Damijana Urankar

University of Ljubljana, Lubliano, Ljubljana, Slovenia

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Publications (20)51.92 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Azocarboxamide (azcH) has been combined for the first time with [Ru–Cym] to generate metal complexes with N,N- and N,O-coordination mode, [(Cym)Ru(azc)Cl] and [(Cym)Ru(azcH)Cl]+[PF6]−. Geometric and electronic structures of the complexes are reported along with their in vitro activities against different tumour cell lines and preliminary results on solution chemistry. Compound [(Cym)Ru(azc)Cl] exhibited remarkable cytotoxic properties. It was cell-type specific and had comparable IC50 values towards both cancer cells and their drug-resistant subline. A tenfold increase in the sensitivity towards [(Cym)Ru(azc)Cl] was noted for the tumour cells with depleted intracellular glutathione (GSH) level, suggesting the essential role of GSH in cell response to this compound.
    Chemistry 11/2014; · 5.93 Impact Factor
  • Aljoša Bolje, Damijana Urankar, Janez Košmrlj
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    ABSTRACT: A combinatorial modular approach based on the “click” copper(I)-catalysed azide–alkyne cycloaddition reaction was used to prepare a library of selected 1,4-disubstituted 1,2,3-triazoles differently functionalized with heteroaryl groups including pyridine, pyrimidine, and pyrazine. Three different copper(I) sources, i.e., CuSO4/sodium ascorbate, CuBr(PPh3)3, and (CuOTf)2·C6H6 were used to promote the coupling reactions of a range of aryl, heteroaryl, and heteroarylmethyl azides with alkyne “click” partners. As the target heteroaryl triazoles were designed to serve as advanced ligands or ligand precursors for metal coordination, they were fully characterized by 1H, 13C, and 15N NMR spectroscopy. The resonances were assigned on the basis of 1D and 2D NMR experiments. 1H–15N gs-HMBC was used as a practical tool to determine 15N NMR chemical shifts at the natural abundance level of the 15N isotope.
    Annalen der Chemie und Pharmacie 10/2014; · 3.10 Impact Factor
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    ABSTRACT: N-(α-ketoacyl)anthranilic acids reacted with phenylhydrazinium chloride in boiling acetic acid to afford 2-(indol-2-carboxamido)benzoic acids in good to excellent yields and 2-indolyl-3,1-benzoxazin-4-ones as by-products. The formation of the latter products could easily be suppressed by hydrolytic workup. Alternatively, by increasing the reaction temperature and/or time, 2-indolyl-3,1-benzoxazin-4-ones can be obtained exclusively. Optimisations of the reaction conditions as well as the scope and the course of the transformations were investigated. The products were characterized by 1H, 13C and 15N NMR spectroscopy. The corresponding resonances were assigned on the basis of the standard 1D and gradient selected 2D NMR experiments (1H–1H gs-COSY, 1H–13C gs-HSQC, 1H–13C gs-HMBC) with 1H–15N gs-HMBC as a practical tool to determine 15N NMR chemical shifts at the natural abundance level of 15N isotope.
    Organic & Biomolecular Chemistry 10/2014; · 3.57 Impact Factor
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    ABSTRACT: 1-(2-Pyridyl)-, 4-(2-pyridyl)-, 1-(2-picolyl)-, and 4-(2-picolyl)-functionalized 1,3,4-trisubstituted 1,2,3-triazolium salts (1A–D, respectively) were investigated as N-heterocyclic carbene (trzNHC) precursors for bidentate coordination to ruthenium(II) through the CNHC and Npyridyl donors. In addition to the pyridyl and picolyl pendant groups, a variety of para-substituted phenyl rings were attached to the 1,2,3-triazolylidene via carbon or nitrogen atoms. The ruthenation was accomplished by metalation with Ag2O to form intermediate silver carbene complexes and subsequent transmetalation with [Ru(η6-p-cymene)Cl2]2. The cationic ruthenium complexes [Ru(η6-p-cymene)(trzNHC)Cl]+ (3A–C) were readily obtained with 1-(2-pyridyl)-, 4-(2-pyridyl)-, and 1-(2-picolyl)-1,2,3-triazolium salts (1A–C) but not with the 4-picolyl analogue (1D). The bidentate coordination of the ligand precursors 1 was followed by multinuclear NMR spectroscopy, revealing significant changes in chemical shifts for triazole C-5, pyridine nitrogen atoms, and the neighboring α-proton (H-6pyridyl) in 13C, 15N, and 1H NMR spectra. The molecular composition of complexes 3A–C was confirmed by elemental analysis and positive ion electrospray ionization (ESI+) mass spectra, the latter showing ions corresponding to [Ru(η6-p-cymene)(trzNHC)Cl]+. The solid-state structures of the three representative complexes were confirmed by single-crystal X-ray analyses; all complexes displayed a typical piano-stool type configuration. Preliminary catalytic activity screening of 3A–C in the oxidation of selected primary and secondary alcohols with tert-butyl hydroperoxide (TBHP) to give carbonyl compounds is also discussed.
    Organometallics 05/2014; 33(10):2588–2598. · 4.15 Impact Factor
  • Organometallics 05/2014; · 4.15 Impact Factor
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    ABSTRACT: Despite efforts made in chemotherapeutic research in the past and present, Mycobacterium tuberculosis (M.tb), the etiological agent of tuberculosis, still causes more than a million deadly casualties each year, second only to HIV. The rapid generation and spread of drug resistant strains, a problem exacerbated by co-infection with HIV demands further efforts in the investigation of novel classes of anti-tubercular compounds. A library of eight substituted diazenecarboxamides, three carbamoyldiazenecarboxylates and four diazene-1,2-dicarboxamides was synthesized in a straightforward manner followed by a biological evaluation of the compounds. We observed minimal inhibitory concentrations below 10 μg/mL against the H37Rv lab strain of M.tb. Three compounds that showed a potency of 90% growth inhibition of M.tb at a concentration lower than 10 μg/mL were further evaluated and showed potency against other clinically relevant mycobacterial species such as Mycobacterium bovis, Mycobacterium avium and Mycobacterium ulcerans. The selected compounds were examined for acute cell toxicity on a murine macrophage like monocyte cell line J774 A.1 in which the cell viability was reduced by 50% at concentrations ranging from 7.4 μg/mL to 20.7 μg/mL. Neither of the three compounds showed signs of genotoxicity by VITOTOX or by Comet assay. The study was complemented by demonstration of the inhibition of intracellular replication of M.tb H37Rv inside J774 A.1 cells at 2 μg/mL concentration and the susceptibility of a MDR LAM-1 strain at concentrations between 5 and 1 μg/mL of the most active compound.
    European Journal of Medicinal Chemistry 01/2014; 74C:85-94. · 3.43 Impact Factor
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    ABSTRACT: N-(α-Ketoacyl)anthranilic acids were prepared by oxidative ring opening of 3-hydroxyquinoline-2,4(1H,3H)-diones by using paraperiodic acid (H5IO6) or sodium periodate (NaIO4). The optimisation of the reaction conditions is described as well as the utilisation of N-(α-ketoacyl)anthranilic acids in the preparation of anthranilic acid hydrochlorides.
    ChemInform 12/2013; 69(51):10826–10835.
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    ABSTRACT: Construction of a library of structurally diverse diazenecarboxamide-extended cis-[Pt(2-picolyl-1,2,3-triazole)Cl2,] and cis-[Pt(propan-1,3-diamine)CBDCA] (CBDCA = 1,1 -cyclobutanedicarboxylate) complexes 1-4 is described. These compounds retain oxidative properties of parent diazenecarboxamides against glutathione as demonstrated by NMR spectroscopy and high resolution mass spectrometry experiments. Cytotoxic activity of 1-4 was investigated against human cervical carcinoma HeLa cells. Four library members were found to possess moderate cytotoxic activity. Some model compounds were also examined, returning [PtCl2L2] (L = 1-(2-picolyl)-4-phenyl-1H-1,2,3-triazole) as the most potent under this investigation with IC50 of 19.05 microM, comparable to that of cisplatin (IC50 = 16.3 microM).
    Acta Chimica Slovenica 06/2013; 60(2):368-74. · 1.14 Impact Factor
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    ABSTRACT: 2-Picolyl azide reacts with cis-[PtCl2(DMSO)2] to form the diimino complex [Pt(II)Cl2{NH═C(H)Py}] with subsequent dinitrogen liberation. The formation of the latter complex is scrutinized in a combined experimental and theoretical analysis. We establish in silico that the transformation involves a highly reactive intermediate containing a Pt═N double bond formed after the extrusion of N2 from the azide functionality. The prerequisites for N2 liberation and for the stabilization of the nitrene-related intermediate are analyzed in detail.
    Inorganic Chemistry 03/2013; · 4.59 Impact Factor
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    ABSTRACT: To increase the effectiveness of cancer treatment, more effective anti-cancer drugs, as well as the new improved strategies of cancer treatment, are urgently needed. Our previous results have shown that various diazenes are cytotoxic to different tumor cells and can even revert the resistance to cisplatin and vincristine. We also demonstrated that unsymmetrical diazenedicarboxamides 1 and 2 exhibited promising cytotoxicity. The aim of the present study was to synthesize new diazenedicarboxamides with acceptable solubility and good cytotoxicity. Here we report the synthesis and biological evaluation of new N,N'-disubstituted diazenedicarboxamides. We found that a modification of either 1 or 2 led to the more active compounds. The most effective among them was diazenedicarboxamide 11, which can be considered as a new potential anticancer agent for the tumors of different origin, as well as for the drug resistant tumors.
    Acta Chimica Slovenica 01/2013; 60(4):842-52. · 1.14 Impact Factor
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    ABSTRACT: 3-Azidoquinoline-2,4(1H,3H)-diones 1, which are readily available from 4-hydroxyquinolin-2(1H)-ones 4 via 3-chloroquinoline-2,4(1H,3H)-diones 5, afford, in copper(I)-catalyzed [3 + 2] cycloaddition reaction with terminal acetylenes, 1,4-disubstituted 1,2,3-triazoles 3 in moderate to excellent yields. The structures of compounds 3 were confirmed by 1 H and 13 C-NMR spectroscopy, combustion analyses and mass spectrometry.
    Molecules 12/2011; 163390:4070-4081. · 2.43 Impact Factor
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    ABSTRACT: The 1,4-disubstituted 1,2,3-triazole ligand prepared by click chemistry 1-(2-picolyl)-4-phenyl-1H-1,2,3-triazole (ppt) was investigated as novel chelating ligand for Ru(II) complexes with potential antitumor activity. The preparation and structural characterization, mainly by NMR spectroscopy in solution and by X-ray crystallography in the solid state, of four new Ru(II) complexes is reported: two isomeric Ru-dmso compounds, trans,cis-[RuCl(2)(dmso-S)(2)(ppt)] (1) and cis,cis-[RuCl(2)(dmso-S)(2)(ppt)] (2), and two half-sandwich Ru-[9]aneS(3) coordination compounds, [Ru([9]aneS(3))(dmso-S)(ppt)][CF(3)SO(3)](2) (3) and [Ru([9]aneS(3))Cl(ppt)][CF(3)SO(3)] (4). In all compounds ppt firmly binds to ruthenium in a bidentate fashion through the pyridyl nitrogen atom and the triazole N2, thus forming a puckered six-membered ring. The chemical behavior in aqueous solution of the water-soluble complexes 3 and 4 was studied by UV-Vis and NMR spectroscopy and compared to that of the previously described organometallic analogue [Ru(η(6)-p-cymene)Cl(ppt)][Cl] (5) in view of their potential antitumor activity. Compounds 3-5 were tested also in vitro for cytotoxic activity against two human cancer cell lines, one sensitive and one resistant to cisplatin, in comparison with cisplatin. Compound 4, the one that aquates faster, was found to be more cytotoxic than cisplatin against human lung squamose carcinoma cell line (A-549).
    Dalton Transactions 04/2011; 40(19):5188-99. · 3.81 Impact Factor
  • Damijana Urankar, Andrej Pevec, Janez Košmrlj
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    ABSTRACT: The coordination of the diazenecarboxamides, which were functionalized with the 1-(2-picolyl)-1H-1,2,3-triazole moiety 1, to platinum(II) were studied, where K2[PtCl4] and cis-[PtCl2(DMSO)2] were used as the platinum sources. The picolyl-triazole (pictri) binding unit enabled chelation to the metal centre through the 1,2,3-triazole N2 and the pyridyl nitrogen atoms under mild reaction conditions. When cis-[PtCl2(DMSO)2] was used, with CH2Cl2 or CH3CN as the reaction solvents, the pure, stable diamminedichloridoplatinum(II) complexes 2 were isolated by filtration in 39 to 83 % yield. The products were structurally characterized in solution by 1H, 13C and 195Pt NMR spectroscopy. The 195Pt NMR chemical shifts for 2 appear in the region of –2203 to –2207 ppm. The structure of complex 2a was confirmed by single-crystal X-ray crystallography. The formation of the platinum complexes 2 was monitored using NMR spectroscopy. The complexation with cis-[PtCl2(DMSO)2] in [D7]dmf proceeded through several intermediates, as indicated by the 195Pt NMR spectra with resonances in the range of –3055 to –2907 ppm. Similarly, the reaction of cis-[PtCl2(DMSO)2] with diazenecarboxamide, which was functionalized with the nonchelating 1-(2-aminoethyl)-1,2,3-triazole derivative, was examined by NMR spectroscopy.
    Berichte der deutschen chemischen Gesellschaft 04/2011; 2011(12). · 2.94 Impact Factor
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    ABSTRACT: An experimental and theoretical DFT study was carried out on the solution behavior in [D7]DMF for bis-chelate complex [Pd(L)2](BF4)2·2CH3CN (L=4-phenyl-1-(2-picolyl)-1,2,3-triazole). In structure of [Pd(L)2]2+, the central square–planar palladium(II) cation is trans-chelated by two L substrates, each through the pyridine and the triazole N2 nitrogen atoms, forming two six-membered metallacycles. These can adopt boat-like conformations anti-trans-[Pd(L)2]2+ and syn-trans-[Pd(L)2]2+ in which the picolyl methylene carbons are anti or syn, respectively, relative to the palladium coordination plane. In solution, the boat-to-boat inversion at both metallacycles takes place. The conformers are in a dynamic equilibrium, which was monitored by variable-temperature (VT) 1H NMR spectroscopy in the temperature range of 223–353K. The equilibrium lies on the side of the anti-trans-[Pd(L)2]2+ conformer and the corresponding reaction enthalpy and entropy is estimated to be 0.6±0.5kcalmol−1 and 0.8±1calmol−1K−1, respectively. From the full-line-shape analysis of resonances in the VT 1H NMR spectra, the activation enthalpy and activation entropy was determined to be 13.0±0.4kcalmol−1 and 2.7±1.6calmol−1K−1, respectively. The activation entropy close to zero suggests a nondissociative mechanism for the isomerisation. DFT investigation revealed that the isomerisation proceeds through a one step mechanism with a barrier of 11.40kcalmol−1. The structures of the syn and anti conformers as well as that of the transition state were characterized. Energy decomposition analysis was carried out in order to explore the origins of the stability difference between the syn and anti isomers.
    Polyhedron 01/2011; 30(14):2368-2373. · 2.05 Impact Factor
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    ABSTRACT: Four new complexes with 2-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)pyridine (ptmp) ligand: [Rh2(O2CCH3)4(ptmp)2] (1), [PdCl3(Hptmp)]·H2O (2), (Hptmp)2[AuCl4]Cl (3), and [Hg4Br8(ptmp)2]n (4) were prepared and their crystal structures were determined by single crystal X-ray diffraction analyses. Three nitrogen atoms of the ligand ptmp are prone to coordinate to the metal ions. In complex 1 ligand ptmp coordinates monodentately through the pyridyl N4 atom to the axial site of Rh. In compound 2 the N4 protonated ptmp, Hptmp+, coordinates Pd by the triazole N3 nitrogen atom. Ionic compound 3 is composed of three types of ions, Hptmp+, AuCl4−, and Cl−, interconnected by hydrogen bonds. Mercury complex 4 is a coordination polymer in which two ptmp ligands stabilize the Hg4Br8 chain, and the coordination involves N2 and N3 nitrogen atoms of the triazole and the pyridyl nitrogen atom N4. The crystal structures of 1−4 are dominated by hydrogen-bonding, C−H···π, and π−π stacking interactions. The potential of ptmp to enable supramolecular associations is examined.
    Crystal Growth & Design. 10/2010; 10(11).
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    ABSTRACT: We report that 1-(2-picolyl)-1,2,3-triazole (click triazole) forms stable complexes with transition-metal ions in which the coordination involves the triazole N2 nitrogen atom and the pendant 2-picolyl group. This is exemplified by model compound 1-(2-picolyl)-4-phenyl-1H-1,2,3-triazole (L(x)) and its complexes with transition-metal ions of Pt(II), Pd(II), Cu(II), Ru(II), and Ag(I). The coordination was investigated experimentally and theoretically. Ligand L(x) easily reacted at room temperature with cis-[PtCl(2)(DMSO)(2)], [Pd(CH(3)CN)(4)](BF(4))(2), CuCl(2), [RuCl(mu-Cl)(eta(6)-p-cymene)](2), and AgNO(3) to give stable chelates [PtCl(2)L(x)] (1), [Pd(L(x))(2)](BF(4))(2) (2), [CuCl(2)(L(x))(2)] (3), [RuCl(eta(6)-p-cymene)L(x)]OTf (4), and [Ag(2)(L(x))(2)(NO(3))(2)] (5), respectively, in 60-98% yield. The structures of 1-5 were unambiguously confirmed by NMR spectroscopy and single-crystal X-ray diffraction analysis. Density functional theory calculations were carried out in order to theoretically investigate the stabilization factors in 1-5. A comparison of the chelating properties of ligand L(x) was made with structurally similar and isomeric 1-(2-aminoethyl)-substituted 1,2,3-triazole (L(y)) and 4-(2-aminoethyl)-substituted 1,2,3-triazole (L(z)). The complexation affinity of L(x) was attributed to pi-back-donation from the metal to the pendant pyridine side arm, whereas the stability of the complexes involving L(y) and L(z) mainly originates from efficient pi-back-donation to the triazole ring.
    Inorganic Chemistry 06/2010; 49(11):4820-9. · 4.59 Impact Factor
  • Damijana Urankar, Janez Košmrlj
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    ABSTRACT: An alternative, mild and highly efficient synthetic approach to platinum complexes with bioactive carrier ligands features a platinum-complex-tolerant copper(I)-catalyzed 1,3-dipolar cycloaddition. As demonstrated by the preparation of novel diazenecarboxamide–carboplatin conjugates, this approach is superior to other methodologies.
    Inorganica Chimica Acta. 01/2010; 363(14):3817-3822.
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    ABSTRACT: Propargyl functionalized diazenes 1 were prepared by two different approaches and were examined as alkyne click components in copper-catalyzed azide–alkyne cycloadditions (CuAAC) with 2-(azidomethyl)pyridine 5a and four α-azido-ω-aminoalkanes C2–C5 (5b–e). Whereas the reactions with azidoalkylamines 5b–e reached completion with copper(II) sulfate without the need of reducing agent typically in no more than few minutes, 2-(azidomethyl)pyridine 5a required the addition of metallic copper and much longer reaction times (2–24h). This difference in the reactivity was studied and addressed in terms of base effect and proximity effect to CuAAC.
    Tetrahedron. 01/2010; 66(14):2602-2613.
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    ABSTRACT: Preparation of diazenes (VI) in three steps from hydrazine hydrochlorides is developed.
    ChemInform 01/2010; 41(34).
  • Damijana Urankar, Janez Kosmrlj
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    ABSTRACT: Azoamides, previously established as bioactive intracellular GSH-depleting agents, were decorated with a terminal alkyne moiety to 4 and then were transformed, by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), into different ligand-arm functionalized azoamides 6. Azides 5 having ligand-arms amenable for binding to platinum(II) were selected for this study. Because, for the fragile azoamides 4, the typically employed reaction conditions for CuAAC failed, several alternative solvents and copper catalysts were tested. Excellent results were obtained with copper(II) sulfate pentahydrate/metallic copper and especially with heterogeneous catalysts, such as copper-in-charcoal, cupric oxide, and cuprous oxide. The heterogeneous catalysts were employed to obtain the desired products in almost quantitative yields by a simple three-step "stir-filter-evaporate" protocol with no or negligible contamination with copper impurities. This is of particular importance because compounds 6 have been designed for coordination.
    Journal of Combinatorial Chemistry 11/2008; 10(6):981-5. · 4.93 Impact Factor

Publication Stats

35 Citations
51.92 Total Impact Points

Institutions

  • 2008–2014
    • University of Ljubljana
      • Faculty of Chemistry and Chemical Technology
      Lubliano, Ljubljana, Slovenia
  • 2013
    • Vrije Universiteit Brussel
      Bruxelles, Brussels Capital Region, Belgium