Jonathan L Nielson

Publications (7)23.33 Total impact

• Article: A Great Barrier Reef Sinularia sp. Yields Two New Cytotoxic Diterpenes.

  Anthony D Wright, Jonathan L Nielson, Dianne M Tapiolas, Catherine H Liptrot, Cherie A Motti
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  ABSTRACT: The methanol extract of a Sinularia sp., collected from Bowden Reef, Queensland, Australia, yielded ten natural products. These included the new nitrogenous diterpene (4R*,5R*,9S*,10R*,11Z)-4-methoxy-9-((dimethylamino)-methyl)-12,15-epoxy-11(13)-en-decahydronaphthalen-16-ol (1), and the new lobane, (1R*,2R*,4S*,15E)-loba-8,10,13(14),15(16)-tetraen-17,18-diol-17-acetate (2). Also isolated were two known cembranes, sarcophytol-B and (1E,3E,7E)-11,12-epoxycembratrien-15-ol, and six known lobanes, loba-8,10,13(15)-triene-16,17,18-triol, 14,18-epoxyloba-8,10,13(15)-trien-17-ol, lobatrientriol, lobatrienolide, 14,17-epoxyloba-8,10,13(15)-trien-18-ol-18-acetate and (17R)-loba-8,10,13(15)-trien-17,18-diol. Structures of the new compounds were elucidated through interpretation of spectra obtained after extensive NMR and MS investigations and comparison with literature values. The tumour cell growth inhibition potential of 1 and 2 along with loba-8,10,13(15)-triene-16,17,18-triol, 14,17-epoxyloba-8,10,13(15)-trien-18-ol-18-acetate, lobatrienolide, (1E,3E,7E)-11,12-epoxycembratrien-15-ol and sarcophytol-B were assessed against three human tumour cell lines (SF-268, MCF-7 and H460). The lobanes and cembranes tested demonstrated 50% growth inhibition in the range 6.8-18.5 µM, with no selectivity, whilst 1 was less active (GI(50) 70-175 µM).
  Marine Drugs 08/2012; 10(8):1619-30. · 3.85 Impact Factor
• Article: Update of spectroscopic data for 4-hydroxydictyolactone and dictyol E isolated from a Halimeda stuposa - Dictyota sp. assemblage.

  Simon P B Ovenden, Jonathan L Nielson, Catherine H Liptrot, Richard H Willis, Dianne M Tapiolas, Anthony D Wright, Cherie A Motti
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  ABSTRACT: The methanol extract of an assemblage of Halimeda stuposa and a Dictyota sp., yielded three natural products characteristic of Dictyota sp., and one of Halimeda sp. These included the xenicane diterpene 4-hydroxydictyolactone (1), and the diterpenes dictyol E (2), 8a,11-dihydroxypachydictyol A (3) and indole-3-carboxaldehyde (4). A minor revision of 1 and new spectroscopic data for 1 and 2 are provided, along with associated anti-cancer activities of compounds.
  Molecules 01/2012; 17(3):2929-38. · 2.39 Impact Factor
• Article: Metachromins U-W: cytotoxic merosesquiterpenoids from an Australian specimen of the sponge Thorecta reticulata.

  Simon P B Ovenden, Jonathan L Nielson, Catherine H Liptrot, Richard H Willis, Dianne M Tapiolas, Anthony D Wright, Cherie A Motti
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  ABSTRACT: Three new merosesquiterpenoids, metachromins U, V, and W (1-3), were isolated from a specimen of the marine sponge Thorecta reticulata collected off Hunter Island, Tasmania, Australia. Structures of the new compounds were elucidated through extensive NMR investigations and comparison with literature values. The cytotoxicities of 1-3 were assessed against a panel of human tumor cell lines (SF-268, H460, MCF-7, and HT-29) and a mammalian cell line (CHO-K1). All compounds were found to have 50% growth inhibition activities in the range 2.1-130 μM, with 2 being the most active (GI50 2.1-10 μM).
  Journal of Natural Products 05/2011; 74(5):1335-8. · 3.13 Impact Factor
• Article: Comosusols A-D and comosone A: cytotoxic compounds from the brown alga Sporochnus comosus.

  Simon P B Ovenden, Jonathan L Nielson, Catherine H Liptrot, Richard H Willis, Anthony D Wright, Cherie A Motti, Dianne M Tapiolas
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  ABSTRACT: Bioassay-guided fractionation of extracts of the brown alga Sporochnus comosus led to the isolation of five new compounds, comosusols A-D (3-6) and comosone A (7). The structures of all isolated compounds were elucidated using standard one- and two-dimensional NMR techniques, as well as comparison with literature values. The cytotoxic activity of all compounds was investigated against a panel of human tumor and mammalian cell lines. These assays found eight of the nine compounds had GI(50) values in the 8-63 μM range.
  Journal of Natural Products 02/2011; 74(4):739-43. · 3.13 Impact Factor
• Source

  Available from: Cherie Ann Motti

  Article: A new diketopiperazine, cyclo-(4-S-hydroxy-R-proline-R-isoleucine), from an Australian specimen of the sponge Stelletta sp.

  Simon P B Ovenden, Jonathan L Nielson, Catherine H Liptrot, Richard H Willis, Dianne M Tapiolas, Anthony D Wright, Cherie A Motti
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  ABSTRACT: While investigating the cytotoxic activity of the methanol extract of an Australian marine sponge Stelletta sp. (Demospongiae), a new diketopiperazine, cyclo-(4-S-hydroxy-R-proline-R-isoleucine) (1), was isolated together with the known bengamides; A (2), F (3), N (4), Y (5), and bengazoles; Z (6), C(4) (7) and C(6) (8). The isolation and structure elucidation of the diketopiperazine (1), together with the activity of 1-8 against a panel of human and mammalian cell lines are discussed.
  Marine Drugs 01/2011; 9(11):2469-78. · 3.85 Impact Factor
• Source

  Available from: Cherie Ann Motti

  Article: Sesquiterpene benzoxazoles and sesquiterpene quinones from the marine sponge Dactylospongia elegans.

  Simon P B Ovenden, Jonathan L Nielson, Catherine H Liptrot, Richard H Willis, Dianne M Tapiolas, Anthony D Wright, Cherie A Motti
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  ABSTRACT: A new sesquiterpene benzoxazole, nakijinol B (3), its acetylated derivative, nakijinol B diacetate (6), and two new sesquiterpene quinones, smenospongines B (4) and C (5), were isolated from the methanol extract of the marine sponge Dactylospongia elegans. Also isolated were the known compounds dactyloquinone B and a 1:1 mixture of ilimaquinone and 5-epi-ilimaquinone. Their structures were determined on the basis of spectroscopic analyses and comparison with literature data. The isolated compounds were assessed for their cytotoxicity against a panel of human tumor cell lines (SF-268, H460, MCF-7, and HT-29) and a normal mammalian cell line (CHO-K1). All compounds were found to have activities in the range 1.8-46 μM and lacked selectivity for tumor versus normal cell lines.
  Journal of Natural Products 12/2010; 74(1):65-8. · 3.13 Impact Factor
• Source

  Available from: Cherie Ann Motti

  Article: Detailed NMR, including 1,1-ADEQUATE, and anticancer studies of compounds from the echinoderm Colobometra perspinosa.

  Anthony D Wright, Jonathan L Nielson, Dianne M Tapiolas, Cherie A Motti, Simon P B Ovenden, Philip S Kearns, Catherine H Liptrot
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  ABSTRACT: From the dichloromethane/methanol extract of the crinoid Colobometra perspinosa, collected south east of Richards Island (Bedara), Family Islands, Central Great Barrier Reef, Australia, 3-(1'-hydroxypropyl)-1,6,8-trihydroxy-9,10-anthraquinone [one of the two stereoisomers of rhodoptilometrin, (1)], 3-propyl-1,6,8-trihydroxy-9,10-anthraquinone (3), 2-[(phenylacetyl)amino]ethanesulfonic acid (4), and 4-hydroxybutanoic acid (5) were isolated. Comparison of (1)H- and (13)C-NMR data for rhodoptilometrin (1) with those reported in the literature showed significant differences for some resonances associated with rings A and C. In an attempt to provide accurately assigned (1)H- and (13)C-NMR data, as well as to confirm the structure of 1, a thorough NMR investigation of this compound was undertaken. Measurements included: concentration dependent (13)C, 1D selective NOE, HSQC, HMBC and 1,1-ADEQUATE. The NMR data for 4 and 5 are reported here for the first time, as is their occurrence from the marine environment. The in vitro anticancer activity of the original extract was found to be associated with 1, 3 and 5.
  Marine Drugs 01/2009; 7(4):565-75. · 3.85 Impact Factor