Synthesis and structure of m-terphenyl thio-, seleno-, and telluroethers

Several routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers were investigated. m-Terphenyl iodides react with diphenyl diselenides or ditellurides (CsOH·H₂O, DMSO, 110 °C) to give the desired compounds in 19−84% yield which significantly extends the previously reported such reactions because o-benzyne cannot be an intermediate as previously suggested. However, the most general synthetic route was that involving reaction of 2,6-diaryl Grignard reagents with sulfur, selenium, or tellurium electrophiles. The m-terphenyl thio-, seleno-, and telluroethers were characterized spectroscopically and, in one case, by single-crystal X-ray analysis. Certain of these compounds showed atropisomerism and barriers for interconversion of isomers were determined by variable-temperature NMR spectroscopy. The barriers for interconverting the syn and anti atropisomers increase on going from the analogous S to Se to Te compounds. Calculations on this isomerization revealed that the barriers are due to rotation about the aryl−aryl bond and that the barriers for rotation about the aryl−chalcogen bond are much lower

Emissions of putative isoprene oxidation products from mango branches under abiotic stress

Although several per cent of net carbon assimilation can be re-released as isoprene emissions to the atmosphere by many tropical plants, much uncertainty remains regarding its biological significance. In a previous study, we detected emissions of isoprene and its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) from tropical plants under high temperature/light stress, suggesting that isoprene is oxidized not only in the atmosphere but also within plants. However, a comprehensive analysis of the suite of isoprene oxidation products in plants has not been performed and production relationships with environmental stress have not been described. In this study, putative isoprene oxidation products from mango (Mangifera indica) branches under abiotic stress were first identified. High temperature/light and freeze-thaw treatments verified direct emissions of the isoprene oxidation products MVK and MACR together with the first observations of 3-methyl furan (3-MF) and 2-methyl-3-buten-2-ol (MBO) as putative novel isoprene oxidation products. Mechanical wounding also stimulated emissions of MVK and MACR. Photosynthesis under 13CO2 resulted in rapid (<30min) labelling of up to five carbon atoms of isoprene, with a similar labelling pattern observed in the putative oxidation products. These observations highlight the need to investigate further the mechanisms of isoprene oxidation within plants under stress and its biological and atmospheric significance. © 2013 The Author

Investigations of Natural Products from Marine Sponge Derived Fungi

Research results described here are from experiments conducted in organic chemistry and marine microbiology. Sponge derived chemistry has provided the marine natural products field with a higher percentage of bioactive leads than temstrial plants or microorganisms. Inspection of these bioactive leads reveals structure types that occur in more than one Demosponge or invertebrate species. It has been hypothesized that this trend indicates complex biosyntheses occmring which include microorganisms associated with the sponges. This theme built on circumstantial evidence is discussed first.Initially we investigated jasplakinolide's occurrence from unrelated sponges including Jaspis aff. johnstoni. Fungi were cultured from this sponge to test the possibility of microorganism biosynthetic involvement. From an unidentified culture we discovered the coriolins, previously known from the temstrial fungus Coriolus consors, and new sesquiterpenes named the chloriolins. We tested the biosynthetic potential of C. consors by growing it in liquid broths with varied salt and fresh water media. We characterized a new coriolin type compound and new and known piperazine diones.Fungi were cultured from the sponge Jaspis aff. coriacea including one strain identified as Aspergillus ochraceus. This fungus produced novel chlorinated polyketides named chlorocarolides which appear to have no ecological connection with sponge's known metabolites. However they do appear analogous to the known Aspergillus metabolite carotic acid. Relative stereochemistry of the chlorocarolides was solved by 1H NMR coupling and molecular modeling analysis.Our fungi library isolated from sponge tissue provided culture extracts screened in two ways: for bioactivity using in-house and off-campus cancer-based bioassays, and for large molecular weight compounds using electrospray ionization mass spectrometry (ESIMS). Polyketides isolated include new nectriapyrones and the novel compound 14,15-secocurvularin. ESIMS results assisted our dereplication process of known compounds isolated.We have shown sponges are a good source for isolating fungi cultures and these cultures may be extracted and purified to provide new and bioactive metabolites from polyketide, terpene, and polypeptide structure classes. Our results indicate that the culturable fungi do not influence the biosynthesis of sponges as once hypothesized and that other classes of microorganisms may merit investigation for their ability to influence sponge metabolite biosynthesis

Investigations of Natural Products from Marine Sponge Derived Fungi

Research results described here are from experiments conducted in organic chemistry and marine microbiology. Sponge derived chemistry has provided the marine natural products field with a higher percentage of bioactive leads than temstrial plants or microorganisms. Inspection of these bioactive leads reveals structure types that occur in more than one Demosponge or invertebrate species. It has been hypothesized that this trend indicates complex biosyntheses occmring which include microorganisms associated with the sponges. This theme built on circumstantial evidence is discussed first.Initially we investigated jasplakinolide's occurrence from unrelated sponges including Jaspis aff. johnstoni. Fungi were cultured from this sponge to test the possibility of microorganism biosynthetic involvement. From an unidentified culture we discovered the coriolins, previously known from the temstrial fungus Coriolus consors, and new sesquiterpenes named the chloriolins. We tested the biosynthetic potential of C. consors by growing it in liquid broths with varied salt and fresh water media. We characterized a new coriolin type compound and new and known piperazine diones.Fungi were cultured from the sponge Jaspis aff. coriacea including one strain identified as Aspergillus ochraceus. This fungus produced novel chlorinated polyketides named chlorocarolides which appear to have no ecological connection with sponge's known metabolites. However they do appear analogous to the known Aspergillus metabolite carotic acid. Relative stereochemistry of the chlorocarolides was solved by 1H NMR coupling and molecular modeling analysis.Our fungi library isolated from sponge tissue provided culture extracts screened in two ways: for bioactivity using in-house and off-campus cancer-based bioassays, and for large molecular weight compounds using electrospray ionization mass spectrometry (ESIMS). Polyketides isolated include new nectriapyrones and the novel compound 14,15-secocurvularin. ESIMS results assisted our dereplication process of known compounds isolated.We have shown sponges are a good source for isolating fungi cultures and these cultures may be extracted and purified to provide new and bioactive metabolites from polyketide, terpene, and polypeptide structure classes. Our results indicate that the culturable fungi do not influence the biosynthesis of sponges as once hypothesized and that other classes of microorganisms may merit investigation for their ability to influence sponge metabolite biosynthesis

Volatile organic compounds as signals in a Plant-Herbivore System: Electrophysiological Responses in Olfactory Sensilla of the Moth Cactoblastis cactorum

The morphological sensillum types on the antennae of male and female Cactoblastis cactorum were visualized by scanning electron microscopy. Electrophysiological recordings were performed for the first time on single olfactory sensilla of C. cactorum. Th

Iron-activated persulfate oxidation degrades aqueous Perfluorooctanoic acid (PFOA) at ambient temperature

Perfluorooctanoic acid (PFOA, C8HF15O2) is an industrial surfactant that is highly resistant to natural breakdown processes such as those mediated by heat, hydrolysis, photolysis, and biodegradation. Many efforts have been developed to breakdown PFOA to less harmful species due to its widespread human exposure and potential toxicity. However, these methods require high temperature or specialized equipment with serious disadvantages of high energy cost for long-term use. We investigated the effectiveness of PFOA degradation by ferrous iron-activated persulfate oxidation (IAPO) under various aqueous geochemical conditions. Approximately 64% of PFOA (initial concentration = 1.64 μmol L−1) was degraded after 4 h under illuminated anoxic conditions at ambient temperature. This degradation rate and magnitude support the potential use of IAPO as a novel inexpensive and environmentally friendly method to remediate PFOA in soil and groundwater. © 2021 Elsevier LtdNational Institute of Environmental Health Sciences24 month embargo; available online 18 May 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Seasonal Variation of Water Quality in Unregulated Domestic Wells

In the United States (U.S.), up to 14% of the population depend on private wells as their primary drinking water source. The U.S. government does not regulate contaminants in private wells. The goals of this study were to investigate the quality of drinking water from unregulated private wells within one mile (1.6 kilometers) of an effluent-dominated river in the arid Southwest, determine differences in contaminant levels between wet and dry seasons, and identify contributions from human sources by specifically measuring man-made organic contaminants (perfluorooctanoic acid (PFOA), perfluorooctane sulfate (PFOS), and sucralose). Samples were collected during two dry seasons and two wet seasons over the course of two years and analyzed for microbial (Escherichia coli), inorganic (arsenic, cadmium, chromium, copper, lead, mercury, nitrate), and synthetic organic (PFOA, PFOS, and sucralose) contaminants. Arsenic, nitrate, and Escherichia coli concentrations exceeded their respective regulatory levels of 0.01 mg/L, 10 mg/L, and 1 colony forming unit (CFU)/100 mL, respectively. The measured concentrations of PFOA and PFOS exceeded the respective Public Health Advisory level. Arsenic, PFOA, PFOS, and sucralose were significantly higher during the dry seasons, whereas E. coli was higher during the wet seasons. While some contaminants were correlated (e.g., As and Hg &#961; = 0.87; PFOA and PFOS &#961; = 0.45), the lack of correlation between different contaminant types indicates that they may arise from different sources. Multi-faceted interventions are needed to reduce exposure to drinking water above health-based guidelines