Structural studies on the toxic principle of Ornithogalum Thyrsoides

Abstract

The main aim of the investigation as described in the thesis, is the isolation and structure elucidation of the toxic principle(s) of the plant 0rnithogalum thyrsoides. Extracts of fresh 0. thyrsoides material were evaluated in a bioassay using weaned guinea pigs. The fractionation of a toxic extract by chromatographic methods on different adsorbents with a variety of eluants was guided by this bioassay and led to the isolation of a single toxic compound for which the trivial name prasinoside G is suggested. The structure viz. 3P-0-(P-o-glucopyranosyl )- 16P-[2-0- (3,4-dimethoxybenzoyl )-P-o-xylopyranosyl-( 1 --3 )-2-0-acetyl-a-L-arabinopyranosyl]-17 ahydroxy- cholest-5-en-22-one is proposed for prasinoside G on the basis of a detailed analysis of its high-field 1H and 13C n.m.r. spectra and two of its derivatives as well as a single-crystal X-ray crystallographic analysis of a hydrolysis product. Detailed results of these studies are given.