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270 results on '"Yancheva, Denitsa"'

52. Modulation Effect on Tubulin Polymerization, Cytotoxicity and Antioxidant Activity of 1H-Benzimidazole-2-Yl Hydrazones.

Author

Argirova, Maria, Guncheva, Maya, Momekov, Georgi, Cherneva, Emiliya, Mihaylova, Rositsa, Rangelov, Miroslav, Todorova, Nadezhda, Denev, Petko, Anichina, Kameliya, Mavrova, Anelia, and Yancheva, Denitsa

Subjects
TUBULINS, HYDRAZONES, STRUCTURAL isomers, POLYMERIZATION, MOLECULAR docking, CANCER cells, BINDING sites
Abstract

1H-benzimidazol-2-yl hydrazones with varying hydroxy and methoxy phenyl moieties were designed. Their effect on tubulin polymerization was evaluated in vitro on porcine tubulin. The compounds elongated the nucleation phase and slowed down the tubulin polymerization comparably to nocodazole. The possible binding modes of the hydrazones with tubulin were explored by molecular docking at the colchicine binding site. The anticancer activity was evaluated against human malignant cell lines MCF-7 and AR-230, as well as against normal fibroblast cells 3T3 and CCL-1. The compounds demonstrated a marked antineoplastic activity in low micromolar concentrations in both screened in vitro tumor models. The most active were the trimethoxy substituted derivative 1i and the positional isomers 1j and 1k, containing hydroxy and methoxy substituents: they showed IC50 similar to the reference podophyllotoxin in both tumor cell lines, accompanied with high selectivity towards the malignantly transformed cells. The compounds exerted moderate to high ability to scavenge peroxyl radicals and certain derivatives—1l containing metha-hydroxy and para-methoxy group, and 1b-e with di/trihydroxy phenyl moiety, revealed HORAC values high or comparable to those of well-known phenolic antioxidants. Thus the 1H-benisimidazol-2-yl hydrazones with hydroxy/methoxy phenyl fragments were recognized as new agents exhibiting promising combined antioxidant and antineoplastic action. [ABSTRACT FROM AUTHOR]

Published
2023
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53. MODEL FOR PHOTODEGRADATION WITH A MODIFIED RATE CONSTANT. PART 1: USE OF ANODICALLY-PREPARED THIN ZnO FILMS FOR METHYL ORANGE PHOTODEGRADATION.

Author

Lilov, Emil, Lilova, Vanya, Nedev, Svetlozar, Kozhukharov, Stephan, Girginov, Christian, and Yancheva, Denitsa

Subjects
THIN films, ATTENUATED total reflectance, PHOTODEGRADATION, EMISSION spectroscopy, ATOMIC force microscopy, ZINC oxide films, OPTICAL spectroscopy, ANODIC oxidation of metals
Abstract

Four sets of samples of anodically prepared ZnO thin films were tested as potential photocatalysts for degradation of methyl orange (MO). The results show that the best properties belong to the samples prepared by anodization in oxalic acid and subsequently annealed 3 hours at 341°C. The dependences of the rate of the reaction on the time of use of the photocatalyst, the temperature of the decomposition reaction, the pH of the solution and the illumination were investigated too. The activation energies of the reactions were derived from the dependence of the rate of the reaction on the temperature. The properties of the acquired ZnO anodic films, as well as their compositions and structures were investigated by various analytical techniques, as follows: Attenuated Total Reflection Fourier Transformation Infrared Spectroscopy (ATR-FTIR), X-ray Diffractometry (XRD), Atomic Force Microscopy (AFM), Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES), Scanning Electron Microscopy (SEM) and UV-VIS Spectrophotometry. [ABSTRACT FROM AUTHOR]

Published
2022

54. 1H-benzimidazole-2-yl hydrazones as tubulin-targeting agents: Synthesis, structural characterization, anthelmintic activity and antiproliferative activity against MCF-7 breast carcinoma cells and molecular docking studies

Author

Anichina, Kameliya, primary, Argirova, Maria, additional, Tzoneva, Rumyana, additional, Uzunova, Veselina, additional, Mavrova, Anelia, additional, Vuchev, Dimitar, additional, Popova-Daskalova, Galya, additional, Fratev, Filip, additional, Guncheva, Maya, additional, and Yancheva, Denitsa, additional

Published
2021
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57. SYNTHESIS OF NEW TRIAZOLE AND THIADIAZOLE DERIVATIVES OF THE N,N'-DISUBSTITUTED BENZIMIDAZOLE-2-THIONE AND EVALUATION OF THEIR ANTITUMOR POTENTIAL.

Author

Anastassova, Neda, Georgieva, Irina, Milanova, Vanya, Tzoneva, Rumiana, Radev, Kuentin, Yancheva, Denitsa, and Mavrova, Anelia

Subjects
TRIAZOLE derivatives, THIADIAZOLES, THIOSEMICARBAZONES, CELL motility, CELL nuclei, STAINS & staining (Microscopy), CELL lines
Abstract

In the present study series of triazole-, thiadiazole- and thiosemicarbazone-benzimidazole hybrid compounds were synthesized as potential anti-cancer agents. In order to determine their antitumor potential and cytotoxic effect (via MTT assay) lung adenocarcinoma (A549) and breast cancer (MDA-MB-231) cell lines were examined. For detection of apoptosis induced by drug treatment, DAPI staining was performed in order to observe the apoptotic alterations in cell nuclei. It was found that the thiadiazole derivative 12 leads to the occurrence of micronuclei, suggesting genotoxic effect. Furthermore, a wound healing assay was performed in order to test whether any changes in cell motility occurred upon treatment with the newly synthesized hybrids, since both cell lines are examples of highly invasive tumours. The cell motility of MDA-MB-231 was impeded mostly by compound 12 (15 % of wound closure) and in A549 compound 9 reduced cell motility by 46 % compared to the control. The obtained results suggest that compound 12 possesses a promising anticancer effect. [ABSTRACT FROM AUTHOR]

Published
2022

59. Benzimidazole-based dual dipeptidyl peptidase-4 and xanthine oxidase inhibitors

Author

Tomović, Katarina, Ilić, Budimir S., Smelcerović, Zaklina, Miljković, Marija, Yancheva, Denitsa, Kojić, Milan, Mavrova, Anelia Ts, Kocić, Gordana, Smelcerović, Andrija, Tomović, Katarina, Ilić, Budimir S., Smelcerović, Zaklina, Miljković, Marija, Yancheva, Denitsa, Kojić, Milan, Mavrova, Anelia Ts, Kocić, Gordana, and Smelcerović, Andrija

Abstract

Multiple-targeting compounds might reduce complex polypharmacy of multifactorial diseases, such as diabetes, and contribute to the greater therapeutic success. Targeting reactive oxygen species-producing enzymes, as xanthine oxidase (XO), might suppress progression of diabetes-associated vascular complications. In this study a small series of benzimidazole derivatives (1-9) was evaluated for inhibitory activity against dipeptidyl peptidase-4 (DPP-4) and XO. One 1,3-disubstituted-benzimidazole-2-imine (5) and 1,3-thiazolo [3,2-a] benzimidazolone derivative (8) were shown as effective dual DPP-4 and XO inhibitors, with IC50 values lower than 200 mu M, and predicted binding modes with both target enzymes. Both selected dual inhibitors (compounds 5 and 8) did not show cytotoxicity to a greater extent on Caco-2 cells even at concentration of 250 mu M. These structures represent new non-purine scaffolds bearing two therapeutic functionalities, being DPP-4 and XO inhibitors, more favorable in comparison to DPP-4 inhibitors with DPP-4 as a single target due to pleiotropic effects of XO inhibition.

Published
2020

61. Evaluation of the combined activity of benzimidazole arylhydrazones as new anti-Parkinsonian agents: monoamine oxidase-B inhibition, neuroprotection and oxidative stress modulation

Author

Anastassova, Neda, primary, Aluani, Denitsa, additional, Kostadinov, Anton, additional, Rangelov, Miroslav, additional, Todorova, Nadezhda, additional, Hristova-Avakumova, Nadya, additional, Argirova, Maria, additional, Lumov, Nikolay, additional, Kondeva-Burdina, Magdalena, additional, Tzankova, Virginia, additional, and Yancheva, Denitsa, additional

Published
2021
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70. Benzo[4,5]thieno[2,3-d]pyrimidine phthalimide derivative, one of the rare noncompetitive inhibitors of dipeptidyl peptidase-4

Author

Tomović, Katarina, Ilić, Budimir S., Miljković, Marija, Dimov, Stefan, Yancheva, Denitsa, Kojić, Milan, Mavrova, Anelia T., Kocić, Gordana, Smelcerović, Andrija, Tomović, Katarina, Ilić, Budimir S., Miljković, Marija, Dimov, Stefan, Yancheva, Denitsa, Kojić, Milan, Mavrova, Anelia T., Kocić, Gordana, and Smelcerović, Andrija

Abstract

A small library of benzo[4,5]thieno[2,3-d]pyrimidine phthalimide and amine derivatives was evaluated for inhibitory activity against dipeptidyl peptidase-4 (DPP-4). The phthalimide derivatives exhibited better activity than the amine precursors, with 2-(2-(3-chlorobenzyl)-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4-yl)isoindoline-1,3-dione (compound 14) as the most effective inhibitor (IC50 = 34.17 +/- 5.11 mu M). The five most potent selected inhibitors did not show cytotoxicity to a greater extent on Caco-2 cells, even at a concentration of 250 mu M. Compound 14 is considered as a novel representative of the rare noncompetitive DPP-4 inhibitors. Molecular docking and dynamics simulation indicated the importance of the Tyr547, Lys554, and Trp629 residues of DPP-4 in the formation of the enzyme-inhibitor complex. These observations could be potentially utilized for the rational design and optimization of novel (structurally similar, with phthalimide moiety, or different) noncompetitive DPP-4 inhibitors, which are anyway rare, but favorable in terms of the saturation of substrate competition.

Published
2019

75. NEW 1,3-DISUBSITUTED BENZIMIDAZOL-2-ONES AS A PROMISING SCAFFOLD FOR THE ANTITRIHINELLOSIS AGENTS DEVELOPMENT.

Author

Mavrova, Anelia, Anichina, Kameliya, Izevbekhai, Oisaemi, Vutchev, Dimitar, Popova-Daskalova, Galya, Yancheva, Denitsa, and Stoyanov, Simeon

Subjects
MOLECULAR shapes, PHASE-transfer catalysis, TRICHINELLA spiralis, DENSITY functional theory, ALBENDAZOLE
Abstract

New 1,3-disubsituted benzimidazol-2-ones are synthesized in order to evaluate their anti-trichinellosis efficacy. Solid-liquid phase transfer catalysis as the most readily available synthesis method was used to prepare the target compounds. The precursors required for the synthesis of the disubstituted benzimidazoles were obtained by means of two methods. Structures analysis of the compounds by means of IR, 1H NMR analysis was performed. The molecular geometry and electron structure of these molecules were evaluated using density functional theory (DFT) methods. Antitricinellosis activity of the compounds was investigated. The parasitological study in vitro showed that some of the tested benzimidazolones possessed higher activity against Trichinella spiralis than albendazole. The data of SAR for most of the tested compounds are comparable with those of albendazole. [ABSTRACT FROM AUTHOR]

Published
2021

76. SYNTHESIS AND STABILITY OF A RAPANA THOMASIANA HEMOCYANIN CONJUGATED WITH VITAMIN B9.

Author

Guncheva, Maya, Raynova, Yuliana, Idakieva, Krassimira, Todinova, Svetla, and Yancheva, Denitsa

Subjects
HEMOCYANIN, N-terminal residues, VITAMINS, DIFFERENTIAL scanning calorimetry, HYDROPHOBIC interactions, STACKING interactions
Abstract

This is the first report on the synthesis of vitamin B9-Rapana thomasiana hemocyanin conjugates (vit. B9-RtH). Proteins modified with 25 and 150 vitamin B9 residues аre obtained in a coupling reaction between N-hydroxysuccinimide-activated γ -carboxylic groups of vitamin B9 and the amino-groups of N-terminal amino acids and lysines comprising the protein. ATR-FTIR spectroscopy is applied to monitor the changes of the secondary structure upon the modification. The comparison of the secondary structure of the native and the vitamin B9-conjugated RtHs shows that the modification results in an increase of the β-structures in a favor of α-helices and coiled structures. The therrmal stability of the novel preparations is evaluated by differential scanning calorimetry (DSC). Despite the serious changes of the conformation, the vit.-B9-RtH conjugates are characterized by a high thermal stability. It is assumed that the changes of the DSC profiles are due to alternative protein-protein interactions, e.g H-bonding, stacking or hydrophobic interactions with vitamin B9 moieties that are possible in the modified RtH molecules. [ABSTRACT FROM AUTHOR]

Published
2020

80. Characterization of Zahari Zograph’s nave wall paintings in the church “The nativity of the virgin” of Rila Monastery (Bulgaria) by vibrational spectroscopy and SEM–EDX analysis

Author

Yancheva, Denitsa, primary, Tapanov, Stefan, additional, Velcheva, Evelina, additional, Stamboliyska, Bistra, additional, Glavcheva, Zornitza, additional, Stoyanov, Simeon, additional, Haralampiev, Nikifor, additional, Fischer, Dieter, additional, and Lederer, Albena, additional

Published
2017
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82. Folate-conjugated Helix lucorumhemocyanin – preparation, stability, and cytotoxicity

Author

Guncheva, Maya, Idakieva, Krassimira, Todinova, Svetla, Stoyanova, Elena, and Yancheva, Denitsa

Abstract

This is the first report on the modification of a hemocyanin from Helix lucorum(HlH), a large molluscan respiratory protein, with folic acid (FA). In a two-step synthetic reaction, we prepared samples of HlH conjugated with 20 and 50 FA residues denoted as FA-HlH-1 and FA-HlH-2, respectively. Comparison of the attenuated total reflectance–Fourier transform infrared spectra in the amide I band region showed a structural rearrangement in the HlH that is due to FA conjugation. The changes in the secondary structure were more noticeable for FA-HlH-2. The thermal stability of HlH was not significantly affected by the FA modification, which is consistent with the observed structural similarities with the native protein. Preliminary cytotoxicity assays showed that FA-HlH-1 and FA-HlH-2 stimulate fibroblast proliferation when applied in concentrations of 50 and 100 μg/well. A negligible reduction of fibroblast growth was observed only for FA-HlH-1 and FA-HlH-2, exposed to 200 μg/well for 48 h. We found that FA-HlH-2 exhibits a low to moderate cytotoxic effect on two breast cancer cell lines, which express folate receptors, a hormone-dependent (MCF-7) and a hormone-independent (MDA-MB-231). FA-HlH-2 protects nontransformed cells and affects only neoplastic cells, which could be an advantage, and the protein could have potential in combination with other chemotherapeutics.

Published
2020
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84. Rapana thomasiana hemocyanin modified with ionic liquids with enhanced anti breast cancer activity

Author

Guncheva, Maya, primary, Paunova, Krasimira, additional, Ossowicz, Paula, additional, Rozwadowski, Zbigniew, additional, Janus, Ewa, additional, Idakieva, Krassimira, additional, Todinova, Svetla, additional, Raynova, Yuliana, additional, Uzunova, Veselina, additional, Apostolova, Sonia, additional, Tzoneva, Rumiana, additional, and Yancheva, Denitsa, additional

Published
2016
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87. Modification of Rapana thomasiana hemocyanin with choline amino acid salts significantly enhances its antiproliferative activity against MCF-7 human breast cancer cells

Author

Guncheva, Maya, primary, Paunova, Krasimira, additional, Ossowicz, Paula, additional, Rozwadowski, Zbigniew, additional, Janus, Ewa, additional, Idakieva, Krassimira, additional, Todinova, Svetla, additional, Raynova, Yuliana, additional, Uzunova, Veselina, additional, Apostolova, Sonia, additional, Tzoneva, Rumiana, additional, and Yancheva, Denitsa, additional

Published
2015
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88. IN SILICO PHARMACOKINETIC AND TOXICOLOGICAL STUDY OF DNASE INHIBITORS.

Author

Kolarević, Ana, Kocić, Gordana, Yancheva, Denitsa, and Šmelcerović, Andrija

Subjects
DEOXYRIBONUCLEASES, DNA restriction enzymes, PHARMACOKINETICS
Abstract

Copyright of Acta Medica Medianae is the property of Acta Medica Medianae and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2016
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89. XANTHINE OXIDASE INHIBITORY PROPERTIES AND IN SILICO STUDY OF THREE N-(α-BROMOACYL)-α-AMINO ESTERS.

Author

Šmelcerović, Žaklina, Tomović, Katarina, Yancheva, Denitsa, Cherneva, Emiliya, Kocić, Gordana, and Petronijević, Živomir

Subjects
XANTHINE oxidase, ESTERS, MOLECULAR structure
Abstract

Copyright of Acta Medica Medianae is the property of Acta Medica Medianae and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2016
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96. L-Prolinamidium hydrogensquarate

Author

Kolev, Tsonko, primary, Yancheva, Denitsa, additional, Spiteller, Michael, additional, Sheldrick, William S., additional, and Mayer-Figge, Heike, additional

Published
2006
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98. 4-Dimethylaminopyridinium-1-squarate

Author

Kolev, Tsonko, primary, Yancheva, Denitsa, additional, Schürmann, Markus, additional, Kleb, Dirk-Christian, additional, Preut, Hans, additional, and Spiteller, Michael, additional

Published
2002
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