Studies in Sponge Chemistry

Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan.

Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. The isolation, characterisation and biological activity testing of a new series of compounds, the hamigerans; namely hamigeran A, debromohamigeran A, hamigeran B, 4-bromohamigeran B, hamigeran C, hamigeran D, hamigeran E and debromohamigeran E, from the sponge Hamigera tarangaensis, collected from the Hen and Chicken Islands, New Zealand, is described in chapter one. The compounds were analysed by detailed highfield one and two dimensional NMR, infrared, and mass spectroscopy along with other physical methods. The structure of hamigeran A was confirmed by X-ray crystallography, and this led to the revision of the structure previously reported for hamigeran E. An X-ray crystal structure of a decomposition product of hamigeran D and a possible decomposition mechanism has confirmed the structure of hamigeran D. Hamigeran B exhibited 100% in vitro virus inhibition against both the Herpes and Polio viruses with only slight cytotoxicity, while hamigeran D showed the strongest in vitro antitumour activity against P388 with an IC50 of 8 μM. 4-Bromohamigeran B, hamigeran C and triethylhamigeran E showed moderate activity against Bacillus subtilis.Chapter two comprises a comprehensive review of secondary metabolites isolated from the dictyoceratid family Thorectidae, and includes a critical examination of its chemotaxonomy in which the taxonomical identification of the sponges Cacospongia cf. linteiformis, Cacospongia scalaris and non-Mediterranean Fasciospongia cavernosa is brought into question.Chapter three describes the isolation of six known compounds, namely furospinosulin 1, cometin C, luffarin X, pentaprenylhydroquinone, pentaprenylquinone, and petrosaspongiolide B from the sponge Thorecta reticulata collected from Kaikoura, New Zealand. The published 1H-NMR assignments of pentaprenylhydroquinone were revised upon examination of the COSY spectrum.The isolation of a new, biologically inactive derivative of tedanolide is described in chapter four. Tedanolide B has been isolated from an unidentified sponge and its structure has been elucidated by examination of its NMR spectra.Chapter five describes the isolation of scalaradial and 12-epi-scalaradial from a sponge belonging to a new genus within the Thorectidae, as well as the isolation of shahamine E from Chelonaplysilla violecea (family Darwinellidae).