13 results on '"IRENA NOVAKOVIC"'
Search Results
2. Preparation and characterization of two types of covalently immobilized amyloglucosidase
- Author
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ZORAN VUJCIC, IRENA NOVAKOVIC, SLOBODAN JOVANOVIC, RADIVOJE PRODANOVIC, and NENAD MILOSAVIC
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glucoamylase ,poly(GMA-co-EGDMA) ,immobilization ,periodate ,starch ,Chemistry ,QD1-999 - Abstract
Amyloglucosidase from A. niger was covalently immobilized onto poly (GMA-co-EGDMA) by the glutaraldehyde and periodate method. The immobilization of amyloglucosidase after periodate oxidation gave a preparate with the highest specific activity reported so far on similar polymers. The obtained immobilized preparates show the same pH optimum, but a higher temperature optimum compared with the soluble enzyme. The kinetic parameters for the hydrolysis of soluble starch by free and both immobilized enzymes were determined.
- Published
- 2005
3. Protein covalent modification by biologically active quinones
- Author
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MIROSLAV J. GASIC, BOGDAN SOLAJA, DRAGANA MILIC, TATJANA BOZIC, NATASA BOZIC, ZORAN VUJCIC, IRENA NOVAKOVIC, and DUSAN SLADIC
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quinone ,avarone ,steroidal quinones ,b-lactoglobulin ,covalent modification ,Chemistry ,QD1-999 - Abstract
The avarone/avarol quinone/hydroquinone couple shows considerable antitumor activity. In this work, covalent modification of b-lactoglobulin by avarone and its derivatives as well as by the synthetic steroidal quinone 2,5(10)-estradiene-1,4,17-trione and its derivatives were studied. The techniques for studying chemical modification of b-lactoglobulin by quinones were: UV/Vis spectrophotometry, SDS PAGE and isoelectrofocusing. SDS PAGE results suggest that polymerization of the protein occurs. It could be seen that the protein of 18 kD gives the bands of 20 kD, 36 kD, 40 kD, 45 kD, 64 kD and 128 kD depending on modification agent. The shift of the pI of the protein (5.4) upon modification toward lower values (from pI 5.0 to 5.3) indicated that lysine amino groups are the principal site of the reaction of b-lactoglobulin with the quinones.
- Published
- 2004
4. Chemical modification of b-lactoglobulin by quinones
- Author
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DUSAN SLADIC, NENAD MILOSAVIC, NATASA BOZIC, TATJANA BOZIC, ZORAN VUJCIC, and IRENA NOVAKOVIC
- Subjects
avarone ,quinone ,b-lactoglobulin ,covalent modification ,Chemistry ,QD1-999 - Abstract
The avarone/avarol quinone/hydroquinone couple, as well as their derivatives show considerable antitumor activity. In this work, covalent modifications of b-lactoglobulin, isolated from cow milk, by avarone, its model compound 2-tert-butyl-1,4-benzoquinone, and several of their alkylthio derivatives were studied. The techniques applied for assaying the modifications were: UV/VIS spectrophotometry, SDS PAGE and isoelectrofocusing. The results of the SDS PAGE suggest that polymerisation of the protein occurs. The shift of the pI of the protein upon modification toward lower values indicates that lysine amino groups are the principal site of the reaction of b-lactoglobulin with the quinones.
- Published
- 2003
5. Regioselectivity of conjugate additions to monoalkyl-1,4-benzoquinones
- Author
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SNEZANA TRIFUNOVIC, MIROSLAV J. GASIC, MARIO ZLATOVIC, IRENA NOVAKOVIC, DUSAN SLADIC, and TATJANA BOZIC
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quinone ,avarone ,conjugate addition ,regioselectivity ,Chemistry ,QD1-999 - Abstract
The regioselectivity of the reaction of conjugate addition of thiols, amines, methanol and hydrogen chloride with the monoalkyl-1,4-benzoquinones avarone and 2-tert-butyl-1,4-benzoquinone was investigated. It was shown that the regioselectivity of the reaction is influenced by the electrophilicity of position 5 in unprotonated 2-alkylquinones, the increased electrophilicity of position 6 in acidic medium, and by the acidity of the intermediate hydroquinones.
- Published
- 2002
6. Синтеза и биолошка активност алкилтио и арилтио деривата терц-бутилхинона
- Author
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Jelena Djordjevic, Stoimir Kolarevic, Jovana Jovanovic-Maric, Mariana Oaldje-Pavlovic, Dusan Sladic, Irena Novakovic, and Branka Vukovic-Gacic
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MTT assay ,antibacterial activity ,comet test ,toxicity ,antioxidant activity ,General Chemistry ,TBQ - Abstract
Biological activity of 2-tert-butyl-1,4-benzoquinone (TBQ) and its derivatives, 2-tert-butyl-5-(2-propylthio)-1,4-benzoquinone, 2-tert-butyl-5- -(propylthio)-1,4-benzoquinone, 2-tert-butyl-5,6-(ethylenedithio)-1,4-benzoquinone, 2-tert-butyl-5-(phenylthio)-1,4-benzoquinone and 2-tert-butyl-6-(phenylthio)- 1,4-benzoquinone, were tested for their antioxidant, antibacterial, toxic, cytotoxic and genotoxic potential. Using the DPPH test, all derivatives showed good antioxidant activity, better than ascorbic acid, and the 2-tert- -butyl-5-(propylthio)-1,4-benzoquinone derivative showed the strongest effect. Better antibacterial potential was observed against Gram-positive bacteria in the broth microdilution method in which the 2-tert-butyl-5-(phenylthio)-1,4- -benzoquinone derivative showed the strongest activity (MIC = 15.6 μM). The results of toxicity tests, using the Brine shrimp test, indicated that the derivatives lose their toxic potential compared to TBQ, except for 2-tert-butyl-6- -(phenylthio)-1,4-benzoquinone, which showed a 3 times stronger effect. Cytotoxicity was assessed by the MTT assay in 24 and 72 h treatments in MRC-5, HS 294T and A549 cell lines in threefold decreasing gradient (11, 33 and 100 μM). Modifications potentiate the cytotoxic effect, and the strongest effect was observed with the 2-tert-butyl-5,6-(ethylendithio)-1,4-benzoquinone derivative. In addition, the genotoxic potential was examined in the MRC-5 cell line using the comet assay. All tested derivatives of TBQ showed a genotoxic effect at all applied subtoxic concentrations. In general, the chemical modifications of TBQ enhanced its biological activity. Испитана је биолошка активност 2-терц-бутил-1,4-бензохинона (TBQ) и његових деривата: 2-терц-бутил-5-(изопропилтио)-1,4-бензохинона, 2-терц-бутил-5-(пропилтио)-1,4-бензохинона, 2-терц-бутил-5,6-(етиленедитио)-1,4-бензохинона, 2-терц-бутил- -5-(фенилтио)-1,4-бензохинона и 2-терц-бутил-6-(фенилтио)-1,4-бензохинона укључујући њихов антиоксидативни, антибактеријски, токсични, цитотоксични и генотоксични потенцијал. Применом DPPH теста, сви деривати су показали добру антиоксидативну активност, бољу од аскорбинске киселине, а најјаче дејство показао је дериват 2-терц-бутил-5-(пропилтио)-1,4-бензохинон. Бољи антимикробни потенцијал је примећен против Грам-позитивних бактерија методом микродилуције у бујону, где је дериват 2-терц-бутил-5-(фенилтио)-1,4-бензохинон показао најјачу активност (MIC = 15,6 μМ). Резултати испитивања токсичности, применом теста на Artemia salina, показују да деривати губе токсични потенцијал у односу на TBQ, осим 2-терц-бутил-6-(фенилтио)- -1,4-бензохинона, који је показао 3 пута јачи ефекат. Цитотоксичност је испитана МТТ тестом у третманима од 24 и 72 h на ћелијским линијама MRC-5, HS 294T и A549 у троструко опадајућем градијенту (11, 33 и 100 μМ). Модификације појачавају цитотоксични ефекат, а најјачи ефекат је примећен код деривата 2-терц-бутил-5,6-(етилендитио)-1,4-бензохинона. Поред тога, генотоксични потенцијал је испитан на ћелијској линији MRC-5 комет тестом. Сви испитивани деривати су показали генотоксични ефекат при свим примењеним субтоксичним концентрацијама. Генерално, хемијске модификације побољшавају биолошку активност 2-терц-бутил-1,4-бензохинона.
- Published
- 2022
7. Qualitative Profiling, Antioxidant and Antimicrobial Activities of Polar and Nonpolar Basil Extracts
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Vera Vidaković, Bojan Vujić, Milka Jadranin, Irena Novaković, Snežana Trifunović, Vele Tešević, and Boris Mandić
- Subjects
sweet basil ,antioxidant potential ,antimicrobial activity ,flavonoid ,phenolic acid ,terpenoid ,Chemical technology ,TP1-1185 - Abstract
Basil (Ocimum basilicum L.) is a widely used culinary herb. In this study, ethanol, dichloromethane, and sunflower oil were used separately as solvents with distinct polarities for the extraction of basil aerial parts to simulate the different polarity conditions in domestic food processing. The oil extract (OE) was re-extracted with acetonitrile, and the chemical composition, antioxidant potential, and antimicrobial activities of the ethanol (EE), dichloromethane (DCME), and acetonitrile (ACNE) extracts were determined. A total of 109 compounds were tentatively identified in EE, DCME, and ACNE by HPLC–DAD/ESI-ToF-MS. Fatty acids were present in all extracts. Phenolic acids and flavonoids dominated in EE. DCME was characterised by triterpenoid acids, while diterpenoids were mainly found in ACNE. The extracts were analysed for their antioxidant capacity using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay. EE and DCME showed significant radical scavenging potential. Antimicrobial activity was explored in eight bacterial, two yeast, and one fungal species. All extracts exhibited high antifungal activity, comparable to or better than that of the commercial drug nistatin. Antibacterial activities were notable for EE and ACNE, while DCME showed no activity against bacteria in the applied concentration ranges. The different polarities of the solvents led to distinctive phytochemical compositions and bioactivities in the extracts.
- Published
- 2024
- Full Text
- View/download PDF
8. Synthesis and biological evaluation of 5-substituted derivatives of benzimidazole
- Author
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Vladimir Sukalovic, T Irena Novakovic, V Sladjana Kostic-Rajacic, Z Jelena Penjisevic, P Vesna Vasic, and B Deana Andric
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Benzimidazole ,arylpiperazines ,Stereochemistry ,Proteus vulgaris ,Bacillus subtilis ,010402 general chemistry ,medicine.disease_cause ,01 natural sciences ,lcsh:Chemistry ,chemistry.chemical_compound ,antibacterial activity ,medicine ,Organic chemistry ,heterocyclic compounds ,Candida albicans ,Escherichia coli ,benzimidazoles ,biology ,Pseudomonas aeruginosa ,antifungal activity ,General Chemistry ,biology.organism_classification ,0104 chemical sciences ,3. Good health ,lcsh:QD1-999 ,chemistry ,Staphylococcus aureus ,Antibacterial activity - Abstract
Series of eight novel 5-substituted derivatives of benzimidazole were synthesized by condensation of corresponding diamine with ethyl-4-[4-(2-chlorophenyl)piperazin-1-yl] butanoate in refluxing 4N hydrochloric acid. In vitro antibacterial activity against ten strains namely, Bacillus subtilis, Clostridium sporogenes, Streptosporangium longisporum, Micrococcus flavus, Sarcina lutea, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Proteus vulgaris and antifungal activity against two fungal strains namely, Candida albicans and Saccharomyces cerevisiae, were evaluated. Of all the compounds screened for activity 2-{3-[4-(2-chlorophenyl)piperazin-1-yl]propyl}-5-iodo-1H-benzimidazole and 2-{3-[4-(2-chlorophenyl)piperazin-1-yl]propyl}-5-methyl-1H-benzimidazole were associated with higher antifungal activity than commercial drugs. [Projekat Ministarstva nauke Republike Srbije, br. 172032]
- Published
- 2014
9. Interactions of cytotoxic amino acid derivatives of tert-butylquinone with DNA and lysozyme
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T Irena Novakovic, T Miroslava Vujcic, J Srdjan Tufegdzic, M Dusan Sladic, V Mario Zlatovic, and P Jovana Vilipic
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quinone ,Circular dichroism ,Stereochemistry ,Intercalation (chemistry) ,minor groove ,010501 environmental sciences ,01 natural sciences ,lcsh:Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,DNA binding ,0105 earth and related environmental sciences ,chemistry.chemical_classification ,Quenching (fluorescence) ,General Chemistry ,DNA Minor Groove Binding ,3. Good health ,Amino acid ,Quinone ,chemistry ,lcsh:QD1-999 ,fluorescence ,Lysozyme ,Ethidium bromide ,030217 neurology & neurosurgery - Abstract
The interactions of nine amino acid derivatives of tert-butylquinone with biomacromolecules were studied. Sodium dodecyl sulphate (SDS) gel electrophoresis and mass spectrometry confirmed the absence of modifications of lysozyme by any of the synthesized compounds. Spectrophotometric studies demonstrated hyperchromism, i.e., the existence of interactions between the quinones and calf thymus DNA (CT-DNA). Determination of the binding constants by absorption titration indicated weak interactions between the quinone derivatives and CT-DNA. The quenching of fluorescence of the intercalator ethidium bromide (EB) from the EB-CT-DNA system and of the minor groove binder Hoechst 33258 (H) from the H-CT-DNA system by the synthesized derivatives indicated interactions of the compounds and CT-DNA. Circular dichroism (CD) spectra demonstrated a non-intercalative binding mode of the quinone derivatives to CT-DNA. Molecular docking results confirmed binding to the minor groove. The electrophoretic pattern showed no cleavage of the pUC19 plasmid in the presence of any of the synthesized compounds. The ability of the derivatives to scavenge radicals was confirmed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. All the presented results suggest that the DNA minor groove binding is the principal mechanism of action of the examined amino acid derivatives. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3545]
- Published
- 2016
10. Synthesis, biological evaluation and docking analysis of substituted piperidines and (2-methoxyphenyl)piperazines
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V Sladjana Kostic-Rajacic, Z Jelena Penjisevic, B Deana Andric, T Irena Novakovic, Vukic Soskic, Vladimir Sukalovic, and M Goran Roglic
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dopamine D2 receptor ,Stereochemistry ,orthosteric binding site ,010401 analytical chemistry ,General Chemistry ,orthosteric bind site ,01 natural sciences ,0104 chemical sciences ,allosteric ,lcsh:Chemistry ,010404 medicinal & biomolecular chemistry ,Piperazine ,chemistry.chemical_compound ,lcsh:QD1-999 ,chemistry ,Docking (molecular) ,dopamine D-2 receptor ,docking analysis ,Biological evaluation - Abstract
A series of sixteen novel substituted piperidines and (2-methoxyphenyl)piperazines were synthesized, starting from the key intermediates 1-(2-methoxyphenyl)-4-(piperidin-4-yl)piperazine and 1-(2-methoxyphenyl)-4-(piperidin-4-ylmethyl)piperazine. Biological evaluation of the synthesized compounds was pointed out for seven compounds, of which 1-(2-methoxyphenyl)-4-{[1-(2-nitrobenzyl)piperidin-4-yl]methyl}piperazine had the highest affinity for the dopamine D2 receptor. For all seven selected compounds docking analysis was performed in order to establish their structure-to-activity relationship. [Projekat Ministarstva nauke Republike Srbije, br. 172032]
- Published
- 2016
11. Composition, Antioxidant Potential, and Antimicrobial Activity of Helichrysum plicatum DC. Various Extracts
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Bojan Vujić, Vera Vidaković, Milka Jadranin, Irena Novaković, Snežana Trifunović, Vele Tešević, and Boris Mandić
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helichrysum plicatum ,antioxidant potential ,antimicrobial activity ,solvent polarity ,phenols ,liquid chromatography-mass spectrometry (lc-ms) ,Botany ,QK1-989 - Abstract
Helichrysum plicatum DC. is widely used in folk medicine in treating a variety of health disorders. The aim of this study was to examine the influence of different extraction solvents on the chemical composition, antioxidant potential, and antimicrobial activities of H. plicatum. Aerial parts were separately extracted with ethanol, dichloromethane, and sunflower oil. The oil extract (OE) was re-extracted with acetonitrile. A total of 142 compounds were tentatively identified in ethanolic (EE), dichloromethane (DCME), and acetonitrile (ACNE) extracts using HPLC-DAD/ESI-ToF-MS. The dominant compound class in all extracts were α-pyrones, alongside flavonoids in EE, terpenoids in DCME and ACNE, and phloroglucinols in DCME. The antioxidant potential of the extracts was assessed by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay. EE and DCME possessed the most potent radical scavenging capacity. Antimicrobial activity was investigated on eight bacterial, two yeast, and one fungal species. All extracts exhibited high antifungal and notable antibacterial activities compared to control substances, with DCME being the most potent. DCME exhibited stronger antimicrobial activity against P. aeruginosa than the standard chloramphenicol.
- Published
- 2020
- Full Text
- View/download PDF
12. Synthesis, Biological Evaluation and Docking Studies of Benzoxazoles Derived from Thymoquinone
- Author
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Una Glamočlija, Subhash Padhye, Selma Špirtović-Halilović, Amar Osmanović, Elma Veljović, Sunčica Roca, Irena Novaković, Boris Mandić, Iztok Turel, Jakob Kljun, Snežana Trifunović, Emira Kahrović, Sandra Kraljević Pavelić, Anja Harej, Marko Klobučar, and Davorka Završnik
- Subjects
thymoquinone ,benzoxazoles ,anticancer activity ,antimicrobial activity ,western blotting ,molecular docking ,Organic chemistry ,QD241-441 - Abstract
Thymoquinone (TQ), a natural compound with antimicrobial and antitumor activity, was used as the starting molecule for the preparation of 3-aminothymoquinone (ATQ) from which ten novel benzoxazole derivatives were prepared and characterized by elemental analysis, IR spectroscopy, mass spectrometry and NMR (1H, 13C) spectroscopy in solution. The crystal structure of 4-methyl-2-phenyl-7-isopropyl-1,3-benzoxazole-5-ol (1a) has been determined by X-ray diffraction. All compounds were tested for their antibacterial, antifungal and antitumor activities. TQ and ATQ showed better antibacterial activity against tested Gram-positive and Gram-negative bacterial strains than benzoxazoles. ATQ had the most potent antifungal effect against Candida albicans, Saccharomyces cerevisiae and Aspergillus brasiliensis. Three benzoxazole derivatives and ATQ showed the highest antitumor activities. The most potent was 2-(4-fluorophenyl)-4-methyl-7-isopropyl-1,3-benzoxazole-5-ol (1f). Western blot analyses have shown that this compound inhibited phosphorylation of protein kinase B (Akt) and Insulin-like Growth Factor-1 Receptor (IGF1R β) in HeLa and HepG2 cells. The least toxic compound against normal fibroblast cells, which maintains similar antitumor activities as TQ, was 2-(4-chlorophenyl)-4-methyl-7-isopropyl-1,3-benzoxazole-5-ol (1e). Docking studies indicated that 1e and 1f have significant effects against selected receptors playing important roles in tumour survival.
- Published
- 2018
- Full Text
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13. Evaluation of the Activity of the Sponge Metabolites Avarol and Avarone and their Synthetic Derivatives Against Fouling Micro- and Macroorganisms
- Author
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Maria Tsoukatou, Jean Philippe Maréchal, Claire Hellio, Irena Novaković, Srdan Tufegdzic, Dusan Sladić, Miroslav J Gašić, Anthony S Clare, Constantinos Vagias, and Vassilios Roussis
- Subjects
Antifouling activity ,settlement inhibition ,antimicrobial activity ,avarol ,avarone ,Organic chemistry ,QD241-441 - Abstract
The sesquiterpene hydroquinone avarol (1) was isolated from the marine sponge Dysidea avara, whereas the corresponding quinone, avarone (2), was obtained by oxidation of avarol, and the significantly more lipophilic compounds [3’-(p-chloro-phenyl)avarone (3), 3’,4’-ethylenedithioavarone (4), 4’-isopropylthioavarone (5), 4’-tert-butylthioavarone (6), 4’-propylthioavarone (7), 4’-octylthioavarone (8)] were obtained by nucleophilic addition of thiols or p-chloroaniline to avarone. All these compounds were tested, at concentrations ranging from 0.5 to 50 μg/mL, for their effect on the settlement of the cyprid stage of Balanus amphitrite, for toxicity to both nauplii and cyprids and for their growth inhibitory activity on marine bacteria (Cobetia marina, Marinobacterium stanieri, Vibrio fischeri and Pseudoalteromonas haloplanktis) and marine fungi (Halosphaeriopsis mediosetigera, Asteromyces cruciatus, Lulworthia uniseptata and Monodictys pelagica).
- Published
- 2007
- Full Text
- View/download PDF
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