School of Chemistry - Research Publications

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    An icosanuclear silver(I) cluster supported by bis (thiosemicarbazonato) ligands
    Paterson, BM ; White, JM ; Donnelly, PS (CSIRO PUBLISHING, 2022-03-10)
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    Article Development and application of Diels-Alder adducts displaying AIE properties
    Gialelis, TL ; Owyong, TC ; Ding, S ; Li, W ; Yu, M ; O'Brien-Simpson, NM ; Zhao, Z ; White, JM ; Yao, B ; Hong, Y (ELSEVIER, 2022-02-16)
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    Phytochemical Profiling and Biological Testing of the Constituents of the Australian Plant Haemodorum brevisepalum
    Norman, EO ; Hombsch, S ; Lever, J ; Brkljaca, R ; White, J ; Gasser, RB ; Taki, AC ; Urban, S (AMER CHEMICAL SOC, 2021-11-15)
    Phytochemical profiling was undertaken on the crude extracts of the bulbs, stems, and the fruits of Haemodorum brevisepalum, to determine the nature of the chemical constituents present. This represents the first study to investigate the fruits of a species of Haemodorum. In total, 13 new and 17 previously reported compounds were isolated and identified. The new compounds were of the phenylphenalenone-type class, with a representative of a novel structural form, named tentatively "oxabenzochromenone" (1), a compound akin to an intermediate in a recently proposed phenylphenalenone metabolic network (2), seven new phenylphenalenones (4-10), four new phenylbenzoisochromenones (11-14), and a new phenylbenzoisochromenone derivative (18). The previously reported compounds identified were of the following structure classes: oxabenzochrysenone (3, 23-26), flavonol (15, 16), phenylbenzoisochromenone (17, 21, 22, 27-30), and phenylphenalenone (19, 20). Compounds 2-4, 6-9, 15-18, 21, 22, and 26 were subjected to antimicrobial evaluation with moderate activity observed against Staphylococcus aureus MRSA and slight activity against Pseudomonas aeruginosa and Candida albicans. Compounds 4, 6-9, 17, and 21 were also evaluated for anthelminthic activity against larvae of the blood-feeding parasitic nematode Haemonchus contortus.
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    Phytochemical Profiling and Biological Activity of the Australian Carnivorous Plant, Drosera magna
    Norman, EO ; Tuohey, H ; Pizzi, D ; Saidah, M ; Bell, R ; Brkljaca, R ; White, JM ; Gasser, RB ; Taki, AC ; Urban, S (AMER CHEMICAL SOC, 2021-02-25)
    Phytochemical profiling was undertaken on the crude extracts of Drosera magna to determine the nature of the chemical constituents present. In total, three new flavonol diglycosides (1-3), one new flavan-3-ol glycoside (4), and 12 previously reported compounds of the flavonol (5, 9), flavan-3-ol (15), flavanone (8), 1,4-napthoquinone (6, 7, 13, 14), 2,3-dehydroxynapthalene-1,4-dione (10-12), and phenolic acid (16) structure classes were isolated and identified. Compounds 1-9, 13, 17, and 18 were assessed for antimicrobial activity, with compounds 6, 7, 8, and 9 showing significant activity. Compounds 1, 2, and 6 were also evaluated for anthelmintic activity against larval forms of Hemonchus contortus, with compound 6 being active.
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    Correction: On the importance of π-hole spodium bonding in tricoordinated HgII complexes.
    Mahmoudi, G ; Masoudiasl, A ; Babashkina, MG ; Frontera, A ; Doert, T ; White, JM ; Zangrando, E ; Zubkov, FI ; Safin, DA (Royal Society of Chemistry (RSC), 2022-05-24)
    Correction for 'On the importance of π-hole spodium bonding in tricoordinated HgII complexes' by Ghodrat Mahmoudi et al., Dalton Trans., 2020, 49, 17547-17551, https://doi.org/10.1039/D0DT03938A.
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    Oxidative damage of proline residues by nitrate radicals (NO3): a kinetic and product study
    Nathanael, JG ; White, JM ; Richter, A ; Nuske, MR ; Wille, U (ROYAL SOC CHEMISTRY, 2020-09-21)
    Tertiary amides, such as in N-acylated proline or N-methyl glycine residues, react rapidly with nitrate radicals (NO3˙) with absolute rate coefficients in the range of 4-7 × 108 M-1 s-1 in acetonitrile. The major pathway proceeds through oxidative electron transfer (ET) at nitrogen, whereas hydrogen abstraction is only a minor contributor under these conditions. However, steric hindrance at the amide, for example by alkyl side chains at the α-carbon, lowers the rate coefficient by up to 75%, indicating that NO3˙-induced oxidation of amide bonds proceeds through initial formation of a charge transfer complex. Furthermore, the rate of oxidative damage of proline and N-methyl glycine is significantly influenced by its position in a peptide. Thus, neighbouring peptide bonds, particularly in the N-direction, reduce the electron density at the tertiary amide, which slows down the rate of ET by up to one order of magnitude. The results from these model studies suggest that the susceptibility of proline residues in peptides to radical-induced oxidative damage should be considerably reduced, compared with the single amino acid.
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    Simulating chalcogen bonding using molecular mechanics: a pseudoatom approach to model ebselen
    Fellowes, T ; White, JM (SPRINGER, 2022-03-01)
    The organoselenium compound ebselen has recently been investigated as a treatment for COVID-19; however, efforts to model ebselen in silico have been hampered by the lack of an efficient and accurate method to assess its binding to biological macromolecules. We present here a Generalized Amber Force Field modification which incorporates classical parameters for the selenium atom in ebselen, as well as a positively charged pseudoatom to simulate the σ-hole, a quantum mechanical phenomenon that dominates the chemistry of ebselen. Our approach is justified using an energy decomposition analysis of a number of density functional theory-optimized structures, which shows that the σ-hole interaction is primarily electrostatic in origin. Finally, our model is verified by conducting molecular dynamics simulations on a number of simple complexes, as well as the clinically relevant enzyme SOD1 (superoxide dismutase), which is known to bind to ebselen. Graphical Abstract Ebselen is an organoselenium drug that has shown promise for the treatment of a number of conditions. Computational modelling of drug-target complexes is commonly performed to determine the likely mechanism of action, however this is difficult in the case of ebselen, as an important mode of interaction is not simulated using current techniques. We present here an extension to common methods, which accurately captures this interaction.
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    Synthesis and evaluation of benzochalcogenazole-benzimidazole derivatives as potential DNA-binding radioprotectors
    Fellowes, T ; Skene, CE ; Martin, RF ; Lobachevsky, P ; Owyong, TC ; Hong, Y ; White, JM ; Koutentis, PA (ARKAT USA, Inc., 2022-01-01)
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    Dysidenin from the Marine Sponge Citronia sp. Affects the Motility and Morphology of Haemonchus contortus Larvae In Vitro
    Ramage, KS ; Taki, AC ; Lum, KY ; Hayes, S ; Byrne, JJ ; Wang, T ; Hofmann, A ; Ekins, MG ; White, JM ; Jabbar, A ; Davis, RA ; Gasser, RB (MDPI, 2021-12-01)
    High-throughput screening of the NatureBank marine extract library (n = 7616) using a phenotypic assay for the parasitic nematode Haemonchus contortus identified an active extract derived from the Australian marine sponge Citronia sp. Bioassay-guided fractionation of the CH2Cl2/MeOH extract from Citronia sp. resulted in the purification of two known hexachlorinated peptides, dysidenin (1) and dysideathiazole (2). Compound 1 inhibited the growth/development of H. contortus larvae and induced multiple phenotypic changes, including a lethal evisceration (Evi) phenotype and/or somatic cell and tissue destruction. This is the first report of anthelmintic activity for these rare and unique polychlorinated peptides.