The inverse type II β-turn on D-Trp-Phe, a pharmacophoric motif for MOR agonists

Herein we propose the D ‐Trp‐Phe sequence within an inverse type II β‐turn as a new kind of pharmacophoric motif for μ‐opioid receptor (MOR) cyclopeptide agonists. Initially, we observed that c[Tyr‐D ‐Pro‐D ‐Trp‐Phe‐Gly] ( 4 ), an analogue of endomorphin‐1 (H‐Tyr‐Pro‐Trp‐Phe‐NH₂) lacking the crucial protonatable amino group of Tyr 1, is a MOR agonist with 10^?8 M affinity. Molecular docking analysis suggested that the relevant interactions with the receptor involve D ‐Trp‐Phe. The bioactive conformation of this region was investigated by selected derivatives of 4 designed to adopt an inverse type II β‐turn. These efforts led to c[Tyr‐Gly‐D ‐Trp‐Phe‐Gly] ( 14 ) and to the cyclotetrapeptide c[D ‐Asp‐1‐amide‐β‐Ala‐D ‐Trp‐Phe] ( 15 ), showing improved nanomolar affinity. Both 14 and 15 selectively bind MOR, as they have negligible affinity for the κ‐ and δ‐opioid receptors. Both 14 and 15 behave as partial MOR agonists in functional assays. Conformational and docking analyses confirm the role of the inverse β‐turn in binding. These results indicate that the D ‐Trp‐Phe inverse β‐turn structure can be used for designing non‐endomorphin‐like peptidomimetic opioid agonists in general, characterized by an atypical mechanism of interaction between ligand and receptor.     

Sugar-derived ionic liquids

Ionic liquids (ILs) are special molten salts with melting points below 100 degrees C that are typically constituted of organic cations (imidazolium, pyridinium, sulfonium, phosphonium, etc.) and inorganic anions. Due to their ionic nature, they are endowed with high chemical and thermal stability, good solvent properties, and non-measurable vapor pressure. Although the recycling of ILs partly compensate their rather high cost, it is important to develop new synthetic approaches to less expensive and environmentally sustainable ILs based on renewable raw materials. In fact, most of these alternative solvents are still prepared starting from fossil feedstocks. Until now, only a limited number of ionic liquids have been prepared from renewable sources (e.g., hydroxy acids, amino acids, terpenes), and even less from naturally occurring carbohydrates. This short review describes the synthesis and applications of chiral and achiral ILs obtained from inexpensive sugars.     

3,3'-diethylthiatricarbocyanine iodide: a highly sensitive chiroptical reporter of DNA helicity and sequence

Using UV-vis absorption and circular dichroism (CD) spectroscopies, we explored the binding interactions of 3,3'-diethylthiatricarbocyanine iodide (Cy7) with polynucleotides of different sequences and helicity. CD showed to be a very diagnostic tool giving different spectroscopic chiroptical signatures for all explored DNA sequences upon Cy7 binding. Cy7 was able to spectroscopically discriminate between the right handed B-DNA of poly(dG-dC)(2) and its left handed Z-DNA counterpart induced by spermine or Co(III)hexamine via nearly opposite induced circular dichroic signal.     

Conceptually new entries into cells

This article summarizes the background and a few preliminary results concerning project 7 of the NCCR Chemical Biology. The general objective is to explore new concepts for cellular uptake, membrane tunneling, sensing and labeling. Emphasis is on the use of dynamic covalent chemistry for counterion activation, slow release of polyions and fluorescent probes, and the generation of activator libraries and polyions that grow and shrink.     

Supercritical CO2 extraction of lipids and astaxanthin from Brazilian redspotted shrimp waste (Farfantepenaeus paulensis)

Brazilian redspotted shrimp (Farfantepenaeus paulensis) waste is an important source of carotenoids such as astaxanthin and lipids with a high ω−3 fatty acids content, mainly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). In order to establish an efficient and environmental friendly recovery process, the lipids and astaxanthin were extracted from the freeze-dried redspotted shrimp waste (including head, tail and shell) using supercritical carbon dioxide. The effects of the extraction conditions of pressure (200-400 bar) and temperature (40-60 °C) on the global yield (X₀), astaxanthin extraction yield and astaxanthin concentration in the extract were evaluated. It was found that the pressure and temperature showed a very low significant effect on the lipid extraction yield using supercritical CO₂. In comparison with lipid extraction by solvents, maximum efficiency of supercritical fluid extraction achieved 64% of hexane extraction yield. On the other hand, temperature and pressure had significant effects on astaxanthin extraction yield. Thegreatest amount of extract was obtained at 43 °C and 370 bar, with 39% of recovery.     

Catalytic hydrothermal conversion of cellulose over SnO2 and ZnO nanoparticle catalysts

The hydrothermal conversion of cellulose in the presence of nanometal oxide particles (SnO₂ and ZnO) was investigated in this study. Both catalysts were synthesized hydrothermally and characterized using TEM, FESEM-EDX, X-ray diffraction spectroscopy and BET (Brunauer, Emmett and Teller) methods. In order to reveal the effect of nano-scale catalysts, experiments were conducted using bulk (non-nano) metal oxide and pure cellulose without any catalyst. The hydrothermal conversion experiments were carried out in a micro autoclave at 300, 400, 500, 600 °C and 1 h reaction time. The compositions of the gaseous products and the aqueous phase were determined with various analytical techniques (GC, ion chromatography, HPLC, UV-vis). Contribution of carbon containing products to the carbon mass balance was also represented. The results indicated both nano and bulk ZnO and SnO₂ to have an effect on the water-gas shift reaction at varying temperatures. The water-gas shift reaction (WGS) proceeded fast at 300 °C in the presence of ZnO, while the rate of WGS was lower at 300 °C in the presence of SnO₂. Nano ZnO led to improved hydrogen yield, while ethane and propane were formed as a result of side reactions in the presence of nano and bulk SnO₂.     

(±)-Catechin,A Root Exudate of the Invasive <Emphasis Type="Italic">Centaurea Stoebe</Emphasis> Lam. (Spotted Knapweed) Exhibits Bacteriostatic Activity Against Multiple Soil Bacterial Populations

Understanding the effects of allelopathic plant chemicals on soil microorganisms is critical to understanding their ecological roles and importance in exotic plant invasion. Centaurea stoebe Lam. (spotted knapweed), an aggressive invasive weed in North America, secretes a racemic mixture of (±)-catechin as a root exudate. This enantiomeric, polyphenolic compound has been reported to have allelopathic effects on surrounding flora and microflora. To better understand how catechin affects microbial communities in the root zone of spotted knapweed, we assessed its impact on the total culturable bacterial component and numerous individual bacterial populations from Romanian (native range) and Montana (invaded range) soils. Catechin suppressed total culturable count numbers from the bacterial community and inhibited growth of some, but not all, soil bacterial populations tested. The native soil bacterial community was significantly more resistant to inhibitory effects of catechin than either the invaded or non-invaded soils. We further show that the inhibitory effect of catechin on nine different soil bacterial strains from seven genera was reversible, demonstrating that it acts via a bacteriostatic rather than bactericidal mechanism. These findings suggest that catechin might affect bacterial community composition and activity in the root zone.     

Dietary n-3 Fatty Acids Significantly Suppress Lipogenesis in Bovine Muscle and Adipose Tissue: A Functional Genomics Approach

Changes in fatty acid composition of longissimus muscle and subcutaneous adipose tissue of German Holstein bulls induced by a grass-silage/n-3 fatty acid based intervention diet versus a maize-silage/n-6 fatty acid based control diet were analyzed and related to shifts in lipogenic gene expression, protein expression, and enzyme activity patterns. Significantly higher amounts of n-3 fatty acids and by mean factors of 2.2–2.5 decreased n-6/n-3 fatty acid ratios in both tissues were obtained upon n-3 fatty acid intervention. In longissimus muscle, these changes of fatty acid profiles were associated with reduced SREBP1c (p = 0.02), ACC (p = 0.00), FAS (p = 0.10) and SCD (p = 0.03) gene expression, Δ6D (p = 0.03) and SCD (p = 0.03) protein expression as well as SCD enzyme activity (p = 0.03). In subcutaneous adipose tissue, significantly reduced ACC (p = 0.00) and FAS (p = 0.01) gene expression, SCD protein expression (p = 0.02) and SCD enzyme activity (p = 0.03) were detected upon n-3 fatty acid intervention, although lower degrees of correlation between gene and corresponding gene products were obtained in relation to longissimus muscle. The study elucidates tissue-specific functional genomic responses to dietary fatty acid manipulation in regard to fatty acid profile tailoring of animal tissues.     

去除废水中顽固污染物:染料废水脱色和生物降解的联合处理过程(英文)

While conventional wastewater treatments for urban effluents are fairly routine and have proved highly effective,industrial wastewater requires more complex and specific treatments.This paper provides a technological strategy for removal of recalcitrant contaminants based on a hybrid treatment system.The model effluent containing a binary mixture of synthetic dyes is treated by a combination of a preliminary physicochemical stage followed by a biological stage based on ligninolytic enzymes produced by Phanerochaete chrysosporium.This proposal includes biosorption onto peat as pretreatment,which decreases the volume and concentration to be treated in the biological reactor,thereby obtaining a completely decolorized effluent.The treated wastewater can therefore be reused in the dyeing baths with the consequent saving of water resources.