No description available.

No description available.

Members of the Annonaceae and Meliaceae, two plant families which are distributed throughout the world, have been studied during the course of this work. The research is an account of the compounds isolated from six members of the Meliaceae (Australian, Indian and South African) and one from the Annonaceae (South African). These families have attracted special attention of scientists world-wide because of the compounds these plants produce and their medicinal applications. Extracts from these species are known to be widely used in traditional medicine and previous studies have demonstrated their anticancer, anti-microbial and other pharmacological activities. Limonoids and protolimonoids were isolated from the Indian Meliaceae specIes, Aphanamixis polystacha and from the South African Meliaceae species Turraea obtusifolia. Extractives from the seeds of Aphanamixis polystacha yielded seven limonoids (2-A to 2-G) from the hexane extract, while the methanol extract only yielded sucrose (2-H). Three of the limonoids (2-B, 2-E and 2-F) were novel and the stereochemistry of polystachin, compound (2-A), was revised. Extractives from Turraea obtusifolia yielded two triterpenoids (3-A and 3-B) and a limonoid (3-C) from the hexane extract of the seed. Several triterpenoids and a benzofuran compound were isolated from the Australian Meliaceae species, Dysoxylum pettigrewianum, Dysoxylum muelleri and Aglaia sapindina. Extractives from Dysoxylum pettigrewianum, yielded three triterpenoids (4-A to 4-C) from the hexane extract of the bark. Two of these triterpenoids (4-Band 4-C) were novel. Extractives from Dysoxylum muelleri yielded two triterpenoids (4-D and 4E) from the methylene chloride extract of the wood. Extractives from Aglaia sapindina yielded a benzofuran compound (4-F) from the hexane extract of the wood. This resulted in the revision of the structure of ferrugin (4-56). A flavonoid (5-A) was isolated from the aqueous extract of the seed of the South African Meliaceae Trichilia dregeana. A polyoxygenated cyclohexane epoxide (6-A) was isolated from the root and leaves of the Annonaceae species, Monanthotaxis caffia. The research undertaken involved the collection, extraction, isolation, purification and structural elucidation of these compounds by infrared, mass and nuclear magnetic resonance spectroscopic techniques. / Thesis (Ph.D.)-University of Natal, 1997.

Includes bibliographical references (leaves 43-46; leaves 52-55). / v, 55, leaves

Although it is only fairly recently that the importance of trace elements in plant nutrition has been established, enormous advances have been made in this field of research and numerous publications of considerable scientific and economic importance, dealing with the subject, have appeared. The physiological functions of zinc in promoting plant growth have not all been satisfactorily identified as yet. There are indications, however, that zinc acts as a catalyst or regulator in plant metabolism. It appears too, that the element plays some role in chlorophyll formation. Zinc deficiency is associated with leaf chlorosis and a general collapse of v ital processes. The analysis of leaves and soils has become an essential part of the study of the nutritional diseases of plants and it is imperative that accurate and reliable methods of analysis should be available. Intro. p. 1.

1. Accurate and reproducible methods for the determination of N and acid- extractable P in soils are described. The variations in N, P, and K found by intensive sampling of three different soil types are presented. 3. Suggestions for the adequate sampling of soils for various purposes arc given. 4. A study is presented of the preparative stages in leaf analysis (washing, drying, grinding and storage) as applied to citrus and pineapple leaf material. Likely errors are pointed out and procedures whereby these may be minimised are described. 5. A reliable wet-ashing procedure for obtaining leaf solutions is described. 6. Accurate and reproducible methods for the determination of total N, P,. K, Ca, Mg, Na, Fe, Mn, Zn and Cu in citrus and pineapple leaves are presented. 7. It is shown that diurnal variations in nutrient concentrations occur in citrus and pineapple leaves. 8. The variations in N, P, K, Ca, Mg, Na, Fe, Mn, Zn and Cu, occurring from tree to tree in 3 different Navel orange blocks are presented. It is shown that if all these elements are to be represented . to within 10% of the mean values on a 19 : 1 probability level, all the trees in the blocks would have to be sampled. Reasonable sampling procedures for various purposes are suggested. 9. The variations in N, P, K, Ca, Mg, Fe, Mn, Zn and Cu, occurring in 3 different Cayenne pineapple plantations are presented and described. Suitable sampling procedures are suggested.

published_or_final_version / Chemistry / Master / Master of Science

published_or_final_version / Chemistry / Master / Master of Science

published_or_final_version / Chemistry / Master / Master of Science

published_or_final_version / Chemistry / Master / Master of Science