Displaying publications 1 - 20 of 136 in total

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  1. Jamaludin NS, Goh ZJ, Cheah YK, Ang KP, Sim JH, Khoo CH, et al.
    Eur J Med Chem, 2013 Sep;67:127-41.
    PMID: 23856069 DOI: 10.1016/j.ejmech.2013.06.038
    The synthesis and characterisation of R3PAu[S2CN((i)Pr)CH2CH2OH], for R = Ph (1), Cy (2) and Et (3)4, is reported. Compounds 1-3 are cytotoxic against the doxorubicin-resistant breast cancer cell line, MCF-7R, with 1 exhibiting greater potency and cytotoxicity than either of doxorubicin and cisplatin. Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis by 1, and necrosis by 2 and 3, are demonstrated, by both extrinsic and intrinsic pathways. Compound 1 activates the p53 gene, 2 activates only the p73 gene, whereas 3 activates both the p53 and p73 genes. Compounds 1 and 3 activate NF-κB, and each inhibits topoisomerase I.
  2. Low ML, Maigre L, Tahir MI, Tiekink ER, Dorlet P, Guillot R, et al.
    Eur J Med Chem, 2016 Sep 14;120:1-12.
    PMID: 27183379 DOI: 10.1016/j.ejmech.2016.04.027
    Copper (II) complexes synthesized from the products of condensation of S-methyl- and S-benzyldithiocarbazate with 2,5-hexanedione (SMHDH2 and SBHDH2 respectively) have been characterized using various physicochemical (elemental analysis, molar conductivity, magnetic susceptibility) and spectroscopic (infrared, electronic) methods. The structures of SMHDH2, its copper (II) complex, CuSMHD, and the related CuSBHD complex as well as a pyrrole byproduct, SBPY, have been determined by single crystal X-ray diffraction. In order to provide more insight into the behaviour of the complexes in solution, electron paramagnetic resonance (EPR) and electrochemical experiments were performed. Antibacterial activity and cytotoxicity were evaluated. The compounds, dissolved in 0.5% and 5% DMSO, showed a wide range of antibacterial activity against 10 strains of Gram-positive and Gram-negative bacteria. Investigations of the effects of efflux pumps and membrane penetration on antibacterial activity are reported herein. Antiproliferation activity was observed to be enhanced by complexation with copper. Preliminary screening showed Cu complexes are strongly active against human breast adenocarcinoma cancer cell lines MDA-MB-231 and MCF-7.
  3. Seng HL, Ong HK, Rahman RN, Yamin BM, Tiekink ER, Tan KW, et al.
    J Inorg Biochem, 2008 Nov;102(11):1997-2011.
    PMID: 18778856 DOI: 10.1016/j.jinorgbio.2008.07.015
    The binding selectivity of the M(phen)(edda) (M=Cu, Co, Ni, Zn; phen=1,10-phenanthroline, edda=ethylenediaminediacetic acid) complexes towards ds(CG)(6), ds(AT)(6) and ds(CGCGAATTCGCG) B-form oligonucleotide duplexes were studied by CD spectroscopy and molecular modeling. The binding mode is intercalation and there is selectivity towards AT-sequence and stacking preference for A/A parallel or diagonal adjacent base steps in their intercalation. The nucleolytic properties of these complexes were investigated and the factors affecting the extent of cleavage were determined to be: concentration of complex, the nature of metal(II) ion, type of buffer, pH of buffer, incubation time, incubation temperature, and the presence of hydrogen peroxide or ascorbic acid as exogenous reagents. The fluorescence property of these complexes and its origin were also investigated. The crystal structure of the Zn(phen)(edda) complex is reported in which the zinc atom displays a distorted trans-N(4)O(2) octahedral geometry; the crystal packing features double layers of complex molecules held together by extensive hydrogen bonding that inter-digitate with adjacent double layers via pi...pi interactions between 1,10-phenanthroline residues. The structure is compared with that of the recently described copper(II) analogue and, with the latter, included in molecular modeling.
  4. Chen BJ, Jamaludin NS, Khoo CH, See TH, Sim JH, Cheah YK, et al.
    J Inorg Biochem, 2016 10;163:68-80.
    PMID: 27529597 DOI: 10.1016/j.jinorgbio.2016.08.002
    Four compounds, R3PAu[S2CN(CH2CH2OH)2], R=Ph (1) and cyclohexyl (2), and Et3PAuS2CNRꞌ2, Rꞌ=Rꞌ=Et (3) and Rꞌ2=(CH2)4(4), have been evaluated for antibacterial activity against a panel of 24 Gram positive (8) and Gram negative (16) bacteria. Based on minimum inhibitory concentration (MIC) scores, compounds 1 and 2 were shown to be specifically potent against Gram positive bacteria whereas compounds 3 and, to a lesser extent, 4 exhibited broad range activity. All four compounds were active against methicillin resistant Staphylococcus aureus (MRSA). Time kill assays revealed the compounds to exhibit both time- and concentration-dependent pharmacokinetics against susceptible bacteria. Each compound was bactericidal against one or more bacteria with 3 being especially potent after 8h exposure; compounds 1 and 3 were bactericidal against MRSA. Compound 3 was the most effective bactericide across the series especially toward B. subtilis, S. saprophyticus, A. hydrophila, P. vulgaris, and V. parahaemolyticus. This study demonstrates the potential of this class of compounds as antibacterial agents, either broad range or against specific bacteria.
  5. Ishak DH, Ooi KK, Ang KP, Akim AM, Cheah YK, Nordin N, et al.
    J Inorg Biochem, 2014 Jan;130:38-51.
    PMID: 24176918 DOI: 10.1016/j.jinorgbio.2013.09.018
    The compound with R=CH2CH3 in Bi(S2CNR2)3 (1) is highly cytotoxic against a range of human carcinoma, whereas that with R=CH2CH2OH (2) is considerably less so. Both 1 and 2 induce apoptosis in HepG2 cells with some evidence for necrosis induced by 2. Based on DNA fragmentation, caspase activities and human apoptosis PCR-array analysis, both the extrinsic and intrinsic pathways of apoptosis have been shown to occur. While both compounds activate mitochondrial and FAS apoptotic pathways, compound 1 was also found to induce another death receptor-dependent pathway by induction of CD40, CD40L and TNF-R1 (p55). Further, 1 highly expressed DAPK1, a tumour suppressor, with concomitant down-regulation of XIAP and NF-κB. Cell cycle arrest at the S and G2/M phases correlates with the inhibition of the growth of HepG2 cells. The cell invasion rate of 2 is 10-fold higher than that of 1, a finding correlated with the down-regulation of survivin and XIAP expression by 1. Compounds 1 and 2 interact with DNA through different binding motifs with 1 interacting with AT- or TA-specific sites followed by inhibition of restriction enzyme digestion; 2 did not interfere with any of the studied restriction enzymes.
  6. Yeo CI, Ooi KK, Akim AM, Ang KP, Fairuz ZA, Halim SN, et al.
    J Inorg Biochem, 2013 Oct;127:24-38.
    PMID: 23850666 DOI: 10.1016/j.jinorgbio.2013.05.011
    The Ph3PAu[SC(OR)=NPh], R=Me (1), Et (2) and iPr (3), compounds are significantly cytotoxic to the HT-29 cancer cell line with 1 being the most active. Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis is demonstrated and both the extrinsic and intrinsic pathways of apoptosis have been shown to occur. Compound 1 activates the p73 gene, whereas each of 2 and 3 activates the p53 gene. An additional apoptotic mechanism is exhibited by 2, that is, via the JNK/MAP pathway.
  7. Yeo CI, Halim SN, Ng SW, Tan SL, Zukerman-Schpector J, Ferreira MA, et al.
    Chem Commun (Camb), 2014 Jun 7;50(45):5984-6.
    PMID: 24763907 DOI: 10.1039/c4cc02040e
    Evidence for C-H···π(CuCl···HNCS) interactions, i.e. C-H···π(quasi-chelate ring) where a six-membered quasi-chelate ring is closed by an N-H···Cl hydrogen bond, is presented based on crystal structure analyses of (Ph3P)2Cu[ROC(=S)N(H)Ph]Cl. Similar intramolecular interactions are identified in related literature structures. Calculations suggest that the energy of attraction provided by such interactions approximates 3.5 kcal mol(-1).
  8. Zukerman-Schpector J, Madureira LS, Wulf GD, Stefani HA, Vasconcelos SN, Ng SW, et al.
    Molecules, 2014;19(2):1990-2003.
    PMID: 24531216 DOI: 10.3390/molecules19021990
    Two independent molecules that differ in terms of rotation about the central S-N bond comprise the asymmetric unit of the title compound 1. The molecules have a V-shape with the dihedral angles between the fused ring system and benzene ring being 79.08(6)° and 72.83(5)°, respectively. The packing is mostly driven by p···p interactions occurring between the tolyl ring of one molecule and the C6 ring of the indole fused ring system of the other. DFT and IRC calculations for these and related 1-(arylsulfonyl)indole molecules showed that the rotational barrier about the S-N bond between conformers is within the 2.5-5.5 kcal/mol range. Crystal data for C16H13NO3S (1): Mr = 299.33, space group Pna21, a = 19.6152(4) Å, b = 11.2736(4) Å, c = 12.6334(3) Å, V = 2793.67(13) Å3, Z = 8, Z' = 2, R = 0.034.
  9. Mansoor MA, Ismail A, Yahya R, Arifin Z, Tiekink ER, Weng NS, et al.
    Inorg Chem, 2013 May 20;52(10):5624-6.
    PMID: 23627942 DOI: 10.1021/ic302772b
    Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi(μ2-O2CCF3)4(THF)3(μ3-O)]2 (1), which was isolated in quantitative yield from the reaction of tetraacetatolead(IV), tetrabutoxytitanium(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex 1 has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, (1)H and (19)F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from 1 by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV-visible spectrophotometry.
  10. Md Yusof EN, S A Ravoof TB, Tiekink ER, Veerakumarasivam A, Crouse KA, Mohamed Tahir MI, et al.
    Int J Mol Sci, 2015 May 15;16(5):11034-54.
    PMID: 25988384 DOI: 10.3390/ijms160511034
    Two bidentate NS ligands were synthesized by the condensation reaction of S-2-methylbenzyldithiocarbazate (S2MBDTC) with 2-methoxybenzaldehyde (2MB) and 3-methoxybenzaldehyde (3MB). The ligands were reacted separately with acetates of Cu(II), Ni(II) and Zn(II) yielding 1:2 (metal:ligand) complexes. The metal complexes formed were expected to have a general formula of [M(NS)2] where M = Cu2+, Ni2+, and Zn2+. These compounds were characterized by elemental analysis, molar conductivity, magnetic susceptibility and various spectroscopic techniques. The magnetic susceptibility measurements and spectral results supported the predicted coordination geometry in which the Schiff bases behaved as bidentate NS donor ligands coordinating via the azomethine nitrogen and thiolate sulfur. The molecular structures of the isomeric S2M2MBH (1) and S2M3MBH (2) were established by X-ray crystallography to have very similar l-shaped structures. The Schiff bases and their metal complexes were evaluated for their biological activities against estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) breast cancer cell lines. Only the Cu(II) complexes showed marked cytotoxicity against the cancer cell lines. Both Schiff bases and other metal complexes were found to be inactive. In concordance with the cytotoxicity studies, the DNA binding studies indicated that Cu(II) complexes have a strong DNA binding affinity.
  11. Tan YS, Ooi KK, Ang KP, Akim AM, Cheah YK, Halim SN, et al.
    J Inorg Biochem, 2015 Sep;150:48-62.
    PMID: 26086852 DOI: 10.1016/j.jinorgbio.2015.06.009
    In the solid state each of three binuclear zinc dithiocarbamates bearing hydroxyethyl groups, {Zn[S2CN(R)CH2CH2OH]2}2 for R = iPr (1), CH2CH2OH (2), and Me (3), and an all alkyl species, [Zn(S2CNEt2)2]2 (4), features a centrosymmetric {ZnSCS}2 core with a step topology; both 1 and 3 were isolated as monohydrates. All compounds were broadly cytotoxic, specifically against human cancer cell lines compared with normal cells, with greater potency than cisplatin. Notably, some selectivity were indicated with 2 being the most potent against human ovarian carcinoma cells (cisA2780), and 4 being more cytotoxic toward multidrug resistant human breast carcinoma cells (MCF-7R), human colon adenocarcinoma cells (HT-29), and human lung adenocarcinoma epithelial cells (A549). Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis in HT-29 cells is demonstrated via both extrinsic and intrinsic pathways. Compounds 2-4 activate the p53 gene while 1 activates both p53 and p73. Cell cycle arrest at the S and G2/M phases correlates with inhibition of HT-29 cell growth. Cell invasion is also inhibited by 1-4 which is correlated with down-regulation of NF-κB.
  12. Ooi KK, Yeo CI, Ang KP, Akim AM, Cheah YK, Halim SN, et al.
    J Biol Inorg Chem, 2015 Jul;20(5):855-73.
    PMID: 26003312 DOI: 10.1007/s00775-015-1271-5
    The phosphanegold(I) carbonimidothioates, Ph3PAu{SC(OR)=NC6H4Me-4} for R = Me (1), Et (2) and iPr (3), feature linear P-Au-S coordination geometries and exhibit potent in vitro cytotoxicity against HT-29 colon cancer cells in both monolayer and multi-cellular spheroid models (e.g., IC50 = 11.9 ± 0.4 and 20.3 ± 0.3 μM for 2, respectively). Both intrinsic and extrinsic pathways of apoptosis are demonstrated by human apoptosis PCR array analysis, caspase activities, DNA fragmentation and cell apoptotic assays. Compounds 1-3 induce an extrinsic pathway that leads to down-regulation of NFκB. Compound 2 also exhibits an extrinsic apoptotic pathway involving the activation of both p53 and p73, whereas 3 activates p53 only. Lys48- and Lys63-linked polyubiquitination are also promoted by 1-3. Each of cytotoxic Ph3PAu{SC(OR)=NC6H4Me-4}, for R = Me (1), Et (2) and iPr (3), induce an intrinsic apoptotic pathway as well as an extrinsic pathway leading to down-regulation of NFκB. Lys48- and Lys63-linked polyubiquitination are promoted by 1-3 and these are able to inhibit cell invasion and to suppress the activity of TrxR.
  13. Cardoso LN, Nogueira TC, Wardell JL, Wardell SM, de Souza MV, Jotani MM, et al.
    Acta Crystallogr E Crystallogr Commun, 2016 Jul 01;72(Pt 7):1025-31.
    PMID: 27555956 DOI: 10.1107/S2056989016009968
    In the title carbohydrazide, C10H7N3O4S, the dihedral angle between the terminal five-membered rings is 27.4 (2)°, with these lying to the same side of the plane through the central CN2C(=O) atoms (r.m.s. deviation = 0.0403 Å), leading to a curved mol-ecule. The conformation about the C=N imine bond [1.281 (5) Å] is E, and the carbonyl O and amide H atoms are anti. In the crystal, N-H⋯O hydrogen bonds lead to supra-molecular chains, generated by a 41 screw-axis along the c direction. A three-dimensional architecture is consolidated by thienyl-C-H⋯O(nitro) and furanyl-C-H⋯O(nitro) inter-actions, as well as π-π inter-actions between the thienyl and furanyl rings [inter-centroid distance = 3.515 (2) Å]. These, and other, weak inter-molecular inter-actions, e.g. nitro-N-O⋯π(thien-yl), have been investigated by Hirshfeld surface analysis, which confirms the dominance of the conventional N-H⋯O hydrogen bonding to the overall mol-ecular packing.
  14. Low ML, Ravoof TB, Tahir MI, Crouse KA, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Nov 1;70(Pt 11):o1207-8.
    PMID: 25484832 DOI: 10.1107/S1600536814023228
    In the title salt of an S-substituted di-thio-carbazate, C16H16N3S2 (+)·Cl(-), the dihedral angles between the almost planar (r.m.s deviation = 0.005 Å) central CN2S2 residue and the terminal pyridinium and phenyl rings are 80.09 (11) and 3.82 (11)°, respectively, indicating the cation has an L-shape; the amine H and thione S atoms are syn. The conformation about each of the imine [1.376 (3) Å] and ethene [1.333 (4) Å] bonds is E. The shortened C-C bond [1.444 (4) Å] linking the double bonds is consistent with conjugation in this part of the mol-ecule. In the crystal, supra-molecular layers with a jagged topology are formed by charged-assisted amine-H⋯Cl(-) and pyridinium-N(+)-H⋯Cl(-) hydrogen bonds. The layers stack along the a axis with no specific directional inter-actions between them.
  15. Zukerman-Schpector J, Caracelli I, Stefani HA, Khan AN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Oct 1;70(Pt 10):o1122-3.
    PMID: 25484707 DOI: 10.1107/S1600536814020832
    In the title compound, C15H20BrNO2, there are two independent mol-ecules (A and B) comprising the asymmetric unit and these adopt very similar conformations. In A, the dihedral angle between the CO2 and MeC=CMe2 groups is 80.7 (3)°, and these make dihedral angles of 3.5 (3) and 84.09 (16)°, respectively, with the bromo-benzene ring. The equivalent dihedral angles for mol-ecule B are 78.4 (3), 2.1 (3) and 78.37 (12)°, respectively. The most prominent inter-actions in the crystal packing are amine-N-H⋯O(carbon-yl) hydrogen bonds between the two independent mol-ecules, resulting in non-centrosymmetric ten-membered {⋯OC2NH}2 synthons. Statistical disorder is noted for each of the terminal methyl groups of the ethyl residues.
  16. Zukerman-Schpector J, Maganhi SH, Moran PJ, de Paula BR, Nucci PR, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Sep 1;70(Pt 9):o1020-1.
    PMID: 25309202 DOI: 10.1107/S1600536814018327
    In the title compound, C17H15NO4, the conformation about the C=C double bond [1.348 (2) Å] is E with the ketone group almost co-planar [C-C-C-C torsion angle = 7.2 (2)°] but the phenyl group twisted away [C-C-C-C = 160.93 (17)°]. The terminal aromatic rings are almost perpendicular to each other [dihedral angle = 81.61 (9)°] giving the mol-ecule an overall U-shape. The crystal packing feature benzene-C-H⋯O(ketone) contacts that lead to supra-molecular helical chains along the b axis. These are connected by π-π inter-actions between benzene and phenyl rings [inter-centroid distance = 3.6648 (14) Å], resulting in the formation of a supra-molecular layer in the bc plane.
  17. Jan CY, Shamsudin NB, Tan AL, Young DJ, Ng SW, Tiekink ER
    PMID: 24765021 DOI: 10.1107/S1600536814003468
    In the title compound, C8H3N3O2 (systematic name: 4-nitro-benzene-1,2-dicarbo-nitrile), the nitro group is twisted out of the plane of the benzene ring to which it is attached [O-N-Cring-Cring torsion angle = 9.80 (13)°]. In the crystal packing, supra-molecular layers with a zigzag topology in the ac plane are sustained by C-H⋯N inter-actions.
  18. Jan CY, Shamsudin NB, Tan AL, Young DJ, Ng SW, Tiekink ER
    PMID: 24765000 DOI: 10.1107/S1600536814002955
    In the title compound, C8H7N3O4 (systematic name: 4-nitro-benzene-1,2-dicarboxamide), each of the substituents is twisted out of the plane of the benzene ring to which it is attached [dihedral angles of 11.36 (2)° for the nitro group, and 60.89 (6) and 34.39 (6)° for the amide groups]. The amide groups are orientated to either side of the least-squares plane through the benzene ring with the amine groups being directed furthest apart. In the crystal, a three-dimensional architecture is established by a network of N-H⋯O hydrogen bonds.
  19. Bernardes BO, Ferreira AB, Wardell JL, Wardell SM, Netto-Ferreira JC, Tiekink ER
    PMID: 24427106 DOI: 10.1107/S1600536813023660
    In the title di-hydro-dioxin, C31H28O5, the dioxane ring has a chair conformation, whereas each of the pyran and dioxine rings has an envelope conformation with methyl-ene and quaternary C atoms, respectively, being the flap atoms. The phenyl rings are cis and form a dihedral angle of 82.11 (10)°. The molecular structure is stabilized by C-H⋯O contacts. In the crystal packing, supra-molecular layers parallel to (101) are sustained by C-H⋯π inter-actions.
  20. Zukerman-Schpector J, Hino CL, Moran PJ, de Paula BR, Ng SW, Tiekink ER
    PMID: 24427096 DOI: 10.1107/S1600536813023374
    In the title compound, C16H20O6, the conformation about the C=C double bond [1.344 (2) Å] is Z. With respect to this bond, the ketone is almost coplanar [C-C-C-O torsion angle = -179.60 (10)°] and the ester is almost perpendicular [C-C-C-O = 78.42 (13)°]. The meth-oxy substituents of the central benzene ring are either almost coplanar [C-C-O-C = 3.54 (15) and 177.70 (9)°] or perpendicular [C-C-O-C = 80.08 12)° for the central substituent]. In the crystal, the three-dimensional architecture features C-H⋯O and π-π [inter-centroid distance = 3.6283 (6) Å] inter-actions.
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