Browsing by Author "Keyzers, Robert Alexander"

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The Isolation of Biologically Active Secondary Metabolites from New Zealand Marine Organisms.
(Te Herenga Waka—Victoria University of Wellington, 2003) Keyzers, Robert Alexander
An improved protocol for the screening of marine sponges using cyclic loading, PSDVB, and both 1D and 2D NMR spectroscopy is described. Using this new methodology, 51 sponges were screened. Further investigations were carried out on seven of the 51 organisms, resulting in the isolation of several known and eight novel compounds. Clathriols A (32) and B (33) are novel sterols isolated from the sponge Clathria lissosclera. Both 32 and 33 possess the rare 14β stereochemistry, a feature only naturally occurring in marine sponges. Both are also moderate anti-inflammatory compounds. Ten spongian diterpenes were isolated from the New Zealand, sponge Chelonaplysilla violacea, six of which are novel. Cadlinolides C (138) and D (139) are similar to several previously reported compounds while pourewic acid A (140), 15-methoxypourewic acid B (141), methylpourewate B (142) and pourewanone (143) have unique structural features and are of biogenetic significance. Pourewanone (143) is the first example of a formate isolated from the marine environment. Several of the novel diterpenes exhibit moderate anti-inflammatory activity. A potent dinoflagellate toxin was partially purified from cultures of the producing organism, Karenia brevisulcata. K. brevisulcata is a new dinoflagellate species implicated in a large toxic algal bloom in Wellington Harbour, New Zealand, which formed during the summer of 1997/1998. Although the toxin could not be identified, some of the functionality present, and several possible substructures, is proposed. The biological activity of the toxin is also described.