TY  - THES
T1  - Isolation, characterisation and biosynthetic precursors of natural products from myxobacteria
A1  - Zander,Wiebke
Y1  - 2011/05/27
N2  - Myxobacteria are an extraordinary group of soil bacteria and versatile producers of numerous biologically active natural products. The aim of the thesis was the characterisation of novel secondary metabolites from these gliding bacteria. An activity guided isolation procedure for the oxygen- and light-sensitive roimatacene (26) from the crude extract of Cytsobacter ferrugineus strain Cb G35 was developed. The mild isolation strategy included among other stabilization techniques the addition of the free radical scavenger 4-ethoxyphenol. The relative configuration of 26 was establishing by applying Rychonovsky's acetonide method combined with 1D and 2D NMR studies and molecular modelling. The absolute configuration of 26 was assigned by Mosher's method. In addition, strain Cb G35 was found to produce a family of six p-hydroxyacetophenone amides 34a-f. The biosynthetic precursors of roimatacene (26) and p-hydroxyacetophenone iso-butanamide (34a) were studied by feeding experiments with D-, 13C- and 15N-labelled precursors. The structures of the myxobacterial sulfangolids 25a-d were verified from their NMR data. The relative configuration of sulfangolid C (25c) was derived by detailed NMR analyses and comparison of the modelled 13R* and 13S* diastereomeres of 25c to finally establish the relative all-trans 13R*,14S*,15R*,16R*,17S*,19S*,20R*,26R*,27R* configuration. The biosynthetic precursors of 25c were studied by feeding experiments.

KW  - Naturstoff
KW  - Sekundärmetabolit
KW  - NMR-Spektroskopie
CY  - Saarbrücken
PB  - Universitäts- und Landesbibliothek
AD  - Postfach 151141, 66041 Saarbrücken
UR  - http://scidok.sulb.uni-saarland.de/volltexte/2011/3932
ER  -