Browsing by Author "Stoyanov N."
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Item IMIDAZOLIDINEDIONE DERIVATIVES OF NALIDIXIC ACID: SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL STUDIES(2021-01-01) Marinov M.; Kostova I.; Naydenova E.; Stoyanov N.Imidazolidine-2,4-diones (hydantoins and spirohydantoins) and nalidixic acid (1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid) are heterocyclic compounds whose ring structures include nitrogen atoms. These substances exhibit potent pharmacological activity as antitumor, antibacterial and antifungal agents, as well as aldose reductase inhibitors. This article presents the synthesis of novel heterocyclic compounds, based on the interaction of imidazolidinediones with nalidixic acid. The imidazolidinedione derivatives obtained were characterized by physicochemical parameters, elemental analysis, IR, 1H and 13C NMR spectral data. The biological activity of the synthesized products was evaluated against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and Salmonella abony, the yeasts Candida albicans and Saccharomyces cerevisiae and the mold Aspergillus brasiliensis. All compounds showed activity against the Gram-positive and Gram-negative bacteria tested.Item New platinum(II) complexes of cycloalkanespiro-5-(2-thiohydantoins). Synthesis and quantum chemical investigation(2015-01-01) Marinova P.; Marinov M.; Delchev V.; Stoyanov N.Synthesis and characterization of new Pt(II) complexes of cyclohexanespiro-5-(2-thiohydantoin) (L1) and cyclohepta-nespiro-5-(2-thiohydantoin) (L2) are discussed. The new complexes are studied by elemental analysis, IR and 1H NMR spectroscopy. The free ligands are investigated by UV-Vis, IR, 1H NMR, 13C NMR and Raman spectroscopy. The ground-state equilibrium geometries of the ligands L1 and L2 and their complexes with Pt(II) are optimized at the BLYP/CEP-31G theoretical level.Item Study on the synthesis, characterization and bioactivities of 3-methyl-9'-fluorenespiro-5-hydantoin(2016-01-01) Marinova P.; Marinov M.; Kazakova M.; Feodorova Y.; Slavchev A.; Blazheva D.; Georgiev D.; Penchev P.; Sarafian V.; Stoyanov N.This work describes a method for synthesis, as well as in vitro antiproliferative and antibacterial investigation of 3-methyl-9'-fluorenespiro-5-hydantoin. The structure of the substituted fluorenylspirohydantoin derivative was verified by UV-Vis, FT-IR, Raman, 1H NMR and 13C NMR spectroscopy, and by using a combination of 2D NMR experiments, which included 1H-1H COSY, HMQC and HMBC sequences. The geometry of the compound was optimized by the B3LYP density functional with 6-31G(d) basis set and the 1H and 13C NMR spectra were predicted with the HF/6-31G(d) calculations at the optimized geometry. The anticancer activity of the 3-methyl-9'-fluorenespiro-5-hydantoin was determined in suspension cell lines originating from tumors in humans (WERI-Rb-1). The cytotoxic effect was evaluated by WST-assay (Roche Applied Science). The antimicrobial effect of the compound against Gram-negative, Gram-positive bacteria and the yeast Candida albicans was investigated.Item Synthesis and antimicrobial activity of 1,8-naphthalimide derivatives of nalidixic acid(2019-01-01) Marinov M.; Kostova I.; Naydenova E.; Stoyanov N.Various naphthalimides are synthesized and their biological activity is studied. The target compounds are prepared by the interaction of different substituted 2-amino-1H-benzo[de]isoquinoline-1,3(2H)-diones with nalidixic acid (1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid). The structures of all synthesized products are verified via their physicochemical parameters, an elemental analysis, IR, 1H and 13C NMR spectroscopy. The antimicrobial activity of the compounds obtained is determined against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram-negative bacteria Essherichia coli, Pseudomonas aeruginosa and Salmonella abony, the yeasts Candida albicans and Saccharomyces cerevisiae and the molds Penicillium chrysogenum and Aspergillus niger. It is found that N-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)-1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide, N-(6-1H-indol-3-yl-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)-1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide and N-(6-piperidin-1-yl-1,3-dioxo-1H-benzo[de] isoquinolin-2(3H)-yl)-1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide are active against the Gram-positive and Gram-negative bacteria tested.Item Synthesis and antimicrobial study of new Pt(IV) and Ru(III) complexes of fluorenylspirohydantoins(2019-01-01) Marinova P.; Marinov M.; Georgiev D.; Becheva M.; Penchev P.; Stoyanov N.The present work presents a synthesis, characterization and antimicrobial activitiy of new Pt(IV) and Ru(III) complexes of (9’-fluorene)-spiro-5-hydantoin (HL1) and (9’-fluorene)-spiro-5-(2-thiohydantoin) (HL2). The complexes were investigated by elemental analysis, UV-Vis and IR spectroscopy. The free ligands were studied by UV-Vis, IR, 1H NMR, 13C NMR and Raman spectroscopy. The antimicrobial tests of HL1 showed week bacteriostatic effect against Staphylococcus aureus ATCC 6538. The results for [Pt(L1)2(H2O)2(OH-)2] complex showed a good antimicrobial activity against Esсherichia coli ATCC 8739, Bacillus licheniformis ATCC 6633, S. aureus and the absence of such effect on the yeasts. The HL2 and its [Pt(L2)2(H2O)2(OH-)2] and [Ru(L2)3(H2O)3] complexes do not possess antimicrobial activity against the tested bacteria and yeasts.Item SYNTHESIS AND CHARACTERIZATION OF N3-ACETYL DERIVATIVES OF SPIROHYDANTOINS(2022-01-01) Marinov M.; Frenkeva M.; Naydenova E.; Penchev P.; Stoyanov N.The following article describes the synthesis of N3-acetyl derivatives of spirohydantoins. The compounds are derived by applying the following technique: the Bucherer-Lieb method (α-series) and the Strecker method (β-series). The synthesized products are characterized by physicochemical parameters, elemental analysis, FTIR, 1H NMR, 13C NMR and 13C DEPT135 spectral data.Item Synthesis and in vitro activity of platinum(II) complexes of two fluorenylspirohydantoins against a human tumour cell line(2014-01-01) Marinova P.; Marinov M.; Kazakova M.; Feodorova Y.; Penchev P.; Sarafian V.; Stoyanov N.This paper presents a method for synthesis and cytotoxicity of new platinum(II) complexes of (9′-fluorene)-spiro-5-hydantoin (L1) and (9′-fluorene)-spiro-5-(2-thiohydantoin) (L2). The new obtained complexes were studied by elemental analysis: ultraviolet-visible, attenuated total reflection Fourier transform infrared (ATR-FTIR), and 1H- and 13C-NMR for Pt(II) compounds and additionally Raman spectroscopy for free ligands. Based on the experimental data, the most probable structure of the complexes is suggested. In the present study, we have examined cytotoxic activity of (9′-fluorene)-spiro-5-hydantoin (L1) and (9′-fluorene)-spiro-5-(2-thiohydantoin) (L2) and their Pt(II) complexes on the retinoblastoma cell line WERI-Rb-1. © 2014 The Author(s). Published by Taylor & Francis.Item Synthesis, characterization and spectroscopic properties of some 2-substituted 1,3-indandiones and their metal complexes(2009-07-10) Ahmedova A.; Atanasov V.; Marinova P.; Stoyanov N.; Mitewa M.New 2-acyl-1,3-indandione derivatives, compounds 1-4, were obtained by condensation of 2-acetyl-1,3-indandione with benzaldehyde, thiophene-2-aldehyde, thiophene-3-aldehyde and furane-2-aldehyde, respectively. The structures of the newly synthesized 2-substituted 1,3-indandiones were characterized by means of spectroscopic methods (FT-IR, 1H and 13C NMR, UV-Vis and MS). Based on the obtained results it is suggested that the compounds exist in the exocyclic enolic form. Mass spectral fragmentation paths are also proposed. In order to verify the possibility for tautomerization processes of the newly synthesized compounds their absorption spectra were recorded in various solvents. Furthermore, the complexation properties of the compounds with metal(II) ions were also studied. A series of non-charged complexes with Cu(II), Cd(II), Zn(II), Co(II) and Ni(II) was isolated and analyzed by elemental analyses and IR. The paramagnetic Cu(II) complexes were studied by EPR and distorted, flattened tetrahedral structures are predicted. The other metal complexes show the presence of water molecules, most probably coordinated to the metal ion, thus forming octahedral geometry. Ultimately, the studied properties of the newly synthesized compounds, 1-4, suggest that they may find application as extracting agents for metal ions, rather than as optical sensors. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2009.