Synthesis of 1,1'-Bicarbazoles by Sequential Iron(III)- and Palladium(II)-Catalyzed Oxidative Coupling Reactions.

The iron(III)-catalyzed oxidative coupling of diarylamines to 2,2'-bis(arylamino)-1,1'-biaryls and subsequent twofold palladium(II)-catalyzed oxidative cyclization provide a convergent synthetic route to 1,1'-bicarbazoles. Screening a range of different palladium(II) salts led to palladium(II) acetate, pivalate, and hexafluoroacetylacetonate as the most efficient catalysts. Remarkably, the twofold palladium(II)-catalyzed oxidative cyclization can also be performed under argon. The mechanism for the oxidative cyclization under an inert gas presumably involves regeneration of the catalytically active palladium(II) species by oxidative addition of pivalic acid.

Omecamtiv mecarbil and Mavacamten target the same myosin pocket despite antagonistic effects in heart contraction.

Inherited cardiomyopathies are amongst the most common cardiac diseases worldwide, leading in the late-stage to heart failure and death. The most promising treatments against these diseases are small-molecules directly modulating the force produced by ß-cardiac myosin, the molecular motor driving heart contraction. Two of these molecules that produce antagonistic effects on cardiac contractility have completed clinical phase 3 trials: the activator Omecamtiv mecarbil and the inhibitor Mavacamten. In this work, we reveal by X-ray crystallography that both drugs target the same pocket and stabilize a pre-stroke structural state, with only few local differences. All atoms molecular dynamics simulations reveal how these molecules can have antagonistic impact on the allostery of the motor by comparing ß-cardiac myosin in the apo form or bound to Omecamtiv mecarbil or Mavacamten. Altogether, our results provide the framework for rational drug development for the purpose of personalized medicine.

In Silico Prediction of MYO1C-Rhodopsin Interactions and Its Significance in Protein Localization and Visual Function.

Rods and cones are photoreceptor neurons in the retina that are required for visual sensation in vertebrates, where proper protein localization and compartmentalization are critical for phototransduction and visual function. In human retinal diseases, improper protein transport to the outer segment (OS) or mislocalization of proteins to the inner segment (IS) could lead to impaired visual responses and photoreceptor cell degeneration, causing a loss of visual function. We showed involvement of an unconventional motor protein, MYO1C, in the proper localization of rhodopsin to the OS, where loss of MYO1C in a mammalian model caused mislocalization of rhodopsin to IS and cell bodies, leading to progressively severe retinal phenotypes. In this study, using modeling and docking analysis, we aimed to identify the protein-protein interaction sites between MYO1C and Rhodopsin to establish a hypothesis that a physical interaction between these proteins is necessary for the proper trafficking of rhodopsin and visual function.

Changes in lipid metabolism driven by steroid signalling modulate proteostasis in C. elegans.

Alzheimer's, Parkinson's and Huntington's diseases can be caused by mutations that enhance protein aggregation, but we still do not know enough about the molecular players of these pathways to develop treatments for these devastating diseases. Here, we screen for mutations that might enhance aggregation in Caenorhabditis elegans, to investigate the mechanisms that protect against dysregulated homeostasis. We report that the stomatin homologue UNC-1 activates neurohormonal signalling from the sulfotransferase SSU-1 in ASJ sensory/endocrine neurons. A putative hormone, produced in ASJ, targets the nuclear receptor NHR-1, which acts cell autonomously in the muscles to modulate polyglutamine repeat (polyQ) aggregation. A second nuclear receptor, DAF-12, functions oppositely to NHR-1 to maintain protein homeostasis. Transcriptomics analyses of unc-1 mutants revealed changes in the expression of genes involved in fat metabolism, suggesting that fat metabolism changes, controlled by neurohormonal signalling, contribute to protein homeostasis. Furthermore, the enzymes involved in the identified signalling pathway are potential targets for treating neurodegenerative diseases caused by disrupted protein homeostasis.

µ-Oxo-bis[(octacosafluoro-meso-tetraphenylporphyrinato)iron(iii)] - synthesis, crystal structure, and catalytic activity in oxidation reactions.

We describe the synthesis and X-ray crystal structure of µ-oxo-bis[(octacosafluoro-meso-tetraphenylporphyrinato)iron(iii)] [(FeTPPF28)2O]. This novel iron complex is an efficient catalyst for oxidative biaryl coupling reactions of diarylamines and carbazoles. The asymmetric oxidative coupling in the presence of an axially chiral biaryl phosphoric acid as co-catalyst provides the 2,2'-bis(arylamino)-1,1'-biaryl in 96% ee. The Wacker-type oxidation of alkenes to the corresponding ketones with (FeTPPF28)2O as catalyst in the presence of phenylsilane proceeds at room temperature with air as the terminal oxidant. For internal and aliphatic alkenes increased ketone/alcohol product ratios were obtained.

Atroposelective Synthesis of 2,2'-Bis(arylamino)-1,1'-biaryls by Oxidative Iron(III)- and Phosphoric Acid-Catalyzed C-C Coupling of Diarylamines.

We describe an iron-catalyzed asymmetric oxidative C-C coupling of diarylamines which proceeds at room temperature with air as final oxidant. Using hexadecafluorophthalocyanine-iron(II) as catalyst in the presence of catalytic amounts of an axially chiral biaryl phosphoric acid, the resulting chiral 2,2'-diamino-1,1'-biaryls are obtained in up to 90 % ee as confirmed by chiral HPLC. A detailed mechanism has been proposed with a radical cation-chiral phosphate ion pair as key intermediate leading to the observed asymmetric induction.

Iron-Catalyzed Oxidative C-O and C-N Coupling Reactions Using Air as Sole Oxidant.

We describe the oxygenation of tertiary arylamines, and the amination of tertiary arylamines and phenols. The key step of these coupling reactions is an iron-catalyzed oxidative C-O or C-N bond formation which generally provides the corresponding products in high yields and with excellent regioselectivity. The transformations are accomplished using hexadecafluorophthalocyanine-iron(II) (FePcF16 ) as catalyst in the presence of an acid or a base additive and require only ambient air as sole oxidant.

Mechanistic Studies on the Hexadecafluorophthalocyanine-Iron-Catalyzed Wacker-Type Oxidation of Olefins to Ketones*.

The hexadecafluorophthalocyanine-iron complex FePcF16 was recently shown to convert olefins into ketones in the presence of stoichiometric amounts of triethylsilane in ethanol at room temperature under an oxygen atmosphere. Herein, we describe an extensive mechanistic investigation for the conversion of 2-vinylnaphthalene into 2-acetylnaphthalene as model reaction. A variety of studies including deuterium- and 18 O2 -labeling experiments, ESI-MS, and 57 Fe Mössbauer spectroscopy were performed to identify the intermediates involved in the catalytic cycle of the oxidation process. Finally, a detailed and well-supported reaction mechanism for the FePcF16 -catalyzed Wacker-type oxidation is proposed.

Isolation and structure elucidation of pyridine alkaloids from the aerial parts of the Mongolian medicinal plant Caryopteris mongolica Bunge.

The seven pyridine alkaloids 1-7, the flavonoid acacetin (8), and L-proline anhydride (9) have been isolated from the aerial parts of the Mongolian medicinal plant Caryopteris mongolica Bunge. The structures of the natural products 1-9 have been assigned by MS, as well as IR, 1D NMR (1H, 13C, DEPT), and 2D NMR (COSY, HSQC, HMBC, NOESY) spectroscopic methods. The compounds 2 and 4-7 represent new chemical structures. Acacetin (8) and L-proline anhydride (9) have been obtained from C. mongolica for the first time.

Loss of Motor Protein MYO1C Causes Rhodopsin Mislocalization and Results in Impaired Visual Function.

Unconventional myosins, linked to deafness, are also proposed to play a role in retinal cell physiology. However, their direct role in photoreceptor function remains unclear. We demonstrate that systemic loss of the unconventional myosin MYO1C in mice, specifically causes rhodopsin mislocalization, leading to impaired visual function. Electroretinogram analysis of Myo1c knockout (Myo1c-KO) mice showed a progressive loss of photoreceptor function. Immunohistochemistry and binding assays demonstrated MYO1C localization to photoreceptor inner and outer segments (OS) and identified a direct interaction of rhodopsin with MYO1C. In Myo1c-KO retinas, rhodopsin mislocalized to rod inner segments (IS) and cell bodies, while cone opsins in OS showed punctate staining. In aged mice, the histological and ultrastructural examination of the phenotype of Myo1c-KO retinas showed progressively shorter photoreceptor OS. These results demonstrate that MYO1C is important for rhodopsin localization to the photoreceptor OS, and for normal visual function.

Myosin 1c: A novel regulator of glucose uptake in brown adipocytes.

OBJECTIVE: The potential of brown adipose tissue (BAT) to influence energy homeostasis in animals and humans is encouraging as this tissue can increase fatty acid and glucose utilization to produce heat through uncoupling protein 1 (UCP1), but the actual mechanism of how the cell regulates glucose uptake is not fully understood. Myosin 1c (Myo1c) is an unconventional motor protein involved in several cellular processes, including insulin-mediated glucose uptake via GLUT4 vesicle fusion in white adipocytes, but its role in glucose uptake in BAT has not previously been investigated. METHODS: Using the specific inhibitor pentachloropseudilin (PClP), a neutralizing antibody assay, and siRNA, we examined the role of Myo1c in mechanisms leading to glucose uptake both in vitro in isolated mouse primary adipocytes and in vivo in mice. RESULTS: Our results show that inhibition of Myo1c removes insulin-stimulated glucose uptake in white adipocytes, while inducing glucose uptake in brown adipocytes, independent of GLUT4, by increasing the expression, translation, and translocation of GLUT1 to the plasma membrane. Inhibition of Myo1c leads to the activation of PKA and downstream substrates p38 and ATF-2, which are known to be involved in the expression of ß-adrenergic genes. CONCLUSIONS: Myo1c is a PKA repressor and regulates glucose uptake into BAT.

Iron-Catalyzed Wacker-type Oxidation of Olefins at Room Temperature with 1,3-Diketones or Neocuproine as Ligands*.

Herein, we describe a convenient and general method for the oxidation of olefins to ketones using either tris(dibenzoylmethanato)iron(III) [Fe(dbm)3 ] or a combination of iron(II) chloride and neocuproine (2,9-dimethyl-1,10-phenanthroline) as catalysts and phenylsilane (PhSiH3 ) as additive. All reactions proceed efficiently at room temperature using air as sole oxidant. This transformation has been applied to a variety of substrates, is operationally simple, proceeds under mild reaction conditions, and shows a high functional-group tolerance. The ketones are formed smoothly in up to 97 % yield and with 100 % regioselectivity, while the corresponding alcohols were observed as by-products. Labeling experiments showed that an incorporated hydrogen atom originates from the phenylsilane. The oxygen atom of the ketone as well as of the alcohol derives from the ambient atmosphere.

UHPLC-IM-Q-ToFMS analysis of maradolipids, found exclusively in Caenorhabditis elegans dauer larvae.

Lipid identification is one of the current bottlenecks in lipidomics and lipid profiling, especially for novel lipid classes, and requires multidimensional data for correct annotation. We used the combination of chromatographic and ion mobility separation together with data-independent acquisition (DIA) of tandem mass spectrometric data for the analysis of lipids in the biomedical model organism Caenorhabditis elegans. C. elegans reacts to harsh environmental conditions by interrupting its normal life cycle and entering an alternative developmental stage called dauer stage. Dauer larvae show distinct changes in metabolism and morphology to survive unfavorable environmental conditions and are able to survive for a long time without feeding. Only at this developmental stage, dauer larvae produce a specific class of glycolipids called maradolipids. We performed an analysis of maradolipids using ultrahigh performance liquid chromatography-ion mobility spectrometry-quadrupole-time of flight-mass spectrometry (UHPLC-IM-Q-ToFMS) using drift tube ion mobility to showcase how the integration of retention times, collisional cross sections, and DIA fragmentation data can be used for lipid identification. The obtained results show that combination of UHPLC and IM separation together with DIA represents a valuable tool for initial lipid identification. Using this analytical tool, a total of 45 marado- and lysomaradolipids have been putatively identified and 10 confirmed by authentic standards directly from C. elegans dauer larvae lipid extracts without the further need for further purification of glycolipids. Furthermore, we putatively identified two isomers of a lysomaradolipid not known so far.