Part I. Isolation and structure elucidation of polar metabolites from sea cucumber Cucumaria frondosa. Part II. Isolation and synthesis of polyaromatic compounds

Part I. Examination of polar fractions of sea cucumber Cucumaria frondosa has afforded a variety of polar metabolites. Their structures present challenges in isolation, purification and elucidation. Saponins from the sea cucumber are chemically and biologically interesting natural products with various bioactivities such as hemolytic, neuromuscular, cytotoxic, and antifungal activities.;From this study, the following polar metabolites were isolated from whole bodies of Cucumaria frondosa--ten new compounds: frondoside B (56), frondoside C (76), frondecaside (74), 77, 78, 81, 84, 93, 94, 95, and five known compounds: 55, 96, 97, 98, 99. In this thesis their isolation, purification and structure elucidation were described and their complete structures were determined by using 1D and 2D nmr experiments--1D: ;Part II. During the course of isolation of marine natural products from the starfish Pteraster militaris and Luidia senegalensis, an array of polyaromatic compounds was encountered. Eventually, it was established that all but one of these originated from Amberlite XAD-2 resin which had been used in the isolation protocols. Since many of these compounds have not been previously reported, they are mentioned in this thesis. Their structures were deduced spectroscopically and chemically and a representative of each series of compound synthesized.