20 results on '"DEJAN GODJEVAC"'
Search Results
2. Oxidation of dibenzothiophene as a model substrate for the removal of organic sulphur from fossil fuels by iron(III) ions generated from pyrite by Acidithiobacillus ferrooxidans
- Author
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VLADIMIR P. BESKOSKI, VALERIJA F. MATIC, JELENA MILIC, DEJAN GODJEVAC, BORIS MANDIC, and MIROSLAV M. VRVIC
- Subjects
Acidithiobacillus ferrooxidans ,iron(III) ion ,DBT ,oxidation ,desulphurization ,Chemistry ,QD1-999 - Abstract
Within this paper a new idea for the removal of organically bonded sulphur from fossil fuels is discussed. Dibenzothiophene (DBT) was used as a model compound of organicmolecules containing sulphur. This form of (bio)desulphurization was performed by an indirect mechanism in which iron(III) ions generated from pyrite by Acidithiobacillus ferrooxidans performed the abiotic oxidation. The obtained reaction products, dibenzothiopene sulfoxide and dibenzothiophene sulfone, are more soluble in water than the basic substrate and the obtained results confirmed the basic hypothesis and give the posibility of continuing the experiments related to application of this (bio)desulphurization process.
- Published
- 2007
3. Flavonoids from flowers of Cephalaria pastricensis and their antiradical activity
- Author
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SLOBODAN MILOSAVLJEVIC, PEDJA JANACKOVIC, VELE TESEVIC, NEBOJSA MENKOVIC, VLATKA VAJS, and DEJAN GODJEVAC
- Subjects
Cephalaria pastricensis ,luteolin 7-O-glucoside ,luteolin 7-O-arabino(1-6)glucoside ,antiradical activity ,DPPH assay ,Chemistry ,QD1-999 - Abstract
Two flavonoid glycosides 1 and 2 having the luteolin structure were isolated from flowers of the endemic plant species Cephalaria pastricensis. They were identified by 1H and 13C NMR, as well as UV/Vis spectroscopy. The structures of 1 and 2 were also confirmed by the spectral data of aglycones and TLC of the sugars obtained after acid hydrolysis. Flavones 1 and 2 showed significant antiradical activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay.
- Published
- 2004
4. Mетаболомикa базиранa на HPTLC за испитивање метаболичких промена током развоја биљке: Artemisia annua студија случаја
- Author
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Jovana Stankovic-Jeremic, Dejan Godjevac, Stefan Ivanovic, Katarina Simic, Antoaneta Trendafilova, Milica Acimovic, and Slobodan Milosavljevic
- Subjects
PCA ,plant metabolomics ,food and beverages ,General Chemistry ,OPLS-DA - Abstract
The application of High Performance Thin Layer Chromatography (HPTLC)-based non-targeted metabolomics as a holistic approach to compare fingerprints of metabolite changes during Artemisia annua development is described. Images of HPTLC chromatograms obtained after derivatization with anisaldehyde-sulphuric acid reagent were used as a dataset for multivariate analysis. Principal component analysis and Orthogonal Partial Least Squares Discriminant Analysis confirmed the discrimination of samples belonging to vegetative phase, flowering stage, and seed formation stage of the plant development. The obtained results showed that the HPTLC-based metabolomics approach can be a very reliable technique for the investigation of metabolic changes during plant development, complementary to GC-MS and NMR-based metabolomics. Описана је холистичка примена нетаргетне метаболомике базиране на високоефикасној танкослојној хроматографији (HPTLC) која омогућава поређење метаболичких профила Artemisia annua и праћење њихових промена током развоја биљке. HPTLC хроматограми након развијања анизалдехидом и сумпорном киселином су коришћени за генерисање података за мултиваријантну анализу. Анализа главних компоненти (PCA) и ортогонална дискриминанта анализа најмањих квадрата (OPLS-DA) су потврдиле разлике између узорака који припадају различитим фенофазама - вегетативној фази, фази цветања и фази формирања семена. Добијени резултати указују да метаболомички приступ заснован на HPTLC методи која је комплементарна са GC-MS и NMR анализом, може бити веома поуздана техника за анализу промене током развоја биљке.
- Published
- 2022
5. GC-MS-based metabolomics for the detection of adulteration in oregano samples
- Author
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Manuela Mandrone, Dejan Godjevac, Stefan Ivanović, Boris Mandić, Mirjana Ristić, Katarina Simic, Marina Todosijević, Ivanovic S., Mandrone M., Simic K., Ristic M., Todosijevic M., Mandic B., and Godevac D.
- Subjects
food.ingredient ,myrtus communis ,OPLS ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Myrtus communis ,food ,Cotinus coggygria ,Partial least squares regression ,Food science ,Olea europaea ,QD1-999 ,2. Zero hunger ,Chromatography ,PCA ,biology ,Chemistry ,Origanum onites ,General Chemistry ,Origanum ,Quinic acid ,biology.organism_classification ,0104 chemical sciences ,Cotinus ,Olea ,Herb ,origanum onites ,Myrtus communi ,chromatography ,Gas chromatography–mass spectrometry ,Origanum vulgare ,Origanum onite - Abstract
Oregano is one of the most used culinary herb and it is often adulterated with cheaper plants. In this study, GC–MS was used for identification and quantification of metabolites from 104 samples of oregano (Origanum vulgare and O. onites) adulterated with olive (Olea europaea), venetian sumac (Cotinus coggygria) and myrtle (Myrtus communis) leaves, at five different concentration levels. The metabolomics profiles obtained after the two-step derivatization, involving methoxyamination and silanization, were subjected to multivariate data analysis to reveal markers of adulteration and to build the regression models on the basis of the oregano-to-adulterants mixing ratio. Orthogonal partial least squares enabled detection of oregano adulterations with olive, Venetian sumac and myrtle leaves. Sorbitol levels distinguished oregano samples adulterated with olive leaves, while shikimic and quinic acids were recognized as discrimination factor for adulteration of oregano with venetian sumac. Fructose and quinic acid levels correlated with oregano adulteration with myrtle. Orthogonal partial least squares discriminant analysis enabled discrimination of O. vulgare and O. onites samples, where catechollactate was found to be discriminating metabolite. Оригано је једна од најчешће коришћених кулинарских биљака и често се криво- твори јефтинијим биљкама. У овој студији, гаснa хроматографијa–масенa спектро- метријa коришћена је за идентификацију и квантификацију метаболита из 104 узорка оригана (Origanum vulgare и O. onites) кривотвореног маслином (Olea europea), венеци- јанским сумаком (Cotinus coggygria) и миртом (Myrtus communis), у пет различитих концентрација. Метаболомички профили добијени након двостепене дериватизације, која укључује метоксиаминовање и силанизацију, подвргнути су мултиваријантној ана- лизи података како би се открили маркери кривотворења и направили регресиони модели на основу односа мешања оригана и биљака за кривотворење. Ортогонална дели- мична анализа најмањих квадрата је омогућила детекцију кривотворења оригана лишћем маслине, венецијанског сумака и мирте. Садржај сорбитола разликовао је узорке оригана кривотворених лишћем маслине, док су шикиминска и кининска кисе- лина препознате као фактор разликовања за кривотворење оригана венецијанским сумаком. Садржај фруктозе и кининске киселине у корелацији су са кривотворењем оригана миртом. Ортогонална делимична анализа најмањих квадрата – дискриминантна анализа је омогућила разликовање узорака O. vulgare и O. onites, при чему је одређено да је катехоллактат метаболит који разликује ове две биљне врсте. Part of the theme issue honoring Professor Emeritus Slobodan Milosavljevićs 80th birthday.
- Published
- 2021
6. Furanocoumarin Content, Antioxidant Activity, and Inhibitory Potential of Heracleum verticillatum, Heracleum sibiricum, Heracleum angustisectum , and Heracleum ternatum Extracts against Enzymes Involved in Alzheimer's Disease and Type II Diabetes
- Author
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Dejan Godjevac, Ivana Sofrenić, Fatih Göger, Milka Todorova, Gülmira Özek, Antoaneta Trendafilova, Süleyman Yur, Boban Andjelkovic, Ina Aneva, and Temel Özek
- Subjects
Antioxidant ,DPPH ,medicine.medical_treatment ,Bioengineering ,01 natural sciences ,Biochemistry ,Bergapten ,Furanocoumarin ,chemistry.chemical_compound ,medicine ,Molecular Biology ,IC50 ,chemistry.chemical_classification ,Traditional medicine ,biology ,010405 organic chemistry ,Chemistry ,Imperatorin ,General Chemistry ,General Medicine ,biology.organism_classification ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Enzyme ,Heracleum ,Molecular Medicine - Abstract
Hexane extracts of Heracleum verticillatum, H. sibiricum, H. angustisectum, and H. ternatum were studied for their furanocoumarin content antioxidant potential and acetylcholinesterase and α-amylase inhibitory activities. Quantification of the furanocoumarins was performed by 1 H-NMR. Pimpinellin was found to be the main component in the roots of all studied species. Bergapten and imperatorin were the major compounds in the fruits of H. sibiricum and H. verticillatum, respectively, while byakangelicol dominated in H. angustisectum and H. ternatum fruits. The leaf and fruit extracts of H. angustisectum demonstrated the highest DPPH radical scavenging activity and TEAC (IC50 0.58 mg/mL and 1.83 mm, respectively). The root extracts of H. verticillatum and H. angustisectum were found to be the most effective against acetylcholinesterase (IC50 0.30 and 0.34 mg/mL, respectively). The studied extracts were not active or demonstrated a weak inhibitory effect (%Inh. up to 29.7) towards α-amylase.
- Published
- 2019
7. Furanocoumarin Content, Antioxidant Activity, and Inhibitory Potential of Heracleum verticillatum, Heracleum sibiricum, Heracleum angustisectum, and Heracleum ternatum Extracts against Enzymes Involved in Alzheimer's Disease and Type II Diabetes
- Author
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Gulmira, Ozek, Suleyman, Yur, Fatih, Goger, Temel, Ozek, Boban, Andjelkovic, Dejan, Godjevac, Ivana, Sofrenic, Ina, Aneva, Milka, Todorova, and Antoaneta, Trendafilova
- Subjects
Heracleum ,Plant Extracts ,Swine ,Biphenyl Compounds ,Antioxidants ,Diabetes Mellitus, Type 2 ,Picrates ,Alzheimer Disease ,Furocoumarins ,Electrophorus ,Acetylcholinesterase ,Animals ,Humans ,Hypoglycemic Agents ,Enzyme Inhibitors ,alpha-Amylases - Abstract
Hexane extracts of Heracleum verticillatum, H. sibiricum, H. angustisectum, and H. ternatum were studied for their furanocoumarin content antioxidant potential and acetylcholinesterase and α-amylase inhibitory activities. Quantification of the furanocoumarins was performed by
- Published
- 2018
8. Impact of the poly(propylene oxide)-b-poly(dimethylsiloxane)-b-poly-(propylene oxide) macrodiols on the surface-related properties of polyurethane copolymers
- Author
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Petar Jovančić, Vele Tešević, Milena Špírková, S Ivan Stefanovic, Vesna Milacic, V Marija Pergal, and Dejan Godjevac
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Materials science ,2D NMR spectroscopy ,General Chemical Engineering ,020101 civil engineering ,02 engineering and technology ,lcsh:Chemical technology ,0201 civil engineering ,surface free energy ,Thermoplastic polyurethane ,chemistry.chemical_compound ,Crystallinity ,morphology ,Copolymer ,lcsh:TP1-1185 ,Propylene oxide ,Fourier transform infrared spectroscopy ,Polyurethane ,General Chemistry ,021001 nanoscience & nanotechnology ,Surface energy ,segmented polyurethanes ,Chemical engineering ,chemistry ,poly(dimethylsiloxane) ,Siloxane ,2D-NMR spectroscopy ,0210 nano-technology - Abstract
Segmented thermoplastic polyurethane copolymers (PURs) were synthesized using 4,4'-methylenediphenyl diisocyanate and 1,4-butanediol as the hard segment and α,ω-dihydroxy-poly(propylene oxide)-b-poly(dimethylsiloxane)-b-poly(propylene oxide) (PPO-PDMS) as the soft segment. The content of incorporated soft segments in PURs varied in the range from 40 to 90 wt.%. The structure, molecular weights and crystallinity of obtained copolymers were monitored by FTIR, 1H, 2D NMR spectroscopy, GPC and DSC analysis, respectively. Surface free energy analysis indicates the presence of hydrophobic (siloxane) groups on the surface, giving highly hydrophobic nature to the obtained PURs films. Water absorption measurements showed that the increase of the hydrophobic PPO-PDMS segment content, led to the decrease of percentage of absorbed water in copolymers. SEM and AFM analysis revealed that copolymers with lower content of PPO-PDMS segments have higher microphase separation between segments. The results obtained in this work indicate that synthesized PURs based on PPO-PDMS, demonstrated proper surface and morphological properties with a great potential for variety of applications such as hydrophobic coatings in biomedicine. [Projekat Ministarstva nauke Republike Srbije, br. 172062]
- Published
- 2016
9. Chemical properties of the cultivated Sideritis raeseri Boiss. & Heldr. subsp. raeseri
- Author
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Aleksandra Konić-Ristić, Teodora Janković, Dejan Pljevljakušić, Katarina Šavikin, Dejan Godjevac, Gordana Zdunić, and Mihailo Ristić
- Subjects
Total phenolics ,DPPH ,Cultivation ,Decoction ,Mineral content ,Sesquiterpene ,01 natural sciences ,High-performance liquid chromatography ,Sideritis raeseri subsp raeseri ,Essential oil ,Analytical Chemistry ,law.invention ,chemistry.chemical_compound ,law ,LC-ESI-MS ,Phenols ,Chromatography ,010405 organic chemistry ,General Medicine ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Sideritis raeseri ,chemistry ,Phytochemical ,Food Science - Abstract
Phytochemical analyses of the cultivated Sideritis raeseri subsp. raeseri in four different stages of flower development were performed. Traditionally used infusion and decoction were also prepared from aerial parts in full flowering stage, and analyses of active compounds and radical scavenging capacity were performed. The highest yield of the essential oil, obtained by hydrodistillation, was noticed in the full flowering phase (0.11%), with sesquiterpene bicyclogermacrene as the main constituent (42.5%). All examined extracts contained phenolic compounds and their amounts varied from 15.3 to 34.1 mg GAE/g DW. The amounts of total phenolics in infusion and decoction were similar (46.5 and 43.9 mg GAE/100 ml, respectively). LC–ESI-MS analyses of all samples allowed the characterisation of 22 phenolic compounds. Two dominant flavone glycosides, 4′- O -methylhypolaetin-7- O -[6‴- O -acetyl-β- d -allopyranosyl (1 → 2)-β- d -glucopyranoside ( 17 ) and 4′- O -methylisoscutellarein-7- O -[6‴- O -acetyl-β- d -allopyranosyl-(1 → 2)]-β- d -glucopyranoside ( 19 ) were quantified using HPLC. Moreover, the mineral content and the percent of transportation were investigated.
- Published
- 2011
10. Polyphenolic compounds in seeds from some grape cultivars grown in Serbia
- Author
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Milovan Veličković, Slobodan Milosavljević, Dejan Godjevac, Ljubodrag Vujisić, Vlatka Vajs, and Vele Tešević
- Subjects
Hydroxybenzoic acid ,hydroxycinnamic acid ,01 natural sciences ,High-performance liquid chromatography ,lcsh:Chemistry ,0404 agricultural biotechnology ,Flavonols ,HPLC/PDA/ESI/MS ,Food science ,Cultivar ,chemistry.chemical_classification ,flavanol monomers ,010401 analytical chemistry ,04 agricultural and veterinary sciences ,General Chemistry ,Hydroxycinnamic acid ,040401 food science ,flavonols ,hydroxybenzoic acid derivative ,0104 chemical sciences ,grape seeds ,Biochemistry ,Proanthocyanidin ,chemistry ,lcsh:QD1-999 ,Polyphenol ,Vitis vinifera ,Composition (visual arts) ,proanthocyanidins - Abstract
Seed extracts from eight grape cultivars (Vitis vinifera) growing in Serbia were screened for their polyphenolic composition by means of HPLC/PDA/ESI/MS analysis. The study revealed 34 phenolic compounds belonging to the following groups: flavan-3-ol monomers, proanthocyanidins, flavonols, hydroxycinnamic acids and hydroxybenzoic acid derivatives. The quantities of the main constituents were determined using PDA/HPLC. Qualitative and quantitative differences among the cultivars were observed.
- Published
- 2010
11. Comparative Analysis of Phenolic Compounds in Seven Hypericum Species and Their Antioxidant Properties
- Author
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Katarina Šavikin, Silvana Petrović, Dejan Godjevac, and Gordana Zdunić
- Subjects
Pharmacology ,Hypericum species ,Antioxidant ,biology ,Traditional medicine ,010405 organic chemistry ,Chemistry ,medicine.medical_treatment ,LC/MS ,Plant Science ,General Medicine ,biology.organism_classification ,01 natural sciences ,HPLC/DAD ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Antioxidant activity ,Complementary and alternative medicine ,Liquid chromatography–mass spectrometry ,Drug Discovery ,medicine ,Chemical analysis ,Hypericum ,Hplc dad - Abstract
A comparative analysis of the phenolic compounds in the 70% EtOH extracts of Hypericum acutum, H. androsaemum, H. barbatum, H. hirsutum, H. maculatum, and H. richeri has been carried out using high-performance liquid chromatography coupled with photodiode array UV detection and high resolution TOF mass spectrometry. Quercetin, astilbin, I3, II8-biapigenin, orientin, 2”- O-acetylorientin, three phenolcarboxylic acids, and eight flavonols 3- O-glycosides were identified in the extracts on the basis of their on-line UV spectra, accurate mass spectral data, and in comparison of retention times with those from the standards. Fingerprint analysis of the extracts revealed significant differences in the qualitative and quantitative chemical composition of the studied species. Antioxidant assays with various reaction mechanisms were used including ferric reducing antioxidant power (FRAP) assay, DPPH, ABTS, superoxide anion radical scavenging capacity and inhibition of liposome peroxidation induced by Fe2+. The most potent were extracts of H. acutum and H. maculatum indicating this Hypericum species interesting for further research aimed as a potentially new source of biologically active compounds.
- Published
- 2017
12. Oxidation of dibenzothiophene as a model substrate for the removal of organic sulphur from fossil fuels by iron(III) ions generated from pyrite by Acidithiobacillus ferrooxidans
- Author
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F Valerija Matic, P Vladimir Beskoski, Boris Mandić, Jelena Milić, Dejan Godjevac, and Miroslav M. Vrvić
- Subjects
oxidation ,Inorganic chemistry ,chemistry.chemical_element ,engineering.material ,Ion ,lcsh:Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,0502 economics and business ,iron(iii) ion ,desulphurization ,030304 developmental biology ,0303 health sciences ,acidithiobacillus ferrooxidans ,business.industry ,05 social sciences ,Fossil fuel ,Substrate (chemistry) ,dbt ,Sulfoxide ,General Chemistry ,Sulfur ,Acidithiobacillus ferrooxidans ,chemistry ,lcsh:QD1-999 ,Dibenzothiophene ,engineering ,Pyrite ,business ,050203 business & management - Abstract
Within this paper a new idea for the removal of organically bonded sulphur from fossil fuels is discussed. Dibenzothiophene (DBT) was used as a model compound of organicmolecules containing sulphur. This form of (bio)desulphurization was performed by an indirect mechanism in which iron(III) ions generated from pyrite by Acidithiobacillus ferrooxidans performed the abiotic oxidation. The obtained reaction products, dibenzothiopene sulfoxide and dibenzothiophene sulfone, are more soluble in water than the basic substrate and the obtained results confirmed the basic hypothesis and give the possibility of continuing the experiments related to application of this (bio)desulphurization process. .
- Published
- 2007
13. Screening inland halophytes from the central Balkan for their antioxidant activity in relation to total phenolic compounds and flavonoids: Are there any prospective medicinal plants?
- Author
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Zora Dajić Stevanović, Dejan Godjevac, Milica Petrović, and Milan Stanković
- Subjects
chemistry.chemical_classification ,Salinity ,Antioxidant ,Ecology ,medicine.medical_treatment ,Secondary metabolites ,Biological activity ,Flavonoid ,15. Life on land ,Biology ,Rutin ,chemistry.chemical_compound ,chemistry ,Halophytes ,Halophyte ,Botany ,medicine ,Food science ,Mentha pulegium ,Gallic acid ,Phenols ,Medicinal plants ,Semiarid arid habitats ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Abstract
This paper presents new data for secondary metabolites and biological activity of the insufficiently studied European inland halophytes as remarkable indicators of Balkan saline habitats. Phenolic content, flavonoid concentrations and antioxidant activity were analyzed in fifteen terrestrial salt tolerant plants collected from eight saline habitats situated in two distinct semiarid regions of Serbia. Total phenols ranged from 31.86 to 212.71 mg of GA/g of extract (gallic acid equivalent – milligrams of gallic acid per gram of extract). Concentration of flavonoids ranged from 41.21 to 146.06 mg of RU/g of extract (rutin equivalent – milligrams of rutin per gram of extract). Antioxidant activity was determined using 1,1-diphenyl-2-picrylhydrazyl radical reagent; obtained values was ranged from 1785.81 to 17.55 μg/ml. A significant relation was noticed between the concentration of phenols and antioxidant activity. Parallel to the analysis of researched halophytes, Camellia sinensis and Ginkgo biloba were analyzed for comparison. The best antioxidant properties were determined for Statice gmelinii, Artemisia santonicum and Mentha pulegium. The results indicate a potential of studied halophytic species as candidates for natural sources of secondary metabolites with high biological activity, whereas their bioactive compounds might have a significant role in adaptations to salt and drought stress.
- Published
- 2015
14. Phenolic composition and free radical scavenging activity of wine produced from the Serbian autochthonous grape variety Prokupac - A model approach
- Author
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Nebojša Menković, Dejan Godjevac, Gordana Zdunić, Katarina Šavikin, and Jelena Zivkovic
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Wine ,0303 health sciences ,Hydroxybenzoic acid ,Chromatography ,030309 nutrition & dietetics ,Chemistry ,Extraction (chemistry) ,food and beverages ,Ethyl gallate ,Fraction (chemistry) ,04 agricultural and veterinary sciences ,General Chemistry ,040401 food science ,anthocyanins ,lcsh:Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,0404 agricultural biotechnology ,lcsh:QD1-999 ,Anthocyanin ,flavonoids ,Composition (visual arts) ,Quercetin ,phenolic acids - Abstract
Phenolic compounds are very important quality parameters of wine because of their impact on colour, taste and health properties. The present study aimed to evaluate the general phenolic composition and free radical scavenging activity of aqueous and organic fractions obtained using liquid/liquid extractions from red wine produced from Serbian autochtonous grape variety Prokupac. Total phenolic contents in different fractions ranged from 48.22 to 289.12 mg GAE/g dry fraction. Phenolic acids (mainly hydroxycinnamic acids) and quercetin-3-glucuronide were the main components of the EtOAc fraction at pH 2.0; catechins, phenolic acids (mainly hydroxybenzoic acids) and quercetin were found in the EtOAc fraction at pH 7.0, while anthocyanins were identified in the aqueous residue after EtOAc extraction. The major anthocyanin extracted into aqueous fraction was malvidin-3-glucoside, while the most abundant non-anthocyanin phenolic compounds from organic fractions were ethyl gallate and trans-caftaric acid. Radical scavenging activity differed significantly among fractions and IC50 values were 138.58 μg/ml for water fraction, 17.83 and 3.47 μg/ml for EtOAc fractions at pH 2.0 and pH 7.0, respectively. As the EtOAc fractions were found to be more potent radical scavengers, it could be assumed that non-anthocyanin phenolic compounds were responsible for such activity in Prokupac wine. [Projekat Ministarstva nauke Republike Srbije, br. 46013]
- Published
- 2014
15. Structural, thermal and surface characterization of thermoplastic polyurethanes based on poly(dimethylsiloxane)
- Author
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Jasna Djonlagic, Jelena Rogan, S Ivan Stefanovic, Vesna Antić, Sanja Ostojić, Vesna Milacic, V Marija Pergal, and Dejan Godjevac
- Subjects
Thermogravimetric analysis ,Materials science ,2D NMR spectroscopy ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,Contact angle ,Gel permeation chromatography ,lcsh:Chemistry ,Crystallinity ,Differential scanning calorimetry ,law ,Polymer chemistry ,Thermal stability ,Crystallization ,thermal properties ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,thermoplastic polyurethanes ,Chemical engineering ,lcsh:QD1-999 ,poly(dimethylsiloxane) ,surface properties ,0210 nano-technology ,Glass transition - Abstract
In this study, the synthesis, structure and physical properties of two series of thermoplastic polyurethanes based on hydroxypropyl-terminated poly(dimethylsiloxane) (HP-PDMS) or hydroxyethoxypropyl-terminated poly(dimethylsiloxane) (EO-PDMS) as soft segments, and 4,4'-methylenediphenyl diisocyanate and 1,4-butanediol as hard segments were investigated. The polyurethanes were synthesized by two-step polyaddition in solution. The effects of the type and content of PDMS segments on the structure, thermal and surface properties of copolymers were studied by H-1-, C-13-nuclear magnetic resonance (NMR) spectroscopy and two-dimensional NMR spectroscopies (heteronuclear multiple bond correlation (HMBC) and rotating-frame nuclear Overhauser effect (ROESY)), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide-angle X-ray scattering (WAXS), scanning electron microscopy (SEM) and water contact angle and water absorption measurements. Thermal properties investigated by DSC indicated that the presence of soft PDMS segments lowers the glass transition and melting temperatures of the hard phase as well as the degree of crystallinity. SEM analysis of the copolymers with a lower soft segment content confirmed the presence of spherulite superstructures, which arise from the crystallization of the hard segments. When compared with polyurethanes prepared from HP-PDMS, the copolymers synthesized from EO-PDMS with the same content of the soft segments had a higher degree of crystallinity, better thermal stability and a less hydrophobic surface. The obtained results showed that the synthesized polyurethanes had good thermal and surface properties, which could be further modified by changing the type or content of the soft segments.
- Published
- 2014
16. Comparative analysis of parthenolide content in Tanacetum larvatum, an endemic species of Montenegro, collected from three different locations
- Author
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Nina Todorović, Nebojša Menković, Slobodan Milosavljević, Dejan Godjevac, V. M. Tadić, Ivana Aljančić, and V. Vajs
- Subjects
0303 health sciences ,010405 organic chemistry ,Chemistry ,Plant Science ,General Chemistry ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,0104 chemical sciences ,03 medical and health sciences ,chemistry.chemical_compound ,Botany ,Parthenolide ,Montenegro ,Endemism ,030304 developmental biology - Published
- 2010
17. Influence of the chemical structure of poly(urea-urethane-siloxane)s on their morphological, surface and thermal properties
- Author
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Dejan Godjevac, Vesna Antić, Jasna Djonlagic, Jelena Rogan, Andrea Martinelli, Iolanda Francolini, Marija V. Pergal, and Milica Balaban
- Subjects
Morphology ,Materials science ,Morphology (linguistics) ,Thermal properties ,morphology ,quantitative c-13 nmr spectroscopy ,quantitative 13c nmr spectroscopy ,thermal properties ,segmented polyurethane-ureas ,hydroxypropyl-terminated pdms ,Polymers and Plastics ,Scanning electron microscope ,Segmented polyurethane-ureas ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Ultimate tensile strength ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Tetrahydrofuran ,Hydroxypropyl-terminated PDMS ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Solvent ,chemistry ,Polymerization ,Chemical engineering ,Siloxane ,Quantitative C-13 NMR spectroscopy ,0210 nano-technology - Abstract
Segmented poly(urethane-urea-siloxane)s (PUUS) were synthesized using 4,4'-methylenediphenyl diisocyanate (MDI) and ethylene diamine (ED) as the hard segment components and hydroxypropyl-terminated poly(dimethylsiloxane) (PDMS) as the soft segment component, where the hard segment content ranged from 38 to 65 wt%. Segmented PUUSs were prepared by a two-step polymerization procedure in tetrahydrofuran/N-methylpyrrolidone (THF/NMP) mixture with a large proportion of polar solvent. The structure, composition and hard segment length were determined by C-13 NMR and two-dimensional correlation spectroscopy. Thermal, mechanical, small-angle X-ray scattering and hydrogen bonding analyses indicated the formation of the microphase-separated copolymers with high tensile strength. Globular superstructures observed in the copolymer films by scanning electron microscopy (SEM) and atomic force microscopy (AFM) were probably arisen from the microstructural organization of the MDI-ED segments, depending on their content and length. The PUUS copolymers showed high water resistance and became more hydrophobic with increasing weight fraction of PDMS.
- Published
- 2013
18. Sastav i antimikrobna aktivnost etarskog ulja iz Galatella linosyris (L.) Rchb. f. (Asteraceae)
- Author
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Ivan Vuckovic, Ljubodrag Vujisić, Dejan Godjevac, Vlatka Vajs, D Petar Marin, Vele Tešević, and Marina Soković
- Subjects
Galatella linosyris ,Sabinene ,01 natural sciences ,essential oil ,law.invention ,lcsh:Chemistry ,Minimum inhibitory concentration ,chemistry.chemical_compound ,law ,Organic chemistry ,Food science ,Essential oil ,Limonene ,antimicrobial activity ,biology ,010405 organic chemistry ,Chemistry ,GC/MS ,General Chemistry ,Asteraceae ,biology.organism_classification ,Antimicrobial ,NMR ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,lcsh:QD1-999 ,Antibacterial activity - Abstract
An investigation of the chemical composition and antimicrobial activity of the essential oil of Galatella linosyris is presented. The chemical analysis (GC/MS, NMR) showed that sabinene (40 %), beta-pinene (35.5 %), alpha-pinene (4.5 %), limonene (4 %), gamma-muurolene (4 %), and (E)-caryophyllene (3.3 %) were dominant components in this oil. Microdilution assays were used to evaluate the minimum inhibitory concentration (MIC) and the minimum bactericidal/fungicidal concentrations (MBC/MFC). G. linosyris essential oil exhibited better antibacterial activity against some of the tested bacteria than antifungal activity. U ovom radu je prikazano ispitivanje hemijskog sastava i antimikrobne aktivnosti etarskog ulja biljne vrste Galatella linosyris. Hemijskom analizom (GC-MS i NMR) je utvrđeno da su glavni sastojci ovog etarskog ulja sabinen (40 %), β-pinen (35,5 %) , α-pinen (4,5 %), limonen (4 %), γ-muurolen (4 %) i (E)-kariofilen (3,3 %). Za procenu minimalne inhibitorne koncentracije (MIC) i minimalne baktericidne/fungicidne koncentracije (MBC/ /MFC) korišćeni su testovi mikrorazblaženja. Etarsko ulje G. linosyris je pokazalo bolju antibakterijsku nego antifungalnu aktivnost.
- Published
- 2012
19. Chemical composition of white currant seed extract
- Author
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Gordana Zdunić, Slobodan Milosavljević, Dejan Godjevac, Vele Tešević, Boban Djordjević, and Vlatka Vajs
- Subjects
0106 biological sciences ,Ribes ,seeds ,01 natural sciences ,lcsh:Chemistry ,03 medical and health sciences ,Organic chemistry ,2D NMR ,indole derivative ,Chemical composition ,030304 developmental biology ,dihydrophaseic acid derivative ,chemistry.chemical_classification ,0303 health sciences ,white currant ,biology ,Glycoside ,General Chemistry ,sesquiterpenoid glucoside ,biology.organism_classification ,3. Good health ,White (mutation) ,Biochemistry ,chemistry ,lcsh:QD1-999 ,Two-dimensional nuclear magnetic resonance spectroscopy ,010606 plant biology & botany - Abstract
From the seeds of white currant (Ribes rubrum, cv. White Champagne), a new sesquiterpenoid glycoside 1 was isolated, along with two known compounds: dihydrophaseic acid 3'-O-beta-D-glucopyranoside (2), and 3-carboxymethyl-indole-1-N-beta-D-glucopyranoside (3). The structure of the new compound was identified as dihydrophaseic acid 3'-O-beta-gentiobioside, based on extensive NMR and MS spectral studies. Iz semena bele ribizle (Ribes rubrum, cv. bela šampanjska) izolovan je novi seskviterpenski glukozid (1), zajedno sa dva poznata jedinjenja: 3'-O-b-D-glukopiranozidom dihidrofazeinske kiseline (2) i 3-karboksimetilindol-1-N-b-D-glukopiranozidom (3). Na osnovu detaljnih NMR i MS studija, struktura novog jedinjenja je određena kao 3'-O-b-genciobiozid dihidrofazeinske kiseline.
- Published
- 2011
20. Relevance of the ability of fructose 1,6-bis(phosphate) to sequester ferrous but not ferric ions
- Author
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Pavle R. Andjus, Ivan Spasojevic, Dejan Godjevac, Mihajlo B. Spasić, David R. Jones, Aleksandar Bajić, and Joanna Zakrzewska
- Subjects
inorganic chemicals ,Iron ,Inorganic chemistry ,P-31 NMR ,medicine.disease_cause ,Biochemistry ,Ferric Compounds ,Antioxidants ,Analytical Chemistry ,Divalent ,Ferrous ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,medicine ,Fructosediphosphates ,Humans ,Chelation ,Ferrous Compounds ,Fructose 1,6-bis(phosphate) ,030304 developmental biology ,chemistry.chemical_classification ,0303 health sciences ,Chemistry ,Organic Chemistry ,General Medicine ,Nuclear magnetic resonance spectroscopy ,Phosphate ,Oxidative Stress ,Cerebrospinal fluid ,Ferric ,EPR ,Ferrous iron binding ,Oxidation-Reduction ,030217 neurology & neurosurgery ,Oxidative stress ,Nuclear chemistry ,medicine.drug - Abstract
The cytoprotective activity of F16BP has been documented in severe conditions such as convulsions, reperfusion injury, septic shock, diabetic complications, hypothermia-induced injury, UV-provoked skin damage and in other processes including apoptosis and excitotoxicity. F16BP shows very efficient cytoprotective activity in astroglial cells exposed to H(2)O(2)-provoked oxidative stress and during neuronal injury caused by hypoxic conditions. As most of the aforementioned processes involve iron activity-related conditions, we investigated the ferric and ferrous iron binding properties of F16BP under physiological conditions using (31)P NMR and EPR spectroscopy. Our results indicate that cytoprotective F16BP activity is predominantly based on ferrous iron sequestration. (31)P NMR spectroscopy of F16BP employing paramagnetic properties of iron clearly showed that F16BP forms stabile complexes with Fe(2+) which was verified by EPR of another divalent cation-Mn(2+). On the other hand, F16BP does not sequester ferric iron nor does it increase its redox activity as shown by (31)P NMR and EPR spin-trapping. Therefore, F16BP may be beneficial in neurodegenerative and other conditions that are characterised by ferric iron stores and deposits.
- Published
- 2010
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