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Investigation of the Complexation Activity of 2,4-Dithiouracil with Au(III) and Cu(II) and Biological Activity of the Newly Formed Complexes
(2024-08-01) Marinova P.; Stoitsov D.; Burdzhiev N.; Tsoneva S.; Blazheva D.; Slavchev A.; Varbanova E.; Penchev P.
The goal of this study is to synthesize, determine the structure, and examine the antimicrobial properties of novel Cu(II) and Au(III) complexes of 2,4-dithiouracil and its derivatives. These complexes were obtained by mixing aqueous solutions of the corresponding metal salts with the ligand dissolved in DMSO and aqueous NaOH, using a metal-to-ligand ratio of 1:4:2. The structures of the new compounds were analyzed by melting point determination, microwave plasma atomic emission spectrometry (MP-AES) for Cu and Au, inductively coupled plasma optical emission spectrometry (ICP-OES) for S, attenuated total reflection (ATR), solution and solid-state NMR, and Raman spectroscopy. The data for 2,4-dithiouracil obtained from the 1H NMR, 13C NMR, distortionless enhancement by polarization transfer spectrum (DEPT-135), proton–proton homonuclear correlation spectrum (1H-1H COSY), long-range 1H-13C heteronuclear multiple bond correlation experiment (HMBC), and heteronuclear single quantum coherence spectra (HSQC) aided the interpretation of the NMR data for the gold and copper complexes. Furthermore, the antimicrobial effect of the free ligands and their complexes was assessed against Gram-positive and Gram-negative bacteria, as well as yeasts.
Methods and algorithms of optimization in computer engineering: review and comparative analysis Métodos y algoritmos de optimización en ingeniería informática: revisión y análisis comparativo
(2024-02-08) Yakhno V.; Kolumbet V.; Halachev P.; Khambir V.; Ivanenko R.
Introduction: the main areas of application of artificial intelligence for algorithmic analysis and optimization of information flows in tasks of multiparametric diagnostics by means of computer engineering are considered. The issues of globalization of all areas of humanitarian, scientific, technical and engineering activities of human society are considered. It is noted that the common denominator of all directions is information flows. The main tools for their management and algorithmic analysis are multi-parametric methods of artificial intelligence. Method: one of its most relevant areas has been highlighted-the use of evolutionary algorithms in combination with modern diagnostic systems based on computer engineering. The possibility of using intelligent analysis of data from biophysical laser systems in assessing the state of “living matter”-the biological media of the human body-is considered. Results: through algorithmic optimization, a set of new cancer detection markers was determined: the statistical parameters of optical anisotropy maps wavelet coefficients linear distributions-the differences between these markers lie in the range from 4 to 20 times; the asymmetry of the wavelet coefficients autocorrelation function-the differences between these markers lie within two orders of magnitude; for normal state, the wavelet coefficients distributions are multifractal; for prostate cancer, the distributions of the wavelet amplitude coefficients are multifractal. Conclusions: a comparative study of the algorithmic optimization of differences of cancer through the use of multiparametric statistical, correlational, fractal and wavelet analysis of polarization tomograms of optical anisotropy of blood layers of donors and prostate cancer sicks is presented.
Performance of diffusion absorption refrigerators at variable power input
(2024-01-01) Stoyanov Y.; Penkova N.; Krumov K.
Absorption refrigerators have been used in recent decades for utilization of waste or solar energy to produce heat or cold for industrial purposes or to condition the microclimate in buildings. Although these units are designed at nominal power input in the generator, they can also operate at variable parameters of the heat source, which is possible in the real situations. An experimental determination of the operating range and the performance of a diffusion absorption refrigerator at heat pump and refrigeration mode were carried out in the present study. The results are useful for predicting the efficiency and the effectiveness of such systems at variable heat source capacities.
Recent Advances in the Application of Nitro(het)aromatic Compounds for Treating and/or Fluorescent Imaging of Tumor Hypoxia
(2024-08-01) Anichina K.; Lumov N.; Bakov V.; Yancheva D.; Georgiev N.
This review delves into recent advancements in the field of nitro(het)aromatic bioreductive agents tailored for hypoxic environments. These compounds are designed to exploit the low-oxygen conditions typically found in solid tumors, making them promising candidates for targeted cancer therapies. Initially, this review focused on their role as gene-directed enzyme prodrugs, which are inert until activated by specific enzymes within tumor cells. Upon activation, these prodrugs undergo chemical transformations that convert them into potent cytotoxic agents, selectively targeting cancerous tissue while sparing healthy cells. Additionally, this review discusses recent developments in prodrug conjugates containing nitro(het)aromatic moieties, designed to activate under low-oxygen conditions within tumors. This approach enhances their efficacy and specificity in cancer treatment. Furthermore, this review covers innovative research on using nitro(het)aromatic compounds as fluorescent probes for imaging hypoxic tumors. These probes enable non-invasive visualization of low-oxygen regions within tumors, providing valuable insights for the diagnosis, treatment planning, and monitoring of therapeutic responses. We hope this review will inspire researchers to design and synthesize improved compounds for selective cancer treatment and early diagnostics.
Phenotypic characterization and molecular identification of Bacillus pumilus isolated from Algerian goat’s milk and evaluation of its synbiotic effect with Hammada scoparia L. extract and ZnO-NPs
(2024-01-01) Chaima B.; Boutlelis D.A.; Touhami L.A.; Ghemam Amara D.; Khemakhem M.M.; Naccache C.; Atanassova M.; Zahnit W.; Ahmad S.F.; Messaoudi M.
This study was conducted to identify and characterize the Bacillus strain from Goat’s milk in Algeria and to evaluate the prebiotic effect of H. scoparia aqueous extract and ZnO-NPs on the isolated Bacillus strain. Potentially probiotic bacteria were isolated and identified based on phenotypic characteristics, including the morphological, physiological (growth temperature, salt tolerance), biochemical (API 10S strip kits), and confirmed by 16S rDNA gene sequencing. Bacillus pumilus specie of lactic acid bacteria were identified. The base pair length of amplified DNA for the isolate was 1500 Bp. The isolates could not grow at 10°C and 45°C and tolerate up to 6% salt. H. scoparia extract and ZnO-NPs have a beneficial effect on the Bacillus pumilus strain for acid tolerance, bile tolerance, and cell surface hydrophobicity respectively; H. scoparia extract and ZnO-NPs results are high comparing to the control group’s results. As the concentration of the tested samples increases, the percentage of probiotic characteristics of Bacillus pumilus increases, in contrast to the control sample. Therefore, they could be useful tools to define adequate combinations in colonic foods development and health benefits. The beneficial physiological and biochemical properties of isolated Bacillus pumilus space from Goat’s milk with the H. scoparia aqueous extract and ZnO-NPs revealed their potential applications in the food industry.
Synthesis, Characterization, and Antibacterial Studies of New Cu(II) and Pd(II) Complexes with 6-Methyl-2-Thiouracil and 6-Propyl-2-Thiouracil
(2023-12-01) Marinova P.; Hristov M.; Tsoneva S.; Burdzhiev N.; Blazheva D.; Slavchev A.; Varbanova E.; Penchev P.
The aim of the present study is to synthesize new metal complexes of 6-methyl-2-thiouracil and 6-propyl-2-thiouracil, elucidate their structures, and investigate their biological properties. All metal complexes were obtained after mixing water solutions of the corresponding metal salts and the ligand dissolved in DMSO and water solutions of NaOH in a metal-to-ligand ratio of 1:4:2. The structures of the new compounds are discussed based on melting point analysis (MP-AES) for Cu and Pd, UV-Vis, IR, ATR, 1H NMR, 13C NMR, and Raman spectroscopy. The interpretation of complex spectra is assisted by the data for 6-methyl-2-thiouracil and 6-propyl-2-thiouracil obtained from 1H-1H COSY, DEPT-135, HMBC and HMQC spectra. In addition, the antimicrobial activity of these complexes and the free ligands are assessed against both Gram-positive and Gram-negative bacteria, as well as yeasts. In general, the addition of metal ions improved the antimicrobial activity of both 6-methyl-2-thiouracil and 6-propyl-2-thiouracil. The Cu(II) complex with 6-methyl-2-thiouracil and the Pd(II) complex with 6-propyl-2-thiouracil exhibited the highest activity against the test microorganisms.
Synthesis and Biological Activities of Some Metal Complexes of 2-Thiouracil and Its Derivatives: A Review
(2024-03-01) Marinova P.E.; Tamahkyarova K.D.
The thionamide antithyroid agents were discovered largely through observations carried out by various researchers in the 1940s that found that sulfhydryl-containing substances were goitrogenic in animals. Prof. Edwin B. Astwood started using these drugs to treat hyperthyroidism. In the current paper, we summarize the development background of these agents and the coordination possibility of 2-thiouracil and its derivatives, as well as the biological activities of some of its complexes. Some of them are used as agents for the treatment of tuberculosis, and arthritis, others have bactericidal and fungicidal activity, the third cytotoxic properties, and could be used to treat various types of cancer.
Synthesis and Antibacterial Studies of a New Au(III) Complex with 6-Methyl-2-Thioxo-2,3-Dihydropyrimidin-4(1H)-One
(2024-06-01) Marinova P.; Burdzhiev N.; Blazheva D.; Slavchev A.
This article describes the synthesis of a new metal complex using 6-methyl-2-thioxo-2,3-dihydropyrimidin-4(1H)-one. The compound was analyzed using several methods, including determining its melting point and employing UV-Vis, IR, ATR, 1H NMR, HSQC, and Raman spectroscopy for the free ligand. The metal complex was formed by combining aqueous solutions of metal salts with the ligand dissolved in DMSO and water, along with NaOH in a metal-to-ligand-to-base ratio of 1:4:2. The NMR signals of the ligand were assigned using 1H-1H COSY, DEPT-135, HMBC, and HMQC spectra. Furthermore, the compound’s antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as yeasts, was assessed.
Impact of Silver Nanoparticle Treatment and Chitosan on Packaging Paper’s Barrier Effectiveness
(2024-08-01) Todorova D.; Yavorov N.; Vrabič-Brodnjak U.
In this study, a comparative analysis of silver nanoparticles treatment and chitosan coating on packaging paper barrier properties was carried out. In order to examine the water, grease, and antibacterial barrier properties of silver nanoparticle-treated and chitosan-coated laboratory-obtained paper samples, a mixture of bleached softwood and hardwood celluloses was used. In order to conduct the comparative analysis SEM, water contact angle, Cobb60, and Kit tests were carried out on a cellulose sample, and four paper samples (three of them treated with silver nanoparticles—1, 2, and 3 mL/20 cm2 or chitosan coated—0.5, 1, and 2 g/m2) together with the inhibition activity against nine Gram-positive and Gram-negative bacteria, yeast, and fungal strains. The study found out that increasing the silver nanoparticle treatment and chitosan coating led to improved water resistance, while grease resistance was improved only for chitosan coated paper samples. Additionally, paper treated with 3 mL/20 cm2 of silver nanoparticles had the highest antibacterial protection (81.6%) against the Gram-positive bacterium Staphylococcus aureus, followed by Gram-negative Escherichia coli (75.8%). For the rest of the studied microorganisms, the average efficiency of the treated paper was 40.79%. The treatment of the paper with 1 and 2 mL/20 cm2 of silver nanoparticles was less effective—27.13 and 39.83%, respectively. The antibacterial protection of 2 g/m2 chitosan-coated paper samples was the most effective (average 79%) against the tested bacterial, yeast, and fungal strains. At 1 and 0.5 g/m2 chitosan coatings, the efficiency was 72.38% and 54.67%, respectively. Gram-positive bacteria, yeasts, and fungal strains were more sensitive to chitosan supplementation.
Corrosion behavior of laser powder bed fusion manufactured nickel-free stainless steels in high-temperature water
(2024-10-01) Goel S.; Bojinov M.; Capek J.; Saario T.; Polatidis E.; Kantonen T.; Salminen A.; Blankenburg M.; Ganvir A.; Que Z.
The paper presents a comprehensive investigation of electrochemical behavior of laser powder bed fusion (PBF-LB/M) nickel-free stainless steels in high-temperature water. The PBF-LB/M nickel-free steels processed with various laser parameters and heat treatments exhibit tunable microstructures. Electrochemical impedance spectroscopy (EIS) indicates a 2–3 times lower oxidation rate for the nickel-free steels compared to wrought 316 L. The outer layer crystallites on nickel-free steels are close to pure Fe oxides. The significantly lower concentration of Ni in the inner oxide and at the alloy/oxide interface account for the important variations of the parameters of water reduction/hydrogen oxidation reactions than wrought 316 L.
Synthesis and Biological Activities of Some Metal Complexes of Peptides: A Review
(2024-06-01) Marinova P.; Tamahkyarova K.
Peptides, both natural and synthetic, are well suited for a wide range of purposes and offer versatile applications in different fields such as biocatalysts, injectable hydrogels, tumor treatment, and drug delivery. The research of the better part of the cited papers was conducted using various database platforms such as MetalPDB. The rising prominence of therapeutic peptides encompasses anticancer, antiviral, antimicrobial, and anti-neurodegenerative properties. The metals Na, K, Mg, Ca, Fe, Mn, Co, Cu, Zn, and Mo are ten of the twenty elements that are considered essential for life. Crucial for understanding the biological role of metals is the exploration of metal-bound proteins and peptides. Aside from essential metals, there are other non-essential metals that also interact biologically, exhibiting either therapeutic or toxic effects. Irregularities in metal binding contribute to diseases like Alzheimer’s, neurodegenerative disorders, Wilson’s, and Menkes disease. Certain metal complexes have potential applications as radiopharmaceuticals. The examination of these complexes was achieved by preforming UV–Vis, IR, EPR, NMR spectroscopy, and X-ray analysis. This summary, although unable to cover all of the studies in the field, offers a review of the ongoing experimentation and is a basis for new ideas, as well as strategies to explore and gain knowledge from the extensive realm of peptide-chelated metals and biotechnologies.
Evaluation of the combined activity of benzimidazole arylhydrazones as new anti-Parkinsonian agents: Monoamine oxidase-B inhibition, neuroprotection and oxidative stress modulation
(2021-11-01) Anastassova N.; Aluani D.; Kostadinov A.; Rangelov M.; Todorova N.; Hristova-Avakumova N.; Argirova M.; Lumov N.; Kondeva-Burdina M.; Tzankova V.; Yancheva D.
Neuroprotective drugs and selective monoamine oxidase inhibitors can slow down the progression and improve symptoms of Parkinson's disease (PD). Since there is an implication of oxidative stress in the pathophysiological mechanisms of the disease, the compounds possessing an ability to reduce the oxidative stress are prime candidates for neuroprotection. Thereby our current study is focused on the development of new multi-target PD drugs capable of inhibiting the activity of monoamine oxidase-B while exerting neuroprotective and antioxidant properties. A small series of benzimidazole derivatives containing hydroxy and methoxy arylhydrazone fragments has been synthesized and the neurotoxicity of the compounds has been evaluated in vitro on neuroblastoma SH-SY5Y cells and on isolated rat brain synaptosomes by measuring the cell viability and the levels of reduced glutathione and a good safety profile has been shown. The 2-hydroxy-4-methoxy substituted arylhydrazone 7 was the least toxic on neuronal SH-SY5Y cells and showed the lowest neurotoxicity in rat brain synaptosomes. The neuroprotective properties of the test compounds were further assessed using two models: H2O2-induced oxidative stress on SH-SY5Y cells and 6-hydroxydopamine-induced neurotoxicity in rat brain synaptosomes. Compound 7 showed more pronounced neuroprotective activity on SH-SY5Y cells, compared to the referent melatonin and rasagiline. It also preserved the synaptosomal viability and the reduced glutathione levels; the effects were stronger than those of rasagiline and comparable to melatonin. All the tested compounds were capable to inhibit human monoamine oxidase-B enzyme to a significant extent, however, compound 7 exerted the most prominent inhibitory activity, similar to selegiline and rasagiline. The carried out molecular docking studies revealed that the activity is related to the appropriate molecular structure enabling the ligand to enter deeper in the narrow and highly lipophylic active site pocket of the human monoamine oxidase-B and has a favoring interaction with the key amino acid residues Tyr326 and Cys172. Since much scientific evidence points out the implication of iron dyshomeostasis in PD, the compounds were tested to reduce the ferrous iron induced oxidative molecular damage on biologically important molecules in an in vitro lecithin containing model system. All the investigated compounds denoted protection effect, stronger than the one of the referent melatonin. In order to support the assignments of the significant neuroprotective and antioxidant pharmacological activities, the radical-scavenging mechanisms of the most promising compound 7 were evaluated using DFT methods. It was found that the most probable free radicals scavenging mechanism in nonpolar phase is the hydrogen atom transfer from the amide group of compound 7, while in polar medium the process is expected to occur by a proton transfer. The current study outlines a perspective leading structure, bearing the potential for a new anti-PD drug. All performed procedures were approved by the Institutional Animal Care Committee of the Medical University of Sofia (Bulgarian Agency for Food Safety with Permission № 190, approved on February 6, 2020).
Core–shell catalyst pellets for effective reaction heat management
(2023-02-01) Zimmermann R.T.; Weber S.; Bremer J.; Idakiev V.; Pashminehazar R.; Sheppard T.L.; Mörl L.; Sundmacher K.
Catalyst research is concerned with synthesizing increasingly active materials, leading to safety issues at reactor scale, unless the reaction heat release is controllable. Computational studies predict that core–shell pellets with catalytically active core and inert shell are beneficial for this purpose, compared to established concepts such as catalyst pellet dilution. At high temperatures, reactant diffusion through the shell becomes rate-determining, resulting in a well-controllable heat release rate, which prevents further temperature increase. Here, industrial catalyst pellets were coated in a fluidized-bed pilot plant, demonstrating large-scale production feasibility. The obtained pellets were characterized via Dynamic Image Analysis, Scanning Electron Microscopy and X-ray Computed Tomography. Conducted CO2 methanation experiments confirm the predicted trends, if the applied shell is fully closed. Furthermore, mathematical and experimental studies demonstrate, that the inert shell shifts selectivity. Based on this work, safer and yet economical reactor operation is anticipated also for other reaction systems.
Fused Triazinobenzimidazoles Bearing Heterocyclic Moiety: Synthesis, Structure Investigations, and In Silico and In Vitro Biological Activity
(2023-07-01) Anichina K.; Georgiev N.; Lumov N.; Vuchev D.; Popova-Daskalova G.; Momekov G.; Cherneva E.; Mihaylova R.; Mavrova A.; Atanasova-Vladimirova S.; Piroeva I.; Yancheva D.
[1,3,5]Triazino[1,2-a]benzimidazole-2-amines bearing heterocyclic moiety in 4-position were synthesized. The compounds were characterized by elemental analysis, IR, 1H-NMR, 13C-NMR, and HRMS spectroscopy. The molecular geometry and electron structure of these molecules were theoretically studied using density functional theory (DFT) methods. The molecular structure of the synthesized fused triazinobenzimidazole was confirmed to correspond to the 3,4-dihydrotriazinobenzimidazole structure through the analysis of spectroscopic NMR data and DFT calculations. The antinematodic activity was evaluated in vitro on isolated encapsulated muscle larvae (ML) of Trichinella spiralis. The results showed that the tested triazinobenzimidazoles exhibit significantly higher efficiency than the conventional drug used to treat trichinosis, albendazole, at a concentration of 50 μg/mL. The compound 3c substituted with a thiophen-2-yl moiety exhibited the highest anthelmintic activity, with a larvicidal effect of 58.41% at a concentration of 50 μg/mL after 24 h of incubation. Following closely behind, the pyrrole analog 3f demonstrated 49.90% effectiveness at the same concentration. The preliminary structure-anti-T. spiralis activity relationship (SAR) of the analogues in the series was discussed. The cytotoxicity of the benzimidazole derivatives against two normal fibroblast cells (3T3 and CCL-1) and two cancer human cell lines (MCF-7 breast cancer cells and chronic myeloid leukemia cells AR-230) was evaluated using the MTT-dye reduction assay. The screening results indicated that the compounds showed no cytotoxicity against the tested cell lines. An in silico study of the physicochemical and pharmacokinetic characteristics of the novel synthesized fused triazinobenzimidazoles showed that they were characterized by a significant degree of drug-likeness and optimal properties for anthelmintic agents.
Analysis of Carotenoids in Sweet Potatoes Using HPLC to Help Combat Vitamin A Deficiency
(2024-01-01) Dolchinkova T.N.
The fascinating and diverse family of organic compounds called carotenoids is widely found in plants, as well as some bacteria and algae. These natural pigments, with vibrant colours ranging from bright yellow to deep red and flamboyant red, attract attention for their importance in plant biology and their effect on human health. One of the most common vitamin deficiencies in the world is vitamin A deficiency. The name carotenoids come from the vegetable carrot (carrot in Latin), where there are many well-known beta-carotenoids. These compounds are essential to biological processes beyond contributing to nature's variety of colours. A deficiency, a persistent public health problem in many parts of the world. The precise quantification of carotenoids, in particular beta-carotene, makes it possible to evaluate the specific contribution of these sweet potatoes to the intake of vitamin A in the diet. This study offers important data that could guide efforts to promote sweet potato consumption, particularly in regions where vitamin A deficiency is a concern. These tubers can be strategically included in diets to improve the availability of vitamin A, helping to mitigate the risks associated with this nutritional deficiency. In sum, this HPLC analysis of carotenoids in sweet potatoes provides a solid basis for the promotion of these tubers as a dietary resource rich in provitamin A, thereby contributing to the fight against vitamin A deficiency and the promotion of health. in the communities concerned.
Antimicrobial activity of (KLAKLAK)–NH2 analogs against pathogenic microbial strains
(2024-01-01) Jaber S.; Evstatieva Y.; Nemska V.; Nikolova D.; Naydenova E.; Georgieva N.; Danalev D.
Many microorganisms pose a threat to human health due to the ever-increasing bacterial resistance to conventional drugs. Nowadays, searching for new alternatives to conventional antibiotics to fight bacterial resistance is a main task. Thus, natural molecules such as amino acids and peptides arise as possible solutions to the problem. The antimicrobial activity of targeted compounds was studied by the agar-diffusion method, using the prepared working solutions of the targeted peptides with the corresponding concentrations. The results of the antimicrobial activity against different test pathogens show specificity, as antimicrobial activity against the used test microorganisms was not found in the investigated short-chain synthetic peptides Si6, Si3 and Si13. Antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, Propionibacterium acnes, Escherichia coli, Pseudomonas aeruginosa, and the yeasts Malassezia furfur and Candida albicans was established for the long-chain synthetic peptides Si1, Si5 and Si16, except Si5 which does not show activity against pathogenic fungal strain C. albicans. The compound Si16 where natural Leu in (KLAKLAK)2-NH2 is replaced by unnatural Nle is the best candidate for medical drug due to the combined antibacterial and antiproliferative effect as well as long hydrolytic stability.
EFFECT OF THE LIMITING DEFORMATION ZONE UNDER CONDITIONS OF ASYMMETRIC LOADING DURING ROLLING OF MEDIUM THICKNESS STRIPS
(2024-01-01) Chigirinsky V.; Naizabekov A.; Lezhnev S.; Kuzmin S.; Panin E.; Tolkushkin A.; Volokitina I.; Yordanova R.; Knapinski M.
The aim of the work is to develop a physical and mathematical model of the process under complex asymmetric loading in conditions of single-area and two-area deformation zone during plastic processing of medium-thickness strips. The stress state in case of loss of stability during rolling of strips of medium thickness was investigated. The patterns of changes in the stress state of the strip under conditions of reach of the limiting deformation zone, as well as the effects of plastic shaping determined by a decrease in contact stresses under conditions of increasing deformation loading, are revealed. The described method is a visual approach to assessing the stress state of a plastic medium under conditions of complex interaction and asymmetric loading.
ISOLATION AND CHARACTERIZATION OF PEPTIDES FROM MILK AS NATURAL INHIBITORS OF ACE I AND FOOD ADDITIVES
(2024-01-01) Yakimova B.; Alexova R.; Dobreva L.; Rainova Y.; Dobrev S.; Danova S.; Angelova S.; Stoineva I.
Inhibition of Angiotensin-converting enzyme I (ACE I) is a modern therapeutic approach to treatment of hypertension. In recent years, research into natural ACE peptide inhibitors without side effects has become important. The aim of this study is to isolate and characterize novel bioactive peptides from skim and/or whole cow’s milk fermented with selected lactobacillus strains. Several homo/heterofermentative strains of the Lactobacillus species of dairy origin have been pre-selected and different milk fermented samples have been studied. A protocol for analyses was designed and the milk proteins were separated by centrifugation at 4°C at 10000 × g, with molecular mass cut off (MWCO) membranes of 3 and 10 kDa. The samples with molecular mass below 3 kDa were further separated by ultrafiltration by dialysis cell (cut off membrane 1 kDa) by continuous stirring at room temperature. The milk fractions under 1 kDa molecular mass were characterized by UPLC-MS. The ACE-inhibitory activity was determined using the FAPGG (N-[3-(2-Furyl) acryloyl]-L-phenylalanyl-glycyl-glycine) degradation method. All tested samples (1 kDa) exhibit ACE I inhibitory activity with IC50 in a range of 6 - 37 mg mL-1. In silico logP prediction of selected peptides was used to assess whether lipophilicity of the compounds falls within the so-called “therapeutically relevant pharmacokinetic space”.
In vitro and ex vivo studies on angiotensin-i converting enzyme (Ace) inhibitory activity of short synthetic peptides
(2021-01-01) Yakimova B.; Mateeva P.; Kardaleva P.; Stoineva I.; Todorova P.; Zamfirova R.; Yanev S.
In our days the interest in the studies of new angiotensin-converting-enzyme (ACE) inhibitors as modulators of the renin-angiotensin-system (RAS) is growing, not only because of their importance as drugs for arterial hypertension treatment, but also for their therapeutic potential during COVID-19 infection. This study presents data for the design and synthesis of short peptides by SPPS strategy and investigates in vitro and ex vivo their potential as ACE inhibitors in the light of structural changes. The obtained results give insight into the structure-activity relationship of peptide sequences and show differences regarding the effects of peptides in two experimental procedures (inhibitory potency on purified ACE activity and AT-I induced rat ileum contractions). Three of the newly synthesized peptides with terminal proline, LAP, LKP and VAP, showed relatively high inhibitory activities.
Study of Ammonia Adsorption on Magnetite Surfaces with Molecular Dynamics Simulations
(2024-07-01) Ivanova N.; Karastoyanov V.; Betova I.; Bojinov M.
The present study proposes an atomistic molecular dynamics model system of a magnetite (Fe3O4) {111} surface. The effect of temperature on the adsorption process of ammonia (NH3) at low concentrations in the aqueous phase has been considered. The molecular dynamics simulations were carried out using the Clay force field (Clay FF) with a modification for the iron atoms in the NPT ensemble at a pressure of 90 bar. The considered system was heated in a temperature range from 293 to 473 K, and additional relaxations were performed at temperatures of interest. Within the scope of this study, the basic parameters of the magnetite surface were calculated and the distances between the ammonia molecules and the surface were determined. A general idea of the degree and rate of adsorption at specific temperatures was obtained. The calculation results were compared to the experimental data where possible and to other available simulations of adsorption processes on metal oxides.

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