Per Kolsaker

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Two cytotoxic triterpenes have been isolated from Euphorbia pulcherrima. Their structures and stereochemistry have been established from NMR, IR, and EI-mass spectroscopy. The compounds were identified as 9,19-cycloart-23-ene-3 beta,25-diol and, 9,19-cycloart-25-ene-3 beta,24-diol. Cytotoxicity evaluation was performed using Ehrlich ascites tumor cells.(More)
Twenty-three Fusarium culmorum and 21 F. graminearumisolates were studied for their ability to produce mycotoxins and other secondary metabolites. The strains were cultivated on rice, and the extracts analysed by gas chromatography mass spectrometry (GC-MS) after derivatization with pentafluoropropionic (PFP) reagent. Two F. culmorum strains formed(More)
The biosynthesis of 2-oxo-3-methylvalerate in Chlorobium vibrioforme was investigated by 13C nuclear magnetic resonance spectroscopy of the oxoacid formed from 13C-labeled acetate by washed suspensions. The threonine pathway could be excluded, and the results are in accord with a mechanism for the formation of 2-oxobutyrate from acetyl coenzyme A and(More)
A method for the separation and identification of chlorinated styrene isomers with fully chlorinated aromatic nuclei in environmental samples is presented. Gas chromatography combined with negative ion chemical ionization mass spectrometry is used. The method has been applied to a combined fish liver and filét extract. All the possible chlorostyrenes with(More)
A metabolic product was formed from ochratoxin B by rat liver microsomal fractions in the presence of NADPH. It was isolated from the incubation mixture by extraction, thin-layer chromatography, high-pressure liquid chromatography, and crystallization. On the basis of mass and nuclear magnetic resonance spectroscopy, the structure is suggested to be(More)
MYCOTOXICOSES AND MYCOTOXINS Production of culmorin compounds and other secondary metabolites by Fusarium culmorum and F. graminearum strains isolated from Norwegian cereals – Wenche Langseth, Mebrat Ghebremeskel, Barbara Kosiak, Per Kolsaker & David Miller 23–34 Seasonal variation in exposure frequency and concentration levels of aflatoxins and ochratoxins(More)
The principal substance in Narthecium ossifragum (L.) Huds, responsible for the nephrotoxic effects on cattle, moose, goats and other ruminants has been isolated and identified by X-ray crystallography as 3-methoxy-2(5H)-furanone. The Fourier-transform infra-red, 1H and 13C nuclear magnetic resonance, and mass spectra are also given. The concentration in(More)
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