction monitoring (SRM) mode using following SRM transitions and collision energies: 147 > 147 (10), 147 > 58 (17), 147 > 59 (17) for meldonium and 150 > 61 (30) for meldonium-d₃ (Internal Standard).

Results. Meldonium concentrations in raw meat samples from calves slaughtered 15 days after completion of the veterinary drug course ranged from 1428 ± 43 to 2627 ± 14 ng per 0.5 g; after 30 days, the corresponding concentrations varied from 922 ± 13 to 1558 ± 28 ng per 0.5 g. Following heat treatment and consumption of the meat samples, maximum concentrations of meldonium in urine reached after 2–5 h following consumption varied depending on the cooking method from 219 ± 2 to 386 ± 1 ng/mL, which significantly exceeds the WADA Minimum Required Performance Level (MRPL). Meldonium was still present in detectable amounts in the urine of volunteers 24–28 h after consumption of the Emidonol® - contaminated meat.

Conclusions. The potential for unintended meldonium use in athletes through the consumption of meat from farm animals contaminated with Emidonol® has been demonstrated. The tested levels could lead to a positive doping test and appropriate sanctions against the athlete.