The efficacy of a cultured Synergistes jonesii inoculum to control hydroxypyridone toxicity in Bos indicus steers fed leucaena/grass diets

An experiment was conducted to investigate the efficacy of a cultured Synergistes jonesii inoculum in degrading the Leucaena leucocephala (leucaena) toxins: 3-hydroxy-4(1H)-pyridone and 3-hydroxy-2(1H)-pyridone (3,4- and 2,3-DHP). Sixteen stall-housed Bos indicus steers naïve to leucaena were fed varying combinations of forage-harvested leucaena and Chloris gayana (Rhodes grass). Dietary treatments, offered at 25 g dry matter/kg LW.day, were: 25% leucaena; 50% leucaena; 100% leucaena; and 50% leucaena, switched to 50% Medicago sativa (lucerne) after 6 weeks at time of inoculation. The experiment was 10 weeks in duration, consisting of a 6-week pre-inoculation period, followed by inoculation with cultured S. jonesii, and a 4-week post-inoculation period. Mean daily dry matter intake was recorded. Twenty-four-hour urine collections and rumen fluid samples were obtained weekly for estimation of total urinary DHP, and detection of S. jonesii using nested polymerase chain reaction analysis including presence of single nucleotide polymorphisms (SNP), respectively. In the pre-inoculation period, total urinary DHP increased quickly to high levels, then gradually declined after Week 3 with 2,3-DHP the dominant isomer through to Week 6. Indigenous strains of S. jonesii were sporadically detected by PCR analysis, indicating S. jonesii was present before inoculation but at the lower limits of detection. After inoculation there was no change in the rate of total DHP degradation or the frequency of detection of S. jonesii, although there was increased rate of degradation of 2,3-DHP. SNP indicated the presence of different strains of S. jonesii in both indigenous and cultured S. jonesii. DMI was low, especially in the 100% treatment, due in part to the high stem content of the forage-harvested leucaena and probable DHP toxicosis. It was concluded that the cultured S. jonesii inoculum did not fully protect animals against leucaena toxicity.

Unexpected solvent effects on the UV/Vis absorption spectra of o -cresol in toluene and benzene: in contrast with non-aromatic solvents

Cresol is a prototype molecule in understanding intermolecular interactions in material and biological systems, because it offers different binding sites with various solvents and protonation states under different pH values. It is found that the UV/Vis absorption spectra of o -cresol in aromatic solvents (benzene, toluene) are characterized by a sharp peak, unlike the broad double-peaks in 11 non-aromatic solvents. Both molecular dynamics simulations and electronic structure calculations revealed the formation of intermolecular π-complexation between o -cresol and aromatic solvents. The thermal movements of solvent and solute molecules render the conformations of o -cresol changing between trans and cis isomers. The π-interaction makes the cis configuration a dominant isomer, hence leading to the single keen-edged UV/Vis absorption peak at approximately 283 nm. The free conformation changes between trans and cis in aqueous solution rationalize the broader absorption peaks in the range of 260–280 nm. The pH dependence of the UV/Vis absorption spectra in aqueous solutions is also rationalized by different protonation states of o -cresol. The explicit solvent model with long-ranged interactions is vital to describe the effects of π-complexation and electrostatic interaction on the UV/Vis absorption spectra of o -cresol in toluene and alkaline aqueous (pH > 10.3) solutions, respectively.

Diels-Alder Cycloaddition: Defucogilvocarcin V (Bodwell), (+)-Carrisone (Danishefsky), (+)-Fusarisetin A (Theodorakis), 9β-Presilphiperfolan-1α-ol (Stoltz), 7-Isocyano-11(20),14-epiamphilectadiene (Shenvi)

Graham J. Bodwell of Memorial University constructed (J. Org. Chem. 2012, 77, 8028) the third aromatic ring of defucogilvocarcin V 4 by the inverse electron demand addition of 1 to 2. The methyl ester 3 provided a useful departure point for the preparation of analogues of 4. Samuel J. Danishefsky of Columbia University and Sloan-Kettering found (Chem. Sci. 2012, 3, 3076) that the kinetic product from the addition of 5 to 6 could be equilibrated with a trace of acid to the more stable regioisomer 7. Oxidation to the enone followed by deoxygenation led to (+)-carissone 8. Michael E. Jung of UCLA developed (Org. Lett. 2012, 14, 5169) Me3Al-triflimide catalysts (not illustrated) for promoting difficult additions such as 5 to 6. Professor Danishefsky had demonstrated the efficacy of cyclobutenones as Diels-Alder dienophiles. More recently, he showed (J. Am. Chem. Soc. 2012, 134, 16080) that intramolecular cyclization of the cyclobutenone 9 led to the transfused, angularly substituted product 11. To prepare (+)-fusarisetin A 14, Emmanuel A. Theodorakis of the University of California San Diego needed (Chem. Sci. 2012, 3, 3378) the all-E geometric isomer of 12. He showed that equilibration of a 3:2 mixture with I2 led to a single dominant isomer that could be taken directly into the cycloaddition. Brian M. Stoltz of CalTech prepared (Angew. Chem. Int. Ed. 2012, 51, 9674) the triene 15 in enantiomerically enriched form by enantioselective allylation of a cycloheptenone derivative. Intramolecular cycloaddition of 15 established the tricyclic skeleton of 9β-presilphiperfolan-1α-ol 17. Ryan A. Shenvi of Scripps/La Jolla devised (J. Am. Chem. Soc. 2012, 134, 19604) the triene 19. Addition of 18 to 19 gave an intermediate that was unraveled with catalytic Yb(OTf)3 to give a trienone, which on heating engaged with the distal alkene to cyclize to 20. This set the stage for diastereoselective conjugate addition leading to 7-isocyano-11(20 ),14-epiamphilectadiene 21.

Characteristics of Organchlorine Pesticides in Sediments of Lianhuan Lake

In this study, sediment samples were collected in Huoshaohei (HSH), Xihulu (XHL), Amuta (AMT), and Talahong (TLH) of Lianhuan Lake. Eleven chemical compounds of OCPs measured using GC-ECD method in the study area, including four HCH isomers (α-HCH, β-HCH, γ-HCH, δ-HCH), three DDT homologues (p,p’-DDT, p,p’-DDD, p,p’-DDE), Aldrin, Dieldrin, Endrin and Heptachlor. The ratio of (DDE + DDD)/∑DDT, the content of ∑HCH and ∑DDT, the correlations among TOC, ∑HCH, ∑DDT and OCPs were analyzed. The results show that HCHs and DDTs are major elements in this region and δ-HCH is the most dominant isomer in HCH, which was evidence of recent input of lindane. And higher amounts of OCPs occur in sediments with higher TOC content, DDTs and HCHs have similar sources which may come from usage of lindane and DDT in recent years.

Competing Diels–Alder intramolecular pathways from cross-conjugated trienes: Fused hydrindenones (bicyclo[4.3.0]nonenones) vs. bridged-ring (bicyclo[3.3.1]nonenones) adducts from a diene-transmissive precursor

D-Isoascorbic acid was converted to the tetraenone 12 to examine its behaviour in the intramolecular Diels–Alder reaction with pendant dienes in a diene-transmissive environment. These studies were directed toward the synthesis of the hydrindenone nucleus via a tether-controlled Diels–Alder reaction. It was anticipated that this would lead to a diene-transmissive strategy for steroids such as Desogestrel®. In contrast to our previous studies with decalins, the dominant isomer (150 °C) was the bicyclo[3.3.1]nonadieneone adduct 23, and none of fused adduct 27 was detected. These products were accompanied by two minor hydrindenone adducts 24 and 25. The isomer ratio was dependent on the temperature of the reaction.Key words: Diels–Alder, hydrindane, pentadienylation, intramolecular cycloaddition, bicyclo[3.3.1]nonenone.

2,4,6-Trinitrotoluene Reduction by Carbon Monoxide Dehydrogenase from Clostridium thermoaceticum

ABSTRACT Purified CO dehydrogenase (CODH) from Clostridium thermoaceticum catalyzed the transformation of 2,4,6-trinitrotoluene (TNT). The intermediates and reduced products of TNT transformation were separated and appear to be identical to the compounds formed by C. acetobutylicum, namely, 2-hydroxylamino-4,6-dinitrotoluene (2HA46DNT), 4-hydroxylamino-2,6-dinitrotoluene (4HA26DNT), 2,4-dihydroxylamino-6-nitrotoluene (24DHANT), and the Bamberger rearrangement product of 2,4-dihydroxylamino-6-nitrotoluene. In the presence of saturating CO, CODH catalyzed the conversion of TNT to two monohydroxylamino derivatives (2HA46DNT and 4HA26DNT), with 4HA26DNT as the dominant isomer. These derivatives were then converted to 24DHANT, which slowly converted to the Bamberger rearrangement product. ApparentKm and k cat values of TNT reduction were 165 ± 43 μM for TNT and 400 ± 94 s−1, respectively. Cyanide, an inhibitor for the CO/CO2 oxidation/reduction activity of CODH, inhibited the TNT degradation activity of CODH.

Observation of buttressing effect and hindered rotation about C(sp2)—C(sp2) single bond in styrenes coordinated to a ruthenium cation, Cp(diphosphine)Ru+

Complexes of (η5-cyclopentadienyl)(bis(di-p-tolylphosphino)ethane)ruthenium(II) cation with some styrenes containing meta or para substituants were prepared and their NMR spectra examined in detail. Variable-temperature NMR studies on the unsubstituted and para-substituted styrene analogues demonstrated occurrence of a restricted rotation about the C(sp2)—C(sp2) single bond of the styrenes where one of the ortho hydrogens of the styrene phenyl group receives a very large diamagnetic shielding effect by one of the phosphine tolyl groups. Similar studies on the meta-substituted styrene complexes showed existence of two unequally populated conformational isomers arising from the similar restricted rotation where the meta substituent in the dominant isomer was placed further away from the C=C group. The origin of such conformational isomerism was deduced to be the buttressing effect of the meta substituent transmitted via the ortho-hydrogen atom. Key words: buttressing effect, hindered rotation, Ru–styrene complex.