N-(1-deoxy-D-fructos-1-yl) fumonisin B(1), the initial reaction product of fumonisin B(1) and D-glucose

Incubation of fumonisin B(1) and D-glucose in aqueous solutions resulted in the formation of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) in addition to the previously reported N-(carboxymethyl) fumonisin B(1). N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) is the first stable product formed after the Amadori rearrangement of the Schiff base formed by the reaction of the primary amine of fumonisin B(1) and the aldehyde group of D-glucose. N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) was synthesized by reacting fumonisin B(1) with an excess of D-glucose in methanol and heating for 6 h at 64 degrees C. It was purified using C(18) and strong cation exchange solid-phase extraction cartridges and characterized by nuclear magnetic resonance and liquid chromatography-mass spectrometry. Subsequently, N,N-dimethylformamide was found to be a better reaction solvent, requiring reaction for only 2-3 h at 64 degrees C and eliminating the formation of methyl esters. Alkaline hydrolysis of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) gave a mixture of hydrolyzed fumonisin B(1) and hydrolyzed N-(carboxymethyl) fumonisin B(1).

Male-specific sesquiterpenes from Phyllotreta and Aphthona flea beetles

It was previously reported that males of the crucifer flea beetle, Phyllotreta cruciferae, feeding on host foliage are attractive to both males and females in the field. Based on this evidence for an aggregation pheromone, volatiles were collected from male and female P. cruciferae feeding on cabbage (Brassica oleracea) and analyzed. For comparison, volatiles were also collected from males and females of three other flea beetle species, Aphthona flava, A. czwalinae, and A. cyparissiae, all feeding on their host, leafy spurge foliage (Euphorbia esula). Six male-specific compounds were isolated from P. cruciferae, and the same compounds plus two additional ones were isolated from males of Aphthona flava, A. czwalinae, and A. cyparissiae. The blends of compounds were relatively consistent within species, but there were characteristic differences between species. Compound structures were studied by mass spectrometry, NMR spectroscopy, UV spectroscopy, polarimetry, chiral and achiral gas chromatography, molecular modeling, and microchemical tests. Three of the compounds were identified as (+)-ar-himachalene; (+)-trans-alpha-himachalene; (+)-y-cadinene. Two others were new enantiomers of himachalene hydrocarbons that were previously identified from the fir trees, Abies alba and Abies nordmanniana. Finally, there were two himachalene alcohols and one norsesquiterpene ketone that is a himachalene analog. Only (+)-ar-himachalene and (+)-y-cadinene are previously known natural products. Electrophysiological activity was demonstrated for five of the compounds. The chemical and electrophysiological patterns are consistent with, but do not prove, a pheromonal function.

Biotransformation of linoleic acid by Clavibacter sp. ALA2: heterocyclic and heterobicyclic fatty acids

Clavibacter sp. ALA2 transformed linoleic acid into a variety of oxylipins. In previous work, three novel fatty acids were identified, (9Z)-12, 13, 17-trihydroxy-9-octadecenoic acid and two tetrahydrofuran-(di)hydroxy fatty acids. In this report, we confirm the structures of the tetrahydrofuran-(di)hydroxy fatty acids by nuclear magnetic resonance as (9Z)-12-hydroxy-13,16-epoxy-9-octadecenoic acid and (9Z)-7,12-dihydroxy-13,16-epoxy-9-octadecenoic acid. Three other products of the biotransformation were identified as novel heterobicyclic fatty acids, (9Z)-12,17;13, 17-diepoxy-9-octadecenoic acid, (9Z)-7-hydroxy-12,17;13,17-diepoxy-9-octadecenoic acid, and (9Z)-12,17;13,17-diepoxy-16-hydroxy-9-octadecenoic acid. Thus, Clavibacter ALA2 effectively oxidized linoleic acid at C-7, -12, -13, -16, and/or -17.

Fatty acids enhanced tubermycin production by Pseudomonas strain 2HS

A new microbial isolate, Pseudomonas 2HS, produced trace amounts of a greenish-yellow pigment when grown aerobically in a 1% yeast extract medium at 30 degrees C and shaken at 250 rpm for 5 days. In contrast, cells produced more greenish-yellow pigment (2.16 mg/15 ml culture) when grown in the presence of 0.5% 12-hydroxyoctadecanoic acid (w/v). The greenish-yellow pigment was identified as phenazine-1-carboxylic acid (tubermycin B), and the Pseudomonas 2HS was identified as P. aeruginosa 2HS. This is the first report that 12-hydroxyoctadecanoic, ricinoleic and other fatty acids can enhance the production of phenazine-1-carboxylic acid by a Pseudomonas species.

Toxigenic strains of Fusarium moniliforme and Fusarium proliferatum isolated from dairy cattle feed produce fumonisins, moniliformin and a new C21H38N2O6 metabolite phytotoxic to Lemna minor L

Corn samples suspected of causing refusal-to-eat syndrome in dairy cattle were examined mycologically. Fusarium moniliforme (14 isolates) and F. proliferatum (12 isolates) were the predominant fungi present. These isolates were tested for mycotoxin production on rice at 25 degrees C. Each strain of F. moniliforme produced fumonisin B1 (FB1: 378-15,600 ppm) and fumonisin B2 (FB2: 2-1050 ppm). Each strain of F. proliferatum produced moniliformin (45-16,000 ppm), FB1 (27-6140 ppm), and FB2 (5-1550 ppm). In addition, a new Fusarium metabolite of molecular composition C21H38N2O6 was produced by 10 of the F. moniliforme isolates and 7 of the F. proliferatum isolates. The metabolite's 1H- and 13C-NMR, HRFAB/MS and IR spectra indicate an alpha amino acid. It is toxic to Lemna minor L. duckweed (LD50 100 micrograms/mL).

Reduction of Carpophilus freemani dobson (Coleoptera: nitidulidae) aggregation pheromone response by synthetic analogues

Analogues of (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene, the major component of the aggregation pheromone of Carpophilus freemani Dobson (Coleoptera: Nitidulidae), were synthesized and the potency of these compounds in suppressing the response of C. freemani to its pheromone in a wind tunnel bioassay was determined. The most potent compounds reduced behavioral response to pheromone 83-96% when the inhibitors were present in 10-fold excess. These compounds are (1Z, 3E,5E)-1-methoxy-3-ethyl-5-methyl-1,3,5-heptatriene, (1E,3E, 5E)-1-cyclopropyl-3-ethyl-5-methyl-1,3,5-heptatriene, and (1Z,3E, 5E)-1-cyclopropyl-3-ethyl-5-methyl-1,3,5-heptatriene. In the presence of fermenting bread dough (a pheromone synergist), the most potent inhibitory compound, (1Z,3E, 5E)-1-cyclopropyl-3-ethyl-5-methyl-1,3,5-heptatriene, was less effective in reducing mean landings (69% vs 99%) than when dough was absent. This inhibitory compound causes a reduction of response to pheromone but does not cause a reduction of response to fermenting food-type volatiles such as fermenting bread dough. Analogues of pheromones that strongly reduce response to pheromones by insects might be useful as biochemical probes to study the pharmacophoric (three-dimensional structure) requirements for pheromone perception.

Microbial production of a novel trihydroxy unsaturated fatty acid from linoleic acid

A bacterium isolated from a dry soil sample collected from McCalla, AL, USA, converted linoleic acid to a novel compound, 12,13,17-trihydroxy-9 (Z)-octadecenoic acid (THOA). The organism is a Gram-positive, non-motile rod (0.5 microns x 2 microns). It was identified as a species of Clavibacter ALA2. The product was purified by high pressure liquid chromatography, and its structure was determined by 1H and 13C nuclear magnetic resonance and Fourier transform infrared spectroscopies, and by mass spectrometer. Maximum production of THOA with 25% conversion of the substrate was reached after 5-6 days of reaction. THOA was not further metabolized by strain ALA2. This is the first report of a 12,13,17-trihydroxy unsaturated fatty acid and its production by microbial transformation. Some dihydroxy intermediates were also detected. THOA has a structure similar to those of known plant self-defense substances.

Substrate specificity of acetylxylan esterase from Schizophyllum commune: mode of action on acetylated carbohydrates

Substrate specificity of a purified acetylxylan esterase from Schizophyllum commune was investigated on a variety of methyl per-O-acetyl glycopyranosides, methyl di-O-acetyl-beta-D-xylopyranosides and acetylated polysaccharides. The enzyme preferentially deacetylated the 3-position of methyl 2,3,4-tri-O-acetyl-beta-D-xylopyranoside and 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside. Removal of the 3-acetyl group from the xylopyranoside was accompanied by a slower deacetylation at positions 2 and 4. A similarly slower, accompanying deacetylation occurred primarily at position 2 with the glucopyranoside. Such specificity corresponds well to the expected function of the esterase in acetylxylan degradation. Of the three possible diacetates of methyl beta-D-xylopyranoside, the 3,4-diacetate was found to be the most rapidly deacetylated. Unexpectedly, products of its deacetylation were a mixture of 2- and 4-monoacetate. The formation of the methyl 2-O-acetyl-beta-D-xylopyranoside involved an enzyme-mediated acetyl group transfer because the rate of the enzyme-catalyzed reaction exceeded the rate of spontaneous migration of acetyl groups. This is the likely mechanism for acetyl removal from position 2 in the native substrate. The enzyme exhibited the highest regioselectivity with methyl 2,3,4,6-tetra-O-acetyl-beta-D-mannopyranoside. An 80% conversion of this substrate to methyl 4,6-di-O-acetyl-beta-D-mannopyranoside, a new mannose derivative, was achieved. In contrast to the majority of lipases and esterases exploited for regioselective deacetylation, the S. commune acetylxylan esterase did not attack the C-6 acetyl linkages in methyl hexopyranosides when other acetyl groups were available.

Polyketide origin of pheromones of Carpophilus davidsoni and C. mutilatus (Coleoptera: Nitidulidae)

Biosynthesis of pheromones from Carpophilus davidsoni Dobson and C. mutilatus Erichson was investigated by feeding the beetles diets containing isotopically substituted (13C and deuterium) fatty acids and then analyzing the resulting labeled pheromone components. (2E,4E,6E,8E)-7-Ethyl-3,5-dimethyl-2,4,6,8-undecate traene, (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-undecatetraen e and (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene from C. davidsoni and (3E,5E,7E)-5-ethyl-7-methyl-3,5,7-undecatriene from C. mutilatus were abundant enough to be analyzed by both NMR spectroscopy and MS. Eleven additional minor analogues were analyzed only by MS. Each hydrocarbon can be assembled from just three different acyl units: The initial unit can be acetate, propionate or butyrate. Propionate is the second unit in all of the analogues encountered so far, extending the chain by two carbons and producing a methyl branch. Subsequent chain-extending units can be either propionate or butyrate, leading to additional methyl or ethyl branches, respectively. The final acyl unit is either propionate or butyrate and it loses its carboxyl carbon during hydrocarbon biosynthesis. A hydrocarbon with four total units is a triene and one with five is a tetraene. Assembly is proposed to be as in usual fatty acid anabolism, except that other precursor units are used in addition to acetate and that the double-bond reduction step of each chain-elongation cycle does not occur, leaving the conjugated, unsaturated system. Seven of the analyzed hydrocarbons were not previously known to occur in C. davidsoni; two of these are novel: (2E,4E,6E,8E)-5,7-diethyl-3-methyl-2,4,6,8-undecate traene and (2E,4E,6E)-3,5-dimethyl-2,4,6-octatriene.

Analytical determination of fumonisins and other metabolites produced by Fusarium moniliforme and related species on corn

Fumonisins, secondary metabolites of the fungus Fusarium moniliforme are potent toxins that can be found in fungal contaminated corn. The detection and measurement of these toxins by HPLC with detection by an evaporative light scattering detector and by electrospray MS is reported. The light scattering detector had enough sensitivity to analyze culture materials, however, clean-up was necessary to detect fumonisins at sub-ppm levels in naturally contaminated corn extracts. The detection limit for FB1 with the light scattering detector was in the low ng range (10-50) while the detection limit of less than 1 ng injected was observed for the electrospray detector. Several previously unreported fumonisin isomers were observed in electrospray chromatograms of culture extracts. Two of these compounds, FA3 and FA4 were isolated and their proposed structure confirmed by NMR experiments.

The structure of the acidic exopolysaccharide produced by Pseudomonas "gingeri" strain Pf9

The structure of the acidic exopolysaccharide produced by the mushroom pathogen Pseudomonas "gingeri" strain Pf9, a bacterium which causes ginger blotch, was investigated by chemical analysis, mass spectrometry and 1D and 2D NMR spectroscopy. The polysaccharide consists of the linear trisaccharide repeating unit [formula: see text] where the cyclic pyruvic acetal groups at O-4 and O-6 of the mannopyranosyl residues have the S-configuration. Methylation analysis under neutral conditions and NMR data showed that the mannose residues are acetylated at O-2. This exopolysaccharide has the same structure as the E. coli K55 capsular polysaccharide and differs from the Klebsiella K5 capsular polysaccharide only in the position of acetylation (C-2 of the glucopyranose residue).