Synthesis of β -Cyperone via Fungal Hydroxylation of thujone-derived tricyclic cyclopropanes

Synthesis of optically active sesquiterpenes with a eudesmane C-skeleton from the chiral starting material thujone involves transformation of a tricyclic intermediate (1R,2R,4S)-1,7-dimethyl-4-(1-methylethyl)tricyclo[4.4.0.0^2,4]dec-6-en-8-one ( 2 ) into the bicyclic compound β -cyperone ( 5 ). Hydroxylation of 2 at C(5) or C(11) permits subsequent opening of the cyclopropane ring and rearrangement to β -cyperone. In this publication, studies involving hydroxylation of 2 by fungal cultures are presented. The resultant products are useful intermediates in efficient synthesis of eudesmane sesquiterpenes. Of five fungi tested, Rhizopus oryzae ATCC 11145 proved most versatile. It hydroxylates at the exocyclic C(11) position in high yield (70%) and, to a lesser extent, at C(5) (5%). Enzymatic activity appears at the end of growth phase and at least 2.2 g of 2 per liter can be metabolized without significant loss of product yield. A second fungus, Cunninghamella echinulata ATCC 9244, proved most useful for hydroxylation of derivatives of 2 for the preparation of derivatives of β -cyperone, although product yields were low (2–20%), some derivatives were nonreactive, and hydroxylation at C(9) occurred. The relationship between precursor structure and enzyme affinity is discussed.     

Elliott-Morse measures and Kakutani's dichotomy theorem

Dedicated to the memory of John Oxtoby     

Bioaccumulation and excretion of arsenic compounds by a marine unicellular alga,polyphysa peniculus

Polyphysa peniculus was grown in artificial seawater in the presence of arsenate, arsenite, monomethylarsonate and dimethylarsinic acid. The separation and identification of some of the arsenic species produced in the cells as well as in the growth medium were achieved by using hydride generation–gas chromatography–atomic absorption spectrometry methodology. Arsenite and dimethylarsinate were detected following incubation with arsenate. When the alga was treated with arsenite, dimethylarsinate was the major metabolite in the cells and in the growth medium; trace amounts of monomethylarsonate were also detected in the cells. With monomethylarsonate as a substrate, the metabolite is dimethylarsinate. Polyphysa peniculus did not metabolize dimethylarsinic acid when it was used as a substrate. Significant amounts of more complex arsenic species, such as arsenosungars, were not observed in the cells or medium on the evidence of flow injection–microwave digestion–hydride generation–atomic absorption spectrometry methodology. Transfer of the exposed cells to fresh medium caused release of most cell–associated arsenicals to the surrounding environment.     

Multiparameter Polynomial Adaptive Stabilizers

In 1983 Morse proved, for unknown scalar one-dimensional linearsystems, the nonexistence of rational or polynomial universalstabilizers (UAS). In 1983, Nussbaum gave an example of an analyticUAS. In our paper, it is shown that there exist time-invariantpolynomial UAS's with multidimensional gain adaptation. Thedesign procedure is developed for linear, minimum-phase systemsof relative degree one. Convergence of the closed-loop systemis proved. Some numerical simulations are provided.     

Use of biosensors for rapid drug residue analysis without sample deconjugation or clean-up: a possible way forward.

The drug salbutamol (SBL) is a beta-agonist that may be used illegally as an animal growth promoter. SBL is also a good example of a drug which is excreted in the form of glucuronides and sulfates. Such metabolites cause complexities in analysing for the presence of drug residues. In the majority of cases a process of deconjugation and sample clean-up is required prior to analysis. This is both time consuming and causes some loss of accuracy. In this study, the urine of calves treated with SBL orally for 3 d was collected during and after medication. Samples were assayed before and after hydrolysis by two different methods, radioimmunoassay (RIA) and a newly developed biosensor immunoassay (BIA). Some samples were also analysed by GC-MS. The results clearly showed that both screening assays (RIA and BIA) found high concentrations of SBL residues throughout the study. This was especially true in the BIA method. It was also demonstrated that urine sample analysis without the need for deconjugation or clean-up could be achieved. Results obtained by GC-MS tended to be an order of magnitude lower than the corresponding screening test results. This work showed that biosensor based veterinary drug residue testing procedures can be developed which can generate results in real time without the need for time consuming sample preparation.     

Monensin carry-over into unmedicated broiler feeds.

European Union Member States are now required to monitor poultry meat for the presence of coccidiostat residues. Among other factors contributing to the production of residue-free food is the ability of animal feed manufacturers to produce medication-free feedstuffs, ensuring the proper observance of withdrawal periods prior to slaughter. Carry-over of medication was investigated in a local poultry feed mill that was using monensin as its principal coccidiostat for broilers. Monensin, at levels in excess of 5% of the therapeutic dose (approximately 110 mg kg-1), was present in 22.5% of 40 withdrawal feeds. Subsequent studies in the mill indicated that most of the contamination occurred during the processing of feeds after the mixing stage. The mill altered its manufacturing process as a result of this study. The consequence of this was that the incidence of monensin withdrawal feeds, at levels greater than 5% of the therapeutic dose, fell from 22.5 to 2.5%. This collaborative study has helped the feed compounder to produce more effective withdrawal feeds, thereby reducing the potential exposure of consumers to unwanted residues of monensin in poultry meat.     

Substitution reactions of 4-methyldibenzothiophene

Succinoylation, acetylation and nitration of 4-methyldibenzothiophene yields 2-substituted products. Bromination however, gave 3-bromo-4-methyldibenzothiophene as the major product along with a small amount of the 2-isomer. The bromo-compounds were used to prepare related derivatives via lithium exchange. 4-Methyldibenzothiophene 5,5-dioxide was also shown to nitrate in the 3-position. The structures of the derivatives were determined by NMR analyses. An alternative synthesis of 4-methyldibenzothiophene is described.     

Quantitative NMR measurements in copolymers of vinylidene chloride and acrylonitrile: The effect of saturation and varying nuclear Overhauser enhancements

Spin-lattice relaxation times and nuclear Overhauser enhancements (NOE) for ¹³C nuclei in copolymers of acrylonitrile and vinylidene chloride were measured at 20.1 and 67.9 MHz. In the ? CCl₂? region of the spectrum T₁ and NOE values of the various resonances are equal within experimental error and are invariant to changes in composition. The T₁ and NOE values of the ? CCl₂? region, however, are not equal to those of the ? CH? or ? CN region. As a result compositions cannot be calculated by direct comparison of the areas in the ? CCl₂? region and either the ? CH? or the ? CN region. Discrepancies can be corrected for the ? CH? resonances by multiplication of the area by an empirical constant. A similar constant for the ? CN region is composition-dependent at 20.1 and 67.9 MHz. A chemical shift anisotropy mechanism is postulated as important for relaxation of the ? CN resonances. The overall influence of variable T₁ and NOE values on quantitative determination of polymer composition is considered.     

Studies Related to Biological Detoxification of Kraft Pulp Mill Effluent. IV.The Biodegradation of 14-Chlorodehydroabietic Acid with Mortierella isabellina

One of the fish-toxic chlorinated resin acids, 14-chlorodehydroabietic acid ( 5 ), found in kraft mill effluent is examined. When exposed to the fungus Mortierella isabellina, 5 is converted into a number of hydroxylated derivatives which show low levels of toxicity to fish. These biotransformation products were isolated and characterized.