Low-molecular bio-constituents with emphasis on post-infectional metabolites of potato
1997
Engstroem, K. (SLU, Uppsala (Sweden). Inst. foer Kemi)
This thesis mainly deals with the structural characterisation of post-infectional sesquiterpenoids accumulated in the stress zones of potato tubers (Solanum tuberosum L.) naturally infected with Phoma foveata and Fusarium spp. Included is an absolute configurational determination of an epimeric pair using NMR techniques, CD measurements and chemical methods. Two more epimeric pairs are described, among other compounds of which five are novel. The antifungal activity to Phytophthora infestans of seven sesquiterpenoids, including a unique post-infectional glucoside and its aglycone, was tested. All sesquiterpenoids suppressed the growth of the pathogen, except for the glucoside and its aglycone which induced a growth stimulation. A study of sugar content during induction of systemic acquired resistance to P. infestans showed large differences in amounts and proportions between the different treatments, indicating that reduced availability of energy might be an induced defence mechanism to the hemibiothrophic fungus. A guinea-pig ileum bioassay-guided isolation from fruits of Solanum tuberosum yielded serotonin, and a distribution study of the substance in the potato plant was performed. The anthraquinone pigments from several Drechslera species and Bipolaris sorokiniana were isolated and characterised. A study of bioactivity to some bacteria was also included.
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