Bjarte Holmelid

New Regiospecific Synthesis of Tri-and Tetra-Substituted Furans

Beta-acyloxy alpha,beta-unsaturated acetylenic ketones have been shown to react with organocuprate reagents and undergo cyclization followed by dehydration to give substituted furans as the final products. The transformation appeared to be versatile, and tri- and tetra-substituted furans were obtained with regiochemical control in moderate to good yields. The best yields were generally obtained when the reactions were performed around -60 degrees C with substrates and cuprates containing sterically demanding substituents. The proposed mechanism for furan formation has been supported by experiments.

Arsenic-containing fatty acids and hydrocarbons in marine oils – determination using reversed-phase HPLC–ICP-MS and HPLC–qTOF-MS

Arsenolipids are the major arsenic species present in marine oils. Several structures of arsenolipids have been elucidated the last 5 years, demonstrating the chemical complexity of this trace element in the marine environment. Several commercial fish oils and marine oils, ranging in total arsenic concentrations from 1.6 to 12.5 mg kg(-1) oil, were analyzed for arsenolipids using reversed-phase high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The arsenolipids were quantified using three different arsenic-containing calibration standards; dimethylarsinate (DMA), triphenylarsinoxide (Ph₃AsO) and a synthesized arsenic-containing hydrocarbon (AsHC) (dimethylarsinoyl nonadecane; C₂₁H₄₃AsO). The observed variation in signal intensity for arsenic during the gradient elution profile in reversed-phase HPLC was compensated for by determining the time-resolved response factors for the arsenolipids. Isotopes of germanium ((74)Ge) and indium ((115)In) were suited as internal standards for arsenic, and were used for verification of the arsenic signal response factors during the gradient elution. Dimethylarsinate was the most suitable calibration standard for the quantification of arsenolipids, with recoveries between 91% and 104% compared to total arsenic measurements in the same extracts. A range of marine oils was investigated, including oils of several fish species, cod liver and seal, as well as three commercial fish oils. The AsHCs - C₁₇H₃₈AsO, C₁₉H₄₂AsO and C₂₃H₃₈AsO - were identified as the major arsenolipids in the extracts of all oils by HPLC coupled with quadrupole time-of-flight mass spectrometry (qTOF-MS). Minor amounts of two arsenic-containing fatty acids (AsFAs) (C₂₃H₃₈AsO₃ and C₂₄H₃₈AsO₃) were also detected in the oils. The sum of the AsHCs and the AsFAs determined in the present study accounted for 17-42% of the total arsenic in the oils.

Mortality and deformities in European lobster (Homarus gammarus) juveniles exposed to the anti-parasitic drug teflubenzuron

This study describes experiments carried out to examine effects of the antiparasitic drug teflubenzuron, used in delousing farmed salmon, on a non-target species, the European lobster (Homarus gammarus). Juvenile lobsters were fed two doses of teflubenzuron, 10 and 20mg/kg successively for 7 days corresponding to a standard medication of the fish (10mg/kg day) and twice the standard dose (20mg/kg day). Monitoring lasted 3 months to include at least one moulting period for all individuals. Cumulative mortality was higher in all replicates given medicated feed compared with the control group. Mean cumulative mortality for each dosing was 41 ± 13% for 10mg/kg and 38 ± 8% for 20mg/kg, i.e. no difference. Drug residue was analysed in all juveniles that died, in addition to 12 juveniles at day 8 and the first 12 surviving lobsters. A decline in concentration of teflubenzuron from over 8,000 ng/g (day 5) to 14 ng/g (day 70) was observed in the juveniles that died during the experiment. Twelve individuals that died contained 82 ng/g or less whereas the mean concentration in the first 12 lobsters that survived moulting was 152 ng/g. Following a single oral administration, the half-life of teflubenzuron in lobster was estimated to 3.4 days and the initial concentration (C0) to 515 ng/g at time t0. At the end of the study a considerable number of juvenile lobsters were observed with deformities in various organs; carapace, walking legs, cheliped, tail fan, abdomen and antenna. The occurrence of observed deformities varied from 0 to 15% in treated replicates and will most likely affect ability to locate and consume food (antenna, claw and walking legs), respiration (carapace) and ability to move/swim (walking legs, tail fan and abdomen). In total, the mortality and senescent damages were close to 50% in all replicates. Juveniles that survived medication without deformities however, moulted and increased in size at each moult equally well as the unmedicated controls.

Toxicological assessment of the anti-salmon lice drug diflubenzuron on Atlantic cod Gadus morhua

Increasing use of the chitin synthesis inhibitor diflubenzuron against the ectoparasitic salmon louse Lepeophtheirus salmonis in marine aquaculture has raised concerns over its environmental impacts. This study evaluated how diflubenzuron affects Atlantic cod Gadus morhua, a fish species often found near Atlantic salmon Salmo salar farms, focusing on uptake kinetics and hepatic transcriptional responses. Two experiments were conducted, one time-series trial in which the fish were given a daily dose (3 mg kg-1 fish) of diflubenzuron for 14 d followed by a 3 wk depuration period, and one dose-response trial with increasing concentrations (3, 10 and 50 mg kg-1 fish). The highest diflubenzuron concentrations were found in the liver at Day 15. No detectable levels of diflubenzuron were found in liver or muscle 3 wk after the end of the treatment. At the molecular level, small effects of diflubenzuron treatment on gene transcription were observed. In the time-series experiment, the strongest effects were seen at Day 8, with 2 transcripts being upregulated (bclx2 and cpt1a) and 8 transcripts being downregulated (gstp1, gstm1, gstt1, ugt1a, nat2, cat, p53 and slc16a9a). Five transcripts (cyp3a, cpt1a, ptgs2, elovl5 and mapk1) responded significantly to diflubenzuron exposure in the dose-response experiment. This study shows that diflubenzuron can be taken up by Atlantic cod, that it is rapidly cleared from the body and that when present this pharmaceutical causes only small effects on the expression of genes involved in detoxification pathways. Taken together, our data suggest that accumulated diflubenzuron at the levels studied would have a relatively small effect on wild Atlantic cod.

Lipids of Dietzia sp. A14101. Part I: A study of the production dynamics of surface-active compounds

Dietzia sp. A14101 belonging to the genus Dietzia (Gram-positive bacteria, Actinomycetes, high G+C content of DNA) was isolated from an oil reservoir model column inoculated with oil-field bacteria (Bødtker et al., 2009). Low interfacial tension (IFT) values were obtained by studying intact strain cells grown on water-immiscible hydrocarbons (HC) (Kowalewski et al. (2004), Kowalewski et al. (2005). Further investigations showed that the adaptation mechanism of Dietzia sp. A14101 to toxic water-immiscible HC involved changes both on the level of fatty acids content and in the physical properties of the cellular surface (development of the negative cellular surface charge and an increased in hydrophobicity) (Hvidsten et al., 2015b). However, these changes could not explain the low IFT values observed in earlier studies of this strain. Generally, low IFT imply a production of surface active compounds of low MW that are lipids by structure (Rosenberg and Ron, 1999). In this paper, it is shown that Dietzia sp. A14101 produces a range of glycolipids on all substrates. The amount of trehalose-containing lipids increases when the strain is grown on hydrocarbons. The production peak seems to coincide with the exponential growth phase, and such increased glycolipid synthesis continues throughout the stationary phase. The results indicate that only low amounts of the hydrocarbon substrate is incorporated directly into the glycolipids produced. Most of the hydrocarbon substrate seems to be employed for the biosynthesis of the neutral lipids and higher amounts of biomass were generated on HC substrates compared to incubations on non-HC substrates. The lipid content of the cell was determined as the total lipid extract (TLE), and was further fractionated (SPE). The hydrophobic and hydrophilic moieties of the isolated surface active compounds were determined (GC-MS, TLC, DART, LC-MS). The changes in the lipid content during the culture development were monitored by 1D and 2D TLC, emulsification and oil-spreading tests.

Non-Polar Natural Products from Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile (Bromeliaceae)

Extensive regional droughts are already a major problem on all inhabited continents and severe regional droughts are expected to become an increasing and extended problem in the future. Consequently, extended use of available drought resistant food plants should be encouraged. Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile are excellent candidates in that respect because they are established drought resistant edible plants from the semi-arid Caatinga region. From a food safety perspective, increased utilization of these plants would necessitate detailed knowledge about their chemical constituents. However, their chemical compositions have previously not been determined. For the first time, the non-polar constituents of B. laciniosa, N. variegata and E. spectabile have been identified. This is the first thorough report on natural products from N. variegata, E. spectabile, and B. laciniosa. Altogether, 20 non-polar natural products were characterized. The identifications were based on hyphenated gas chromatography-high resolution mass spectrometry (GC-HRMS) and supported by 1D and 2D Nuclear Magnetic Resonance (NMR) plant metabolomics.

Iodination of Anilines with Sodium Dichloroiodate

Iodinated aromatic compounds have been synthetic targets for decades, and a number of methods have been developed for iodination of arenes. The simplest and mildest are those relying on the electrophilicity of iodine in dichloroiodate salts. At least one such reagent, sodium dichloroiodate, is utilized on an industrial scale to obtain triply iodinated benzenes, which constitute the key structural motif in several X-ray contrast agents. Since this process has to be very carefully controlled to minimize the formation of by-products (in particular azoarenes), this inspired us to study the iodination of some anilines with sodium dichloroiodate in greater detail. In order to evaluate the sensitivity of the industrial process to pH, exploratory experiments were performed using 2,4-dimethylaniline (1a). Under acidic conditions (pH 1–2) iodination of 1a with sodium dichloroiodate proceeded smoothly to give a clean product mixture from which pure 2-iodo-4,6-dimethylaniline (2a) was isolated in 88% yield. However, under basic conditions 2a was not formed at all and a complex product mixture was obtained from which the only reasonably pure product isolated in low yield (4%) was 2,20,4,40-tetramethylazobenzene (3a). The iodination of benzene derivatives is influenced by the nature of the substituents. It was therefore of interest to investigate the reaction of some activated and deactivated aniline derivatives under the conditions applied to 1a (room temperature; acidic and basic conditions; variable amounts of sodium dichloroiodate). Dimethylanilines 1b–1d (Scheme 1 and Table 1) gave relatively simple reaction mixtures under acidic conditions; in order for all the starting materials to be consumed, an excess of sodium dichloroiodate had to be utilized. Under these conditions 2,3-dimethylaniline (1b) gave a 44% yield of 2b but also afforded 4,6-diiodo-2,3-dimethylaniline (19%) with the use of a 60% molar excess of the reagent. Under the same conditions but with a 3.8 molar excess of the reagent, 3,5-dimethylaniline (1c) gave a complex mixture; use of a much larger excess of sodium dichloroiodate (4.8 molar) led to 2,4,6-triiodo-3,5dimethylaniline (78%) as the sole isolatable product (Table 1). 2,6-Dimethylaniline (1d) exhibited a third type of reactivity; while iodination still occurred to afford 4-iodo-2,6dimethylaniline (2d) in 21% yield, the main product was 2,6-dimethyl-p-benzoquinone4-(20,60-dimethyl)anil in 28% yield. Under basic conditions (KOH in methanol/H2O),

1,1,2,2,7,7,8,8-Octaethoxyocta-3,5-diyne

1,1,2,2,7,7,8,8-Octaethoxyocta-3,5-diyne has been observed as a minor product in several syntheses utilizing 3,3,4,4-tetraethoxybut-1-yne (TEB) as starting material. In order to access this highly functionalized diyne, we have developed a procedure that provides the title compound in excellent yield.