Phototemtide A,a Cyclic Lipopeptide Heterologously Expressed from Photorhabdus temperata Meg1, Shows Selective Antiprotozoal Activity

A new cyclic lipopeptide, phototemtide A ( 1 ), was isolated from Escherichia coli expressing the biosynthetic gene cluster pttABC from Photorhabdus temperata Meg1. The structure of 1 was elucidated by HR-ESI-MS and NMR experiments. The absolute configurations of amino acids and 3-hydroxyoctanoic acid in 1 were determined by using the advanced Marfey's method and comparison after total synthesis of 1 , respectively. Additionally, three new minor derivatives, phototemtides B–D ( 2 – 4 ), were identified by detailed HPLC–MS analysis. Phototemtide A ( 1 ) showed weak antiprotozoal activity against Plasmodium falciparum, with an IC₅₀ value of 9.8 μm . The biosynthesis of phototemtides A–D ( 1 – 4 ) was also proposed.     

Reorganization of perylene bisimide J-aggregates: from delocalized collective to localized individual excitations

Water-induced reorganization of individual one-dimensional J-aggregates of perylene bisimide (PBI) dyes was observed by fluorescence microscopy. Fluorescence spectra and decay kinetics of individual J-aggregates immobilized on glass surfaces were measured under a dry nitrogen atmosphere and under humid conditions. The fluorescence properties of PBI J-aggregates arisen from collective excitons under dry nitrogen atmosphere were changed to those of non-interacting dye monomers when water vapor was introduced into the environment (sample chamber). Time-dependent changes of the fluorescence spectra and lifetimes upon exposure to water vapor suggest an initial coordination of water molecules at defect sites leading to the formation of H-type dimer units that act as exciton quenchers, and a subsequent slower disintegration of the hydrogen-bonded J-aggregate into monomers that lack resonance coupling. Our present studies resulted in a direct demonstration of how drastically the optical properties of molecular ensembles and characteristics of their excited states can be changed by delicate reorganization of dye molecules at nanometre scales.     

Structure−Activity Relationships of Cinnamate Ester Analogues as Potent Antiprotozoal Agents

Protozoal infections are still a global health problem, threatening the lives of millions of people around the world, mainly in impoverished tropical and sub-tropical regions. Thus, in view of the lack of efficient therapies and increasing resistances against existing drugs, this study describes the antiprotozoal potential of synthetic cinnamate ester analogues and their structure-activity relationships. In general, Leishmania donovani and Trypanosoma brucei were quite susceptible to the compounds in a structure-dependent manner. Detailed analysis revealed a key role of the substitution pattern on the aromatic ring and a marked effect of the side chain on the activity against these two parasites. The high antileishmanial potency and remarkable selectivity of the nitro-aromatic derivatives suggested them as promising candidates for further studies. On the other hand, the high in vitro potency of catechol-type compounds against T. brucei could not be extrapolated to an in vivo mouse model.     

Intergenerational Metabolomic Analysis of Mothers with a History of Gestational Diabetes Mellitus and Their Offspring

Shared metabolomic patterns at delivery have been suggested to underlie the mother-to-child transmission of adverse metabolic health. This study aimed to investigate whether mothers with gestational diabetes mellitus (GDM) and their offspring show similar metabolomic patterns several years postpartum. Targeted metabolomics (including 137 metabolites) was performed in plasma samples obtained during an oral glucose tolerance test from 48 mothers with GDM and their offspring at a cross-sectional study visit 8 years after delivery. Partial Pearson’s correlations between the area under the curve (AUC) of maternal and offspring metabolites were calculated, yielding so-called Gaussian graphical models. Spearman’s correlations were applied to investigate correlations of body mass index (BMI), Matsuda insulin sensitivity index (ISI-M), dietary intake, and physical activity between generations, and correlations of metabolite AUCs with lifestyle variables. This study revealed that BMI, ISI-M, and the AUC of six metabolites (carnitine, taurine, proline, SM(-OH) C14:1, creatinine, and PC ae C34:3) were significantly correlated between mothers and offspring several years postpartum. Intergenerational metabolite correlations were independent of shared BMI, ISI-M, age, sex, and all other metabolites. Furthermore, creatinine was correlated with physical activity in mothers. This study suggests that there is long-term metabolic programming in the offspring of mothers with GDM and informs us about targets that could be addressed by future intervention studies.     

MgO as a non-pyrolyzable pore former in porous membrane supports

The gas permeability of Y_0.03Zr_0.97O₂ (3Y-TZP) porous supports from thermoplastic feedstocks has been improved by adding MgO as a non-pyrolyzable pore former. Common pyrolyzable pore formers such as graphite often produce tortuous and narrow pore channels with low gas permeability, limiting the performance of oxygen transport membranes or other membranes relying on gas transport to the active membrane surface. Thermoplastic feedstocks for extrusion of tubular 3Y-TZP supports were prepared with four different amounts of pyrolyzable pore formers and/or MgO as non-pyrolyzable pore former. The MgO was removed after sintering by leaching in acetic acid. With this technique we obtained porosities above 70 vol% and gas permeabilities above 3?10^?14?m². Compared to samples with only pyrolyzable pore formers, the non-pyrolyzable pore former increases the gas permeability and reduces the tortuosity.     

Ahp Cyclodepsipeptides: The Impact of the Ahp Residue on the “Canonical Inhibition” of S1 Serine Proteases

S1 serine proteases are by far the largest and most diverse family of proteases encoded in the human genome. Although recent decades have seen an enormous increase in our knowledge, the biological functions of most of these proteases remain to be elucidated. Chemical inhibitors have proven to be versatile tools for studying the functions of proteases, but this approach is hampered by the limited availability of inhibitor scaffold structures with the potential to allow rapid discovery of selective, noncovalent small‐molecule protease inhibitors. The natural product class of Ahp cyclodepsipeptides is an unusual class of small‐molecule canonical inhibitors; the incorporation of protease cleavage sequences into their molecular scaffolds enables the design of specific small‐molecule inhibitors that simultaneously target the S and S′ subsites of the protease through noncovalent mechanisms. Their synthesis is tedious, however, so in this study we have investigated the relevance of the Ahp moiety for achieving potent inhibition. We found that although the Ahp residue plays an important role in inhibition potency, appropriate replacement with β‐hydroxy amino acids results in structurally less complex derivatives that inhibit serine proteases in the low micromolar range.     

Rhabdopeptides as Insect‐Specific Virulence Factors from Entomopathogenic Bacteria

Six novel linear peptides, named “rhabdopeptides”, have been identified in the entomopathogenic bacterium Xenorhabdus nematophila after the discovery of the corresponding rdp gene cluster by using a promoter trap strategy for the detection of insect‐inducible genes. The structures of these rhabdopeptides were deduced from labeling experiments combined with detailed MS analysis. Detailed analysis of an rdp mutant revealed that these compounds participate in virulence towards insects and are produced upon bacterial infection of a suitable insect host. Furthermore, two additional rhabdopeptide derivatives produced by Xenorhabdus cabanillasii were isolated, these showed activity against insect hemocytes thereby confirming the virulence of this novel class of compounds.     

POLYMER-SUPPORTED REAGENTS FOR MOLECULAR SEPARATIONS

A Hammett study of the complexing abilities of various polymer-supported reagents for phenols, anilines, and benzoic acids is described. For each polymeric reagent, the percent absorbed of each family of compounds is correlated with the Hammett substituent constants. A carboxylic acid resin shows no interaction with phenols and benzoic acids; only a weak interaction with anilines is found since 25% of each is absorbed regardless of the substituent present on the aromatic ring. This contrasts with the strong interaction displayed by the sulfonic resin and the moderate interaction of the phosphinic resin. Phosphonic and phosphonate monoester resins absorb increasing amounts of anilines as their basicity increases. The purely coordinating- phosphonate diester resin absorbs uniformly low levels of the three families of compounds with no substituent effect on the percent absorbed. The sulfonic resin quantitatively absorbs the anilines within the temperature range 6 to 40 C while the phosphinic resin absorbs decreasing levels within the same range. The phosphinic resin is more selective than the sulfonic resin under competitive conditions     

Effect of processing routes on the mechanical, thermal and morphological properties of PLA-based hybrid biocomposite

Due to environmental awareness and depletion of petroleum oil, bioplastics and their composites are one of the most researchable topics throughout the world. Polymers that are produced from renewable sources are expected to be the best alternative to replace conventional polymers. The bottles neck of these bioplastics is its cost which limits its application in certain purposes. Bioplastics filled or reinforced with natural fibers can reduce cost and improve properties, like stiffness, strength and toughness of biocomposites. Impact strength and fracture toughness are the main demerits of short fiber-filled biocomposite. On the other hand, when nanoclay, having a very high aspect ratio, is mixed with bioplastics it may significantly affect the thermal and mechanical properties of the final composites. A composite may also suffer dispersion inefficiency, which is considered the key factor to improve the properties. The aim of this paper was to hybridize nanoclay and short kenaf fiber in polylactic acid (PLA) by double extrusion method and followed by mechanical, thermal and morphological characterizations. Mechanical properties showed improvement with nanoclay, specifically the impact strength increased more than 50 % compared with unreinforced PLA. A double extruded composite showed 3–10 % better tensile and flexural properties than the single extruded composite. Similarly, addition of nanoclay increased decomposition and melting temperatures (T _m) from 198 to 225 °C and 152 to 155 °C, respectively. Crystallization temperature (T _c), however, dropped with nanoclay from 116 to 106 °C and storage modulus (E’) increased by about 1 GPa. These findings were also supported by scanning electron micrograph (SEM) and transmission electron micrograph (TEM) where in double extruded composite a better dispersion of nanoclay was observed. By employing X-ray diffraction (XRD) it was found that higher percentage of crystallinity was obtained while Fourier transform infrared (FTIR) displayed new bond formation. The presence of nanoclay enhanced thermal and mechanical properties of the hybrid composite.     

Lipids in infant formulas: Current and future innovations

Lipids in infant formulas are designed to mimic the composition of human milk and/or approximate the performance of the breastfed infant. Human milk lipids exhibit a complex, highly variable nature, varying by population, dietary intake, time of day, length of feeding and others. Continued understanding and characterization of human milk lipids has led to infant formula innovations aimed at a better comparison to human milk and/or improved dietary lipid utilization in the formula‐fed infant. The underlying aim of such innovation is the generation of outcomes as comparable to human milk feeding as possible. The present paper briefly reviews the current understanding of human milk lipid composition, with a focus on how this knowledge drives current and future innovations in the area of infant formula lipids.