Displaying publications 1 - 20 of 25 in total

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  1. Jotani MM, Syed S, Halim SN, Tiekink ER
    PMID: 26958398 DOI: 10.1107/S2056989016000980
    The asymmetric unit of the title salt, C14H16N4O2 (2+)·2C9H5O6 (-), comprises half a dication, being located about a centre of inversion, and one anion, in a general position. The central C4N2O2 group of atoms in the dication are almost planar (r.m.s. deviation = 0.009 Å), and the carbonyl groups lie in an anti disposition to enable the formation of intra-molecular amide-N-H⋯O(carbon-yl) hydrogen bonds. To a first approximation, the pyridinium and amide N atoms lie to the same side of the mol-ecule [Npy-C-C-Namide torsion angle = 34.8 (2)°], and the anti pyridinium rings are approximately perpendicular to the central part of the mol-ecule [dihedral angle = 68.21 (8)°]. In the anion, one carboxyl-ate group is almost coplanar with the ring to which it is connected [Cben-Cben-Cq-O torsion angle = 2.0 (3)°], whereas the other carboxyl-ate and carb-oxy-lic acid groups are twisted out of the plane [torsion angles = 16.4 (3) and 15.3 (3)°, respectively]. In the crystal, anions assemble into layers parallel to (10-4) via hy-droxy-O-H⋯O(carbon-yl) and charge-assisted hy-droxy-O-H⋯O(carboxyl-ate) hydrogen bonds. The dications are linked into supra-molecular tapes by amide-N-H⋯O(amide) hydrogen bonds, and thread through the voids in the anionic layers, being connected by charge-assisted pyridinium-N-O(carboxyl-ate) hydrogen bonds, so that a three-dimensional architecture ensues. An analysis of the Hirshfeld surface points to the importance of O-H⋯O hydrogen bonding in the crystal structure.
  2. Safbri SA, Halim SN, Tiekink ER
    PMID: 26958388 DOI: 10.1107/S2056989016000700
    The common feature of the title compounds, [Zn(C5H10NO2S2)2(C10H8N2)]·2H2O, (I), and [Zn(C6H12NOS2)2(C10H8N2)], (II), is the location of the Zn(II) atoms on a twofold rotation axis. Further, each Zn(II) atom is chelated by two symmetry-equivalent and symmetrically coordinating di-thio-carbamate ligands and a 2,2'-bi-pyridine ligand. The resulting N2S4 coordination geometry is based on a highly distorted octa-hedron in each case. In the mol-ecular packing of (I), supra-molecular ladders mediated by O-H⋯O hydrogen bonding are found whereby the uprights are defined by {⋯HO(water)⋯HO(hy-droxy)⋯} n chains parallel to the a axis and with the rungs defined by 'Zn[S2CN(CH2CH2)2]2'. The water mol-ecules connect the ladders into a supra-molecular layer parallel to the ab plane via water-O-H⋯S and pyridyl-C-H⋯O(water) inter-actions, with the connections between layers being of the type pyridyl-C-H⋯S. In (II), supra-molecular layers parallel to the ab plane are sustained by hy-droxy-O-H⋯S hydrogen bonds with connections between layers being of the type pyridyl-C-H⋯S.
  3. Syed S, Jotani MM, Halim SN, Tiekink ER
    PMID: 27006815 DOI: 10.1107/S2056989016002735
    The asymmetric unit of the title 2:1 co-crystal, 2C8H8O2·C14H14N4O2, comprises an acid mol-ecule in a general position and half a di-amide mol-ecule, the latter being located about a centre of inversion. In the acid, the carb-oxy-lic acid group is twisted out of the plane of the benzene ring to which it is attached [dihedral angle = 28.51 (8)°] and the carbonyl O atom and methyl group lie approximately to the same side of the mol-ecule [hy-droxy-O-C-C-C(H) torsion angle = -27.92 (17)°]. In the di-amide, the central C4N2O2 core is almost planar (r.m.s. deviation = 0.031 Å), and the pyridyl rings are perpendicular, lying to either side of the central plane [central residue/pyridyl dihedral angle = 88.60 (5)°]. In the mol-ecular packing, three-mol-ecule aggregates are formed via hy-droxy-O-H⋯N(pyrid-yl) hydrogen bonds. These are connected into a supra-molecular layer parallel to (12[Formula: see text]) via amide-N-H⋯O(carbon-yl) hydrogen bonds, as well as methyl-ene-C-H⋯O(amide) inter-actions. Significant π-π inter-actions occur between benzene/benzene, pyrid-yl/benzene and pyrid-yl/pyridyl rings within and between layers to consolidate the three-dimensional packing.
  4. Syed S, Halim SN, Jotani MM, Tiekink ER
    PMID: 26870591 DOI: 10.1107/S2056989015024068
    The title 2:1 co-crystal, 2C7H5NO4·C14H14N4O2, in which the complete di-amide mol-ecule is generated by crystallographic inversion symmetry, features a three-mol-ecule aggregate sustained by hydroxyl-O-H⋯N(pyrid-yl) hydrogen bonds. The p-nitro-benzoic acid mol-ecule is non-planar, exhibiting twists of both the carb-oxy-lic acid and nitro groups, which form dihedral angles of 10.16 (9) and 4.24 (4)°, respectively, with the benzene ring. The di-amide mol-ecule has a conformation approximating to a Z shape, with the pyridyl rings lying to either side of the central, almost planar di-amide residue (r.m.s. deviation of the eight atoms being 0.025 Å), and forming dihedral angles of 77.22 (6)° with it. In the crystal, three-mol-ecule aggregates are linked into a linear supra-molecular ladder sustained by amide-N-H⋯O(nitro) hydrogen bonds and orientated along [10-4]. The ladders are connected into a double layer via pyridyl- and benzene-C-H⋯O(amide) inter-actions, which, in turn, are connected into a three-dimensional architecture via π-π stacking inter-actions between pyridyl and benzene rings [inter-centroid distance = 3.6947 (8) Å]. An evaluation of the Hirshfeld surfaces confirm the importance of inter-molecular inter-actions involving oxygen atoms as well as the π-π inter-actions.
  5. Rahima ZA, Abdul Halim SN, How FN
    PMID: 26396883 DOI: 10.1107/S2056989015014462
    The title compound, C14H19NS2, crystallizes in the thione form with the presence of a C=S bond. The piperidine ring adopts a chair conformation. The dihedral angle between the essentially planar di-thio-carbamate and p-tolyl fragments is 74.46 (10)°.
  6. Ahmad J, Abdul Halim SN, How FN
    PMID: 26090195 DOI: 10.1107/S2056989015009159
    The title compound, Ph3(PhCH2)P(+)·Cl(-)·H2O, was obtained unintentionally as the product of an attempted synthesis of a silver di-thio-carbamate complex using benzyl-tri-phenyl-phospho-nium as the counter-ion. The asymmetric unit consists of a phospho-nium cation and a chloride anion, and a water mol-ecule of crystallization. In the crystal, the chloride ion is linked to the water mol-ecule by an O-H⋯Cl hydrogen bond. The three units are further linked via C-H⋯Cl and C-H⋯O hydrogen bonds and C-H⋯ π inter-actions, forming a three-dimensional structure.
  7. Al'Abri AM, Mohamad S, Abdul Halim SN, Abu Bakar NK
    Environ Sci Pollut Res Int, 2019 Apr;26(11):11410-11426.
    PMID: 30805837 DOI: 10.1007/s11356-019-04467-w
    A novel porous coordination polymer adsorbent (BTCA-P-Cu-CP) based on a piperazine(P) as a ligand and 1,2,4,5-benzenetetracarboxylic acid (BTCA) as a linker was synthesized and magnetized to form magnetic porous coordination polymer (BTCA-P-Cu-MCP). Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscope(FESEM), energy-dispersive X-ray spectroscopy(EDS), CHN, and Brunauer-Emmett-Teller(BET) analysis were used to characterize the synthesized adsorbent. BTCA-P-Cu-MCP was used for removal and preconcentration of Pb(II) ions from environmental water samples prior to flame atomic absorption spectrometry(FAAS) analysis. The maximum adsorption capacity of BTCA-P-Cu-MCP was 582 mg g-1. Adsorption isotherm, kinetic, and thermodynamic parameters were investigated for Pb(II) ions adsorption. Magnetic solid phase extraction (MSPE) method was used for preconcentration of Pb(II) ions and the parameters influencing the preconcentration process have been examined. The linearity range of proposed method was 0.1-100 μg L-1 with a preconcentration factor of 100. The limits of detection and limits of quantification for lead were 0.03 μg L-1 and 0.11 μg L-1, respectively. The intra-day (n = 7) and inter-day (n = 3) relative standard deviations (RSDs) were 1.54 and 3.43% respectively. The recoveries from 94.75 ± 4 to 100.93 ± 1.9% were obtained for rapid extraction of trace levels of Pb(II) ions in different water samples. The results showed that the BTCA-P-Cu-MCP was steady and effective adsorbent for the decontamination and preconcentration of lead ions from the aqueous environment.
  8. Abdul Halim SN, Ali HM, Ng SW
    PMID: 21588862 DOI: 10.1107/S1600536810039516
    In the title compound, [Mn(C(13)H(8)N(3)O(3))(2)]·C(3)H(7)NO·H(2)O, the metal atom is O,N,O'-chelated by two deprotonated Schiff bases and exists in a distorted octa-hedral geometry. The N-H groups, the carbonyl group of the DMF mol-ecule and the uncoord-inated water mol-ecule engage in N-H⋯O and O-H⋯O hydrogen-bonding inter-actions, generating a hydrogen-bonded ribbon that propagates along [110].
  9. Abdul Halim SN, Ali HM, Ng SW
    PMID: 21588861 DOI: 10.1107/S1600536810039504
    The metal atom of the title compound, [Zn(C(13)H(8)N(3)O(2)S)(2)]·C(3)H(7)NO·H(2)O, is O,N,O'-chelated by two deprotonated Schiff bases and it exists in a distorted octa-hedral geometry. The N-H groups of the ligands, the carbonyl group of the DMF mol-ecule and uncoordinated water mol-ecule engage in N-H⋯O and O-H⋯O inter-actions, generating a hydrogen-bonded ribbon that propagates along [110]. One thienyl ring is disordered over two positions in a 1:1 ratio.
  10. Safbri SA, Halim SN, Jotani MM, Tiekink ER
    PMID: 26958378 DOI: 10.1107/S2056989016000165
    The title compound, [Cd(C6H12NOS2)2(C4H10N2)], features a distorted square-pyramidal coordination geometry about the central Cd(II) atom. The di-thio-carbamate ligands are chelating, forming similar Cd-S bond lengths and define the approximate basal plane. One of the N atoms of the piperazine mol-ecule, which adopts a chair conformation, occupies the apical site. In the crystal, supra-molecular layers propagating in the ac plane are formed via hy-droxy-O-H⋯O(hy-droxy), hy-droxy-O-H⋯N(terminal-piperazine) and coordinated-piperazine-N-H⋯O(hy-droxy) hydrogen bonds; the layers also feature methine-C-H⋯S inter-actions and S⋯S [3.3714 (10) Å] short contacts. The layers stack along the b-axis direction with very weak terminal-piperazine-N-H⋯O(hy-droxy) inter-actions between them. An evaluation of the Hirshfeld surfaces confirms the importance of inter-molecular inter-actions involving oxygen and sulfur atoms.
  11. Al-Mohammed NN, Shakir RM, Alias Y, Abdullah Z, Abd Halim SN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1838.
    PMID: 21837205 DOI: 10.1107/S1600536811024664
    The title mol-ecule, C(26)H(30)O(9)S(3), adopts an extended conformation whereby two approximately parallel benzene rings [dihedral angle = 8.32 (10)°] are orientated in opposite directions along the pseudo-threefold axis through the central quaternary C atom, while a third ring occupies a position mid-way and face-on to these rings [dihedral angles = 82.28 (10) and 78.81 (7)°]. The crystal packing is dominated by C-H⋯O contacts and π-π inter-actions [ring centroid distance = 3.6902 (12) Å].
  12. Al-Mehana WN, Shakir RM, Yahya R, Abd Halim SN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1659.
    PMID: 21837059 DOI: 10.1107/S1600536811022410
    The complete mol-ecule in the title compound, C(22)H(20)N(2)O(4), is generated by the application of an inversion centre. With the exception of the terminal acetyl-ene groups [C-O-C-C = -78.02 (17)°], the remaining atoms constituting the mol-ecule are essentially coplanar. The configuration around the C=N bond [1.282 (2) Å] is E. The formation of supra-molecular chains mediated by C-H⋯O inter-actions, occurring between methyl-ene H and meth-oxy O atoms, is the most notable feature of the crystal packing.
  13. Ishak DH, Tajuddin HA, Abdullah Z, Abd Halim SN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1658.
    PMID: 21837058 DOI: 10.1107/S1600536811022409
    In the title compound, C(10)H(9)N(3)O(3), there is a small twist between the benzene and triazole rings [dihedral angle = 6.32 (7)°]; the carb-oxy-lic acid residue is almost coplanar with the benzene ring to which it is attached [O-C-C-C torsion angle = 1.49 (19)°]. The main deviation from coplanarity of the non-H atoms is found for the hy-droxy group which is almost perpendicular to the remaining atoms [N-C-C-O torsion angle = -75.46 (16)°]. In the crystal, the presence of O-H⋯O (between carboxyl groups) and O-H⋯N (between the hy-droxy group and the triazole ring) hydrogen bonds leads to supra-molecular chains along [03[Formula: see text]]. The chains are connected into sheets via C-H⋯O(hy-droxy) inter-actions.
  14. Al-Madhagi WM, Mohd Hashim N, Awad Ali NA, Alhadi AA, Abdul Halim SN, Othman R
    PeerJ, 2018;6:e4839.
    PMID: 29892499 DOI: 10.7717/peerj.4839
    Background: Peperomia belongs to the family of Piperaceae. It has different uses in folk medicine and contains rare compounds that have led to increased interest in this genus. Peperomia blanda (Jacq.) Kunth is used as an injury disinfectant by Yemeni people. In addition, the majority of Yemen's population still depend on the traditional remedy for serious diseases such as cancer, inflammation and infection. Currently, there is a deficiency of scientific evidence with regards to the medicinal plants from Yemen. Therefore, this study was performed to assess the chemical profile and in vitro antioxidant and cytotoxic activities of P. blanda.

    Methods: Chemical profiling of P. blanda was carried out using gas chromatography mass spectrometry (GCMS) followed by isolation of bioactive compounds by column chromatography. DPPH• and FRAP assays were used to evaluate antioxidant activity and the MTT assay was performed to estimate the cytotoxicity activity against three cancer cell lines, namely MCF-7, HL-60 and WEHI-3, and three normal cell lines, MCF10A, WRL-68 and HDFa.

    Results: X-ray crystallographic data for peperomin A is reported for the first time here and N,N'-diphenethyloxamide was isolated for the first time from Peperomia blanda. Methanol and dichloromethane extracts showed high radical scavenging activity with an IC50 of 36.81 ± 0.09 µg/mL, followed by the dichloromethane extract at 61.78 ± 0.02 µg/mL, whereas the weak ferric reducing activity of P. blanda extracts ranging from 162.2 ± 0.80 to 381.5 ± 1.31 µg/mL were recorded. In addition, petroleum ether crude extract exhibited the highest cytotoxic activity against all the tested cancer cell lines with IC50 values of 9.54 ± 0.30, 4.30 ± 0.90 and 5.39 ± 0.34 µg/mL, respectively. Peperomin A and the isolated mixture of phytosterol (stigmasterol and β-sitosterol) exhibited cytotoxic activity against MCF-7 and WE-HI cell lines with an IC50 of (5.58 ± 0.47, 4.62 ± 0.03 µg/mL) and (8.94 ± 0.05, 9.84 ± 0.61 µg/mL), respectively, compared to a standard drug, taxol, that has IC50 values of 3.56 ± 0.34 and 1.90 ± 0.9 µg/mL, respectively.

    Conclusion: The activities of P. blanda extracts and isolated compounds recorded in this study underlines the potential that makes this plant a valuable source for further study on anticancer and antioxidant activities.

  15. Nazarbahjat N, Nordin N, Abdullah Z, Abdulla MA, Yehye WA, Halim SN, et al.
    Molecules, 2014;19(8):11520-37.
    PMID: 25093989 DOI: 10.3390/molecules190811520
    New thiosemicarbazide derivatives 2-6 were synthesised by reacting 2-(ethylsulfanyl)benzohydrazide with various aryl isothiocyanates. The cyclisation of compounds 2-6 under reflux conditions in a basic medium (aqueous NaOH, 4 N) yielded compounds 7-11 that contain a 1,2,4-triazole ring. All of the synthesised compounds were screened for their antioxidant activities. Compounds 2, 3, and 7 showed better radical scavenging in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, with IC50 values of 1.08, 0.22, and 0.74 µg/mL, respectively, compared to gallic acid (IC50, 1.2 µg/mL). Compound 3 also showed superior results in a ferric reducing antioxidant power (FRAP) assay (3054 µM/100 g) compared to those of ascorbic acid (1207 µM/100 g).
  16. 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.
  17. 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.
  18. Al'Abri AM, Abdul Halim SN, Abu Bakar NK, Saharin SM, Sherino B, Rashidi Nodeh H, et al.
    J Environ Sci Health B, 2019;54(12):930-941.
    PMID: 31407615 DOI: 10.1080/03601234.2019.1652072
    This article demonstrates the first application of a copper-based porous coordination polymer (BTCA-P-Cu-CP) as a carbon paste electrode (CPE) modifier for the detection of malathion. The electrochemical behavior of BTCA-P-Cu-CP/CPE was explored using cyclic voltammetry (CV) while chrono-amperometry methods were applied for the analytical evaluation of the sensor performance. Under optimized conditions, the developed sensor exhibited high reproducibility, stability, and wide dynamic range (0.6-24 nM) with the limits of detection and sensitivity equal to 0.17 nM and 5.7 µAnMcm-1, respectively, based on inhibition signal measurement. Furthermore, the presence of common coexisting interfering species showed a minor change in signals (<4.4%). The developed sensor has been applied in the determination of malathion in spiked vegetable extracts. It exhibited promising results in term of fast and sensitive determination of malathion in real samples at trace level with recoveries of 91.0 to 104.4%. (RSDs < 5%, n = 3). A comparison of the two studied techniques showed that the HPLC technique is unable to detect malathion when the concentration is lower than 1.8 µM while 0.006 µM is detected with appropriate RSDs 0.2-5.2% (n = 3) by amperometric method. Due to the high sensitivity and selectivity, this new electrochemical sensor will be useful for monitoring trace malathion in real samples.
  19. 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).
  20. 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.
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