de Nys, Rocky (1991) Natural products chemistry and chemical ecology of tropical marine algae. PhD thesis, James Cook University.

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Abstract

This thesis reports results from an investigation of the natural product chemistry and chemical ecology of tropical marine algae. The research has led to the discovery of novel metabolites in a number of algal species and demonstrated the ecological role of selected isolated metabolites.

Chapter one provides a general overview of the roles of secondary metabolites in the marine algae, including a review of all algal secondary metabolites previously investigated for their role in ecological interactions.

The algal Division Rhodophyta proved to be a rich source of secondary metabolites. Chapter two describes the structural elucidation of novel metabolites from the algae Laurencia mariannensis, L. majuscula, Dasyphila plumerioides and Delisea pulchra using chemical manipulations and high field nuclear magnetic resonance spectroscopy. The presence of previously reported metabolites, a number of which have now been fully characterised or reassigned, is also described.

The algal Divisions Chlorophyta, Phaeophyta and Cyanophyta proved to be less chemically rich than the Rhodophyta yielding only previously reported metabolites. Chapters three to five describe chemical investigations of the Chlorophyta Microdictyon obscurum and Chlorodesmis jastigata, the Phaeophyta Sargassum spp., and the Cyanophyta Lyngbya sp.

An opportunistic investigation of the natural product chemistry of the blue coral H eliopora coerulea (Alcyonacea) yielded interesting secondary metabolites of potential ecological significance. Chapter six describes the elucidation of novel metabolites from H. coerulea.

The ecological role of selected algal metabolites is described in the latter part of the thesis. Chapter seven treats the chemically mediated interaction between the red alga P locamium hamatum and the alcyonacean soft coral Sinularia cruciata. Experimental studies have shown that the algal secondary metabolite chloromertensene plays a major role in allelopathic interactions with S. cruciata. The importance of natural irradiance levels on the distribution of the alga and its possible influence on the selection of secondary metabolites with allelopathic function is also discussed.

Chapter eight identifies the chemical defences of the temperate red alga Delisea pulchra against common herbivores. In situ feeding experiments were carried out to determine the deterrent effect of purified metabolites isolated from the alga on selected herbivore species.

Item ID:	16979
Item Type:	Thesis (PhD)
Keywords:	biological products, marine algae, tropical marine algae, metabolites, biochemistry, chemical ecology
Date Deposited:	19 Apr 2011 00:32
FoR Codes:	06 BIOLOGICAL SCIENCES > 0601 Biochemistry and Cell Biology > 060104 Cell Metabolism @ 34% 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 33% 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060702 Plant Cell and Molecular Biology @ 33%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50% 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 50%
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