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Article ; Online: Synthesis of Novel Biologically Active Proflavine Ureas Designed on the Basis of Predicted Entropy Changes

Ladislav Janovec / Eva Kovacova / Martina Semelakova / Monika Kvakova / Daniel Kupka / David Jager / Maria Kozurkova

Molecules, Vol 26, Iss 4860, p

2021 Volume 4860

Abstract: A novel series of proflavine ureas, derivatives 11a – 11i , were synthesized on the basis of molecular modeling design studies. The structure of the novel ureas was obtained from the pharmacological model, the parameters of which were determined from ... ...

Abstract	A novel series of proflavine ureas, derivatives 11a – 11i , were synthesized on the basis of molecular modeling design studies. The structure of the novel ureas was obtained from the pharmacological model, the parameters of which were determined from studies of the structure-activity relationship of previously prepared proflavine ureas bearing n -alkyl chains. The lipophilicity (Log P ) and the changes in the standard entropy (Δ S °) of the urea models, the input parameters of the pharmacological model, were determined using quantum mechanics and cheminformatics. The anticancer activity of the synthesized derivatives was evaluated against NCI-60 human cancer cell lines. The urea derivatives azepyl 11b , phenyl 11c and phenylethyl 11f displayed the highest levels of anticancer activity, although the results were only a slight improvement over the hexyl urea, derivative 11j , which was reported in a previous publication. Several of the novel urea derivatives displayed GI 50 values against the HCT-116 cancer cell line, which suggest the cytostatic effect of the compounds azepyl 11b –0.44 μM, phenyl 11c –0.23 μM, phenylethyl 11f –0.35 μM and hexyl 11j –0.36 μM. In contrast, the novel urea derivatives 11b , 11c and 11f exhibited levels of cytotoxicity three orders of magnitude lower than that of hexyl urea 11j or amsacrine.
Keywords	proflavine ureas ; molecular design ; cytostatic activity ; cytotoxicity ; Organic chemistry ; QD241-441
Subject code	500
Language	English
Publishing date	2021-08-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Bacterial reduction of ferric iron and co-respiration of O2 and Fe3+ at various oxygen concentrations

Daniel Kupka

Acta Montanistica Slovaca, Vol 10, Iss special issue 1, Pp 178-

2005 Volume 185

Abstract: Acidiphilium SJH, was cultivated in laboratory bioreactor under aerobic, micro-aerobic and anaerobic conditions. The bacterium oxidized organic substratum D-galactose to carbon dioxide using oxygen and ferric iron as terminal electron acceptor. The ... ...

Abstract	Acidiphilium SJH, was cultivated in laboratory bioreactor under aerobic, micro-aerobic and anaerobic conditions. The bacterium oxidized organic substratum D-galactose to carbon dioxide using oxygen and ferric iron as terminal electron acceptor. The reduction of ferric iron to ferrous iron was observed in either fully aerobic or anoxic conditions. Bacterial growth measured as turbidity and the substrate oxidation measured as CO2 production showed an exponential pattern. The maximum specific growth rate μ = 0,12 h-1 (generation time of 5.8 h) was observed under aerobic conditions. The molar ratio of CO2 produced to O2 consumed CO2/O2 of approx. 1.16 in fully aerobic conditions indicate bacterial preference of oxygen as electron acceptor though weak reduction of ferric iron by the bacterial culture was apparent. Under conditions with the oxygen limitation, the molar CO2/O2 ratio increased to above 4 with a marked prevalence of Fe3+ as the electron acceptor. The co-respiration of both oxygen and ferric iron regardless of the concentration of soluble oxygen suggests a constitutive synthesis of the “iron-reductase” enzyme system in this bacterium. On the other hand, the bacterial growth was inhibited in cultures sparged with a pure nitrogen gas. The organic substrate oxidation and ferric iron reduction by apparently non-growing bacteria was linear and extremely slow for a few days. The recovery and acceleration of bacterial growth and ferric iron reduction was observed after changing the inconvenient incubation in pure N2 atmosphere into incubation allowing the CO2 accumulation within the medium in a closed reactor. Reduction of ferric iron to ferrous iron in micro-aerobic conditions proceeded most rapidly and completely. The change in the Fe3+/Fe2+ ratio caused decrease of the oxidation-reduction potential of the medium (Eh) from approx. 800 mV to approx.350 mV with respect to the Nernst’s equation.
Keywords	Acidiphilium ; ferric iron reduction ; co-respiration ; Geology ; QE1-996.5 ; Science ; Q ; DOAJ:Earth Sciences ; DOAJ:Earth and Environmental Sciences
Subject code	551 ; 660
Language	English
Publishing date	2005-11-01T00:00:00Z
Publisher	Technical University of Kosice
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Bacterial Oxidation and Reduction of Iron in the Processes of Creation and Treatment of Acid Mining Waters

Daniel Kupka

Acta Montanistica Slovaca, Vol 9, Iss 4, Pp 467-

2004 Volume 472

Abstract: Acid mine drainages (AMDs) arise at the weathering of sulphidic minerals. The occurrence of acidic streams is commonly associated with the human mining activities. Due to the disruption and excavation of sulphide deposits, the oxidation processes have ... ...

Abstract	Acid mine drainages (AMDs) arise at the weathering of sulphidic minerals. The occurrence of acidic streams is commonly associated with the human mining activities. Due to the disruption and excavation of sulphide deposits, the oxidation processes have initiated. Acidic products of sulphide oxidation accelerate the degradation of accompanying minerals. AMDs typically contain high concentrations of sulfuric acid and soluble metals and cause serious ecological problems due to the water pollution and the devastation of adjacent country. Microbial life in these extremely acidic environments may be considerably diverse. AMDs are abundant in bacteria capable to oxidize and/or to reduce iron. The rate of bacterial oxidation of ferrous iron released from pyrite surfaces is up to one million times faster than the chemical oxidation rate at low pH. Bacterial regeneration of ferric iron maintains the continuity of pyrite oxidation and the production of AMDs. Another group of microorganisms living in these environments are acidophilic ferric iron reducing bacteria. This group of microorganisms has been discovered only relatively recently. Acidophilic heterotrophic bacteria reduce ferric iron in either soluble or solid forms to ferrous iron. The reductive dissolution of ferric iron minerals brings about a mobilization of iron as well as associated heavy metals. The Bacterial oxidation and reduction of iron play an important role in the transformation of either crystalline or amorphous iron-containing minerals, including sulphides, oxides, hydroxysulfates, carbonates and silicates. This work discusses the role of acidophilic bacteria in the natural iron cycling and the genesis of acidic effluents. The possibilities of application of iron bacteria in the remediation of AMDs are also considered.
Keywords	acid mine drainage (AMD) ; iron oxidation ; iron reduction ; Acidithiobacillus ferrooxidans ; Acidiphilium ; Geology ; QE1-996.5 ; Science ; Q ; DOAJ:Earth Sciences ; DOAJ:Earth and Environmental Sciences
Subject code	540
Language	English
Publishing date	2004-12-01T00:00:00Z
Publisher	Technical University of Kosice, the Faculty of Mining, Ecology, Process Control and Geotechnologies (F BERG)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Synthesis of the cytotoxic phytosphingosines and their isomeric analogues

Raschmanová, Jana Špaková / Daniel Kupka / Dávid Jáger / Jozef Gonda / Martina Bago Pilátová / Miroslava Martinková

Carbohydrate research. 2018 Oct., v. 468

2018

Abstract: A straightforward synthesis of l-lyxo- and l-xylo-phytosphingosine along with their isomeric analogues has been accomplished. The salient features of this approach are the utilization of [3,3]-sigmatropic rearrangements to install a C-N bond and ... ...

Abstract	A straightforward synthesis of l-lyxo- and l-xylo-phytosphingosine along with their isomeric analogues has been accomplished. The salient features of this approach are the utilization of [3,3]-sigmatropic rearrangements to install a C-N bond and application of a late stage Wittig or OCM reaction to incorporate the hydrophobic chain unit. The final compounds were evaluated regarding their ability to alter both leukaemia and solid tumor cancer cells viability.
Keywords	carbohydrates ; chemical bonding ; cytotoxicity ; hydrophobicity ; leukemia ; neoplasm cells
Language	English
Dates of publication	2018-10
Size	p. 1-12.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	1435-7
ISSN	1873-426X ; 0008-6215
ISSN (online)	1873-426X
ISSN	0008-6215
DOI	10.1016/j.carres.2018.08.001
Database	NAL-Catalogue (AGRICOLA)

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Article: Degradation of Reactive Black 5 by electrochemical oxidation

Jager, David / Daniel Kupka / Miroslava Vaclavikova / Lucia Ivanicova / George Gallios

Chemosphere. 2018 Jan., v. 190

2018

Abstract: Degradation of commercial grade Reactive Black 5 (RB5) azo dye by chemical and electrochemical treatment was examined using a dimensionally stable anode and stainless steel cathodes as electrode materials, with NaCl as supporting electrolyte. The ... ...

Abstract	Degradation of commercial grade Reactive Black 5 (RB5) azo dye by chemical and electrochemical treatment was examined using a dimensionally stable anode and stainless steel cathodes as electrode materials, with NaCl as supporting electrolyte. The electrochemical treatment was compared to the chemical treatment with hypochlorite generated by electrolysis. The compounds present in the commercial grade RB5 azo dye and the products of its electrochemical degradation were separated using ion-pairing high performance liquid chromatography on reversed phase. The separated species were detected by diode array detector and electrospray ionization mass spectrometry. A suitable ion-pairing reversed phase HPLC-MS method with electrospray ionization for the separation and identification of the components was developed. The accurate mass of the parent and fragment ions were used in the determination of the empirical formulas of the components using the first-order mass spectra. Structural formulas of degradation products were proposed using these information and principles of organic chemistry and electrochemistry.
Keywords	anodes ; azo dyes ; cathodes ; chemical treatment ; diodes ; electrochemistry ; electrolysis ; electrospray ionization mass spectrometry ; high performance liquid chromatography ; ionization ; ions ; organic chemistry ; oxidation ; sodium chloride ; stainless steel
Language	English
Dates of publication	2018-01
Size	p. 405-416.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	120089-6
ISSN	1879-1298 ; 0045-6535 ; 0366-7111
ISSN (online)	1879-1298
ISSN	0045-6535 ; 0366-7111
DOI	10.1016/j.chemosphere.2017.09.126
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Article: Stereoselective synthesis and antiproliferative activity of the isomeric sphinganine analogues

Čonková, Miroslava / Daniel Kupka / Dávid Jáger / Dominika Jacková / Jozef Gonda / Martina Bago Pilátová / Miroslava Martinková

Carbohydrate research. 2019 Jan. 15, v. 472

2019

Abstract: A flexible synthetic approach to biologically active sphingoid base-like compounds with a 3-amino-1,2-diol framework was achieved through a [3,3]-sigmatropic rearrangement and late stage olefin cross-metathesis as the key transformations. The ... ...

Abstract	A flexible synthetic approach to biologically active sphingoid base-like compounds with a 3-amino-1,2-diol framework was achieved through a [3,3]-sigmatropic rearrangement and late stage olefin cross-metathesis as the key transformations. The stereochemistry of the newly created stereogenic centre was assigned via a single crystal X-ray analysis of the (4S,5R)-5-(hydroxymethyl)-4-vinyloxazolidine-2-thione. In order to rationalise the observed stereoselectivity of the aza-Claisen rearrangement, DFT calculations were carried out. The targeted isomeric sphingoid bases were screened in vitro for anticancer activity on a panel of seven human malignant cell lines. Cell viability experiments revealed that C17-homologues are more active than their C12 congeners.
Keywords	antineoplastic activity ; carbohydrates ; cell viability ; human cell lines ; olefin ; stereochemistry ; stereoselective synthesis ; stereoselectivity ; X-radiation
Language	English
Dates of publication	2019-0115
Size	p. 76-85.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	1435-7
ISSN	1873-426X ; 0008-6215
ISSN (online)	1873-426X
ISSN	0008-6215
DOI	10.1016/j.carres.2018.09.008
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Effluent water quality and the ochre deposit characteristics of the abandoned Smolník mine, East Slovakia

Daniel Kupka / Zuzana Pállová / Andrea Horňáková / Marcela Achimovičová / Viktor Kavečanský

Acta Montanistica Slovaca, Vol 17, Iss 1, Pp 56-

2012 Volume 64

Abstract: This paper presents the results of a 20-year survey of selected physical and chemical parameters of mine drainage and associatedstream sediments at the abandoned Smolník deposit (East Slovakia). The Smolník mine was in operation intermittently fromthe ... ...

Abstract	This paper presents the results of a 20-year survey of selected physical and chemical parameters of mine drainage and associatedstream sediments at the abandoned Smolník deposit (East Slovakia). The Smolník mine was in operation intermittently fromthe 14th century for Au, Ag, Cu, Fe and pyrite (FeS2). In 1990 - 1994 the mine was finally closed and flooded. In 1997 a remediationeffort was initiated in an attempt to improve the quality of acid mine drainage (AMD) from the mine site. Monitoring of the AMD waterparameters has continued since 2000 in quarterly intervals. Considering the concentration of dissolved constituents and the flow rateof the AMD, the abandoned Smolník deposit brings about continuous loading of more than 500 kg of dissolved metals per dayto the adjacent Smolník stream.The ochreous precipitates formed from AMD stream were characterized by elemental analysis, X-ray diffraction and scanningelectron microscopy. Schwertmannite was the dominant solid phase in the precipitates. The chemical analysis of AMD and the elementalcomposition of related sediments indicated selective scavenging potential of the precipitates for arsenic and other metal species.
Keywords	Acid mine drainage ; water quality ; monitoring ; sediments ; schwertmannite ; iron ; sulfate precipitation ; Geology ; QE1-996.5 ; Science ; Q ; DOAJ:Earth Sciences ; DOAJ:Earth and Environmental Sciences
Subject code	550
Language	English
Publishing date	2012-12-01T00:00:00Z
Publisher	Technical University of Kosice
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Secondary Iron Minerals Present in AMD Sediments from Smolník Abandoned Mine

Dakos, Zuzana / Daniel Kupka / Katarína Jablonovská / Marcela Achimovičová / Michal Kovařík / Václav Krištúfek

Nova biotechnologica et chimica. 2013 Jan. 15, v. 11, no. 2

2013

Abstract: The genesis of acid mine drainage (AMD) is conditioned by existence of indigenous chemolithotrophic iron and sulfur oxidizing bacteria, especially of genus Acidithiobacillus. The result of the oxidizing weathering of metal sulfides is a sequential ... ...

Abstract	The genesis of acid mine drainage (AMD) is conditioned by existence of indigenous chemolithotrophic iron and sulfur oxidizing bacteria, especially of genus Acidithiobacillus. The result of the oxidizing weathering of metal sulfides is a sequential formation of ochreous precipitates in drainage systems and in the surroundings of AMD seepage on the surface. The long-term monitoring of AMD waters collected at the shaft Pech that receives the majority of waters draining the flooded Smolník mine area point out the enduring contamination risk of particular components in the environment of Smolník mine area. Elemental analysis, X-ray diffraction, Mossbauer spectroscopy and scanning electron microscopy of the ochreous precipitates formed from Smolník AMD stream revealed schwertmannite as the dominant solid phase in the precipitates. The chemical analysis of AMD effluents and the elemental composition of related sediments indicated considerable scavenging potential of the ochreous precipitates towards metal cations and oxyanions of arsenic and sulfate
Keywords	acid mine drainage ; Acidithiobacillus ; arsenic ; bacteria ; chemical analysis ; drainage systems ; effluents ; elemental composition ; iron ; metal ions ; minerals ; monitoring ; Mossbauer spectroscopy ; oxyanions ; risk ; scanning electron microscopy ; sediments ; seepage ; streams ; sulfates ; sulfides ; sulfur ; weathering ; X-ray diffraction
Language	English
Dates of publication	2013-0115
Size	p. 87-92.
Publishing place	Versita
Document type	Article
ZDB-ID	2677357-0
ISSN	1338-6905
ISSN	1338-6905
DOI	10.2478/v10296-012-0009-9
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Preparation of iron oxides and oxihydroxides

Iveta Štyriaková / Silvia Čuvanová / Daniel Kupka / Alexandra Vašková

Acta Montanistica Slovaca, Vol 11, Iss special issue 2, Pp 397-

2006 Volume 402

Abstract: Iron oxides are common minerals that occur in the environment, either naturally or as a result of human activities.The most common Fe(III)-hydroxides and -oxides include ferrihydrite (Fe5HO8 .4H2O) that transforms to hematite (a-Fe2O3 ) and/or goethite ( ... ...

Abstract	Iron oxides are common minerals that occur in the environment, either naturally or as a result of human activities.The most common Fe(III)-hydroxides and -oxides include ferrihydrite (Fe5HO8 .4H2O) that transforms to hematite (a-Fe2O3 ) and/or goethite (a-FeOOH).That depends on the solution composition, temperature and pH. Depending on the composition of the solid and solution, oxidation can transform the green rust (a product formed by a metal corrosion) to lepidocrocite (γ -FeOOH) or magnetite (Fe(II)Fe(III) 2O4 ). Weathering can degrade magnetite to maghemite (γ –Fe2O3 ) and all of the Fe-oxides are subject to an attack and dissolution by organic acids and ligands that are formed during the breakdown of biological material. Iron oxides can be prepared by hydrolysis of acidic Fe3+ solutions or by controlled oxidation of Fe2+ solutions. Goethite, lepidocrocite and magnetite were prepared by oxidation of Fe2+ solutions under slightly different values of pH, Fe concentrations and rates of oxidation. Maghemite was prepared by a thermal transformation from synthetic lepidocrocite heated in a furnace at 250 °C for 2h. Hematite was prepared by forced hydrolysis of Fe3+ solution from a chlorine system (FeCl3) at the temperature close to 100 °C under strongly acidic conditions (pH 1-2). Main mineral phases were confirmed by the RTG diffraction and IR spectroscopy method. Iron oxides are excellent, renewable adsorbents, and often control free metals through adsorption reaction.
Keywords	iron oxides ; oxihydroxides ; synthesis ; oxidation ; hydrolysis ; Geology ; QE1-996.5 ; Science ; Q ; DOAJ:Earth Sciences ; DOAJ:Earth and Environmental Sciences
Subject code	540
Language	English
Publishing date	2006-12-01T00:00:00Z
Publisher	Technical University of Kosice
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Biodegradation of polycyclic aromatic hydrocarbons in soil contaminated with coal tar

Ondrej Tischler / Jaroslav Briančin / Peter Sekula / Daniel Kupka

Acta Montanistica Slovaca, Vol 11, Iss special issue 2, Pp 314-

2006 Volume 320

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are a group of serious contaminants of air, water soil and sediments. Persistence and accumulation of PAHs in the environment is due to their hydrophobicity and hence low solubility and bioavailability to microbial ...

Abstract	Polycyclic aromatic hydrocarbons (PAHs) are a group of serious contaminants of air, water soil and sediments. Persistence and accumulation of PAHs in the environment is due to their hydrophobicity and hence low solubility and bioavailability to microbial action. This work presents an evidence of biodegradation of PAHs in a soil sample taken from a coal gasification plant contaminated with coal tar. The degradation of the contaminant by indigenous microorganisms was studied under aerobic conditions at 15 ºC in a laboratory glass column. The oxidation kinetic of organic carbon was monitored by measuring the oxygen consumption rate and the carbon dioxide production rate. The biodegradation rates observed were in the range of 0.2 to 7 mg C kg-1 h-1. Approximately 14 000 mg kg-1 of the total organic carbon was completely mineralized to CO2 during 6 months. The sum of 16 EPA PAHs decreased from the initial concentration of 21 331 mg kg-1 to the value of 2 774 mg kg-1after 6 months of biodegradation. The thermogravimetric analysis revealed a 34 % weight decrease of organic mater content during the 6-month degradation period.
Keywords	Polycyclic aromatic hydrocarbons ; PAH ; coal tar ; bio-degradation ; gas analysis ; respiration ; thermogravimetry ; Geology ; QE1-996.5 ; Science ; Q ; DOAJ:Earth Sciences ; DOAJ:Earth and Environmental Sciences
Subject code	550
Language	English
Publishing date	2006-12-01T00:00:00Z
Publisher	Technical University of Kosice
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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