Studies in marine natural products : Biologically active compounds from the New Zealand algae and invertebrata
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
In the search for new classes of compounds with antiviral, antitumour or antibacterial activity, a number of benthic marine species were examined. The extract of Tedania connectens was found to contain three compounds with intense in vitro antiviral and cytotoxic activity (IC₅₀ against P388 murine leukemia cells was 20-40 pg/ml). Examination of the mass spectra of these compounds indicated the presence the known compound tedanolide, together with a deoxy and a chlorinated derivative. Attempts to convert the antiviral and cytotoxic compound thyrsiferol to thyrsifer-18-one and to the 18-epimer were unsuccessful. However, the ¹H and ¹³C NMR spectra of thyrsiferyl acetate, including all the pro-r and pro-s proton resonances, were completely assigned using a combination of 2D NMR spectroscopy and molecular mechanics calculations. Two new dimeric butenolides were isolated from the red alga Delisea elegans, and their structures determined by single X-ray crystallography. The crystal structure of discorhabdin C, a cytotoxic pigment from a sponge of the genus Latrunculia, was determined, as was the crystal structure of the p-bromobenzoyl derivative of the known compound eudistomin K. Several computer programs were written to assist data analysis. The program ''MassCalc'' was written to free the chemist from the tedious computational tasks usually associated with interpreting mass spectra. A group of five programs were written to simplify the interpretation of the results of molecular mechanics and X-ray crystallography calculations.