Per Kolsaker

Production of culmorin compounds and other secondary metabolites by Fusarium culmorum and F. graminearum strains isolated from Norwegian cereals

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 nivalenol and its acetylated derivatives (chemotype II), while all F. graminearum and the otherF. culmorum isolates produced deoxynivalenol (DON) via 3-acetyldeoxynivalenol (3-acetyl-DON) (chemotype IA). 15-hydroxy-culmorin, followed by 5-hydroxy-culmorin were the main other metabolites produced F. culmorum, while 5-, 12- and an unidentified hydroxy-culmorin, suggested to be 14-hydroxy-culmorin, were the main metabolites of F. graminearum. The hydroxy-culmorin profile was found to be significantly different for the two Fusarium species. Minor amounts of about ten other hydroxy-culmorins, four hydroxy-culmorones and 3,13-dihydroxy-epiapotrichothecene were also detected in most cultures. Traces of sambucinol seemed to be present in some of the isolates, but were not detected in any significant amounts. The precursors in the biosynthetic sequence to 3-acetyldeoxynivalenol,7,8-dihydroxycalonectrin and 15-deacetyl-7,8-dihydroxycalonectrin,were detected in most cultures. We also report the assignment of both the 1H and13C NMR data of 15-deacetyl-7,8-dihydroxycalonectrin, which has only been reported incorrectly before.

Isolation and characterization of 3-methoxy-2(5H)-furanone as the principal nephrotoxin from Narthecium ossifragum (L.) Huds.

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 four different batches of plant material varied from 113 to 344 microg g(-1) (wet weight). Extracts of N. ossifragum and fractions derived from them, including purified 3-methoxy-2(5H)-furanone, were each dosed intraruminally, to young goats. 3-Methoxy-2(5H)-furanone of 99.9% purity (15 mg kg(-1) live weight) caused increased concentration of creatinine in serum within 2-3 days, typical of kidney damage caused by N. ossifragum, while toxic effect was obtained down to 4 mg kg(-1) live weight with less purified material (> or = 95%). Toxic effect was also obtained with synthesized 3-methoxy-2(5H)-furanone (30 mg kg(-1) live weight). The isomer 4-methoxy-2(5H)-furanone, detected in some of the batches of the plant material, was not toxic when dosed at 60 mg kg(-1) live weight.

The analogy between CO and C(CN)2. Part 2. Structural properties of N,N-dialkylaminobenzamides and the analogously substituted 2-(phenylmethylene)propanedinitriles

The barrier to rotation around the carbon amino nitrogen bond in 2-[N,N-dimethylamino(phenyl)methylene]propanedinitrile (4a), 2-[N,N-diethylamino(phenyl)methylene]propanedinitrile (4b), 2-[(phenyl)pyrrolidin-1-ylmethylene]propanedinitrile (4c), N,N-dimethylbenzamide (5a), N,N-diethylbenzamide (5b) and (phenyl)pyrrolidin-1-ylmethanone (5c) were determined using dynamic 1H NMR spectroscopy. X-Ray crystal structures of 4a, 4b, 4c and 5a were determined, and quantum chemical calculations were carried out for 4a and 5a and for the transition structures for the rotation process of these two compounds. The barriers were generally lower than for the vinyl analogues 1 and 2. Although the calculated transition structures for 4a and 5a indicate some steric strain, the reduction of the barriers, especially for series 4, indicates that steric strain is more important in the ground state, thus raising its energy relatively more than for the transition state.

Nucleophilic substitution reactions of allylic halides carrying electron-withdrawing substituents in the γ-position. Formation of cyclopropanes from dimethyl 2-bromo-2-methylpropylidenemalonate

Reaction of dimethyl 2-bromo-2-methylpropylidenemalonate with sodium methoxide or potassium cyanide in methanol produces cyclopropane derivatives in high yields, thus indicating an overall substitution with nucleophilic attack occurring at the β-position of the allylic halide.