Publications by authors named "Vladimir Klochkov"

The spectral characteristics of cyclosporin C (CsC) with the addition of Dy ions in acetonitrile (CDCN) and CsC with Dy incorporated into dodecylphosphocholine (DPC) micelle in deuterated water were investigated by high-resolution NMR spectroscopy. The study was focused on the interaction between Dy ions and CsC molecules in different environments. Using a combination of one-dimensional and two-dimensional NMR techniques, we obtained information on the spatial features of the peptide molecule and the interaction between CsC and the metal ion.

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Here, we report a synthesis of fluoroquinolones carrying a monoterpene moiety at the C7 position of aromatic structure. The minimal inhibitory concentrations of fluoroquinolone fused with trans-3-hydroxy-cis-myrtanylamine 18 against Staphylococcus aureus (MSSA isolates) were two- to eightfold lower compared to moxifloxacin, although fourfold higher against MRSA isolates. The fluoroquinolone fused with (-)-nopylamine 16 was four- to eightfold less active on MSSA compared to moxifloxacin, while had similar activity on MRSA.

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It has been shown that human seminal fluid is a major factor in enhancing HIV activity. The SEM2(49-107) peptide is a product of cleavage after ejaculation by internal prostheses of the semenogelin 2 protein, expressed in seminal vesicles. It is established that the peptide SEM2(49-107) forms amyloid fibrils, which increase probability of contracting HIV infection.

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GdVO:Eu nanoparticles (OVNPs) have previously been shown to exhibit anti-aging effects in old rats.The accelerated aging model (overnutrition in early postnatal ontogenesis (POF)) was used to confirm the effect of OVNPs as a potential geroprotector. A comparative study of the effect of OVNPs, calorierestriction (CR) and CR-mimetic-metformin was carried out using a number of criteria: survival, prooxidant-antioxidant balance in the liver and blood, physiological parameters of male Wistar rats with accelerated aging.

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The therapeutic potential of redox-active nanoscale materials as antioxidant- or reactive oxygen species (ROS)-inducing agents was intensely studied. Herein, we demonstrate that the synthesized and characterized GdVO:Eu and LaVO:Eu nanoparticles, which have been already shown to have redox-active, anti-inflammatory, antibacterial, and wound healing properties, both in vitro and in vivo, worsen oxidative stress of L929 cells triggered by hydrogen peroxide or -butyl hydroperoxide (tBuOOH) at the concentrations that are safe for intact L929 cells. This effect was observed upon internalization of the investigated nanosized materials and is associated with the cleavage of caspase-3 and caspase-9 without recruitment of caspase-8.

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The design of fluorescent probes based on biocompatible luminophores for medical diagnostics is one of the rapidly developing areas worldwide. Here, we report the synthesis of a novel BODIPYs containing a propanoic acid residue at the α-position of one of the pyrrole rings conjugated to (+)-myrtenol or thiotherpenoid. Both conjugates are quite photostable (t ∼ 40 h) and exhibit high fluorescence efficiency (φ ∼ 77-90 %).

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We have studied the effect of calcium ions (Ca) at various concentrations on the structure of lipid vesicles in the presence of amyloid-beta peptide Aβ(25-35). In particular, we have investigated the influence of calcium ions on the formation of recently documented bicelle-like structures (BLSs) emerged as a result of Aβ(25-35) triggered membrane disintegration. First, we have shown by using small-angle X-ray and neutron scattering that peptide molecules rigidify the lipid bilayer of gel phase DPPC unilamellar vesicles (ULVs), while addition of the calcium ions to the system hinders this effect of Aβ(25-35).

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Article Synopsis
  • Ribosome biogenesis is a complex and energy-demanding process, where any small errors can lead to serious consequences for the cell, including death.
  • Biogenesis factors like RimP play a crucial role in this process by assisting the proper assembly of ribosomal proteins and rRNA.
  • This study details how RimP interacts with the 30S ribosomal subunit in Staphylococcus aureus, providing insights into its binding and structural dynamics through advanced techniques like cryo-EM and NMR spectroscopy.
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Our complementary experimental data and molecular dynamics (MD) simulations results reveal the structure of previously observed lipid bicelle-like structures (BLSs) formed in the presence of amyloid-beta peptide Aβ(25-35) below the main phase transition temperature (T) of saturated phosphatidylcholine lipids and small unilamellar vesicles (SUVs) above this temperature. First, we show by using solid-state P nuclear magnetic resonance (NMR) spectroscopy that our BLSs being in the lipid gel phase demonstrate magnetic alignment along the magnetic field of NMR spectrometer and undergo a transition to SUVs in the lipid fluid phase when heated through the T. Secondly, thanks to the BLS alignment we present their lipid structure.

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  • A new method for synthesizing pyrazolo[3,4-]pyridines is introduced, using 3-arylidene-1-pyrrolines and aminopyrazoles in a single reaction process.
  • The reaction involves a series of steps: nucleophilic addition, electrophilic substitution, and C-N bond cleavage, resulting in derivatives with a primary amino group.
  • This method allows researchers to stop the reaction at the electrophilic substitution phase, offering an easier way to create the challenging pyrazolopyrrolopyridine structure.
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  • Researchers created two types of polysiloxanes (cubic and linear) with branches made of polyoxyethylene using specific chemicals, finding that these new materials don't easily self-condense.* -
  • A detailed study showed how varying the amount of copper chloride affects the structure of these polysiloxanes and their ability to improve the absorption characteristics of certain membranes made from block copolymers.* -
  • The developed membranes demonstrated increased sorption capacity and high permeability for organic dyes and metal ions, which linked their internal structures to successful chemical reactions involving an analytical reagent (PAN) and copper chloride.*
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It is known that four peptide fragments of predominant protein in human semen Semenogelin 1 (SEM1) (SEM1(86-107), SEM1(68-107), SEM1(49-107) and SEM1(45-107)) are involved in fertilization and amyloid formation processes. In this work, the structure and dynamic behavior of SEM1(45-107) and SEM1(49-107) peptides and their N-domains were described. According to ThT fluorescence spectroscopy data, it was shown that the amyloid formation of SEM1(45-107) starts immediately after purification, which is not observed for SEM1(49-107).

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Article Synopsis
  • Peptides, like cyclosporins, are essential for various biological activities, and their functions can be influenced by how easily they pass through cell membranes.
  • Molecular dynamics simulations and NMR spectroscopy were used to study cyclosporins C, E, H, and L, revealing similarities in their spatial structures and changes when interacting with lipid bilayers.
  • Understanding how these peptides interact with model membranes can provide insights into their membrane permeability, which is crucial for their biological effects.
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. Rare-earth orthovanadate nanoparticles (ReVO:Eu, Re = Gd, Y or La) are promising agents for photodynamic therapy of cancer due to their modifiable redox properties. However, their toxicity limits their application.

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  • Researchers developed polyurethane membranes that allow vapor to pass through using aminoethers of boric acid (AEBA), modified with bulk adducts from diphenylol propane diglycidyl ether and ethanolamine (EM).
  • These modifications reduced the size of AEBA-EM particles and their viscosity, which helped the membranes become more permeable to vapor.
  • The enhanced vapor permeability, which was tripled in the modified polyurethanes, occurs due to reduced cluster size that creates channels for water molecules, improving the membranes' efficiency in dehydrating isopropanol.
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The control over bacterial diseases requires the development of novel antibacterial agents. The use of antibacterial nanomedicines is one of the strategies to tackle antibiotic resistance. The study was designed to assess the antimicrobial activity of cerium oxide (CeO ) nanoparticles (NP) of two different sizes (CeO NP1 [1-2 nm] and CeO NP2 [10-12 nm]) and their cytotoxicity towards eukaryotic cells.

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SEM1(68-107) is a peptide corresponding to the region of semenogelin 1 protein from 68 to 107 amino acid position. SEM1(68-107) is an abundant component of semen, which participates in HIV infection enhanced by amyloid fibrils forming. To understand the causes influencing amyloid fibril formation, it is necessary to determine the spatial structure of SEM1(68-107).

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Due to its unique redox chemistry, nanoceria is considered as potent free radical scavenger and antioxidant. However, their protective capacity in aging organisms remains controversial. To detect the anti-aging effects associated with the redox activity of 2 and 10 nm nano-CeO2, different test systems were used, including in vitro analysis, in situ assay of mitochondria function and in vivo studies of suitable nano-CeO on aging of male Wistar rats from 22 months-old to the end of life.

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  • The study focuses on the etherification reaction of -phosphoric acid (OPA) with polyoxypropylene glycol, using triethanolamine (TEOA) and triethylamine (TEA) as catalysts under low-temperature conditions.
  • It finds that triethylamine leads to complete etherification, resulting in branched OPA ethers and possible polyphosphate structures, while triethanolamine causes incomplete etherification, leaving some phosphate anions unreacted.
  • The research also includes an analysis of the kinetics of the reaction and the properties of polyurethane ionomer films created from aminoethers of -phosphoric acid (AEPA).
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The search for novel antimicrobial agents is of huge importance. Nanomaterials can come to the rescue in this case. The aim of this study was to assess the cytotoxicity and antimicrobial effects of rare-earth-based orthovanadate nanoparticles.

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  • The study investigates how the pore inhibitor cyclosporin A (CsA) and its analogue alisporivir (Ali) impact rat skeletal muscle mitochondria, revealing that both increase calcium capacity without affecting oxidative phosphorylation at low concentrations.
  • At higher concentrations (5 μM), both agents suppress oxygen consumption, with Ali causing more notable effects, linked to reduced membrane potential and inhibited electron transport due to coenzyme Q mobility issues.
  • The research shows that neither CsA nor Ali impacts hydrogen peroxide production, but both decrease membrane fluidity in liposomes and mitochondrial membranes, suggesting their lipophilic properties may hinder mitochondrial efficiency.
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  • The paper discusses the design and analysis of a BODIPY biomarker combined with a thioterpene fragment to improve its structural and biological properties.
  • It examines how this conjugate interacts with erythrocytes (red blood cells) and its potential use in bioimaging, confirming the molecular structure through various spectroscopic methods.
  • The results indicate that the conjugate has high photostability and fluorescence, effectively entering erythrocytes without causing toxicity, which enhances its application in biological contexts.
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Nanotechnology can be applied to design antibacterial agents to combat antibiotic resistance. The aim of the present study was to assess the antimicrobial effects and cytotoxicity of GdYVO:Eu nanoparticles (NPs). Biofilm inhibition activity, antimicrobial activity, bacterial viability inhibition and DNA cleavage activity of GdYVO:Eu NPs were studied.

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Platelet aggregation causes various diseases and therefore challenges the development of novel antiaggregatory drugs. In this study, we report the possible mechanism of platelet aggregation suppression by newly synthesized myrtenol-derived monoterpenoids carrying different heteroatoms (sulphur, oxygen, or nitrogen). Despite all tested compounds suppressed the platelet aggregation in vitro, the most significant effect was observed for the S-containing compounds.

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