Effects of bis homoallylic and homoallylic hydroxyl substitution on the olefinic 13C resonance shifts in fatty acid methyl esters

Substitution of a hydroxyl group at the bis homoallylic position (OH group located three carbons away from the olefinic carbon) in C18 unsaturated fatty acid esters (FAE) induces a 0.73 +/- 0.05 ppm upfield and a 0.73 +/- 0.06 ppm downfield shift on the delta and epsilon olefinic 13C resonances relative to the unsubstituted FAE, respectively. If the hydroxyl group is located on the carboxyl side of the double bond of the bis homoallylic hydroxy fatty acid esters (BHAHFA), the olefinic resonances are uniformly shifted apart by [formula: see text] where delta delta dbu represents the absolute value of the double bond resonance separation in the unsubstituted FAE and 1.46 ppm is the sum of the absolute values of the delta and epsilon shift parameters. With hydroxyl substitution on the terminal methyl side of the double bond, the olefinic shift separation is equal to [formula: see text] In homoallylic (OH group located two carbons away from the olefinic carbon) substituted FAE the gamma and delta induced hydroxyl shifts for the cis double bond resonances are +3.08 and -4.63 ppm, respectively while the trans double bond parameters are +4.06 and -4.18 ppm, respectively. The double bond resonance separation in homoallylic hydroxy fatty acid esters (HAHFA) can be calculated from the formula [formula: see text] for cis and [formula: see text] for the trans case when the OH substitution is on the carboxyl side of the double bond. Conversely, when the OH resides on the terminal methyl side, the double bond shift separations for cis and trans isomers are [formula: see text] and [formula: see text] respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

A new fumonisin from solid cultures of Fusarium moniliforme

A new fumonisin has been isolated from Fusarium moniliforme isolate MRC826 grown on corn. It was shown by NMR and mass spectrometry to be an isomer of fumonisin B2 that has free hydroxyl groups at C-3 and C-10 instead of the normal C-3 and C-5. This new fumonisin was detected in cultures of most isolates of F. moniliforme that were examined and was usually present at concentrations similar to those of fumonisin B2. Two isolates of F. moniliforme that produce significantly higher levels of this new isomer were identified.

Hydroperoxide Lyase and Other Hydroperoxide-Metabolizing Activity in Tissues of Soybean, Glycine max

Hydroperoxide lyase (HPLS) activity in soybean (Glycine max) seed/seedlings, leaves, and chloroplasts of leaves required detergent solubilization for maximum in vitro activity. On a per milligram of protein basis, more HPLS activity was found in leaves, especially chloroplasts, than in seeds or seedlings. The total yield of hexanal from 13(S)-hydroperoxy-cis-9,trans-11-octadecadienoic acid (13S-HPOD) from leaf or chloroplast preparations was 58 and 66 to 85%, respectively. Because of significant competing hydroperoxide-metabolizing activities from other enzymes in seed/seedling preparations, the hexanal yields from this source were lower (36-56%). Some of the products identified from the seed or seedling preparations indicated that the competing activity was mainly due to both a hydroperoxide peroxygenase and reactions catalyzed by lipoxygenase. Different HPLS isozyme compositions in the seed/seedling versus the leaf/chloroplast preparations were indicated by differences in the activity as a function of pH, the K(m) values, relative V(max) with 13S-HPOD and 13(S)-hydroperoxy-cis-9,trans-11,cis-15-octadecatrienoic acid (13S-HPOT), and the specificity with different substrates. With regard to the latter, both seed/seedling and chloroplast HPLS utilized the 13S-HPOD and 13S-HPOT substrates, but only seeds/seedlings were capable of metabolizing 9(S)-hydroperoxy-trans-10,cis-12-octadecadienoic acid into 9-oxononanoic acid, isomeric nonenals, and 4-hydroxynonenal. From 13S-HPOD and 13S-HPOT, the products were identified as 12-oxo-cis-9-dodecenoic acid, as well as hexanal from 13S-HPOD and cis-3-hexenal from 13S-HPOT. In seed preparations, there was partial isomerization of the cis-3 or cis-9 into trans-2 or trans-10 double bonds, respectively.

4-O-(1-carboxyethyl)-L-rhamnose, a second unique acidic sugar found in an extracellular polysaccharide from Butyrivibrio fibrisolvens strain 49

Butyrivibrio fibrisolvens strain 49 excretes a polysaccharide that contains D-glucose, D-galactose, 4-O-(1-carboxyethyl)-D-galactose, and an acidic component of previously unknown structure. We report here the identity of the unknown as 4-O-(1-carboxyethyl)-L-rhamnose. The structure of this previously unknown compound was deduced from (1) comprehensive electron-impact and chemical-ionization mass-spectroscopic studies of differentially labelled derivatives prepared from the unknown, (2) 13C-n.m.r. and 1H-n.m.r. studies of purified neutral sugars derived from the unknown and (3) chemical degradation experiments.

Leucine auxotrophy specifically alters the pattern of trichothecene production in a T-2 toxin-producing strain of Fusarium sporotrichioides

The biosynthetic pathway for trichothecenes in the filamentous fungus Fusarium sporotrichioides NRRL 3299 has been further characterized. Experiments using the techniques of mutational analysis and the incorporation of radiolabeled precursors indicated that leucine is a direct precursor to the isovalerate moiety present in the trichothecene, T-2 toxin. Analysis of trichothecene production in a UV-induced leucine auxotroph also revealed the existence of a branched biosynthetic pathway which results in the coproduction of T-2 toxin and the T-2 toxin analogs neosolaniol, 8-isobutyryl-neosolaniol, and 8-propionyl-neosolaniol. Leucine limitation imposed by the leucine auxotroph simultaneously led to underproduction of T-2 toxin and overproduction of these T-2 toxin analogs, which are produced in small amounts by the wild-type parent. Furthermore, it was shown that the ratio of T-2 toxin to T-2 toxin analogs produced by the leucine auxotroph can be modulated by the concentration of leucine in the medium. These results suggest that the four trichothecenes mentioned above are derived from a common intermediate and that there is competition for this intermediate among the branched pathways leading to these four cometabolites.

Cyclic fatty esters: hydroperoxides from autoxidation of methyl 9-(6-propyl-3-cyclohexenyl)-(Z)8-nonenoate

Autoxidation of the cyclic fatty acid ester, methyl 9-(6-propyl-3-cyclohexenyl)-(Z)8-nonenoate (I) was investigated to characterize the hydroperoxide isomers formed and to provide basic information on their chemistry, detection and effect on the quality of polyunsaturated cooking oils. Oxidation at 60 C with 1% hydroperoxide initiator produced a monohydroperoxide fraction containing five positional isomers (7-, 11-, 12-, 13- and 14-OOH), resolved by high performance liquid chromatography, as their allylic hydroxy esters. Their structures were established by 1H- and 13C-NMR spectroscopy and by capillary gas chromatography-mass spectrometry (GC-MS) as trimethylsilyl ether derivatives. Two additional isomers (8- and 9-OOH) were detected by GC-MS in only trace (less than 1%) quantities. Capillary GC resolved some geometric and stereoisomers, as well as positional isomers. Compared to photosensitized oxidation, two additional positional isomers (11- and 14-OOH) were produced by autoxidation. More stereoisomers were formed, and oxidation of the ring double bond was favored 8:1 over that of the side chain. This selectivity may be attributed to greater steric hindrance for oxygen attack at the side-chain double bond. A free radical mechanism is proposed to explain the greater isomeric complexity of the hydroperoxide products compared to photosensitized oxidation.

Isolation and structure of rolliniastatin 1 from the South American tree Rolliniamucosa

Rolliniamucosa (Annonaceae), known in primitive medical practices of Indonesia and the West Indies as a treatment for tumors, has been investigated employing the seeds from a South American variety and the murine P388 lymphocytic leukemia (PS) for bioassay. The principal antineoplastic constituent (PS, 28% life extension, at 0.25 mg/kg and ED504.5 × 10−5 μg/mL) was found to be a new bis-tetrahydrofuran designated rolliniastatin 1. Structural elucidation of rolliniastatin 1 was accomplished by a combination of high resolution nuclear magnetic resonance (300 MHz), mass spectral, and X-ray crystal structure techniques.

Cyclic fatty esters: synthesis, characterization, and lipolysis of isomeric triglycerides of 9-(6-propyl-3-cyclohexenyl)-(Z)8-nonenoic acid

Triglycerides of a model cyclic fatty acid (CFA) 9-(6-propyl-3-cyclohexenyl)-(Z)8-nonenoic acid (Ia) were synthesized for biological and toxicity evaluations. The monoacid triglyceride II (CyCyCy) was interesterified with triolein (OOO) to obtain mixtures of diacid triglycerides: III (OOCy), IV (OCyO), V (OCyCy), and VI (CyOCy). The interesterification mixtures were separated by preparative HPLC into two 'critical pairs' of isomeric triglycerides. Triglycerides III-VI were synthesized and a 13C-NMR method was developed to estimate 'critical pairs'. CFA-triglycerides were characterized by IR, NMR, HPLC and capillary GLC, and their relative rates of hydrolysis by lipase were compared. Although tricyclin (II) was completely resistant to lipolysis, triglycerides III and VI hydrolyzed significantly slower than triolein, and the 'critical pairs' hydrolyzed as readily as triolein. Therefore, partial CFA-triglycerides formed in heat-abused fats can undergo lipolysis and likely be absorbed like normal dietary fats.

Isolation and characterization of two new fusaric acid analogs from Fusarium moniliforme NRRL 13,163

Fusarium moniliforme NRRL 13,163 produced two new fusaric acid analogs, a 10,11-dihydroxyfusaric acid and a diacid of fusaric acid in which the C-11 methyl was oxidized to a carboxyl. Several hundred milligrams of the 10,11-dihydroxyfusaric acid were routinely recovered from a kilogram of corn grit medium. It crystallized as white, irregularly shaped rectangles that melted at 153 to 154 degrees C. The diacid analog of fusaric acid crystallized as white rods that melted at 210 to 211 degrees C. Unlike the consistent recovery experienced with the 10,11-dihydroxyfusaric acid, the diacid analog proved difficult to purify after the initial discovery and was detectable in subsequent fermentations only by mass spectrometry.

Phytoecdysteroids of Diploclisia glaucescens Seed

Five phytoecdysteroids were isolated from the seeds of DIPLOCLISIA GLAUCESCENS and identified by spectrometric methods ( (1)H-NMR, (13)C-NMR and CIMS). One of them, 24- EPI- makisterone A, has not been reported before. The other four - 20-hydroxyecdysone, makisterone A, 24(28)-dehydromakisterone A and pterosterone - were known previously. The (13)C-NMR spectrum of 24(28)-dehydromakisterone A is presented for the first time.