Cyclosmenospongine, a new sesquiterpenoid aminoquinone from an Australian marine sponge Spongia sp.

A new sesquiterpenoid aminoquinone, cyclosmenospongine (1), containing a dihydropyran ring, was isolated from an Australian marine sponge Spongia sp., along with the known metabolites, smenospongiarine, ilimaquinone and smenospongine. The structure of 1 was determined from spectroscopic data.     

Isolation,purification and identification of two new alkaloids metabolites from marine-derived Verrucosispora sp. FIM06025

Chemical investigation of a marine-derived actinomycete strain Verrucosispora sp. FIM06025 isolated from a marine sponge sample collected from the East China Sea, resulted in the discovery of two new alkaloids, (2-(hydroxymethyl)-3-(2-(hydroxymethyl)-3-methylaziridin-1-yl) (2-hydroxyphenyl) methanone (1) and 2-(1-hydroxyethyl)-3,4-dihydrobenzo [f] [1,4]oxazepin-5(2H)-one (2). The structures of compounds 1 and 2 were determined by the detailed analysis of 1D, 2D NMR and HR-TOF-MS data, along with literature data analysis. The bioefficacy investigations revealed that compound 1 exhibited a broad spectrum of antimicrobial activity with MIC (minimum inhibitory concentration) values ranging from 3.4 to 200?μg·mL^?1 against H. pylori, P. aeroginosa, A. baumanniiin, E. coli and K. pneumonia, S. aureus, C. albicans and E. faecium, however, compound 2, up to 200?μg/mL, displayed no antibacterial activity against these bacteria.     

Vortex‐in‐cell method combined with a boundary element method for incompressible viscous flow analysis

In this study, an immersed boundary vortex‐in‐cell (VIC) method for simulating the incompressible flow external to two‐dimensional and three‐dimensional bodies is presented. The vorticity transport equation, which is the governing equation of the VIC method, is represented in a Lagrangian form and solved by the vortex blob representation of the flow field. In the present scheme, the treatment of convection and diffusion is based on the classical fractional step algorithm. The rotational component of the velocity is obtained by solving Poisson's equation using an FFT method on a regular Cartesian grid, and the solenoidal component is determined from solving an integral equation using the panel method for the convection term, and the diffusion term is implemented by a particle strength exchange scheme. Both the no‐slip and no‐through flow conditions associated with the surface boundary condition are satisfied by diffusing vortex sheet and distributing singularities on the body, respectively. The present method is distinguished from other methods by the use of the panel method for the enforcement of the no‐through flow condition. The panel method completes making use of the immersed boundary nature inherent in the VIC method and can be also adopted for the calculation of the pressure field. The overall process is parallelized using message passing interface to manage the extensive computational load in the three‐dimensional flow simulations. Copyright © 2011 John Wiley & Sons, Ltd.     

Total Synthesis and Stereochemical Reassignment of Mandelalide A

The total synthesis of the tunicate metabolite mandelalide A and the correction of its originally assigned stereochemistry are reported. Key features of the convergent, fully stereocontrolled route include the use of a Prins cyclization for the diastereoselective construction of the tetrahydropyran subunit, Rychnovsky–Bartlett cyclization for the preparation of the tetrahydrofuran moiety, Suzuki coupling, Horner–Wadsworth–Emmons macrocyclization, and glycosylation to append the L ‐rhamnose‐derived pyranoside.     

Variations of δ15N-Values and Hydrolyzable Amino Acids in Settling Particles in the Ocean

Abstract

The modification of nitrogen isotopic signals during particle sedimentation in the sea is of great interest for the use of sedimentary δ¹⁵N-values as a paleoceanographic tool. The effect of organic matter degradation on such modification was studied by analyzing nitrogen, hydrolyzable amino acids (THAA) and δ¹⁵N-values in a suit of marine settling particles collected from the Bay of Bengal, Indian Ocean, by using time-series sediment traps, and in underlying sediments. The flux of settling particles showed temporal variations which are related to the monsoons, the major climatic feature of this marine region. During high flux periods settling particles are enriched in nitrogenous material that is less degraded and exhibit higher δ¹⁵N-values than particles showing characteristics of degradation. At the sediment surface more than 95% of the settling particulate nitrogen is lost and the δ¹⁵N-values of the residual sedimentary nitrogen are higher than those of settling particles. The observed increase is interpreted to be due to fractionation during degradation of organic matter.     

利用脉冲功率技术开采海底富钴结壳的试验研究

为了克服采用传统机械方法开采海底富钴结壳时破碎头易磨损、效率低以及贫化率高等缺点,通过试验方法研究了一种利用脉冲功率技术开采海底富钴结壳的新技术。采用12级全固态Marx电路和半导体开关IGBT研制了高压脉冲电源,该电源可产生负高压方波脉冲,其上升沿上升时间约100 ns,最高幅值可达40 kV,脉宽可调。破碎方式采用针针电极并与岩石同侧表面紧密接触。为了使两电极与岩石同侧表面接触的部位电势尽可能高,采用不锈钢针作为正、负电极,且电极间距可调。研究发现当电极间距约为3 mm时,该电源产生的幅值约32.5 kV的高压脉冲可在高压油中的砂岩内部形成等离子通道并破碎砂岩。放电既可发生在高压脉冲上升沿阶段,也可发生在上升沿上升时间之后。从放电过程中的电压电流波形来看,等离子通道回路中有电流时其两端存在明显的压降,因此等离子通道具有阻性,而且阻值在放电过程中是变化的。     

Genus Smenospongia: Untapped Treasure of Biometabolites—Biosynthesis,Synthesis, and Bioactivities

Marine sponges continue to attract remarkable attention as one of the richest pools of bioactive metabolites in the marine environment. The genus Smenospongia (order Dictyoceratida, family Thorectidae) sponges can produce diverse classes of metabolites with unique and unusual chemical skeletons, including terpenoids (sesqui-, di-, and sesterterpenoids), indole alkaloids, aplysinopsins, bisspiroimidazolidinones, chromenes, γ-pyrones, phenyl alkenes, naphthoquinones, and polyketides that possessed diversified bioactivities. This review provided an overview of the reported metabolites from Smenospongia sponges, including their biosynthesis, synthesis, and bioactivities in the period from 1980 to June 2022. The structural characteristics and diverse bioactivities of these metabolites could attract a great deal of attention from natural-product chemists and pharmaceuticals seeking to develop these metabolites into medicine for the treatment and prevention of certain health concerns.     

Extraction of the Anticancer and Antimicrobial Agent,Prodigiosin, from Vibrio gazogenes PB1 and Its Identification by 1D and 2D NMR

Prodigiosin is a secondary metabolite produced in several species of bacteria. It exhibits antimicrobial and anticancer properties. Methods for the extraction and identification of prodigiosin and their related derivatives from bacterial cultures typically depend on solvent-based extractions followed by NMR spectroscopy. The estuarine bacterium, V. gazogenes PB1, was previously shown to produce prodigiosin. This conclusion, however, was based on analytical data obtained from ultraviolet-visible absorption spectrophotometry and infrared spectroscopy. Complete dependence on these techniques would be considered inadequate for the accurate identification of the various members of the prodiginine family of compounds, which possess very similar chemical structures and near-identical optical properties. In this study, we extracted prodigiosin from a culture of Vibrio gazogenes PB1 cultivated in minimal media, and for the first time, confirmed the synthesis of prodigiosin Vibrio gazogenes PB1 using NMR techniques. The chemical structure was validated by ¹H and ¹³C NMR spectroscopy, and further corroborated by 2D NMR, which included ¹H-¹H-gDQFCOSY, ¹H-¹³C-gHSQC, and ¹H-¹³C-gHMBC, as well as ¹H-¹H-homonuclear decoupling experiments. Based on this data, previous NMR spectral assignments of prodigiosin are reaffirmed and in some cases, corrected. The findings will be particularly relevant for experimental work relating to the use of V. gazogenes PB1 as a host for the synthesis of prodigiosin.     

A Review of Diterpenes from Marine-Derived Fungi: 2009–2021

Marine-derived fungi are important sources of novel compounds and pharmacologically active metabolites. As an important class of natural products, diterpenes show various biological activities, such as antiviral, antibacterial, anti-inflammatory, antimalarial, and cytotoxic activities. Developments of equipment for the deep-sea sample collection allow discoveries of more marine-derived fungi with increasing diversity, and much progress has been made in the identification of diterpenes with novel structures and bioactivities from marine fungi in the past decade. The present review article summarized the chemical structures, producing organisms and biological activities of 237 diterpenes which were isolated from various marine-derived fungi over the period from 2009 to 2021. This review is beneficial for the exploration of marine-derived fungi as promising sources of bioactive diterpenes.     

Discovery of Hyrtinadine A and Its Derivatives as Novel Antiviral and Anti-Phytopathogenic-Fungus Agents

Plant diseases caused by viruses and fungi have a serious impact on the quality and yield of crops, endangering food security. The use of new, green, and efficient pesticides is an important strategy to increase crop output and deal with the food crisis. Ideally, the best pesticide innovation strategy is to find and use active compounds from natural products. Here, we took the marine natural product hyrtinadine A as the lead compound, and designed, synthesized, and systematically investigated a series of its derivatives for their antiviral and antifungal activities. Compound 8a was found to have excellent antiviral activity against the tobacco mosaic virus (TMV) (inactivation inhibitory effect of 55%/500 μg/mL and 19%/100 μg/mL, curative inhibitory effect of 52%/500 μg/mL and 22%/100 μg/mL, and protection inhibitory effect of 57%/500 μg/mL and 26%/100 μg/mL) and emerged as a novel antiviral candidate. These compound derivatives displayed broad-spectrum fungicidal activities against 14 kinds of phytopathogenic fungi at 50 μg/mL and the antifungal activities of compounds 5c, 5g, 6a, and 6e against Rhizoctonia cerealis are higher than that of the commercial fungicide chlorothalonil. Therefore, this study could lay a foundation for the application of hyrtinadine A derivatives in plant protection.