STUDIES IN NATURAL PRODUCTS CHEMISTRY: A. TOWARD THE ISOLATION OF A FLOWERING HORMONE. B. FAB-MS AS A STEREOCHEMICAL PROBE: APPLICATION TO THE GLYCOSIDIC BOND. C. CHARACTERIZATION AND ANALYSIS OF TRICHOTHECENE MYCOTOXINS BY MS (FAST ATOM BOMBARDMENT).

摘要

A reexamination of the problems associated with the isolation of a flowering hormone led to the measurement of the kinetics of flowering for photoinduced Xanthium strumarium. It is shown that the rate of flowering can be controlled. After developing an adequate bioassay procedure attempts to isolate a flower-promoting substance from extracts of photoinduced plant material of the same species were not successful. Some extracts however exhibited some flower-accelerating activity in plants that had been previously subjected to one inductive short-day cycle. These results suggest that there does not exist a single hormonal factor capable of inducing flowering. A concerted action enzyme/hormone however could account for the induction/regulation of the flowering process.;Mass spectrometry has been used to analyse a series of fungal toxins in the trichothecene family. Fast atom bombardment (FAB) is an excellent ionization technique for a crude fungal extract and can be used as a fast, efficient and reliable screening test for the presence of the toxins. The fragmentation patterns of the trichothecenes nivalenol, deoxynivalenol, 3-Acetyl and 15-Acetyl deoxynivalenol, T-2, HT-2, diacetylscirpenol and dihydrodiacetyldeoxynivalenol have been established using linked-scan techniques. These data are evaluated in terms of a definitive analytical method for the quantitative analysis and the characterization of the toxins. The fragmentation patterns are discussed in terms of their use in structure elucidation problem.;Fast atom bombardment mass spectrometry (FAB-MS) has attracted much attention in the past few years because of its ability to allow for high molecular weight determination. A series of oligosaccharides were examined under these conditions with a view to defining rules that would aid in structure elucidation problems (e.g. sequencing) in addition to providing further insight into the general understanding of the matrix-related phenomena occurring in FAB. The method appears to be highly stereochemistry-dependent and an approach based upon stereoelectronic concepts can be used to correlate the stereochemistry of the glycosidic bond with certain features of the mass spectrum.