Thesis (M. Med. Sc.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 40-47).

No description available.

No description available.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1991. / Includes bibliographical references (leaves 100-107) / Microfiche. / xiii, 107 leaves, bound ill. 29 cm

Thesis (M. Ag. Sci.)--University of Adelaide, 1988. / Typescript. Includes bibliographical references (leaves 51-61).

Thesis (M.Med.Sc.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 40-47). Also available in print.

Thesis (Doctoral)--University of Stockholm, 1983. / Includes articles on which author's Review is based. Includes bibliographical references.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on Dec. 2, 2009). Includes bibliographical references.

Thesis (M.S.)--University of North Carolina at Greensboro, 2007. / Title from PDF title page screen. Advisor: Jason Reddick; submitted to the Dept. of Chemistry. Includes bibliographical references (p. 41-46).

In order to compare the pyrrolizidine alkaloid content of two closely related species, Senecio chrysocoma and S. paniculatus, nine populations of plants distributed between the two species, were examined. Three novel pyrrolizidine alkaloids, 7ß-angelyl-l-methylene-8∝-pyrrolizidine, 7ß-angelyl-l-methylene-8∝-pyrrolizidine and 7ß-angelyl-l-methyleneSO!-pyrrolizidine-4-oxide, as well as eight known pyrrolizidine alkaloids, 7-angelylhastanecine, 9-angelylhastanecine, 7-angelylplatynecine, 9-angelylplatynecine, 9-angelylplatynecine-4-oxide, sarracine, neosarracine and retrorsine, were isolated and identified by NMR and GC-MS techniques. Traces of five tiglyl isomers, 9-tiglylplatynecine, 9-tigl ylplatynecine-4-oxide, 7ß-tiglyl-l-methylene-8∝-pyrrolizidine, sarranicine and neosarranicine, were also isolated and tentatively identified; however, these compounds could have been artefacts of the extraction and analytical procedures. While both species of plant investigated, S. chrysocoma and S. paniculatus, were found to be morphologically different, their pyrrolizidine alkaloid content was, in fact, very similar. The presence of retrorsine in S. paniculatus plant extracts, but not in those from S. chrysocoma plants, was the only major chemical difference observed. It is perhaps significant that retrorsine was the only macrocyclic pyrrolizidine to be identified. A comprehensive, computerised database of physical data for pyrrolizidine alkaloids has been compiled, which has facilitated the identification of new pyrrolizidines and the examination of trends in proton and carbon-13 NMR data for pyrrolizidine alkaloids. A stereospecific synthesis of 7ß-angelyl-l-methylene-8∝-pyrrolizidine was undertaken toconfirm the absolute stereochemistry of the product isolated from S. chrysocoma and S. paniculatus. An inseparable 5:2 mixture of 7ß-angelyl-l-methylene-8∝-pyrrolizidine and 7ß-angelyl-l,2-didehydro-l-methyl-8∝-pyrrolizidine, together with a small amount of tiglyl isomer, was finally synthesised. The application of various chiral differentiating chromatographic and spectroscopic techniques confirmed that both the natural and synthetic products had the same stereochemistry, permitting the natural alkaloid to be identified as 7ß-angelyl-methylene-8∝-pyrrol izidine