Mono- and Dimeric Xanthones with Anti-Glioma and Anti-Inflammatory Activities from the Ascidian-Derived Fungus Diaporthe sp. SYSU-MS4722

Seven new xanthones, diaporthones A−G (1−7), together with 13 known analogues, including five mono- (8−14) and six dimeric xanthones (15−20), were obtained from the ascidian-derived fungus Diaporthe sp. SYSU-MS4722. Their planar structures were established by extensive spectroscopic analyses, including 1D and 2D NMR and high-resolution mass spectrometry (HR-ESIMS). The absolute configurations of 1−7 were clearly identified by X-ray crystallographic analysis and calculation of the ECD Spectra. Compounds 15−20 showed significant anti-inflammatory activity with IC50 values between 6.3 and 8.0 μM. In addition, dimeric xanthones (15−20) showed selective cytotoxicity against T98G cell lines with IC50 values ranging from 19.5 to 78.0 μM.

Intelligent systems based on photonics

This paper discusses the prospects of photonics, shows the relevance and applicability of photonics research. The poten-tial of photonics technologies to answer the socio-economic challenges of the digital transformation age is revealed. Opportunities that emerge with the introduction of photonic devices to various technical systems designed for environ-mental protection and quality of life improvement are demonstrated. Concrete photonics structures and devices for such key applications as spectroscopy, analog optical calculations, and optical neural networks are closely examined. Possi-ble applications for photonic sensors and new type spectrometers are outlined, their competitive advantages explored. Various geometries of extra fine compact photonic spectrometers are presented: based on digital planar diagrams, inte-grated into the photonic waveguides, metasurfaces, diffraction gratings with varying parameters. The benefits of analog optical computations against conventional electronic devices are discussed. Various nanophotonic structures designed for differential and integral operators are studied, solutions for edge detection are proposed. The concept for artificial intelligence implementation on the photonics platform using optical neural networks is analyzed. Various solutions are examined: containing sequences of diffraction elements and based on Huygens–Fresnel principle, as well as planar structures comprised of waveguides that interact as Mach–Zehnder interferometer. SPIE estimation of the international photonics market proposes that the peak of interest for this field is yet to be achieved and photonics will claim its place in the future technological landscape.

Absolute Configuration Determination of Two Diastereomeric Neovasifuranones A and B from Fusarium oxysporum R1 by a Combination of Mosher’s Method and Chiroptical Approach

Endophytic fungi are one of prolific sources of bioactive natural products with potential application in biomedicine and agriculture. In our continuous search for antimicrobial secondary metabolites from Fusarium oxysporum R1 associated with traditional Chinese medicinal plant Rumex madaio Makino using one strain many compounds (OSMAC) strategy, two diastereomeric polyketides neovasifuranones A (3) and B (4) were obtained from its solid rice medium together with N-(2-phenylethyl)acetamide (1), 1-(3-hydroxy-2-methoxyphenyl)-ethanone (2) and 1,2-seco-trypacidin (5). Their planar structures were unambiguously determined using 1D NMR and MS spectroscopy techniques as well as comparison with the literature data. By a combination of the modified Mosher’s reactions and chiroptical methods using time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) and optical rotatory dispersion (ORD), the absolute configurations of compounds 3 and 4 are firstly confirmed and, respectively, characterized as (4S,7S,8R), (4S,7S,8S). Bioassay results indicate that these metabolites 1–5 exhibit weak inhibitory effect on Helicobacter pylori 159 with MIC values of ≥16 μg/mL. An in-depth discussion for enhancement of fungal metabolite diversity is also proposed in this work.

The effects of bending on plasmonic modes in nanowires and planar structures

In this work, we investigate the effects of bends on the surface plasmon resonances in nanowires (NWs) and isolated edges of planar structures using electron energy loss spectroscopy experiments and theoretical calculations. Previous work showed that the sharp bends in NWs do not affect their resonant modes. Here, we study previously overlooked effects and analyze systematically the evolution of resonant modes for several bending angles from 30° to 180°, showing that bending can have a significant effect on the plasmonic response of a nanostructure. In NWs, the modes can experience significant energy shifts that depend on the aspect ratio of the NW and can cause mode intersection and antinode bunching. We establish the relation between NW modes and edge modes and show that bending can even induce antinode splitting in edge modes. This work demonstrates that bends in plasmonic planar nanostructures can have a profound effect on their optical response and this must be accounted for in the design of optical devices.

Linear and Nonlinear Electrostatic Excitations and Their Stability in a Nonextensive Anisotropic Magnetoplasma

In the present work, the propagation of (non)linear electrostatic waves is reported in a normal (electron–ion) magnetoplasma. The inertialess electrons follow a non-extensive q-distribution, while the positive inertial ions are assumed to be warm mobile. In the linear regime, the dispersion relation for both the fast and slow modes is derived, whose properties are analyzed parametrically, focusing on the effect of nonextensive parameter, component of parallel anisotropic ion pressure, component of perpendicular anisotropic ion pressure, and magnetic field strength. The reductive perturbation technique is employed for reducing the fluid equation of the present plasma model to a Zakharov–Kuznetsov (ZK) equation. The parametric role of physical parameters on the characteristics of the symmetry planar structures such solitary waves is investigated. Furthermore, the stability of the pulse soliton solution of the ZK equation against the oblique perturbations is investigated. Furthermore, the dependence of the instability growth rate on the related physical parameters is examined. The present investigation could be useful in space and astrophysical plasma systems.

Synthesis of Azepine- or Azocine-Embedded Hexabenzocoronene-Based Nanographenes

Classical polycyclic aromatic hydrocarbons (PAHs) are a large group of π-conjugated planar structures. To explore more properties of PAHs, new structures were designed including nonplanar topologies and heteroatom-doping moieties. As an important nanographene (NG) unit, hexabenzocoronene (HBC) and its derivatives have been intensively researched. Numbers of HBC-based nonplanar NGs were developed and the heteroatom-doped HBC-based NGs have been designed and synthesized as well. Herein, we synthetically summarized some synthetic methods for seven- or eight-membered ring containing HBC-based NGs, and discussed our newly synthesized azepine- or azocine-embedded NGs by using a modified synthetic route and a traditional Müllen’s synthetic method, respectively.

Absolute Structure Determination and Kv1.5 Ion Channel Inhibition Activities of New Debromoaplysiatoxin Analogues

Potassium channel Kv1.5 has been considered a key target for new treatments of atrial tachyarrhythmias, with few side effects. Four new debromoaplysiatoxin analogues with a 6/6/12 fused ring system were isolated from marine cyanobacterium Lyngbya sp. Their planar structures were elucidated by HRESIMS, 1D and 2D NMR. The absolute configuration of oscillatoxin J (1) was determined by single-crystal X-ray diffraction, and the absolute configurations of oscillatoxin K (2), oscillatoxin L (3) and oscillatoxin M (4) were confirmed on the basis of GIAO NMR shift calculation followed by DP4 analysis. The current study confirmed the absolute configuration of the pivotal chiral positions (7S, 9S, 10S, 11R, 12S, 15S, 29R and 30R) at traditional ATXs with 6/12/6 tricyclic ring system. Compound 1, 2 and 4 exhibited blocking activities against Kv1.5 with IC50 values of 2.61 ± 0.91 µM, 3.86 ± 1.03 µM and 3.79 ± 1.01 µM, respectively. However, compound 3 exhibited a minimum effect on Kv1.5 at 10 µM. Furthermore, all of these new debromoaplysiatoxin analogs displayed no apparent activity in a brine shrimp toxicity assay.

Antibacterial Meroterpenoids, Merochlorins G–J from the Marine Bacterium Streptomyces sp.

Four new chlorinated meroterpenoids, merochlorins G−J (1−4), and 10, a dihydronaphthalenedione precursor, along with known merochlorins A (5) and C−F (6−9), were obtained from cultivation of the bacterium strain Streptomyces sp. CNH-189, which was isolated from marine sediment. The planar structures of compounds 1−4 and 10 were elucidated by interpretation of MS, UV, and NMR spectroscopic data. The relative configurations of compounds 1−4 were determined via analysis of nuclear Overhauser effect (NOE) spectroscopic data, after which their absolute configurations were established by comparing the experimental electronic circular dichroism (ECD) spectra of compounds 1−4 to those of previously reported possible enantiomer models and DP4 calculations. Compound 3 displayed strong antibacterial activities against Bacillus subtilis, Kocuria rhizophila, and Staphylococcus aureus, with MIC values of 1, 2, and 2 μg/mL, respectively, whereas compound 1 exhibited weak antibacterial effects on these three strains, with a 16−32 μg/mL MIC value range.

Stereomutation in Tetracoordinate Centers via Stabilization of Planar Tetracoordinated Systems

The quest for stabilizing planar forms of tetracoordinate carbon started five decades ago and intends to achieve interconversion between [R]- and [S]-stereoisomers without breaking covalent bonds. Several strategies are successful in making the planar tetracoordinate form a minimum on its potential energy surface. However, the first examples of systems where stereomutation is possible were reported only recently. In this study, the possibility of neutral and dications of simple hydrocarbons (cyclopentane, cyclopentene, spiropentane, and spiropentadiene) and their counterparts with the central carbon atom replaced by elements from groups 13, 14, and 15 are explored using ab initio MP2 calculations. The energy difference between the tetrahedral and planar forms decreases from row II to row III or IV substituents. Additionally, aromaticity involving the delocalization of the lone pair on the central atom appears to help in further stabilizing the planar form compared to the tetrahedral form, especially for the row II substituents. We identified 11 systems where the tetrahedral state is a minimum on the potential energy surface, and the planar form is a transition state corresponding to stereomutation. Interestingly, the planar structures of three systems were found to be minimum, and the corresponding tetrahedral states were transition states. The energy profiles corresponding to such transitions involving both planar and tetrahedral states without the breaking of covalent bonds were examined. The systems showcased in this study and research in this direction are expected to realize molecules that experimentally exhibit stereomutation.

Self-Assembling Flexible 3D-MEAs for Cortical Implants

Flexible Multi Electrode Arrays (MEAs) for neural interfacing reduce the mechanical mismatch between the soft brain tissue and the electrode arrays allowing accurate signal recordings and neural stimulation while reducing inflammatory responses. Many standard manufacturing processes of MEAs are designed for planar structures and the production of three-dimensional structures is challenging. In the present study, shaft structures with one to two circular gold microelectrodes (10 - 20 μm), each on a base polyimide (PI) substrate, were investigated. We describe a fabrication method, with which shafts made from bi-layer PI flip into the third dimension, which is a first step towards spontaneous assembly of electrodes in flexible 3D MEAs for neuroelectronic applications. A lift-up of the shafts was achieved by the contraction of a second PI layer and a steady nitrogen flow during polycondensation. This shrinking PI was structured in pits with a width of 5 - 600 μm. We achieved liftup angles of up to 42 degrees. The shaft structures can be hardened and later be used for neural implantation experiments.