Expanding the Diversity of Plant Monoterpenoid Indole Alkaloids Employing Human Cytochrome P450 3A4

Human drug-metabolizing cytochrome P450 monooxygenases (CYPs) have enormous substrate promiscuity; this makes them promising tools for the expansion of natural product diversity. Here, we used CYP3A4 for the targeted diversification of a plant biosynthetic route leading to monoterpenoid indole alkaloids. In silico, in vitro and in planta studies proved that CYP3A4 was able to convert the indole alkaloid vinorine into vomilenine, the former being one of the central intermediates in the ajmaline pathway in the medicinal plant Rauvolfia serpentina (L.) Benth. ex Kurz. However, to a much larger extent, the investigated conversion yielded vinorine (19R,20R)-epoxide, a new metabolite with an epoxide functional group that is rare for indole alkaloids. The described work represents a successful example of combinatorial biosynthesis towards an increase in biodiversity of natural metabolites. Moreover, characterisation of the products of the in vitro and in planta transformation of potential pharmaceuticals with human CYPs might be indicative of the route of their conversion in the human organism.     

Mercury concentrations in commercial fish species from Lake Winnipeg, 1971–2019

Concentrations of total mercury (THg) in the axial musculature of northern pike (Esox lucius), walleye (Sander vitreus), lake whitefish (Coregonus clupeaformis), and sauger (Sander canadensis) were analyzed from several regions of Lake Winnipeg and three main inflows, focusing on Mossy Bay in the North Basin of the lake. Length-standardized means (standard means) indicated THg concentrations in pike of 550 mm fork length (0.44 ppm) and walleye measuring 400 mm (0.38 ppm) from Mossy Bay were highest in 1971 and declined to 0.13 and 0.22 ppm, respectively, by 1974. Standard means of both these species have been similar since 2010 (walleye; approximately 0.11 ppm) and 2013 (pike; approximately 0.17 ppm), except for a significant increase to 0.15 ppm in walleye in 2019, potentially related to concurrent changes in trophic interactions with invasive fish and invertebrate species. Standard means of 300 mm long sauger (0.23–0.29 ppm) did not decline significantly between 1971 and 1974, and those of 350 mm long whitefish ranged from 0.006 to 0.028 ppm from 1983 to 2016 with no clear temporal trend. In concert with data from other areas of Lake Winnipeg and the three inflows for 2000–2019, these results indicate higher contemporary concentrations in the South Basin of the lake. This latitudinal gradient in fish THg is assumed to be a result of continuous mercury inputs from the Red and the Winnipeg River, whereas a former point source of industrial mercury in the Saskatchewan River is no longer relevant. According to human consumption limits based on tolerable daily intake calculations and current THg concentrations of fish from Mossy Bay, substantial quantities of whitefish, pike, and walleye fish can be safely eaten.     

Application of organosilane coatings for improved anti-adhesive properties enabling facilitated demolding in polymer processing

Easy and residue-free demolding is an everlasting topic in the plastics processing industry. Typically, facile ejection of the produced parts from the mold is provided by separation agents (silicon sprays, surface coatings). In this work, a perfluoroalkyl-based organosilane coating is applied to exchangeable substrates of an injection mold. Besides the simple application, the coating can also be restored easily in a procedure based on flame treatment. Coating and recoating are proven by contact angle measurements with water, while the anti-adhesive effect and the related relief during demolding are evaluated using a special measuring device in an instrumented two-plate injection mold. The results reveal that the organosilane layer reduces the demolding forces and the resulting static friction coefficient by 50%. Furthermore, multiple recoating significantly improves the durability of the anti-adhesive coating. Based on these findings, the easily applicable and renewable organosilane coating represents a suitable alternative to conventional release coatings.     

Planning for Sustainable Transport in Germany and the USA: A Comparison of the Washington,DC and Stuttgart Regions

Federal, state, and local governments in Germany and the USA strive to make passenger transport more sustainable to combat oil dependence, climate change, local pollution, and negative public health outcomes. This paper compares the Washington, DC and Stuttgart regions to demonstrate differences and similarities between the German and US land-use and transport planning systems. To illustrate local planning for more sustainable transport, we compare two best-practice examples for integrating transport and land-use planning: the Rosslyn–Ballston Corridor in Arlington County in the DC metro region and Scharnhauser Park in the City of Ostfildern in the Stuttgart region. In spite of significant differences in motorization, travel behaviour, sustainability, and planning systems, both Arlington County and the City of Ostfildern promote sustainable transport using comparable strategies: (1) mixed-use development around public transport stations; (2) comprehensive long-range plans; (3) citizen participation; and (4) coordinated transport, housing, and economic development policies.     

How Different Characterization Techniques Elucidate the Nature of the Gold Species in a Polycrystalline Au/TiO2 Catalyst

TiO₂‐supported gold species were prepared via the deposition‐precipitation route, with conservation of the initial speciation by freeze‐drying. The structural and electronic properties of the Au species were investigated by X‐ray absorption spectroscopy, electron microscopy, and IR spectroscopy of adsorbed CO in four states. Exclusively Au^III was deposited on the TiO₂ surface in patches ranging from isolated Au ions to three‐dimensional clusters. This paper illustrates in detail the unique contributions of all characterization techniques to this structural model.     

Photo-vulcanization using thiol-ene chemistry: Film formation,morphology and network characteristics of UV crosslinked rubber latices

The photo-vulcanization with versatile thiol-ene chemistry represents an innovative approach to crosslink diene-rubber materials both in latex and in solid film state. In this work, the structure of elastomer-based thiol-ene networks and the morphology after film formation are studied in detail using electron microscopic techniques, atomic force microscopy and multiple-quantum solid-state NMR spectroscopy. Additionally, film formation properties and corresponding macroscopic properties of photo-vulcanized natural rubber (NR) latex and its synthetic counterpart, isoprene rubber (IR) latex, are determined in dependence on the curing procedure (pre- and post-vulcanization). The results reveal that thiol-ene cured elastomers comprise homogenously distributed crosslinks with a low amount of short chain defects. Whilst photochemically pre-cured NR latex particles provide coherent films, the film formation and mechanical properties of IR are strongly governed by the crosslink density of the latex particles. In film state, photo-vulcanization promotes narrow crosslink distributions and excellent tensile properties of both NR and IR.     

Improved Second Generation Iron Pincer Complexes for Effective Ester Hydrogenation

Hydrogenation of esters to alcohols with a well‐defined iron ^iPr2PNP pincer complex has been recently reported by us and other groups. We now introduce a novel and sterically less hindered ^Et2PNP congener that provides superior catalytic activity in the hydrogenation of various carboxylic acid esters and lactones compared to the known complex. Successful hydrogenation proceeds under relatively mild conditions (60 °C) with lower catalyst loadings.

     

Characterization of an Invertebrate-Type Dopamine Receptor of the American Cockroach,Periplaneta americana

We have isolated a cDNA coding for a putative invertebrate-type dopamine receptor (Peadop2) from P. americana brain by using a PCR-based strategy. The mRNA is present in samples from brain and salivary glands. We analyzed the distribution of the PeaDOP2 receptor protein with specific affinity-purified polyclonal antibodies. On Western blots, PeaDOP2 was detected in protein samples from brain, subesophageal ganglion, thoracic ganglia, and salivary glands. In immunocytochemical experiments, we detected PeaDOP2 in neurons with their somata being located at the anterior edge of the medulla bilaterally innervating the optic lobes and projecting to the ventro-lateral protocerebrum. In order to determine the functional and pharmacological properties of the cloned receptor, we generated a cell line constitutively expressing PeaDOP2. Activation of PeaDOP2-expressing cells with dopamine induced an increase in intracellular cAMP. In contrast, a C-terminally truncated splice variant of this receptor did not exhibit any functional property by itself. The molecular and pharmacological characterization of the first dopamine receptor from P. americana provides the basis for forthcoming studies focusing on the significance of the dopaminergic system in cockroach behavior and physiology.     

High‐Affinity Carbohydrate Binding by Trimeric Benzoboroxoles Measured on Carbohydrate Arrays

Carbohydrates are involved in a wide range of biological processes of pharmaceutical relevance. The selective recognition of carbohydrates is therefore of great interest in biology and medicine. In this study we present the synthesis of fluorescent multimeric benzoboroxoles and the analysis of multivalent binding processes to immobilized carbohydrate arrays by fluorescence spectroscopy. We observed high binding affinities of trimeric benzoboroxoles by determination of K_Dsurf values for their interaction with α‐Gal on glass chips. The observed K_Dsurf values were in the mid‐nM range (49 and 104 nM ) and are comparable to the K_Dsurf values for binding of natural lectins, such as that of ConA to immobilized α‐Man (79 nM ). The array technology was found to be an excellent tool for studying the binding processes of multivalent lectin mimetics with respect to profiling and quantitation.     

Pneumocandin Biosynthesis: Involvement of a trans‐Selective Proline Hydroxylase

Echinocandins are cyclic nonribosomal hexapeptides based mostly on nonproteinogenic amino acids and displaying strong antifungal activity. Despite previous studies on their biosynthesis by fungi, the origin of three amino acids, trans‐4‐ and trans‐3‐hydroxyproline, as well as trans‐3‐hydroxy‐4‐methylproline, is still unknown. Here we describe the identification, overexpression, and characterization of GloF, the first eukaryotic α‐ketoglutarate/Fe^II‐dependent proline hydroxylase from the pneumocandin biosynthesis cluster of the fungus Glarea lozoyensis ATCC 74030. In in vitro transformations with L ‐proline, GloF generates trans‐4‐ and trans‐3‐hydroxyproline simultaneously in a ratio of 8:1; the latter reaction was previously unknown for proline hydroxylase catalysis. trans‐4‐Methyl‐L ‐proline is converted into the corresponding trans‐3‐hydroxyproline. All three hydroxyprolines required for the biosynthesis of the echinocandins pneumocandins A₀ and B₀ in G. lozoyensis are thus provided by GloF. Sequence analyses revealed that GloF is not related to bacterial proline hydroxylases, and none of the putative proteins with high sequence similarity in the databases has been characterized so far.