Browsing by Author "Mavrova A."
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Item 2-Alkyl-Substituted-4-Amino-Thieno[2,3-d]Pyrimidines: Anti-Proliferative Properties to In Vitro Breast Cancer Models(2023-09-01) Iliev I.; Mavrova A.; Yancheva D.; Dimov S.; Staneva G.; Nesheva A.; Tsoneva I.; Nikolova B.Thienopyrimidines are structural analogs of quinazolines, and the creation of new 2-alkyl derivatives of ethyl 4-aminothienopyrimidine-6-carboxylates for the study of their anti-proliferative properties is of great pharmacological interest. Some 2-alkyl-4-amino-thieno[2,3-d]pyrimidines 2–5 were synthesized, and their cyto- and phototoxicity against BALB 3T3 cells were established by an in vitro 3T3 NRU test. The obtained results indicate that the tested compounds are not cytotoxic or phototoxic, and that they are appropriate to be studied for their anti-proliferative and anti-tumor properties. The anti-proliferative potential of the compounds was investigated on MCF-7 and MDA-MB-231 cancer cells, as well as a MCF-10A cell line (normal human mammary epithelial cells). The most toxic to MCF-7 was thienopyrimidine 3 with IC50 13.42 μg/mL (IC50 0.045 μM), followed by compound 4 (IC50 28.89 μg/mL or IC50 0.11 μM). The thienopyrimidine 4 revealed higher selectivity to MCF-7 and lower activity (IC50 367 μg/mL i.e., 1.4 μM) than compound 3 with MCF-10A cells. With respect to MDA-MB-231 cells, ester 2 manifested the highest effect with IC50 52.56 μg/mL (IC50 0.16 μM), and 2-ethyl derivative 4 revealed IC50 62.86 μg/mL (IC50 0.24 μM). It was estimated that the effect of the substances on the cell cycle progression was due to cell cycle arrest in the G2 stage for MDA-MB-231, while arrest in G1 was detected for the estrogen (ER)-positive MCF-7 cell line. The tested compound’s effects on the change of the zeta potential in the tumorigenic cells utilized in this study were determined. The calculation which we performed of the physicochemical properties and pharmacokinetic parameters influencing the biological activity suggested high intestinal absorption, as well as drug-likeness.Item Benzimidazoles Containing Piperazine Skeleton at C-2 Position as Promising Tubulin Modulators with Anthelmintic and Antineoplastic Activity(2023-11-01) Anichina K.; Mavrova A.; Vuchev D.; Popova-Daskalova G.; Bassi G.; Rossi A.; Montesi M.; Panseri S.; Fratev F.; Naydenova E.Benzimidazole anthelmintic drugs hold promise for repurposing as cancer treatments due to their interference with tubulin polymerization and depolymerization, manifesting anticancer properties. We explored the potential of benzimidazole compounds with a piperazine fragment at C-2 as tubulin-targeting agents. In particular, we assessed their anthelmintic activity against isolated Trichinella spiralis muscle larvae and their effects on glioblastoma (U-87 MG) and breast cancer (MDA-MB-231) cell lines. Compound 7c demonstrated exceptional anthelmintic efficacy, achieving a 92.7% reduction in parasite activity at 100 μg/mL after 48 hours. In vitro cytotoxicity analysis of MDA-MB 231 and U87 MG cell lines showed that derivatives 7b, 7d, and 7c displayed lower IC50 values compared to albendazole (ABZ), the control. These piperazine benzimidazoles effectively reduced cell migration in both cell lines, with compound 7c exhibiting the most significant reduction, making it a promising candidate for further study. The binding mode of the most promising compound 7c, was determined using the induced fit docking–molecular dynamics (IFD–MD) approach. Regular docking and IFD were also employed for comparison. The IFD–MD analysis revealed that 7c binds to tubulin in a unique binding cavity near that of ABZ, but the benzimidazole ring was fitted much deeper into the binding pocket. Finally, the absolute free energy of perturbation technique was applied to evaluate the 7c binding affinity, further confirming the observed binding mode.Item Design, Cytotoxicity and Antiproliferative Activity of 4-Amino-5-methyl-thieno[2,3-d]pyrimidine-6-carboxylates against MFC-7 and MDA-MB-231 Breast Cancer Cell Lines(2022-05-01) Mavrova A.; Dimov S.; Sulikovska I.; Yancheva D.; Iliev I.; Tsoneva I.; Staneva G.; Nikolova B.Novel 4-amino-thieno[2,3-d]pyrimidine-6-carboxylates substituted at the second position were prepared by cyclocondensation of 2-amino-3-cyano-thiophene and aryl nitriles in an acidic medium. The design of the target compounds was based on structural optimization. The derivatives thus obtained were tested in vitro against human and mouse cell lines. The examination of the compound effects on BLAB 3T3 and MFC-10A cells showed that they are safe, making them suitable for subsequent experiments to establish their antitumor activity. The photoirritancy factor of the compounds was calculated. Using the MTT test, the antiproliferative activity to MCF-10A, MCF-7 and MDA-MB-231 cell lines was estimated. The best antiproliferative effect in respect to the MCF-7 cell line revealed compound 2 with IC50 4.3 ± 0.11 µg/mL (0.013 µM). The highest selective index with respect to MCF-7 cells was shown by compound 3 (SI = 19.3), and to MDA-MB-231 cells by compound 2 (SI = 3.7). Based on energy analysis, the most stable conformers were selected and optimized by means of density functional theory (DFT). Ligand efficiency, ligand lipophilicity efficiency and the physicochemical parameters of the target 4-amino-thienopyrimidines were determined. The data obtained indicated that the lead compound among the tested substances is compound 2.Item DEVELOPMENT OF BENZIMIDAZOLE DERIVATIVES AS NON-NUCLEOSIDE HIV-1 REVERSE TRANSCRIPTASE INHIBITORS (REVIEW)(2022-01-01) Anichina K.; Mavrova A.The benzimidazole heterocycle system is a very important structure in the medicinal chemistry due to its use as a building block of a wide range of bioactive compounds. This review highlights the progress of the synthesis and the optimization of benzimidazole compounds as Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs) against Human Immunodeficiency Virus Type 1 (HIV-1). Since the discovery of NSC 625487 (1-(2’,6’-difluorophenyl)-lH,3H-thiazolo[3,4-a]benzimidazole) as potential anti-retroviral drug candidate, three structural subclasses of benzimidazole HIV-1 NNRTIs in the groups of 1H,3H-thiazolo[3,4-a]benzimidazoles, 2-aryl-1-benzylbenzimidazoles and 1,3-dihydro-benzimidazol-2-ones/2-thione were synthesized and studied up to now. In the current review we report their structural modifications in chronological order and discuss the structure-activity relationship (SAR) to demonstrate the sequential progress in this area. Thus, this study may contribute to the further development and synthesis of novel representatives of the benzimidazole family as anti-HIV-1 agents in the future.Item 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.Item 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.Item Hepatotoxicity and antioxidant activity of some new N,N′-disubstituted benzimidazole-2-thiones, radical scavenging mechanism and structure-activity relationship(2018-03-01) Anastassova N.; Mavrova A.; Yancheva D.; Kondeva-Burdina M.; Tzankova V.; Stoyanov S.; Shivachev B.; Nikolova R.A new method for the synthesis of 1,3-disubstituted benzimidazole derivatives was developed using aza-Michael addition. The target compounds were synthesized in good yields and purity and tested on isolated hepatocytes for their toxicity and antioxidant activity. The antioxidant properties of the substances with lowest toxicity were evaluated using oxidative stress induced by tert-butyl hydroperoxide (tert-BOOH). Some of them as methyl 3-[3-(3-methoxy-3-oxopropyl)-5-benzoyl-2-thioxo-2,3-dihydro-1H-benzimidazol-1-yl]propanoate 10 and 1,3-bis[3-(hydrazinooxy)-3-oxopropyl]-5-benzoyl-1,3-dihydro-2H-benzimidazole-2-thione 15 exhibited statistically significant cytoprotective and antioxidant effects which were similar to those of quercetin. In order to estimate the influence of the structure on the biological properties, structural characterization of the studied compounds was performed by X-ray diffraction analysis and DFT methods. On the basis of the calculated reaction enthalpies of hydrogen atom abstraction (HAT mechanism) and single-electron transfer (SET mechanism) the mechanisms of the antioxidant action of the tested compounds were studied. Subsequently it was established that the HAT mechanism governs the radical scavenging of 10 and 15 in the lipid phase, while the SET mechanism is preferred in water medium for 10 and competitive to HAT for 15.Item Modulation Effect on Tubulin Polymerization, Cytotoxicity and Antioxidant Activity of 1H-Benzimidazole-2-Yl Hydrazones(2023-01-01) Argirova M.; Guncheva M.; Momekov G.; Cherneva E.; Mihaylova R.; Rangelov M.; Todorova N.; Denev P.; Anichina K.; Mavrova A.; Yancheva D.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.Item SYNTHESIS OF NEW TRIAZOLE AND THIADIAZOLE DERIVATIVES OF THE N,N’-DISUBSTITUTED BENZIMIDAZOLE-2-THIONE AND EVALUATION OF THEIR ANTITUMOR POTENTIAL(2022-01-01) Anastassova N.; Georgieva I.; Milanova V.; Tzoneva R.; Radev K.; Yancheva D.; Mavrova A.In the present study series of triazole-, thiadiazoleand 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.Item Synthesis of some novel 2-substituted-[1,3]thiazolo[3,2-a]benzimidazol-3(2h)-ones as potent cytostatic agents(2016-01-01) Mavrova A.; Wesselinova D.; Anichina K.An optimized method for the synthesis of new 2-substituted-thiazolo[2,3-a]benzimidazole-3(2H)-ones was developed which enabled the target compounds to be obtained in relative good yields through one pot process.Four cancer cell lines: human colorectal cancer cell line HT-29, breast cancer cells MDA-MB-231, cervical cancer cells HeLa, human liver carcinoma cell line HepG2 and human diploid cell line Lep-3 were used to estimate the effects of the newly synthesized compounds on cell proliferation. The initial biological screening in vitro, using MTS tetrazolium assay showed that the tested thiazolobenzimidazolones (compounds 7 and 11) demonstrated selective cytotoxicity against HT-29 cells (IC50 - 3.5.10-2 μM and IC50 - 5.0.10-2 μM, respectively), while compound 9 manifested selective cytotoxicity against Hep G2. Beside that the compounds 9 and 11 induced proliferation activity towards Lep3 cells at extremely low concentrations. EC50 values were 3.4.10-2 μM and 1.410-2 μM, correspondingly. The activity results towards HT-29 and Hep G2 cells indicated the necessity for further investigation in vivo to estimate the exact inhibition pathway of the cellular processes.