title: In vivo ESR spin trapping detection of carbon-centered alpha-Farnesene radicals.
abstract: Lyophilisates of the ascomycetes Penicillium solitum and Aspergillus niger converted alpha-farnesene to 7-hydroxyfarnesene as the major product. The radical mechanism of this bioconversion was proven by electron spin resonance (ESR) and GC-MS using the spin trapping technique. Intermediate carbon-centered radicals of alpha-farnesene were captured using two spin traps, 2-methyl-2-nitrosopropane and alpha-(4-pyridyl-1-oxide)- N- tert-butylnitrone, respectively. The evaluation of the coupling constants and hyperfine couplings of the ESR spectra showed that tertiary carbon radicals were trapped. The radical position at C7 of alpha-farnesene was derived from EI and CI mass spectra of the corresponding MNP spin adduct. The present study demonstrates that the complementary application of ESR and MS spectrometric data allows the detailed evaluation of a radical mechanism of a fungal terpene transformation reaction.
authors.affiliation: Institut für Lebensmittelchemie, Zentrum für Angewandte Chemie der Leibniz Universität Hannover, Wunstorfer Strasse 14, D-30453 Hannover, Germany. krings@lci.uni-hannover.de
authors.forename: Ulrich
authors.initials: U
authors.lastname: Krings
authors.forename: Mogens L
authors.initials: ML
authors.lastname: Andersen
authors.forename: Ralf G
authors.initials: RG
authors.lastname: Berger
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005609:Free Radicals / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D025282:Mycelium / Q000737:chemistry; D010407:Penicillium / Q000378:metabolism; D012717:Sesquiterpenes / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005609:Free Radicals; D012717:Sesquiterpenes; C062672:alpha-farnesene