STUDIES ON THE CHEMICAL CONSTITUENTS OF STOKEYIA INDICA, ERVATAMIA CORONARIA AND HAPLOPHYLLUM SPECIES

Abstract

The thesis is divided into four parts. Part-A describes studies on the chemical constituents of Haplophyllum burbaumii. Investigation on the stem bark of H. buxbaumii has led to the isolation of five new ligan glucosides: Part-B describes studies on the chemical constituents of Stokeyia indica. Investigation on S. judica has led to the isolation and structure elucidation of a novel linear metabolite (stokerine, 11), besides loliolide (12) and fucosterol (13) isolated for the first time from this brown alga. Part-C describes studies on the chemical constituents of Ervatamia coronaria. Investigation on the twigs of E. coronaria has led to the isolation of the following compounds. Part-D of the thesis contains the Experimental section, and is followed b the References. Modern spectroscopic techniques including 2D NMR experiments (2D-J-resolved, COSY-45, NOESY, NOE, HeteroCOSY, SECSY) were employed and chemical transformations were carried out to establish the structures of the above mentioned compounds. The stereochemistry was established by extensive NOE difference measurements. Temperature dependent 1H-NMR studies were carried out to gain insight into the conformational equilibria existing in compounds (3), (5) and (10).