Igor Popa

Email: igor.popa@upol.cz
Adresa
:
17. listopadu 12, 771 46 Olomouc
Telefon: (+420) 58563 4497
Fax: (+420) 58563 4357

 

Show publications

Publications

2011

  • [DOI] M. Kubala, J. Vacek, I. Popa, M. Janovska, P. Kosina, J. Ulrichova, Z. Travnicek, and V. Simanek, “The fluorescence properties and NMR analysis of protopine and
    allocryptopine,” JOURNAL OF LUMINESCENCE, vol. 131, iss. 7, pp. 1340-1345, 2011.
    [Bibtex]
    @article ISI:000291132900016,
    Author = Kubala, Martin and Vacek, Jan and Popa, Igor and Janovska, Marika and
       Kosina, Pavel and Ulrichova, Jitka and Travnicek, Zdenek and Simanek,
       Vilim,
    Title = The fluorescence properties and NMR analysis of protopine and
       allocryptopine,
    Journal = JOURNAL OF LUMINESCENCE,
    Year = 2011,
    Volume = 131,
    Number = 7,
    Pages = 1340-1345,
    Month = JUL,
    Abstract = The fluorescence properties of protopine and allocryptopine in aqueous
       and organic environments are described for the first time. The
       fluorescence of alkaloids and their pH-dependent interconversion to
       cationic forms (transannular interaction) were studied using
       steady-state and time-resolved fluorescence techniques. For the analysis
       of tricyclic base and cis/trans tetracyclic cations of the alkaloids,
       NMR and X-ray crystallography were used. (C) 2011 Elsevier B.V. All
       rights reserved.,
    DOI = 10.1016/j.jlumin.2011.02.038,
    ISSN = 0022-2313,
    Unique-ID = ISI:000291132900016,
    
  • [DOI] R. Novotna, I. Popa, and Z. Travnicek, “Zinc(II) chlorido complexes of protonated kinetin and its derivatives:
    Synthesis, properties and X-ray structure of [Zn(Hkinetin)Cl(3)]center
    dot kinetin,” INORGANICA CHIMICA ACTA, vol. 365, iss. 1, pp. 113-118, 2011.
    [Bibtex]
    @article ISI:000285624200017,
    Author = Novotna, Radka and Popa, Igor and Travnicek, Zdenek,
    Title = Zinc(II) chlorido complexes of protonated kinetin and its derivatives:
       Synthesis, properties and X-ray structure of [Zn(Hkinetin)Cl(3)]center
       dot kinetin,
    Journal = INORGANICA CHIMICA ACTA,
    Year = 2011,
    Volume = 365,
    Number = 1,
    Pages = 113-118,
    Month = JAN 15,
    Abstract = The syntheses and characterization of five novel zinc(II) complexes with
       protonated kinetin (6-furfurylaminopurine) and its derivatives are
       described. Based on the results following from elemental analyses (C, H,
       N), FTIR, Raman, (1)H and (13)C NMR spectroscopy, conductivity
       measurements, thermogravimetric (TG) and differential thermal analyses
       (DTA), and single crystal X-ray analysis, the complexes of the general
       composition [Zn(HL(n))Cl(3)]center dot xL(n) (1-5) have been prepared,
       where L(1) = kinetin (6-furfurylaminopurine), L(2) =
       6-(5-methylfurfurylamino) purine, L(3) = 2-chloro-6-furfurylaminopurine,
       L(4) = 2-chloro-6-(5-methylfurfurylamino) purine and L(5) =
       2-chloro-6-furfurylamino-9-isopropylpurine, and x = 1/2-2. The structure
       of [Zn(HL(1))Cl(3)]center dot L(1) (1) has been determined by single
       crystal X-ray analysis. The Zn(II) atom is tetrahedrally coordinated by
       three chlorido ligands and one N3-protonated organic molecule forming a
       ZnCl(3)N donor set. The organic ligand L(1) is coordinated to the Zn(II)
       centre through the N7 atom of the purine moiety. NMR spectroscopic study
       confirmed the N3 and N7 atom to be the protonation, and coordination
       site, respectively. (C) 2010 Elsevier B.V. All rights reserved.,
    DOI = 10.1016/j.ica.2010.08.040,
    ISSN = 0020-1693,
    Unique-ID = ISI:000285624200017,
    
  • [DOI] Z. Travnicek, R. Novotna, J. Marek, I. Popa, and M. Sipl, “Transformations of the natural cytokinin N6-isopentenyladenine in
    aqueous acidic media: structural aspects,” ORGANIC & BIOMOLECULAR CHEMISTRY, vol. 9, iss. 16, pp. 5703-5713, 2011.
    [Bibtex]
    @article ISI:000293230300015,
    Author = Travnicek, Zdenek and Novotna, Radka and Marek, Jaromir and Popa, Igor
       and Sipl, Michal,
    Title = Transformations of the natural cytokinin N6-isopentenyladenine in
       aqueous acidic media: structural aspects,
    Journal = ORGANIC \& BIOMOLECULAR CHEMISTRY,
    Year = 2011,
    Volume = 9,
    Number = 16,
    Pages = 5703-5713,
    Abstract = N6-Isopentenyladenine (L1) was subjected to variously acidic media in
       0.1 M, 1 M and 2 M HCl. In dependence on the acidity of the medium, the
       formation of three main acid hydrolysis products, involving the
       N6-isopentenyladeninium (HL1) (1),
       7,8,9,10-tetrahydro-7,7-dimethyl-3H-pyrimido[ 2,1-i]purin-6-ium (HL2)
       (2) or
       5-amino-4-(4,4-dimethyl-3,4,5,6-tetrahydropyrimidin-2-yl)-imidazolium
       (H(2)L3) (3-5) cations, were determined and characterized by
       multinuclear solution-state NMR spectroscopy and in the solid state by
       single crystal X-ray analysis. The coordination abilities of these
       transformation products have been also investigated. The compounds of
       the compositions [Zn(HL1)Cl(3)]center dot H(2)O (1),
       [Zn(3)(HL2)(2)Cl(8)] (2), (H(2)L3)[CuCl(4)] (4) and
       (H(2)L3)[ZnCl(4)] (5) have been prepared in dependence on the acidity
       of the medium used by the reactions of L1 with ZnCl(2)center dot
       1.5H(2)O or CuCl(2)center dot 2H(2)O. Based on the NMR spectroscopic and
       X-ray crystallographic results, the mechanism of transformation of L1 in
       the acidic medium, involving the protonation, cyclization and ring
       fission, has been suggested.,
    DOI = 10.1039/c1ob05649b,
    ISSN = 1477-0520,
    Unique-ID = ISI:000293230300015,
    

2010

  • [DOI] Z. Travnicek, P. Starha, I. Popa, R. Vrzal, and Z. Dvorak, “Roscovitine-based CDK inhibitors acting as N-donor ligands in the
    platinum(II) oxalato complexes: Preparation, characterization and in
    vitro cytotoxicity,” EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY, vol. 45, iss. 10, pp. 4609-4614, 2010.
    [Bibtex]
    @article ISI:000282112700024,
    Author = Travnicek, Zdenek and Starha, Pavel and Popa, Igor and Vrzal, Radim and
       Dvorak, Zdenek,
    Title = Roscovitine-based CDK inhibitors acting as N-donor ligands in the
       platinum(II) oxalato complexes: Preparation, characterization and in
       vitro cytotoxicity,
    Journal = EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY,
    Year = 2010,
    Volume = 45,
    Number = 10,
    Pages = 4609-4614,
    Month = OCT,
    Abstract = The reactions of potassium bis(oxalato)platinate dihydrate with two
       molar equivalents of the potent adenine-based cyclin-dependent kinase
       inhibitor 2-(1-ethyl-2-hydroxyethylamino)-N6-(benzyl)-9-isopropyladenine
       (Roscovitine: Ros) and its benzyl-substituted analogues, i.e
       2-(1-ethy1-2-hydroxyethylamino)-N6-(2-methoxybenzyl)-9-isopropyladenine
       (2OMeRos),
       2-(1-ethy1-2-hydroxyethylamino)-N6-(3-methoxybenzyl)-9-isopropyladenine
       (3OMeRos) and
       2-(1-ethy1-2-hydroxyethylamino)-N6-(4-methoxybenzyl)-9-isopropyladenine
       (4OMeRos), were performed and the [Pt(oxXRos)(2)] 3/4 H(2)O (1),
       [Pt(ox)(2OMeRos)(2)] H(2)O (2), (Pt(ox)(3OMeR-os)(2)] 1/2H(2)O (3) and
       [Pt(ox)(4OMeRos)(2)] 3/4 H(2)O (4) platinum(II) oxalato complexes were
       obtained. The methods of the elemental analysis, IR. Raman and NMR
       spectroscopy, ESI + mass spectrometry, molar conductivity measurement
       and TG/DTA thermal analysis were performed to characterize the obtained
       products. The complexes 1-4 Involve tetracoordinated central Pt(11) atom
       with one bidentate-coordinated oxalate dianion (ox) and two monodentate
       adenine-based molecules (nRos), thus giving the square-planar geometry
       around the metal centre with a PtN(2)O(2) donor set. In vitro cytotoxic
       activity of the complexes against ovarian carcinoma (A2780), cisplatin
       resistant ovarian carcinoma (A2780cis). malignant melanoma (G-361), lung
       carcinoma (A549). cervix epitheloid carcinoma (HeLa). breast
       adenocarcinoma (MCF7) and osteosarcoma (HOS) human cancer cell lines was
       evaluated. All the tested complexes exceeded the in vitro cytotoxicity
       of cisplatin and oxaliplatin against HeLa. A2780cis and, except for 2,
       also against HOS cancer cells The complex 1 was also tested for its
       cytotoxicity in primary cultures of human hepatocytes and it was not
       found to be hepatotoxic up to the concentration of 50.0 mu M. (C) 2010
       Elsevier Masson SAS. All rights reserved.,
    DOI = 10.1016/j.ejmech.2010.07.025,
    ISSN = 0223-5234,
    Unique-ID = ISI:000282112700024,
    
  • [DOI] A. Klanicova, Z. Travnicek, J. Vanco, I. Popa, and Z. Sindelar, “Dinuclear copper(II) perchlorate complexes with 6-(benzylamino)purine
    derivatives: Synthesis, X-ray structure, magnetism and antiradical
    activity,” POLYHEDRON, vol. 29, iss. 13, pp. 2582-2589, 2010.
    [Bibtex]
    @article ISI:000282389900003,
    Author = Klanicova, Alena and Travnicek, Zdenek and Vanco, Jan and Popa, Igor and
       Sindelar, Zdenek,
    Title = Dinuclear copper(II) perchlorate complexes with 6-(benzylamino)purine
       derivatives: Synthesis, X-ray structure, magnetism and antiradical
       activity,
    Journal = POLYHEDRON,
    Year = 2010,
    Volume = 29,
    Number = 13,
    Pages = 2582-2589,
    Month = SEP 3,
    Abstract = The reactions of Cu(ClO4)(2)center dot 6H(2)O with 6-(benzylamino)purine
       derivatives in a stoichiometric 1:2 metal-to-ligand ratio led to the
       formation of penta-coordinated dinuclear complexes of the formula
       [Cu(2)(mu-L(1-8))(4)(ClO(4))2](ClO(4))(2).nsolv, where L(1) =
       6-(2-fluorobenzylamino)purine (complex 1), L(2) =
       6-(3-fluorobenzylamino)purine (2), L(3)= 6-(4-fluorobenzylamino)purine
       (3), L(4)= 6-(2-chlorobenzylamino)purine (4), L(5) =
       6-(3-chlorobenzylamino)purine (5), L(6)=6-(4-chlorobenzylamino)purine
       (6), L(7)= 6-(3-methoxybenzylamino)purine (7) and L(8)=
       6-(4-methoxybenzylamino)purine (8); n = 0-4 and solv = H(2)O, EtOH or
       MeOH. All the complexes have been fully characterized by elemental
       analysis, FTIR, UV-Vis and EPR spectroscopy, and by magnetic and
       conductivity measurements. Variable temperature (80-300 K) magnetic
       susceptibility data of 1-8 showed the presence of a strong
       antiferromagnetic exchange interaction between two Cu(II) (S= 1/2) atoms
       with J ranging from -150.0(1) to -160.3(2)cm(-1). The compound 6 center
       dot 4EtOH center dot H(2)O was structurally characterized by single
       crystal X-ray analysis. The Cu center dot center dot center dot Cu
       separation has been found to be 2.9092(8) angstrom. The antiradical
       activity of the prepared compounds was tested by in vitro SOD-mimic
       assay with IC(50) in the range 8.67-41.45 mu M. The results of an in
       vivo antidiabetic activity assay were inconclusive and the glycaemia in
       pre-treated animals did not differ significantly from the positive
       control. (C) 2010 Elsevier Ltd. All rights reserved.,
    DOI = 10.1016/j.poly.2010.06.007,
    ISSN = 0277-5387,
    Unique-ID = ISI:000282389900003,
    
  • [DOI] L. Dvorak, I. Popa, P. Starha, and Z. Travnicek, “In Vitro Cytotoxic-Active Platinum(II) Complexes Derived from
    Carboplatin and Involving Purine Derivatives,” EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, iss. 22, pp. 3441-3448, 2010.
    [Bibtex]
    @article ISI:000281061700006,
    Author = Dvorak, Lukas and Popa, Igor and Starha, Pavel and Travnicek, Zdenek,
    Title = In Vitro Cytotoxic-Active Platinum(II) Complexes Derived from
       Carboplatin and Involving Purine Derivatives,
    Journal = EUROPEAN JOURNAL OF INORGANIC CHEMISTRY,
    Year = 2010,
    Number = 22,
    Pages = 3441-3448,
    Month = AUG,
    Abstract = Six platinum(II) complexes of the general formula
       [Pt(cbdc)-(HL(n))(2)] (1-6; cbdc = cyclobutane-1,1-dicarboxylate and
       HL(1)-HL(6) = benzyl-substituted
       6-benzylamino-2-chloro-9-iso-propylpurine derivatives) have been
       synthesized by the reaction of [Pt(cbdc)(dmso)(2)] with the
       corresponding HL(n) compound. The prepared complexes were characterized
       by elemental analysis and FTIR, Raman and NMR ((1)H, (13)C, (15)N and
       (195)Pt) spectroscopy. Based on the results of these techniques, it can
       be concluded that the central Pt(II) atom of the complexes 1-6 is
       coordinated to two oxygen atoms originating from the
       cyclobutane-1,1-dicarboxylate group and to two nitrogen atoms from two
       HL(n) molecules, that is, having a PtN(2)O(2) donor set. Detailed
       multinuclear and two-dimensional NMR studies indicated the N-7 atom to
       be the coordination site of the purine derivatives. The coordination
       mode was proven by a single-crystal X-ray analysis of the
       [Pt(cbdc)(dmso)-(HL(7))]center dot H(2)O (7a center dot H(2)O)
       intermediate [HL(7) =
       2-chloro-6-(2-methoxybenzyl)amino-9-isopropylpurine]. The geometry is
       slightly distorted square-planar and the central Pt(II) atom is
       coordinated to one bidentate cyclobutane-1,1-dicarboxylate dianion, one
       dmso molecule through the sulfur atom and one HL7 molecule through the
       N-7 atom of the purine ring, that is, with a PtNO(2)S donor set. The
       complexes 1-6 were tested for their in vitro cytotoxicity against K-562
       (chronic myelogenous leukaemia) and MCF7 (breast adenocarcinoma) human
       cancer cell lines. Values of IC(50) (drug concentrations lethal for 50\%
       of the tumour cells) ranged from 4.5 to 14.1 mu m for the K-562 cells
       and from 4.3 to 21.0 mu m for the MCF7 cells. The in vitro
       cytotoxicities were in several cases comparable or even higher than
       those of therapeutically used platinum-based anticancer drugs, that is,
       cisplatin, carboplatin and oxaliplatin.,
    DOI = 10.1002/ejic.201000322,
    ISSN = 1434-1948,
    Unique-ID = ISI:000281061700006,
    
  • [DOI] R. Novotna, Z. Travnicek, and I. Popa, “Synthesis and characterization of the first zinc(II) complexes involving
    kinetin and its derivatives: X-ray structures of
    2-chloro-N6-furfuryl-9-isopropyladenine and
    [Zn(kinetin)(2)Cl(2)]center dot CH(3)OH,” INORGANICA CHIMICA ACTA, vol. 363, iss. 10, pp. 2071-2079, 2010.
    [Bibtex]
    @article ISI:000278592200003,
    Author = Novotna, Radka and Travnicek, Zdenek and Popa, Igor,
    Title = Synthesis and characterization of the first zinc(II) complexes involving
       kinetin and its derivatives: X-ray structures of
       2-chloro-N6-furfuryl-9-isopropyladenine and
       [Zn(kinetin)(2)Cl(2)]center dot CH(3)OH,
    Journal = INORGANICA CHIMICA ACTA,
    Year = 2010,
    Volume = 363,
    Number = 10,
    Pages = 2071-2079,
    Month = JUN 20,
    Abstract = A series of the first zinc(II) complexes of the general composition
       [Zn(L(n))(2)Cl(2)]center dot xSolv (1-5) involving kinetin
       [N6-furfuryladenine, L(1), xSolv = CH(3)OH, complex 1] and its
       derivatives, i.e. N6-(5-methylfurfuryl)adenine (L(2), xSolv = 2H(2)O,
       2), 2-chloro-N6-furfuryladenine (L(3), 3),
       2-chloro-N6-(5-methylfurfuryl)adenine (L(4), 4) and
       2-chloro-N6-furfuryl-9-isopropyladenine (L(5), 5), as N-donor ligands
       has been synthesized. The complexes have been fully characterized by
       elemental analyses (C, H, N), FTIR, Raman, (1)H and (13)C NMR
       spectroscopy, conductivity measurements, thermogravimetric (TG) and
       differential thermal (DTA) analyses. Single crystal X-ray analysis
       determined the molecular structures of
       2-chloro-N6-furfuryl-9-isopropyladenine (L(5)) and the complex
       [Zn(L(1))(2)Cl(2)]center dot CH(3)OH. The Zn(II) ion is tetrahedrally
       coordinated by two chlorido ligands and two molecules of the L(1)
       organic compound. The two ligands L(1) are coordinated to the central
       Zn(II) ion via the N7 atoms. This conclusion can also be drawn from
       multinuclear NMR spectroscopic experiments. (C) 2010 Elsevier B.V. All
       rights reserved.,
    DOI = 10.1016/j.ica.2010.02.004,
    ISSN = 0020-1693,
    Unique-ID = ISI:000278592200003,
    
  • [DOI] P. Starha, Z. Travnicek, and I. Popa, “Platinum(II) oxalato complexes with adenine-based carrier ligands
    showing significant in vitro antitumor activity,” JOURNAL OF INORGANIC BIOCHEMISTRY, vol. 104, iss. 6, pp. 639-647, 2010.
    [Bibtex]
    @article ISI:000277946300004,
    Author = Starha, Pavel and Travnicek, Zdenek and Popa, Igor,
    Title = Platinum(II) oxalato complexes with adenine-based carrier ligands
       showing significant in vitro antitumor activity,
    Journal = JOURNAL OF INORGANIC BIOCHEMISTRY,
    Year = 2010,
    Volume = 104,
    Number = 6,
    Pages = 639-647,
    Month = JUN,
    Abstract = [Pt(L)(2)(ox)] (1), [Pt(2-OMeL)(2)(ox)] (2), [Pt(3-OMeL)(2)(ox)]
       (3), [Pt(2,3-diOMeL)(2)(ox)] (4), [Pt(2,4-diOMeL)(2)(ox)] (5),
       [Pt(3,4-diOMeL)(2)(ox)] (6) and [Pt(3,5-diOMeL)(2)(ox)]center dot
       4H(2)O (7) platinum(II) oxalato (ox) complexes were synthesized using
       the reaction of potassium bis(oxalato)platinate(II) dihydrate with
       2-chloro-N6-(benzyl)-9-isopropyladenine or its benzyl-substituted
       analogues (nL). The complexes 1-7, which represent the first
       platinum(II) oxalato complexes involving adenine-based ligands, were
       fully characterized by various physical methods including multinuclear
       and two dimensional NMR spectroscopy. A single-crystal X-ray analysis of
       [Pt(2,4-diOMeL)(2)(ox)]center dot 2DMF (5 center dot 2DMF;
       DMF=N,N'-dimethylformamide), proved the slightly distorted square-planar
       geometry in the vicinity of the Pt(II) ion with one
       bidentate-coordinated oxalate dianion and two adenine derivatives (nL)
       coordinated to the Pt(II) centre through the N7 atom of an adenine
       moiety, thereby giving a PtN(2)O(2) donor set. In vitro cytotoxicity of
       the prepared complexes was tested by an MTT assay against osteosarcoma
       (HOS) and breast adenocarcinoma (MCF7) human cancer cell lines. The best
       results were achieved for the complexes 2 and 5 in the case of both cell
       lines, whose IC(50) values equalled 3.6 +/- 1.0, and 4.3 +/- 2.1 mu M
       (for 2), and 5.4 +/- 3.8, and 3.6 +/- 2.1 mu M (for 5), respectively.
       The IC(50) equals 9.2 +/- 1.5 mu M against MCF7 cells in the case of 1.
       The in vitro cytotoxicity of the mentioned complexes significantly
       exceeded commercially used platinum-based anticancer drugs cisplatin
       (34.2 +/- 6.4 mu M and 19.6 +/- 4.3 mu M) and oxaliplatin (>50.0 mu M
       for both cancer cell lines). (C) 2010 Elsevier Inc. All rights reserved.,
    DOI = 10.1016/j.jinorgbio.2010.02.005,
    ISSN = 0162-0134,
    Unique-ID = ISI:000277946300004,
    
  • [DOI] J. Nisler, M. Zatloukal, I. Popa, K. Dolezal, M. Strnad, and L. Spichal, “Cytokinin receptor antagonists derived from 6-benzylaminopurine,” PHYTOCHEMISTRY, vol. 71, iss. 7, pp. 823-830, 2010.
    [Bibtex]
    @article ISI:000277908400016,
    Author = Nisler, Jaroslav and Zatloukal, Marek and Popa, Igor and Dolezal, Karel
       and Strnad, Miroslav and Spichal, Lukas,
    Title = Cytokinin receptor antagonists derived from 6-benzylaminopurine,
    Journal = PHYTOCHEMISTRY,
    Year = 2010,
    Volume = 71,
    Number = 7,
    Pages = 823-830,
    Month = MAY,
    Abstract = Recently we reported 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55) as
       the first molecule to antagonize cytokinin activity at the receptor
       level. Here we report the synthesis and in vitro biological testing of
       eleven BAP derivatives substituted in the benzyl ring and in the C2, N7
       and N9 positions of the purine moiety. The ability of the compounds to
       interact with Arabidopsis cytokinin receptors AHK3 and CRE1/AHK4 was
       tested in bacterial receptor and in live-cell binding assays, and in an
       Arabidopsis ARR5:GUS (Arabidopsis response regulator 5) reporter gene
       assay. Cytokinin activity of the compounds was determined in classical
       cytokinin biotests (tobacco callus, wheat leaf senescence and Amaranthus
       bioassays). 6(2,5-Dihydroxybenzylamino)purine (LGR-991) was identified
       as a cytokinin receptor antagonist. At the molecular level LGR-991
       blocks the cytokinin receptor CRE1/AHK4 with the same potency as PI-55.
       Moreover, LGR-991 acts as a competitive inhibitor of ANK3, and
       importantly shows reduced agonistic effects in comparison to PI-55 in
       the ARR5:GUS reporter gene assay and in cytokinin bioassays. LGR-991
       causes more rapid germination of Arabidopsis seeds and increases
       hypocotyl length of dark-grown seedlings, which are characteristics of
       plants with a reduced cytokinin status. LGR-991 exhibits a structural
       motive that might lead to preparation of cytokinin antagonists with a
       broader specificity and reduced agonistic properties. (C) 2010 Elsevier
       Ltd. All rights reserved.,
    DOI = 10.1016/j.phytochem.2010.01.018,
    ISSN = 0031-9422,
    Unique-ID = ISI:000277908400016,
    
  • [DOI] P. Starha, I. Popa, and Z. Travnicek, “Palladium(II) oxalato complexes involving
    N6-(benzyl)-9-isopropyladenine-based N-donor carrier ligands: Synthesis,
    general properties, (1)H, (13)C and (15)N\(1)H\ NMR characterization
    and in vitro cytotoxicity,” INORGANICA CHIMICA ACTA, vol. 363, iss. 7, pp. 1469-1478, 2010.
    [Bibtex]
    @article ISI:000276190300021,
    Author = Starha, Pavel and Popa, Igor and Travnicek, Zdenek,
    Title = Palladium(II) oxalato complexes involving
       N6-(benzyl)-9-isopropyladenine-based N-donor carrier ligands: Synthesis,
       general properties, (1)H, (13)C and (15)N\(1)H\ NMR characterization
       and in vitro cytotoxicity,
    Journal = INORGANICA CHIMICA ACTA,
    Year = 2010,
    Volume = 363,
    Number = 7,
    Pages = 1469-1478,
    Month = APR 20,
    Abstract = Reactions of potassium bis(oxalato)palladate dihydrate,
       K(2)[Pd(ox)(2)]center dot 2H(2)O, with two molar equivalents of
       N6-(benzyl)-9-isopropyladenine-based organic molecules (L(1-7)), i.e.
       2-chloro-N6-(2-methoxybenzyl)-9-isopropyladenine (L(1)),
       2-chloro-N6-(3-methoxybenzyl)-9-isopropyladenine (L(2)),
       2-chloro-N6-(3,5-dimethoxybenzyl)-9-isopropyladenine (L(3)),
       2-(1-ethyl-2-hydroxyethylamino)-N6-(benzyl)-9-isopropyladenine (L(4)),
       2-(1-ethyl-2-hydroxyethylamino)-N6-(2-methoxybenzyl)-9-isopropyladenine
       (L(5)),
       2-(1-ethyl-2-hydroxyethylamino)-N6-(3-methoxybenzyl)-9-isopropyladenine
       (L(6)) and
       2-(1-ethyl-2-hydroxyethylamino)-N6-(4-methoxybenzyl)-9-isopropyladenine
       (L(7)), provided a series of seven palladium(II) oxalato (ox) complexes
       of the general formula [Pd(ox)(L(1-7))(2)]center dot nH(2)O (1-7; n =
       0 for 4, 5 and 7, (3)/(4) for 1 and 2, 1 for 6, and 3 for 3). The
       compounds were characterized by elemental analysis, IR, Raman, (1)H,
       (13)C and (15)N\(1)H\ NMR spectroscopy, ESI+ mass spectrometry, molar
       conductivity and TG/DTA thermal analysis. The geometry of
       [Pd(ox)(L(2))(2)] (2) was optimized on the B3LYP/6-311G*/LANL2DZ
       level of theory. The complexes 4-7 represent the first palladium(II)
       oxalato complexes with a PdN(2)O(2) donor set, which involve highly
       potent purine-based cyclin-dependent kinase (CDK) inhibitors (L(4-7)) as
       carrier N-donor ligands. The selected complexes 1, 3-5 and 7 were tested
       by an MTT assay for their in vitro cytotoxic activity against human
       osteosarcoma (HOS) cancer cell line. The highest activity was found for
       the complexes 5 (IC(50) = 34.9 mu M) and 7 (IC(50) = 39.2 mu M). (C)
       2010 Elsevier B.V. All rights reserved.,
    DOI = 10.1016/j.ica.2010.01.035,
    ISSN = 0020-1693,
    Unique-ID = ISI:000276190300021,
    
  • [DOI] Z. Travnicek, I. Popa, M. Cajan, R. Zboril, V. Krystof, and J. Mikulik, “The first iron(III) complexes with cyclin-dependent kinase inhibitors:
    Magnetic, spectroscopic (IR, ES+ MS, NMR, (57)Fe Mossbauer),
    theoretical, and biological activity studies,” JOURNAL OF INORGANIC BIOCHEMISTRY, vol. 104, iss. 4, pp. 405-417, 2010.
    [Bibtex]
    @article ISI:000274921200007,
    Author = Travnicek, Zdenek and Popa, Igor and Cajan, Michal and Zboril, Radek and
       Krystof, Vladimir and Mikulik, Jiri,
    Title = The first iron(III) complexes with cyclin-dependent kinase inhibitors:
       Magnetic, spectroscopic (IR, ES+ MS, NMR, (57)Fe Mossbauer),
       theoretical, and biological activity studies,
    Journal = JOURNAL OF INORGANIC BIOCHEMISTRY,
    Year = 2010,
    Volume = 104,
    Number = 4,
    Pages = 405-417,
    Month = APR,
    Abstract = The first Fe(III) complexes 1-6 with cyclin-dependent kinase (CDK)
       inhibitors of the type [Fe(L(n))Cl(3)]center dot nH(2)O (n = 0 for 1,
       1 for 2, 2 for 3-6; L(1)-L(6) = C2- and phenyl-substituted CDK
       inhibitors derived from 6-benzyl-amino-9-isopropylpurine), have been
       synthesized and characterized by elemental analysis, IR, (57)Fe
       Mossbauer, (1)H and (13)C NMR, and ES+ mass spectroscopies, conductivity
       and magnetic susceptibility measurements, and thermogravimetric analysis
       (TGA) and differential scanning calorimetry (DSC). The study revealed
       that the compounds are mononuclear, tetrahedral high-spin (S = 5/2)
       Fe(III) complexes with an admixture of an S = 3/2 spin state originating
       probably from five-coordinated Fe(III) ions either connecting with a
       bidentate coordination mode of the CDK inhibitor ligand or relating to
       the possibility that one crystal water molecule enters the coordination
       sphere of the central atom in a portion of molecules of the appropriate
       complex. Nearly spin-only value of the effective magnetic moment (5.82
       mu(eff)/mu(B)) was determined for compound 1 due to absence of crystal
       water molecule(s) in the structure of the complex. Based on NMR data and
       DFT calculations, we assume that the appropriate organic ligand is
       coordinated to the Fe(III) ion through the N7 atom of a purine moiety.
       The cytotoxicity of the complexes was tested in vitro against selected
       human cancer cell lines (G-361, HOS, K-562 and MCF-7) along with the
       ability to inhibit the CDK2/cyclinE kinase. The best cytotoxicity
       (IC(50): 4-23 mu M) and inhibition activity (IC(50): 0.02-0.09 mu M)
       results have been achieved in the case of complexes 2-4, and complexes
       3,4 and 6, respectively. In addition, the X-ray structure of
       2-chloro-6-benzylamino-9-isopropylpurine, i.e. a precursor for the
       preparation of L(1), L(4) and L(5), is also described. (C) 2009 Elsevier
       Inc. All rights reserved.,
    DOI = 10.1016/j.jinorgbio.2009.12.002,
    ISSN = 0162-0134,
    Unique-ID = ISI:000274921200007,
    
  • [DOI] R. Novotna, Z. Travnicek, and I. Popa, “X-ray crystallographic and NMR study of the tautomerism in kinetin,
    kinetin riboside and their derivatives: A comparison between the solid
    state and solution,” JOURNAL OF MOLECULAR STRUCTURE, vol. 963, iss. 2-3, pp. 202-210, 2010.
    [Bibtex]
    @article ISI:000274867800017,
    Author = Novotna, Radka and Travnicek, Zdenek and Popa, Igor,
    Title = X-ray crystallographic and NMR study of the tautomerism in kinetin,
       kinetin riboside and their derivatives: A comparison between the solid
       state and solution,
    Journal = JOURNAL OF MOLECULAR STRUCTURE,
    Year = 2010,
    Volume = 963,
    Number = 2-3,
    Pages = 202-210,
    Month = JAN 29,
    Abstract = N6-furfuryladenine (kinetin, 1), 2-chloro-N6-furfuryladenine (2),
       N6-furfuryladenosine (kinetin riboside, 3) and
       2-chloro-N6-(5-methylfurfuryl)adenosine (4) have been prepared and their
       structural properties have been studied using a single crystal X-ray
       analysis (2, 4) and multinuclear 1D and 2D NMR spectroscopy (1-4). The
       molecular structure of 2 revealed the presence of the 3H-amino and
       7H-amino tautomeric forms with the occupancy of 82(3)\%, and 18(3)\%,
       respectively, for the corresponding hydrogen. The NMR study revealed the
       presence of tautomeric equilibria in 1, 2 and 4 in dimethyl sulfoxide or
       N,N'-dimethylformamide solutions at 300 K and 340 K. It has been found
       that the 9H-amino/7H-amino, 1H,7H-imino/1H,9H-imino and
       9H-amino/7H-amino, and amino/1H-imino equilibria exist in 1, 2, and 4,
       respectively. The presence of a tautomeric equilibrium has not been
       observed in the case of 3. (c) 2009 Elsevier B.V. All rights reserved.,
    DOI = 10.1016/j.molstruc.2009.10.036,
    ISSN = 0022-2860,
    Unique-ID = ISI:000274867800017,
    
  • [DOI] Z. Travnicek, R. Pastorek, P. Starha, I. Popa, and V. Slovak, “Nickel(II) N-Benzyl-N-methyldithiocarbamato Complexes as Precursors for
    the Preparation of Graphite Oxidation Accelerators,” ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE, vol. 636, iss. 8, pp. 1557-1564, 2010.
    [Bibtex]
    @article ISI:000280659500023,
    Author = Travnicek, Zdenek and Pastorek, Richard and Starha, Pavel and Popa, Igor
       and Slovak, Vaclav,
    Title = Nickel(II) N-Benzyl-N-methyldithiocarbamato Complexes as Precursors for
       the Preparation of Graphite Oxidation Accelerators,
    Journal = ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE,
    Year = 2010,
    Volume = 636,
    Number = 8,
    Pages = 1557-1564,
    Abstract = The nickel(II) N-benzyl-N-methyldithiocarbantato (BzMedtc) complexes
       [Ni(BzMedtc)(PPh(3))Cl] (1), [Ni(BzMedtc)(PPh(3))Br] (2),
       [Ni(BzMedtc)(PPh(3))I] (3), and [Ni(BzMedtc)(PPh(3))(NCS)] (4) were
       synthesized using the reaction of [Ni(BzMedtc)(2)] and
       [NiX(2)(PPh(3))(2)] (X = Cl, Br, I and NCS). Subsequently, complex 1
       was used for the preparation of [Ni(BzMedtc)(PPh(3))(2)]ClO(4) (5),
       [Ni(BzMedtc)(PPh(3))(2)]BPh(4) (6), and
       [Ni(BzMedtc)(PPh(3))(2)]PF(6) (7). The obtained complexes 1-7 were
       characterized by elemental analysis, thermal analysis and spectroscopic
       methods (IR, UV/Vis, (31)P\(1)H\ NMR). The results of the
       magnetochemical and molar conductivity measurements proved the complexes
       as diamagnetic non-electrolytes (1-4) or 1:1 electrolytes (5-7). The
       molecular structures of 4 and 5 center dot H(2)O were determined by a
       single-crystal X-ray analysis. In all cases, the Ni(II) atom is
       tetracoordinated in a distorted square-planar arrangement with the
       S(2)PX, and S(2)P(2) donor set, respectively. The catalytic influence of
       selected complexes 1, 3, 5, and 6 on graphite oxidation was studied. The
       results clearly indicated that the presence of the products of thermal
       degradation processes of the mentioned complexes has impact on the
       course of graphite oxidation. A decrease in the oxidation start
       temperatures by about 60-100 degrees C was observed in the cases of all
       the tested complexes in comparison with pure graphite.,
    DOI = 10.1002/zaac.201000091,
    ISSN = 0044-2313,
    Unique-ID = ISI:000280659500023,
    

2009

  • [DOI] M. Siller, P. Anzenbacher, E. Anzenbacherova, K. Dolezal, I. Popa, and M. Strnad, “Interactions of olomoucine II with main drug-metabolizing enzymes of
    human liver microsomal fraction,” TOXICOLOGY LETTERS, vol. 189, pp. S108, 2009.
    [Bibtex]
    @article ISI:000269778800315,
    Author = Siller, Michal and Anzenbacher, Pavel and Anzenbacherova, Eva and
       Dolezal, Karel and Popa, Igor and Strnad, Miroslav,
    Title = Interactions of olomoucine II with main drug-metabolizing enzymes of
       human liver microsomal fraction,
    Journal = TOXICOLOGY LETTERS,
    Year = 2009,
    Volume = 189,
    Pages = S108,
    Month = SEP 13,
    Note = 46th Congress of the European-Societies-of-Toxicology, Dreden, GERMANY,
       SEP 13-16, 2009,
    Organization = European Soc Toxicol,
    DOI = 10.1016/j.toxlet.2009.06.349,
    ISSN = 0378-4274,
    Unique-ID = ISI:000269778800315,
    
  • [DOI] P. Starha, Z. Travnicek, and I. Popa, “Synthesis, characterization and in vitro cytotoxicity of the first
    palladium(II) oxalato complexes involving adenine-based ligands,” JOURNAL OF INORGANIC BIOCHEMISTRY, vol. 103, iss. 7, pp. 978-988, 2009.
    [Bibtex]
    @article ISI:000267768200006,
    Author = Starha, Pavel and Travnicek, Zdenek and Popa, Igor,
    Title = Synthesis, characterization and in vitro cytotoxicity of the first
       palladium(II) oxalato complexes involving adenine-based ligands,
    Journal = JOURNAL OF INORGANIC BIOCHEMISTRY,
    Year = 2009,
    Volume = 103,
    Number = 7,
    Pages = 978-988,
    Month = JUL,
    Abstract = The first [Pd(L(n))(2)(ox)] xH(2)O oxalato(ox) complexes involving
       2-chloro-N6-(benzyl)-9-isopropyladenine (L(1): complex 1),
       2-chloro-N6-(4-methoxybenzyl)-9-isopropyladenine (L(2); 2),
       2-chloro-N6-(2,3-dimethoxybenzyl)-9-isopropyladenine (L(3); 3),
       2-chloro-N6-(2,4-dimethoxybenzyl)-9-isopropyladenine (L(4); 4), and
       2-chloro-N6-(4-methylbenzyl)-9-isopropyladenine (L(5); 5) have been
       synthesized by the reactions of potassium bis(oxalato)palladate(II)
       dihydrate, [K(2)Pd(ox)(2)]center dot 2H(2)O, with the mentioned
       organic compounds (H(2)ox = oxalic acid; x = 0 for 1-3 and 5 or 2 for
       4). Elemental analyses (C, H, N), FTIR, Raman and NMR ((1)H, (13)C,
       (15)N) spectroscopies, conductivity measurements and thermal studies
       (thermogravimetric and differential thermal analyses, TG/DTA) have been
       used to characterize the prepared complexes. The molecular structures of
       [Pd(L(2))(2)(ox)] (2) and [Pd(L(5))(2)(ox)]center dot L(5)center dot
       Me(2)CO (5 center dot L(5)center dot Me(2)CO) have been determined by a
       single crystal X-ray analysis. The geometry of these complexes is
       slightly distorted square-planar with two appropriate L(n) (n = 2 or 5)
       molecules mutually arranged in the head-to-head (2) or head-to-tail (5)
       orientation. The L(n) ligands are coordinated to the central Pd(II) ion
       via the N7 atoms. The same conclusions regarding the binding properties
       of L(1)-L(5) ligands can be made based on multinuclear NMR spectra. In
       vitro cytotoxicity of the complexes 1-5 has been evaluated against human
       chronic myelogenous leukaemia (K562) and human breast adenocarcinoma
       (MCF7) cancer cell lines. Significant cytotoxicity has been determined
       for the complexes 3 (IC(50) = 6.2 mu M) and 5 (IC(50) m 6.8 mu M) on the
       MCF7 cell line, which is even better than that found for the well-known
       and widely-used platinum-bearing antineoplastic drugs, i.e. oxaliplatin
       and cisplatin. (C) 2009 Elsevier Inc. All rights reserved.,
    DOI = 10.1016/j.jinorgbio.2009.04.008,
    ISSN = 0162-0134,
    Unique-ID = ISI:000267768200006,
    
  • L. Spichal, T. Werner, I. Popa, M. Riefler, T. Schmelling, and M. Strnad, “PI-55 is a purine-derived cytokinin antagonist that blocks cytokinin
    action via receptor inhibition,” FEBS JOURNAL, vol. 276, pp. 390-391, 2009.
    [Bibtex]
    @article ISI:000267069901194,
    Author = Spichal, L. and Werner, T. and Popa, I. and Riefler, M. and Schmelling,
       T. and Strnad, M.,
    Title = PI-55 is a purine-derived cytokinin antagonist that blocks cytokinin
       action via receptor inhibition,
    Journal = FEBS JOURNAL,
    Year = 2009,
    Volume = 276,
    Pages = 390-391,
    Month = JUL,
    Note = 34th Congress of the Federation-of-European-Biochemical-Societies,
       Prague, CZECH REPUBLIC, JUL 04-09, 2009,
    Organization = Federat European Biochem Soc,
    ISSN = 1742-464X,
    Unique-ID = ISI:000267069901194,
    
  • [DOI] M. Siller, P. Anzenbacher, E. Anzenbacherova, K. Dolezal, I. Popa, and M. Strnad, “Interactions of Olomoucine II with Human Liver Microsomal Cytochromes
    P450,” DRUG METABOLISM AND DISPOSITION, vol. 37, iss. 6, pp. 1198-1202, 2009.
    [Bibtex]
    @article ISI:000266147500008,
    Author = Siller, Michal and Anzenbacher, Pavel and Anzenbacherova, Eva and
       Dolezal, Karel and Popa, Igor and Strnad, Miroslav,
    Title = Interactions of Olomoucine II with Human Liver Microsomal Cytochromes
       P450,
    Journal = DRUG METABOLISM AND DISPOSITION,
    Year = 2009,
    Volume = 37,
    Number = 6,
    Pages = 1198-1202,
    Month = JUN,
    Abstract = Olomoucine II is a cyclin-dependent kinase inhibitor and a potential
       antineoplastic agent because it can arrest animal cell cycles. This
       study examines its interactions with human liver microsomal cytochrome
       P450 (P450) enzymes. Spectroscopic and high-performance liquid
       chromatography (HPLC) methods were used to estimate the degree of
       olomoucine II-mediated inhibition of enzymatic activities of eight
       drug-metabolizing P450s in vitro. In addition, mass spectrometry coupled
       with HPLC was used to identify an olomoucine II metabolite
       (2,5-dihydroxyroscovitine) formed in the reaction mixtures, and CYP3A4
       was found to be responsible for the hydroxylation of the N(6)-benzyl
       ring at position 5, leading to this compound. Olomoucine II
       significantly inhibited the enzymatic activities of CYP1A2, CYP2C9, and
       (to a lesser degree) CYP3A4. The results indicate that use of olomoucine
       II as a drug could affect the activities of CYP3A4, CYP1A2, and CYP2C9
       in vivo. Hence, the clinical relevance of these interactions should be
       carefully evaluated.,
    DOI = 10.1124/dmd.108.025502,
    ISSN = 0090-9556,
    Unique-ID = ISI:000266147500008,
    
  • [DOI] L. Szucova, L. Spichal, K. Dolezal, M. Zatloukal, J. Greplova, P. Galuszka, V. Krystof, J. Voller, I. Popa, F. J. Massino, J. Jorgensen, and M. Strnad, “Synthesis, characterization and biological activity of ring-substituted
    6-benzylamino-9-tetrahydropyran-2-yl and 9-tetrahydrofuran-2-ylpurine
    derivatives,” BIOORGANIC & MEDICINAL CHEMISTRY, vol. 17, iss. 5, pp. 1938-1947, 2009.
    [Bibtex]
    @article ISI:000264067900020,
    Author = Szucova, Lucie and Spichal, Lukas and Dolezal, Karel and Zatloukal,
       Marek and Greplova, Jarmila and Galuszka, Petr and Krystof, Vladimir and
       Voller, Jiri and Popa, Igor and Massino, Frank J. and Jorgensen, Jan-Elo
       and Strnad, Miroslav,
    Title = Synthesis, characterization and biological activity of ring-substituted
       6-benzylamino-9-tetrahydropyran-2-yl and 9-tetrahydrofuran-2-ylpurine
       derivatives,
    Journal = BIOORGANIC \& MEDICINAL CHEMISTRY,
    Year = 2009,
    Volume = 17,
    Number = 5,
    Pages = 1938-1947,
    Month = MAR 1,
    Abstract = In an attempt to improve specific biological functions of cytokinins
       routinely used in plant micropropagation, 33
       6-benzylamino-9-tetrahydropyran-2-ylpurine (THPP) and
       9-tetrahydrofuran-2-ylpurine (THFP) derivatives, with variously
       positioned hydroxy and methoxy functional groups on the benzyl ring,
       were prepared. The new derivatives were prepared by condensation of
       6-chloropurine with 3,4-dihydro-2H-pyran or 2,3-dihydrofuran and then by
       the condensation of these intermediates with the corresponding
       benzylamines. The prepared compounds were characterized by elemental
       analyses, TLC, HPLC, melting point determinations, CI+ MS and (1)H NMR
       spectroscopy. The cytokinin activity of all the prepared derivatives was
       assessed in three classical cytokinin bioassays (tobacco callus, wheat
       leaf senescence and Amaranthus bioassay). The derivatives
       6-(3-hydroxybenzylamino)-9-tetrahydropyran-2-ylpurine (3) and
       6-(3-hydroxybenzylamino)-9-tetrahydrofuran-2-ylpurine (23) were
       selected, because of the high affinity of their parent compound
       meta-topolin (mT, 6-(3-hydroxybenzylamino) purine) to cytokinin
       receptors, as model compounds for studying their perception by the
       receptors CRE1/AHK4 and AHK3 in a bacterial assay. Both receptors
       perceived these two derivatives less well than they perceived the parent
       compound. Subsequently, the susceptibility of several new derivatives to
       enzyme degradation by cytokinin oxidase/dehydrogenase was studied.
       Substitution of tetrahydropyran-2-yl (THP) at the N(9) position
       decreased the turnover rates of all new derivatives to some extent. To
       provide a practical perspective, the cytotoxicity of the prepared
       compounds against human diploid. broblasts (BJ) and the human cancer
       cell lines K-562 and MCF-7 was also assayed in vitro. The prepared
       compounds showed none or marginal cytotoxicity compared to the
       corresponding N(9)-ribosides. Finally, the pH stability of the two model
       compounds was assessed in acidic and neutral water solutions (pH 3-7) by
       high-performance liquid chromatography (HPLC). (C) 2009 Elsevier Ltd.
       All rights reserved.,
    DOI = 10.1016/j.bmc.2009.01.041,
    ISSN = 0968-0896,
    Unique-ID = ISI:000264067900020,
    
  • [DOI] P. Starha, Z. Travnicek, R. Herchel, I. Popa, P. Suchy, and J. Vanco, “Dinuclear copper(II) complexes containing 6-(benzylamino)purines as
    bridging ligands: Synthesis, characterization, and in vitro and in vivo
    antioxidant activities,” JOURNAL OF INORGANIC BIOCHEMISTRY, vol. 103, iss. 3, pp. 432-440, 2009.
    [Bibtex]
    @article ISI:000263693900016,
    Author = Starha, Pavel and Travnicek, Zdenek and Herchel, Radovan and Popa, Igor
       and Suchy, Pavel and Vanco, Jan,
    Title = Dinuclear copper(II) complexes containing 6-(benzylamino)purines as
       bridging ligands: Synthesis, characterization, and in vitro and in vivo
       antioxidant activities,
    Journal = JOURNAL OF INORGANIC BIOCHEMISTRY,
    Year = 2009,
    Volume = 103,
    Number = 3,
    Pages = 432-440,
    Month = MAR,
    Abstract = A series of dinuclear copper(II) complexes involving
       6-(benzylamino)purine derivatives, (HL(n)), as bridging ligands were
       synthesized, characterized and tested for both their in vitro and in
       vivo antioxidant activities. Based on results of elemental analyses,
       temperature dependence of magnetic susceptibility measurements, UV-vis,
       FTIR, EPR, NMR and MALDI-TOF mass spectroscopy, conductivity
       measurements and thermal analyses, the complexes with general
       compositions Of [Cu(2)(mu-HL(n))(4)Cl(2)]Cl(2)center dot 2H(2)O (1-4)
       and [Cu(2)(mu-HL(n))(2)(mu-Cl)(2)Cl(2)] (5-7) were prepared [where n
       = 1-4; HL(1) = 6-[(2-methoxybenzyl)amino]purine, HL(2) =
       6-[(4-methoxybenzyl)amino]purine, HL(3) =
       6-[(2,3-dimethoxybenzyl)amino]purine and HL(4) =
       6[(3,4-dimethoxybenzyl)amino]purine). In the case of complexes 2, 3, 5
       and 7, the antioxidant activities were studied by both in vitro
       [superoxide dismutase-mimic (SOD-mimic) activity) and in vivo
       (cytoprotective effect against the alloxan-induced diabetes
       (antidiabetic activity)) methods. The obtained IC(50) value of the
       SOD-mimic activity for the complex 5 (IC(50) = 0.253 mu M) was shown to
       be even better than that of the native bovine Cu,Zn-SOD enzyme (IC(50) =
       0.480 mu M), used as a standard. As for the antidiabetic activity, the
       pretreatment of mice with complexes 3 and 7 led to the complete
       elimination of cytotoxic attack of alloxan and its free radical
       metabolites, used as a diabetogenic agent. The cytoprotective effect of
       these compounds was proved by the preservation of the initial blood
       glucose levels of the pretreated animals, as against the untreated
       control group. (C) 2008 Elsevier Inc. All rights reserved.,
    DOI = 10.1016/j.jinorgbio.2008.12.009,
    ISSN = 0162-0134,
    Unique-ID = ISI:000263693900016,
    
  • [DOI] L. Spichal, T. Werner, I. Popa, M. Riefler, T. Schmuelling, and M. Strnad, "The purine derivative PI-55 blocks cytokinin action via receptor
    inhibition," FEBS JOURNAL, vol. 276, iss. 1, pp. 244-253, 2009.
    [Bibtex]
    @article ISI:000261683900022,
    Author = Spichal, Lukas and Werner, Tomas and Popa, Igor and Riefler, Michael and
       Schmuelling, Thomas and Strnad, Miroslav,
    Title = The purine derivative PI-55 blocks cytokinin action via receptor
       inhibition,
    Journal = FEBS JOURNAL,
    Year = 2009,
    Volume = 276,
    Number = 1,
    Pages = 244-253,
    Month = JAN,
    Abstract = One of several potential approaches to study mechanisms of action of
       biologically active compounds is to develop their agonists and
       antagonists. In the present study, we report the identification of the
       first known molecule antagonizing the activity of the plant hormone
       cytokinin at the receptor level. This compound,
       6-(2-hydroxy-3-methylbenzylamino)purine, designated PI-55 in the present
       study, is structurally closely related to cytokinin 6-benzylaminopurine,
       but substitutions at specific positions of the aromatic side chain
       strongly diminished its cytokinin activity and conferred antagonistic
       properties. PI-55 competitively inhibited the binding of the natural
       ligand trans-zeatin to the Arabidopsis cytokinin receptors cytokinin
       response 1 (CRE1)/Arabidopsis histidine kinase (AHK) 4 and AHK3 and
       repressed induction of the cytokinin response gene ARR5:GUS. Genetic
       analysis revealed that CRE1/AHK4 is the primary target of PI-55.
       Cytokinin bioassays also demonstrated the anticytokinin effect of PI-55
       in several other species. Furthermore, we show that PI-55 accelerated
       the germination of Arabidopsis seeds and promoted the root growth and
       formation of lateral roots, thus phenocopying the known consequences of
       a lowered cytokinin status and demonstrating its potential to inhibit
       cytokinin perception in planta. PI-55 is the first example for the
       targeted development of a cytokinin antagonist and represents an initial
       step for the preparation of cytokinin antagonists with broad activity
       and reduced agonistic properties.,
    DOI = 10.1111/j.1742-4658.2008.06777.x,
    ISSN = 1742-464X,
    Unique-ID = ISI:000261683900022,
    

2008

  • [DOI] Z. Travnicek, J. Mikulik, M. Cajan, R. Zboril, and I. Popa, "Novel iron complexes bearing N6-substituted adenosine derivatives:
    Synthesis, magnetic, (57)Fe Mossbauer, DFT, and in vitro cytotoxicity
    studies," BIOORGANIC & MEDICINAL CHEMISTRY, vol. 16, iss. 18, pp. 8719-8728, 2008.
    [Bibtex]
    @article ISI:000259173400046,
    Author = Travnicek, Zdenek and Mikulik, Jiri and Cajan, Michal and Zboril, Radek
       and Popa, Igor,
    Title = Novel iron complexes bearing N6-substituted adenosine derivatives:
       Synthesis, magnetic, (57)Fe Mossbauer, DFT, and in vitro cytotoxicity
       studies,
    Journal = BIOORGANIC \& MEDICINAL CHEMISTRY,
    Year = 2008,
    Volume = 16,
    Number = 18,
    Pages = 8719-8728,
    Month = SEP 15,
    Abstract = Iron complexes (1-7) involving N6-benzyladenosine derivatives of the
       predominant composition [Fe(L(n))Cl(3)]center dot H(2)O \where L(1) =
       N6-(2-fluorobenzyl)adenosine (1), L(2) = N6-(4-fluorobenzyl)adenosine
       (2), L(3) = N6-(2-trifluoromethylbenzyl)adenosine (3), L(4) =
       N6-(3-trifluoromethylbenzyl)adenosine (4), L(5) =
       N6-(4-trifluoromethylbenzyl)adenosine (5), L(6) =
       N6-(4-trifluoromethoxybenzyl)adenosine (6), and L(7) =
       N6-(4-chlorobenzyl)adenosine (7)\ have been synthesized. The compounds
       have been characterized by elemental analysis, variable-temperature and
       in-field (57)Fe Mossbauer, ES+ MS, FTIR, (1)H and (13)C NMR
       spectroscopies, magnetochemical and conductivity measurements, thermal
       (TGA/DSC/DTA) analyses, and DFT calculations. It has been found that the
       organic molecule is coordinated to iron via N7 atom of the appropriate
       adenosine derivative and the products are represented by mixtures of
       complexes with various iron oxidation (Fe(III)/Fe(II)) and spin states
       (S = 5/2, 4/2, 3/2, 2/2) and geometries (tetrahedral or trigonal
       bipyramidal). It is caused by the fact that partial redox processes
       proceed during the reactions due to the presence of a ribose moiety,
       which is oxidized to the corresponding 5'-ribotic acid, and
       simultaneously, a portion of Fe(III) cations is reduced to Fe(II) ones.
       Moreover, a significant effect of crystal water molecules on
       stereochemistry, and hence, on magnetic and spectral properties of the
       prepared complexes has been found. The compounds have been tested for
       their in vitro cytotoxicity against the following human cancer cell
       lines: malignant melanoma (G-361), osteogenic sarcoma (HOS), chronic
       myelogenous leukemia (K-562), and breast adenocarcinoma (MCF-7). The
       most important results have been obtained for complex 2 with IC(50)
       values 8-16 mu M against HOS, K-562, and MCF-7 cell lines, and for
       complex 6 with IC50 value 4 mu M against MCF-7 cell line. (C) 2008
       Elsevier Ltd. All rights reserved.,
    DOI = 10.1016/j.bmc.2008.07.082,
    ISSN = 0968-0896,
    Unique-ID = ISI:000259173400046,
    
  • [DOI] L. Szucova, Z. Travnicek, I. Popa, and J. Marek, "Preparation and cis-to-trans transformation study of square-planar
    [Pt(L(n))2Cl(2)] complexes bearing cytokinins derived from
    6-benzylaminopurine (L(n)) by view of NMR spectroscopy and X-ray
    crystallography," POLYHEDRON, vol. 27, iss. 12, pp. 2710-2720, 2008.
    [Bibtex]
    @article ISI:000258616400029,
    Author = Szucova, Lucie and Travnicek, Zdenek and Popa, Igor and Marek, Jaromir,
    Title = Preparation and cis-to-trans transformation study of square-planar
       [Pt(L(n))2Cl(2)] complexes bearing cytokinins derived from
       6-benzylaminopurine (L(n)) by view of NMR spectroscopy and X-ray
       crystallography,
    Journal = POLYHEDRON,
    Year = 2008,
    Volume = 27,
    Number = 12,
    Pages = 2710-2720,
    Month = AUG 21,
    Abstract = Mononuclear, square-planar platinum(II) complexes involving derivatives
       of aromatic cytokinins as the ligands, and having the general formula
       cis-[Pt(L(n))(2)Cl(2)] (1-3) and trans-[Pt(L(n))(2)Cl(2)] (4-6),
       where n = 13, L(1) = 2-chloro-6-(benzylamino)-9-isopropylpurine, L(2) =
       2-chloro-6-[(4-methoxybenzyl)amino]-9-isopropylpurine and L(3) =
       2-chloro-6-[(2-methoxybenzyl)-amino]-9-isopropylpurine, have been
       synthesized and characterized by elemental analysis, MALDI-TOF mass, FT
       IR, (1)H, (13)C, (15)N and (195)Pt NMR spectral measurements. Dynamic
       cis-to-trans isomerization process of complex 1 in
       N,N'-dimethylformamide (DMF) has been investigated by means of
       multinuclear NMR spectroscopy. The solid-state structures of 1, 4 center
       dot (DMF)(2), and 5 have been determined by single crystal X-ray
       analysis. X-ray structures revealed that the heterocyclic ligands are
       coordinated to platinum via nitrogen atom N(7) in all the complexes
       studied. In vitro cytotoxicity of the prepared complexes against MCF7,
       G361, K562, and HOS has been evaluated. Owing to low solubility of the
       complexes in water, the cytotoxicity has been only tested up to 5 mu M
       concentration. Unfortunately, all complexes have been found to be
       non-cytotoxic in the accessible concentration range.,
    DOI = 10.1016/j.poly.2008.05.021,
    ISSN = 0277-5387,
    Unique-ID = ISI:000258616400029,
    

2007

  • [DOI] Z. Travnicek, I. Popa, M. Cajan, R. Herchel, and J. Marek, "The first platinum(IV) complexes involving aromatic cytokinins or
    cyclin-dependent kinase inhibitors derived from 6-benzylaminopurine:
    X-ray structures of (BohH(2)(2+))[PtCl6] center dot H2O and
    (RosH(2)(2+))(2)[PtCl6]Cl-2 center dot 4H(2)O," POLYHEDRON, vol. 26, iss. 18, pp. 5271-5282, 2007.
    [Bibtex]
    @article ISI:000251617700011,
    Author = Travnicek, Zdenek and Popa, Igor and Cajan, Michal and Herchel, Radovan
       and Marek, Jaromir,
    Title = The first platinum(IV) complexes involving aromatic cytokinins or
       cyclin-dependent kinase inhibitors derived from 6-benzylaminopurine:
       X-ray structures of (BohH(2)(2+))[PtCl6] center dot H2O and
       (RosH(2)(2+))(2)[PtCl6]Cl-2 center dot 4H(2)O,
    Journal = POLYHEDRON,
    Year = 2007,
    Volume = 26,
    Number = 18,
    Pages = 5271-5282,
    Month = NOV 20,
    Abstract = A series of Pt(IV) complexes with cytokinins or CDK-inhibitors derived
       from 6-benzylaminopurine (Bap) of the composition [Pt-IV(LH+)Cl-5]
       (1-14), where LH+ stands for protonated form of the Bap derivative
       (1-12), Boh =
       6-(benzylamino)-2-[(3-hydroxypropyl)amino]-9-isopropylpurine, bohemine
       (13) and Ros =
       6-(benzylamino)-2-[(1-hydroxymethylpropyl)amino]-9-isopropylpurine,
       roscovitine (14), have been prepared. They have been fully characterized
       by microanalysis, conductivity, FT-IR, H-1, C-13, N-15 and Pt-195 NMR
       and ES+ mass spectroscopy. It has been found that the cytokinin molecule
       is coordinated via N9 atom to platinum(IV) and N1, N7-protonated in case
       of complexes 1-12, and N7 coordinated and NI-protonated in case of
       complexes with CDK inhibitors (13 and 14). Predicted molecular
       geometries of the complexes have been supported by DFT calculations at
       the B3LYP level with the 6-311+G**/LANL2DZ and aug-cc-pVDZ/LANL2DZ
       basis sets. All of the compounds have been tested in vitro for their
       cytotoxicity against four human cancer cell lines: malignant melanoma
       (G361), osteogenic sarcoma (HOS), chronic myelogenous erythroleukemia
       (K562) and breast adenocarcinoma (MCF7). The best result has been
       achieved for complex 14, where IC50 = 17 mu M against K562. The
       molecular structures of two ionic pair compounds (BohH(2)(2+))[PtCl6]
       center dot H2O (15) and (RosH(2)(2+))(2)[PtCl6]Cl-2 center dot 4H(2)O
       (16) have been determined by a single crystal X-ray analysis. (c) 2007
       Elsevier Ltd. All rights reserved.,
    DOI = 10.1016/j.poly.2007.07.026,
    ISSN = 0277-5387,
    Unique-ID = ISI:000251617700011,
    
  • [DOI] K. Dolezal, I. Popa, E. Hauserova, L. Spichal, K. Chakrabarty, O. Novak, V. Krystof, J. Voller, J. Holub, and M. Strnad, "Preparation, biological activity and endogenous occurrence of
    N-6-benzyladenosines," BIOORGANIC & MEDICINAL CHEMISTRY, vol. 15, iss. 11, pp. 3737-3747, 2007.
    [Bibtex]
    @article ISI:000246649000015,
    Author = Dolezal, Karel and Popa, Igor and Hauserova, Eva and Spichal, Lukas and
       Chakrabarty, Kuheli and Novak, Ondrej and Krystof, Vladimir and Voller,
       Jiri and Holub, Jan and Strnad, Miroslav,
    Title = Preparation, biological activity and endogenous occurrence of
       N-6-benzyladenosines,
    Journal = BIOORGANIC \& MEDICINAL CHEMISTRY,
    Year = 2007,
    Volume = 15,
    Number = 11,
    Pages = 3737-3747,
    Month = JUN 1,
    Abstract = Cytokinin activity of forty-eight 6-benzyladenosine derivatives at both
       the receptor and cellular levels as well as their anticancer properties
       were compared in various in vitro assays. The compounds were prepared by
       the condensation of 6-chloropurine riboside with corresponding
       substituted benzylamines and characterized by standard collection of
       physico-chemical methods. The majority of synthesized derivatives
       exhibited high activity in all three of the cytokinin bioassays used
       (tobacco callus, wheat leaf senescence and Amaranthus bioassay). The
       highest activities were observed in the senescence bioassay. For several
       of the compounds tested, significant differences in activity were found
       between the bioassays used, indicating that diverse recognition systems
       may operate. This suggests that it may be possible to modulate
       particular cytokinin-dependent processes with specific compounds. In
       contrast to their high activity in bioassays, the tested compounds were
       recognized with only very low sensitivity in both Arabidopsis thaliana
       AHK3 and AHK4 receptor assays. The prepared derivatives were also
       investigated for their antiproliferative properties on cancer and normal
       cell lines. Several of them showed very strong cytotoxic activity
       against various cancer cell lines. On the other hand, they were not
       cytotoxic for normal murine fibroblast (NIH/3T3) cell line. This
       anticancer activity of cytokinin ribosides may be important, given that
       several of them occur as endogenous compounds in different organisms.
       (c) 2007 Elsevier Ltd. All rights reserved.,
    DOI = 10.1016/j.bmc.2007.03.038,
    ISSN = 0968-0896,
    Unique-ID = ISI:000246649000015,
    
  • [DOI] Z. Travnicek, L. Szucova, and I. Popa, "Synthesis, characterization and assessment of the cytotoxic properties
    of cis and trans-[Pd(L)(2)Cl-2] complexes involving
    6-benzylamino-9-isopropylpurine derivatives," JOURNAL OF INORGANIC BIOCHEMISTRY, vol. 101, iss. 3, pp. 477-492, 2007.
    [Bibtex]
    @article ISI:000244773800012,
    Author = Travnicek, Zdenek and Szucova, Lucie and Popa, Igor,
    Title = Synthesis, characterization and assessment of the cytotoxic properties
       of cis and trans-[Pd(L)(2)Cl-2] complexes involving
       6-benzylamino-9-isopropylpurine derivatives,
    Journal = JOURNAL OF INORGANIC BIOCHEMISTRY,
    Year = 2007,
    Volume = 101,
    Number = 3,
    Pages = 477-492,
    Month = MAR,
    Abstract = A series of square-planar Pd(II) complexes of the composition
       cis-[Pd(L-n)(2)Cl-2] \L-1 = 2-chloro-6-benzylamino-9-isopropyipurine
       (1), L-2 = 2-chloro-6-[(4-methoxybenzyl)amino]-9-isopropylpurine (2),
       L-3 = 2-chloro-6-[(2-methoxybenzyl)amino]-9-isopropylpurine (3) and
       2-[(chloropropyl)aminol-6-benzylamino-9-isopropylpurine (6)] has been
       synthesized by the reaction of PdCl2 with L-n in a 1:2 molar ratio. In
       contrast, the same reaction followed by recrystallization of the product
       from N,N'-dimethylformamide (DMF) leads to trans-[Pd(L-n)(2)Cl-2] -
       nDMF \L-3, n = 0 (4), n = 1(4*DMF); L-4 =
       2-chloro-6-[(2,3-dimethoxybenzyl)-amino]-9-isopropylpurine, n = 0 (5),
       n = 1.5 (5*DMF). The compounds have been characterized by elemental
       analyses, conductivity measurements, electrospray mass spectra in the
       positive ion mode (ES + MS), FTIR, H-1 and C-13 NMR spectra,
       thermogravimetric analysis (TGA) and differential scanning calorimetry
       (DSC). Moreover, the complexes 2 and 6 have been also investigated by
       N-15 NMR spectroscopy. The molecular structures of L-5,
       \(H2+L5)(Cl-)(2)\ - H2O, i.e. the protonated form of L-5,
       trans-[Pd(L-3)(2)Cl-2](4) and trans-[Pd(L-4)(2)Cl-2] (5) have been
       determined by single crystal X-ray analysis. NMR data and X-ray
       structures revealed that the organic molecules are coordinated to Pd via
       N7 atom of a purine moiety. All the complexes and the corresponding
       ligands have been tested in vitro for their cytotoxicity against four
       human cancer cell lines: breast adenocarcinoma (MCF7), malignant
       melanoma (G361), chronic myelogenous leukaemia (K562) and osteogenic
       sarcoma (HOS). Promising in vitro cytotoxic effect has been found for
       cis-[Pd(L-2)(2)Cl-2] (2), having the IC50 values of 12, 10, 25, and 14
       mu M against MCF7, G361, K562, and HOS, respectively, and for
       trans-[Pd(L-3)(2)Cl-2] - DMF (4) with the IC50 value of 15 mu M
       against G361. (c) 2006 Elsevier Inc. All rights reserved.,
    DOI = 10.1016/j.jinorgbio.2006.11.010,
    ISSN = 0162-0134,
    Unique-ID = ISI:000244773800012,
    
  • [DOI] Z. Travnicek and I. Popa, "2-chloro-6-[(2,6-dimethoxybenzyl)amino]9-isopropylpurine 0.125-hydrate," ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE, vol. 63, iss. Part 2, pp. O629-O631, 2007.
    [Bibtex]
    @article ISI:000245187300247,
    Author = Travnicek, Zdenek and Popa, Igor,
    Title = 2-chloro-6-[(2,6-dimethoxybenzyl)amino]9-isopropylpurine 0.125-hydrate,
    Journal = ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE,
    Year = 2007,
    Volume = 63,
    Number = Part 2,
    Pages = O629-O631,
    Month = FEB,
    Abstract = The secondary structure in the title compound, C17H20ClN5O2 center dot
       0.125H(2)O, is stabilized by N-H center dot center dot center dot N
       hydrogen bonds that connect molecules into centrosymmetric dimers; the
       dimers are linked via a variety of intermolecular interactions.,
    DOI = 10.1107/S1600536807000268,
    ISSN = 1600-5368,
    Unique-ID = ISI:000245187300247,
    
  • [DOI] Z. Travnicek and I. Popa, "2-chloro-6-[(4-hydroxy-3,5-dimethoxybenzyl)amino]-9-isopropylpurine," ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE, vol. 63, iss. Part 2, pp. O728-O730, 2007.
    [Bibtex]
    @article ISI:000245187300291,
    Author = Travnicek, Zdenek and Popa, Igor,
    Title = 2-chloro-6-[(4-hydroxy-3,5-dimethoxybenzyl)amino]-9-isopropylpurine,
    Journal = ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE,
    Year = 2007,
    Volume = 63,
    Number = Part 2,
    Pages = O728-O730,
    Month = FEB,
    Abstract = The structure of the title compound, C17H20ClN5O3, consists of discrete
       molecules of a 6-(benzylamino) purine derivative. The secondary
       structure is stabilized by N-(HO)-O-... hydrogen bonds connecting
       molecules into centrosymmetric dimers and by weak interatomic contacts
       of the types C-(HCl)-Cl-... and C (HO)-O-...,and by pi-pi stacking
       interactions.,
    DOI = 10.1107/S1600536807001511,
    ISSN = 1600-5368,
    Unique-ID = ISI:000245187300291,
    
  • [DOI] J. Stranska, M. Sebela, P. Tarkowski, P. Rehulka, J. Chmelik, I. Popa, and P. Pec, "Inhibition of plant amine oxidases by a novel series of diamine
    derivatives," BIOCHIMIE, vol. 89, iss. 1, pp. 135-144, 2007.
    [Bibtex]
    @article ISI:000243630100012,
    Author = Stranska, Jana and Sebela, Marek and Tarkowski, Petr and Rehulka, Pavel
       and Chmelik, Josef and Popa, Igor and Pec, Pavel,
    Title = Inhibition of plant amine oxidases by a novel series of diamine
       derivatives,
    Journal = BIOCHIMIE,
    Year = 2007,
    Volume = 89,
    Number = 1,
    Pages = 135-144,
    Month = JAN,
    Abstract = A series of N,N'-bis(2-pyridinylmethyl)diamines was synthesized and
       characterized for their inhibition effects towards plant
       copper-containing amine oxidase (EC 1.4.3.6) and polyamine oxidase (EC
       1.5.3.11), which mediate the catabolic regulation of cellular
       polyamines. Even though these enzymes catalyze related reactions and,
       among others, act upon two common substrates (spermidine and spermine),
       their molecular and kinetic properties are different. They also show a
       different spectrum of inhibitors. It is therefore of interest to look
       for compounds providing a dual inhibition (i.e. inhibiting both enzymes
       with the same inhibition potency), which would be useful in
       physiological studies involving modulations of polyamine catabolism. The
       synthesized diamine derivatives comprised from two to eight carbon atoms
       in the alkyl spacer chain. Kinetic measurements with pea (Pisum
       sativum?) diamine oxidase and oat (Avena sativa) polyamine oxidase
       demonstrated reversible binding of the compounds at the active sites of
       the enzymes as they were almost exclusively competitive inhibitors with
       K-i values ranging from 10(-5) to 10(-3) M. In case of oat polyamine
       oxidase, the Ki values were significantly influenced by the number of
       methylene groups in the inhibitor molecule. The measured inhibition data
       are discussed with respect to enzyme structure. For that reason, the oat
       enzyme was analyzed by de novo peptide sequencing using mass
       spectrometry and shown to be homologous to polyamine oxidases from
       barley (isoform 1) and maize. We cony clude that some of the studied
       N,N'-bis(2-pyridinylmethyl)diamines might have a potential to be
       starting structures in design of metabolic modulators targeted to both
       types of amine oxidases. (c) 2006 Elsevier Masson SAS. All rights
       reserved.,
    DOI = 10.1016/j.biochi.2006.08.001,
    ISSN = 0300-9084,
    Unique-ID = ISI:000243630100012,
    
  • F. Sersen, D. Loos, J. Csollei, I. Popa, J. Vanco, and F. Gregan, "Antioxidative activity of potential antihypertensives with dual effect," CHEMICKE LISTY, vol. 101, iss. 1, pp. 60-64, 2007.
    [Bibtex]
    @article ISI:000243899600009,
    Author = Sersen, Frantisek and Loos, Dusan and Csollei, Jozef and Popa, Igor and
       Vanco, Jan and Gregan, Fridrich,
    Title = Antioxidative activity of potential antihypertensives with dual effect,
    Journal = CHEMICKE LISTY,
    Year = 2007,
    Volume = 101,
    Number = 1,
    Pages = 60-64,
    Abstract = The antioxidative properties of four
       1-(2-benzofuran2-yl-2-hydroxyethyl)-4-phenylpiperazines were studied by
       indirect spectrophotometric and direct ESR spin-trap methods. The
       radical scavenging activity of the tested compounds was determined. The
       compounds exhibit interesting structure-specific redox properties.
       Scavenging of DPPH radicals gave very poor results. The studied
       compounds did not affect the elimination of superoxide anion radicals;
       however, they caused stimulation of O-2(-.) radical production. The
       hydroxyl radicals, however, were scavenged only by 2-fluorophenyl
       derivatives, whereas the 4-fluorophenyl derivatives exhibited a slightly
       prooxidative effect. The capture of HO. radicals by 2-fluorophenyl
       derivatives was, according to the results of NMR analyses, attributed to
       the interaction with non-protonated piperazine nitrogen atom, which is
       stabilized by the hydrogen bond between the hydroxy group and fluorine
       atom.,
    ISSN = 0009-2770,
    Unique-ID = ISI:000243899600009,
    

2006

  • [DOI] A. Klanicova, Z. Travnicek, I. Popa, M. Cajan, and K. Dolezal, "Synthesis, characterization and in vitro cytotoxicity of Co(II)
    complexes with N6-substituted adenine derivatives: X-ray structures of
    6-(4-chlorobenzylamino)purin-di-ium diperchlorate dihydrate and
    [Co-6(mu-L-6)(4)Cl-8(DMSO)(10)] center dot 4DMSO," POLYHEDRON, vol. 25, iss. 6, pp. 1421-1432, 2006.
    [Bibtex]
    @article ISI:000236698900022,
    Author = Klanicova, A and Travnicek, Z and Popa, I and Cajan, M and Dolezal, K,
    Title = Synthesis, characterization and in vitro cytotoxicity of Co(II)
       complexes with N6-substituted adenine derivatives: X-ray structures of
       6-(4-chlorobenzylamino)purin-di-ium diperchlorate dihydrate and
       [Co-6(mu-L-6)(4)Cl-8(DMSO)(10)] center dot 4DMSO,
    Journal = POLYHEDRON,
    Year = 2006,
    Volume = 25,
    Number = 6,
    Pages = 1421-1432,
    Month = APR 17,
    Abstract = Cobalt(II) complexes of the composition [Co(L-1)Cl(H2O)(2)]center dot
       H2O (1), [Co(L-2)Cl(H2O)(2)]center dot 2H(2)O (2),
       [Co(L-3)Cl(H2O)(2)]center dot H2O (3) [Co(L-4)Cl(H2O)(2)]center dot
       H2O (4), [Co(L-5)Cl(H2O)(2)] center dot H2O (5) and
       [Co(L-6)Cl(H2O)(2)]center dot H2O (6), where HL1 =
       6-(3-chlorobenzylamino)purine, HL2 = 6-(4-chlorobenzylamino)purine, HL3
       = 6-(2,3-dimethoxybenzylamino)purine, HL4 =
       6-(3,4-dimethoxybenzylamino)purine. HL5 = 6-(3-fluorobenzylamino)purine
       and HL6 = 6-(4-fluorobenzylamino)purine, have been prepared. The
       compounds have been characterized by elemental analyses, ES+ mass,
       UN-Vis, IR and NMR spectroscopies, magnetic measurements, molar
       conductances and thermogravimetric analysis as mononuclear tetrahedral
       high-spin cobalt(II) complexes. In vitro cytotoxicities of the complexes
       were tested by a Calcein AM assay against the following human tumour
       cell lines: malignant melanoma (G361), chronic myelogenous
       erythroleukemia, (K562), osteogenic sarcoma (HOS) and breast
       adenocarcinoma (MCF7). The molecular structures of
       6-(4-chlorobenzylamino)purin-di-ium diperchlorate dihydrate, [H2+
       L-2](ClO4)(2) center dot 2H(2)O, and a hexanuclear Co(II) complex,
       [Co-6(mu-L-6)(4)Cl-8(DMSO)(10)]center dot 4DMSO (7). have been
       determined by a single crystal X-ray analysis. To elucidate the manner
       of the organic ligand coordination to cobalt, the geometry of the
       complex 2 was optimized Using DFT calculations at the B3LYP/6-311+G*
       level of the theory. (c) 2005 Elsevier Ltd. All rights reserved.,
    DOI = 10.1016/j.poly.2005.09.032,
    ISSN = 0277-5387,
    Unique-ID = ISI:000236698900022,
    
  • [DOI] Z. Travnicek, J. Marek, and I. Popa, "6-(2-Chloro-4-fluorobenzylamino)purine," ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE, vol. 62, iss. Part 4, pp. O1536-O1538, 2006.
    [Bibtex]
    @article ISI:000236470100255,
    Author = Travnicek, Z and Marek, J and Popa, I,
    Title = 6-(2-Chloro-4-fluorobenzylamino)purine,
    Journal = ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE,
    Year = 2006,
    Volume = 62,
    Number = Part 4,
    Pages = O1536-O1538,
    Month = APR,
    Abstract = In the title molecule, C12H9ClFN5, all bond lengths and angles show
       normal values. The mean planes of the benzene ring and the purine ring
       system make a dihedral angle of 77.79 (5)degrees. Intermolecular N - H
       (. . .) N hydrogen bonds link the molecules into ribbons extending along
       the [110] direction. The crystal packing is further stablized by weak
       C - H (. . .) F and C - H (. . .) Cl interactions.,
    DOI = 10.1107/S1600536806009895,
    ISSN = 1600-5368,
    Unique-ID = ISI:000236470100255,
    
  • [DOI] K. Dolezal, I. Popa, V. Krystof, L. Spichal, M. Fojtikova, J. Holub, R. Lenobel, T. Schmulling, and M. Strnad, "Preparation and biological activity of 6-benzylaminopurine derivatives
    in plants and human cancer cells," BIOORGANIC & MEDICINAL CHEMISTRY, vol. 14, iss. 3, pp. 875-884, 2006.
    [Bibtex]
    @article ISI:000234091700026,
    Author = Dolezal, K and Popa, I and Krystof, V and Spichal, L and Fojtikova, M
       and Holub, J and Lenobel, R and Schmulling, T and Strnad, M,
    Title = Preparation and biological activity of 6-benzylaminopurine derivatives
       in plants and human cancer cells,
    Journal = BIOORGANIC \& MEDICINAL CHEMISTRY,
    Year = 2006,
    Volume = 14,
    Number = 3,
    Pages = 875-884,
    Month = FEB 1,
    Abstract = To study the structure-activity relationships of aromatic cytokinins,
       the cytokinin activity at both the receptor and cellular levels, as well
       as CDK inhibitory and anticancer properties of 38 6-benzylaminopurine
       (BAP) derivatives were compared in various in vitro assays. The
       compounds were prepared by the condensation of 6-chloropurine with
       corresponding substituted benzylamines. The majority of synthesised
       derivatives exhibited high activity in all three of the cytokinin
       bioassays employed (tobacco callus, wheat senescence and Amaranthus
       bioassay). The highest activities were obtained in the senescence
       bioassay. For some compounds tested, significant differences of activity
       were found in the bioassays used, indicating that diverse recognition
       systems may operate and suggesting that it may be possible to modulate
       particular cytokinin-dependent processes with specific compounds.
       Position-specific steric and hydrophobic effects of different phenyl
       ring substituents on the variation of biological activity were
       confirmed. In contrast to their high activity in bioassays, the BAP
       derivatives were recognised with much lower sensitivity than
       trans-zeatin in both Arabidopsis thaliana AHK3 and AHK4 receptor assays.
       The compounds were also investigated for their effects on
       cyclin-dependent kinase 2 (CDK2) and for antiproliferative properties on
       cancer and normal cell lines. Several of the tested compounds showed
       stronger inhibitory activity and cytotoxicity than BAP. There was also a
       significant positive correlation of the inhibitory effects on human and
       plant CDKs with cell proliferation of cancer and cytokinin-dependent
       tobacco cells, respectively. This suggests that at least a part of the
       antiproliferative effect of the new cytokinins was due to the inhibition
       of CDK activity. (c) 2005 Elsevier Ltd. All rights reserved.,
    DOI = 10.1016/j.bmc.2005.09.004,
    ISSN = 0968-0896,
    Unique-ID = ISI:000234091700026,
    
  • [DOI] L. Szucova, Z. Travnicek, M. Zatloukal, and I. Popa, "Novel platinum(II) and palladium(II) complexes with cyclin-dependent
    kinase inhibitors: Synthesis, characterization and antitumour activity," BIOORGANIC & MEDICINAL CHEMISTRY, vol. 14, iss. 2, pp. 479-491, 2006.
    [Bibtex]
    @article ISI:000234091500019,
    Author = Szucova, L and Travnicek, Z and Zatloukal, M and Popa, I,
    Title = Novel platinum(II) and palladium(II) complexes with cyclin-dependent
       kinase inhibitors: Synthesis, characterization and antitumour activity,
    Journal = BIOORGANIC \& MEDICINAL CHEMISTRY,
    Year = 2006,
    Volume = 14,
    Number = 2,
    Pages = 479-491,
    Month = JAN 15,
    Abstract = The Pt(H) and Pd(II) complexes of the types cis-[Pt(L-1)(2)Cl-2]center
       dot H2O (1), cis-[Pt(L-2)(2)Cl-2]center dot 3H(2)O (2), trans-
       [Pd(L-1)(2)Cl-2]center dot H2O (3), trans-[Pd(L2)(2)Cl-2]center dot
       H2O (4), trans-[Pd(L-3)(2)Cl-2]2DMF (5) and
       trans-[Pd(L-4)(2)Cl-2]2DMF (6) (L-1-L-4 = cyclin-dependent kinase
       inhibitors derived from 6-benzylamino-9-isopropylpurine) have been
       prepared and characterized. The complexes have been studied by elemental
       analyses, conductivity measurements, ES+ MS, FT-IR, H, C-13 and Pt-195
       NMR spectra, differential scanning calorimetry and thermogravimetric
       analysis. The molecular structures of L-1,
       trans-[Pd(L-3)(2)Cl-2](.)2DMF (5) and trans- [Pd(L-4)(2)Cl-2](.)2DMF
       (6) have been determined by single crystal X-ray analysis. The complexes
       have been tested in vitro due to their presumable anticancer activity
       against the following human cancer cell lines: K-562, MCF7, G-361 and
       HOS. Satisfying results were obtained for the complex 1 with IC50 values
       of 6 mu M acquired against G-361 as well as against HOS cell lines. The
       lowest values of IC50 were achieved for the complexes 3 and 4 against
       MCF 7 cell line with IC50 3 mu M (for 3) and also 3 mu M (for 4). (c)
       2005 Elsevier Ltd. All rights reserved.,
    DOI = 10.1016/j.bmc.2005.08.033,
    ISSN = 0968-0896,
    Unique-ID = ISI:000234091500019,
    

2005

  • [DOI] E. Hauserova, J. Swaczynova, K. Dolezal, R. Lenobel, I. Popa, M. Hajduch, D. Vydra, K. Fuksova, and M. Strnad, "Batch immunoextraction method for efficient purification of aromatic
    cytokinins," JOURNAL OF CHROMATOGRAPHY A, vol. 1100, iss. 1, pp. 116-125, 2005.
    [Bibtex]
    @article ISI:000234158600015,
    Author = Hauserova, E and Swaczynova, J and Dolezal, K and Lenobel, R and Popa, I
       and Hajduch, M and Vydra, D and Fuksova, K and Strnad, M,
    Title = Batch immunoextraction method for efficient purification of aromatic
       cytokinins,
    Journal = JOURNAL OF CHROMATOGRAPHY A,
    Year = 2005,
    Volume = 1100,
    Number = 1,
    Pages = 116-125,
    Month = DEC 23,
    Abstract = A range of benzylaminopurines naturally occur in plants and exhibit high
       biological activity. Others have been synthesized, such as
       6-(2-hydroxy-3-methoxybenzylamino)purine riboside (2OH3MeOBAPR), which
       has shown interesting anti-cancer activity under in vitro conditions. In
       order to study the biological activity of this interesting compound in
       more detail, a rapid and highly efficient method for its purification
       from complex samples (e.g. blood and plant extracts) is needed.
       Therefore, we prepared monoclonal antibodies against 2OH3MeOBAPR. The
       antibody had undetectable cross-reactivity with all natural isoprenoid
       cytokinins, but relatively high cross-reactivity with aromatic
       cytokinins as well as some synthetic di- and tri-substituted
       6-benzylaminopurines and the corresponding ribosides. The antibody also
       showed strong responses and specificity in enzyme-linked immunoassays
       (ELISAs). In addition, it was used to prepare, for the first time, an
       immunoaffinity sorbent with high specificity and capacity for aromatic
       cytokinins. A batch immunoextraction method was then developed and
       optimized for the purification of 2OH3MeOBAPR from murine blood samples.
       The high efficacy and simplicity of this method (in off-line combination
       with HPLC-MS) for the isolation of target analytes from biological
       material is demonstrated in this study. (c) 2005 Elsevier B.V. All
       rights reserved.,
    DOI = 10.1016/j.chroma.2005.09.020,
    ISSN = 0021-9673,
    Unique-ID = ISI:000234158600015,
    
  • [DOI] Z. Travnicek, M. Sipl, and I. Popa, "Palladium(II) complexes containing cytokinins derived from
    6-benzylaminopurine," JOURNAL OF COORDINATION CHEMISTRY, vol. 58, iss. 16, pp. 1513-1521, 2005.
    [Bibtex]
    @article ISI:000233020800015,
    Author = Travnicek, Z and Sipl, M and Popa, I,
    Title = Palladium(II) complexes containing cytokinins derived from
       6-benzylaminopurine,
    Journal = JOURNAL OF COORDINATION CHEMISTRY,
    Year = 2005,
    Volume = 58,
    Number = 16,
    Pages = 1513-1521,
    Month = NOV 10,
    Abstract = A series of palladium(II) complexes of general formula [Pd(LH+)Cl-3]
       (1-12) containing 6-benzylaminopurine derivatives has been prepared
       [L=6-(2-methoxybenzylamino) purine (1), 6-(3-methoxybenzylamino)purine
       (2), 6-(4-methoxybenzylamino) purine (3), 6-(2-hydroxybenzylamino)
       purine (4), 6-(3-hydroxybenzylamino)purine (5),
       6-(4-hydroxybenzylamino)purine (6), 6-(2-fluorobenzylamino)purine (7),
       6-(3-fluorobenzylamino)purine (8), 6-(4-fluorobenzylamino)purine (9),
       6-(2-chlorobenzylamino)purine (10), 6-(3-chlorobenzylamino)purine (11)
       and 6-(4-chlorobenzylamino)purine (12)]. The compounds have been
       characterized by elemental analysis, IR, ES+ MS and H-1- and C-13-NMR
       spectroscopy, and two of them, 6 and 12, also by TG/DSC analyses. The
       complexes have been screened in vitro against the four human tumour cell
       lines G-361, HOS, K-562 and MCF7.,
    DOI = 10.1080/00958970500258898,
    ISSN = 0095-8972,
    Unique-ID = ISI:000233020800015,
    
  • [DOI] Z. Travnicek, A. Klanicova, I. Popa, and J. Rolcik, "Synthetic, spectral, magnetic and in vitro cytotoxic activity studies of
    cobalt(II) complexes with cytokinin derivatives: X-ray structure of
    6-(3-methoxybenzylamino)purinium chloride monohydrate," JOURNAL OF INORGANIC BIOCHEMISTRY, vol. 99, iss. 3, pp. 776-786, 2005.
    [Bibtex]
    @article ISI:000227374900013,
    Author = Travnicek, Z and Klanicova, A and Popa, I and Rolcik, J,
    Title = Synthetic, spectral, magnetic and in vitro cytotoxic activity studies of
       cobalt(II) complexes with cytokinin derivatives: X-ray structure of
       6-(3-methoxybenzylamino)purinium chloride monohydrate,
    Journal = JOURNAL OF INORGANIC BIOCHEMISTRY,
    Year = 2005,
    Volume = 99,
    Number = 3,
    Pages = 776-786,
    Month = MAR,
    Abstract = Cobalt(II) complexes with 6-(2-hydroxybenzylamino)purine (HL1),
       6-(2-methoxybenzylamino)purine (HL2), 6-(3-methoxybenzylamino)purine
       (HL3) and 6-(4-methoxybenzylamino)purine (HL4) of the composition
       [Co(L-1)Cl(H2O)(2)] (.) H2O (1), [Co(L-2)Cl(H2O)(2)] (2),
       [Co(L-3)(2)(H2O)(2)] (.) 2H(2)O (3), [Co(L-4)(2)(H2O)(2)] (.) 2H(2)O
       (4) have been synthesized. The compounds have been characterized by
       elemental analysis, FT-IR, ES + MS (electrospray mass spectra in the
       positive ion mode) and electronic spectroscopies, magnetic and
       conductivity data as tetrahedral high-spin cobalt(II) complexes. The
       thermal stability of the complexes has also been studied. The
       cytotoxicity of the complexes (1-4) was determined by a Calcein
       acetoxymethyl (AM) assay. Human malignant melanoma (G361), human chronic
       myelogenous erythroleukemia (K562), human osteogenic sarcoma (HOS) and
       human breast adenocarcinoma (MCF7) cell lines were used for the testing.
       The molecular structure of 6-(3-methoxybenzylamino)purinium chloride
       monohydrate, H2L3+ (.) Cl (.) H2O i.e. a protonated form of the free HL3
       ligand, has been determined by a single crystal X-ray analysis. The
       geometry optimisation and infrared frequencies calculations of HL1, HL2,
       and H2L3+ and H2L4+ were performed using density-functional theory (DFT)
       calculations at the B3LYP/6-31G* level of the theory. The geometry of
       complex (1) was optimised at the same level of the theory. (C) 2004
       Elsevier Inc. All rights reserved.,
    DOI = 10.1016/j.jinorgbio.2004.12.002,
    ISSN = 0162-0134,
    Unique-ID = ISI:000227374900013,
    

2004

  • [DOI] Z. Travnicek, I. Popa, and K. Dolezal, "6-(4-methoxybenzylamino)purin-3-ium chloride," ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS, vol. 60, iss. Part 9, pp. O662-O664, 2004.
    [Bibtex]
    @article ISI:000224226700035,
    Author = Travnicek, Z and Popa, I and Dolezal, K,
    Title = 6-(4-methoxybenzylamino)purin-3-ium chloride,
    Journal = ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS,
    Year = 2004,
    Volume = 60,
    Number = Part 9,
    Pages = O662-O664,
    Month = SEP,
    Abstract = The title compound, C13H14N5O+.Cl-, belongs to the group of aromatic
       cytokinins. These compounds affect a variety of important physiological
       processes in plants and animals as well as in bacteria, including cell
       division, differentiation and senescence. The structure consists of a
       6-(4-methoxybenzylamino)purinium cation and a Cl. anion. The cation
       moiety exists as the N3-protonated N7 tautomer. The cation contains
       nearly planar benzene and purine ring systems, with a dihedral angle of
       77.46 (5)degrees. The crystal structure is stabilized by
       N-amino-H...N-purine hydrogen bonds connecting two adjacent molecules,
       thus forming centrosymmetric dimers.,
    DOI = 10.1107/S0108270104016749,
    ISSN = 0108-2701,
    Unique-ID = ISI:000224226700035,
    

2002

  • [DOI] Z. Travnicek, M. Malon, I. Popa, K. Dolezal, and M. Strnad, "Preparation and cytotoxic activity of nickel(II) complexes with
    6-benzylaminopurine derivatives," TRANSITION METAL CHEMISTRY, vol. 27, iss. 8, pp. 918-923, 2002.
    [Bibtex]
    @article ISI:000179572700019,
    Author = Travnicek, Z and Malon, M and Popa, I and Dolezal, K and Strnad, M,
    Title = Preparation and cytotoxic activity of nickel(II) complexes with
       6-benzylaminopurine derivatives,
    Journal = TRANSITION METAL CHEMISTRY,
    Year = 2002,
    Volume = 27,
    Number = 8,
    Pages = 918-923,
    Month = NOV,
    Abstract = Nickel(II) complexes with 6-benzylaminopurine (BAP) derivatives, namely
       6-(3-chlorobenzylamino) purine (HL1), 6-4-chlorobenzylamino) purine
       (HL2) and 6-(4-fluorobenzylamino) purine (HL3), have been prepared and
       characterized by elemental analyses, i.r., u.v.-v.i.s., ES+ and FAB+
       mass spectroscopy, magnetic susceptibility and conductivity
       measurements, and by thermal analysis. The complexes are:
       [Ni(L-1(H2O)(2)Cl].H2O, [Ni(L-1)(H2O)(NO3)].H2O,
       [Ni(L-2)(H2O)(2)Cl], [Ni(L-2)(H2O)(2)(NO3)].H2O,
       [Ni(HL2)(H2O)Cl-2].EtOH and [Ni(L-3)(H2O)(2)Cl]. They have been
       tested in vitro for their possible cytotoxic activity against G-361 (
       human malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human
       chronic myelogenous leukemia) and MCF-7 ( human breast adenocarcinoma)
       cell lines.,
    DOI = 10.1023/A:1021385217317,
    ISSN = 0340-4285,
    Unique-ID = ISI:000179572700019,