Structural and Functional Analysis of Bacterial Sulfonosphingolipids and Rosette-Inducing Factor 2 (RIF-2) by Mass Spectrometry-Guided Isolation and Total Synthesis

We have analyzed the abundance of bacterial sulfonosphingolipids, including rosette-inducing factors (RIFs), in seven bacterial prey strains by using high-resolution tandem mass spectrometry (HRMS²) and molecular networking (MN) within the Global Natural Product Social Molecular Networking (GNPS) web platform. Six sulfonosphingolipids resembling RIFs were isolated and their structures were elucidated based on comparative MS and NMR studies. Here, we also report the first total synthesis of two RIF-2 diastereomers and one congener in 15 and eight synthetic steps, respectively. For the total synthesis of RIF-2 congeners, we employed a decarboxylative cross-coupling reaction to synthesize the necessary branched α-hydroxy fatty acids, and the Garner-aldehyde approach to generate the capnine base carrying three stereogenic centers. Bioactivity studies in the choanoflagellate Salpingoeca rosetta revealed that the rosette inducing activity of RIFs is inhibited dose dependently by the co-occurring sulfonosphingolipid sulfobacins D and F and that activity of RIFs is specific for isolates obtained from Algoriphagus.     

Nanoimprint texturing of transparent flexible substrates for improved light management in thin‐film solar cells

We present a nanoimprint based approach to achieve efficient light management for solar cells on low temperature transparent polymer films. These films are particularly low‐priced, though sensitive to temperature, and therefore limiting the range of deposition temperatures of subsequent solar cell layers. By using nanoimprint technology, we successfully replicated optimized light trapping textures of etched high temperature ZnO:Al on a low temperature PET film without deterioration of optical properties of the substrate. The imprint‐textured PET substrates show excellent light scattering properties and lead to significantly improved incoupling and trapping of light in the solar cell, resulting in a current density of 12.9 mA/cm², similar to that on a glass substrate. An overall efficiency of 6.9% was achieved for a flexible thin‐film silicon solar cell on low cost PET substrate. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Pentafluorophenyl Ester‐based Polymersomes as Nanosized Drug‐Delivery Vehicles

In this work, activated ester chemistry is employed to synthesize biocompatible and readily functionalizable polymersomes. Via aminolysis of pentafluorophenyl methacrylate‐based precursor polymers, an N‐(2‐hydroxypropyl) methacrylamide (HPMA)‐analog hydrophilic block is obtained. The precursor polymers can be versatile functionalized by simple addition of suitable primary amines during aminolysis as demonstrated using a fluorescent dye. Vesicle formation is proven by cryoTEM and light scattering. High encapsulation efficiencies for hydrophilic cargo like siRNA are achieved using dual centrifugation and safe encapsulation is demonstrated by gel electrophoresis. In vitro studies reveal low cytotoxicity and no protein adsorption‐induced aggregation in human blood serum occurs, making the vesicles interesting candidates as nanosized drug carriers.

     

Characterization and Antineoplasic Effect of Extracts Obtained from <Emphasis Type="Italic">Pleurotus sajor</Emphasis>-<Emphasis Type="Italic">caju</Emphasis> Fruiting Bodies

Fungi of the Pleurotus genus present a great industrial interest due to their possibility of producing pharmacological compounds, pigments, aromas, organic acids, polysaccharides, enzymes, vitamins, amino acids, etc. Among the therapeutic products, we can highlight those with antineoplasic activity, attributed to the fungi cell wall components. Based on this, the objective of this work was to study the antineoplasic capacity of the polysaccharidic fractions obtained from Pleurotus sajor-caju fruiting bodies. Female Swiss mice were inoculated with the Ehrlich ascitic tumor (5 × 10⁶ cells/animal) in ascitic form. The polysaccharidic fractions were administered intraperitoneally, during a 6-day period. Fractions FI and FII presented a lower volume of ascitic liquid (3.1 and 1.8 mL, respectively) and a higher reduction in the number of neoplasic cells present in the ascitic liquid (86.2% and 85%, respectively), when compared to the positive control (group inoculated with the tumor but without treatment). These fractions were characterized in terms of monosaccharide composition. Glucose was the major component detected, followed by galactose and mannose. The anomeric carbon configuration of the β-glucan was confirmed by the ¹³C NMR (δ 103.7). Substituted and free C3 and C6 were also detected. Protein bands were confirmed through infrared analysis.     

η5,η1-Coordinated cyclopentadienyl transition metal complexes featuring σ-metal–carbon ansa bridges

An overview of η⁵,η¹-coordinated transition metal ansa complexes is given. These compounds bear one or more coordinated cyclopentadienyl moieties connected with a η¹-bridging σ-bonded carbon chain featuring a length of at least two carbon atoms. Synthetic approaches, as well as characterisation and applications are described.     

Asymmetric Organocatalysis with Sulfones

Asymmetric organocatalysis has become a powerful tool for the synthesis of optically active compounds. Whereas early research mainly focused on combining simple reagents as a proof‐of‐concept for asymmetric organocatalysis, recent investigations are directed towards extending the concept to more target‐ and diversity‐oriented synthesis. As a result of the many transformation possibilities and their ability to generate both nucleophilic and electrophilic reaction partners, sulfones have become especially important substrates in the field of organocatalysis.     

Phototransformation of imidacloprid on isolated tomato fruit cuticles and on tomato fruits

Imidacloprid, a neonicotinoid insecticide, is widely used in plant protection to prevent crop losses. The objective of this study was to show the photochemical fate of imidacloprid on plant surfaces by irradiation experiments on isolated tomato fruit cuticles and tomato fruits (Lycopersicon esculentum Mill.). Imidacloprid spiked samples were irradiated both under sunlight simulator and natural sunlight conditions for 24 h, which resulted in recoveries of 23% and 24%, respectively, if isolated cuticles were studied. On whole tomato fruits, recoveries were 33% and 71%, respectively. Similar results were obtained on cuticles spiked with the formulation Confidor and irradiated under natural sunlight. However, on tomato fruits the application of Confidor resulted in a higher loss (56%) of imidacloprid. During all irradiation experiments both on cuticles and whole fruits, 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-imine was generally formed at 10–14 mol%, but different other photoproducts were also detected in low amounts, whereas N-nitrosoimidacloprid was only detected under natural sunlight conditions. Rapid photodegradation of imidacloprid could be demonstrated in all experiments. The identified photoproducts, 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-imine and N-nitrosoimidacloprid, are possible reaction partners for plant cuticle constituents to form cuticle bound residues.     

Channel inclusion of primary alcohols in isostructural solvates of the antiretroviral nevirapine: an X-ray and thermal analysis study

X-ray structural and thermoanalytical data for a series of solvates 2–7 of the anti-HIV drug nevirapine containing primary alcohols CH₃(CH₂) _n OH with n = 2–7 are reported. The structures of 2–7 are based on a common isostructural framework comprising centrosymmetric hydrogen-bonded nevirapine dimers and contain a common channel parallel to the crystal b-axis whose repeat length spans a narrow range (~8.43–8.52 Å) in the series and accommodates the various solvent molecules in 2–7. Thermogravimetry yielded a guest–host ratio close to 0.5 for the 1-butanol solvate 3 and a steady decrease in this ratio from 0.43 to 0.32 for the solvates 4–7. This anomalous stoichiometric variation was resolved following successful X-ray analysis of solvate 3 which revealed that the length spanned by the disordered 1-butanol molecule is commensurate with the channel periodicity b, resulting in a stoichiometric compound. Instead, solvates 5–7, for which single crystal X-ray data were available, showed significant disorder for the solvent molecules, attributed to their increasing chain lengths being incommensurate with the parameter b.