来自海洋放线菌N331抗菌化合物SR-B的核磁共振分析

从分离筛选的海洋放线菌N331的发酵液中分离、纯化得到一种无色结晶抗菌化合物SR—B,通过对其质谱、多种核磁共振谱的结构信息进行分析,鉴定其分子结构。结果表明化合物SR—B的分子式为C22H27O7N3S,确定为灰绿霉素（griseoviridin）。分析并获得了灰绿霉素较完整的核磁共振谱信息,并首次从海洋放线菌中分离得到灰绿霉素。     

Cold-Active Xylanase Produced by Fungi Associated with Antarctic Marine Sponges

Despite their potential biotechnological applications, cold-active xylanolytic enzymes have been poorly studied. In this work, 38 fungi isolated from marine sponges collected in King George Island, Antarctica, were screened as new sources of cold-active xylanases. All of them showed xylanase activity at 15 and 23 °C in semiquantitative plate assays. One of these isolates, Cladosporium sp., showed the highest activity and was characterized in detail. Cladosporium sp. showed higher xylanolytic activity when grown on beechwood or birchwood xylan and wheat bran, but wheat straw and oat bran were not so good inducers of this activity. The optimal pH for xylanase activity was 6.0, although pH stability was slightly wider (pH 5–7). On the other hand, Cladosporium sp. showed high xylanase activity at low temperatures and very low thermal stability. Interestingly, thermal stability was even lower after culture media were removed and replaced by buffer, suggesting that low molecular component(s) of the culture media could be important in the stabilization of cold-active xylanase activity. To the best of our knowledge, this study is the first report on extracellular xylanase production by fungi associated with Antarctic marine sponges.     

吸铜海洋真菌Fusarium sp.#ZZF51的代谢产物二（5-丁基-2-吡啶甲酸）合铜络合物的研究

A copper coordination compound ZZF51(A) named bis(5‐butyl‐2‐pyridinecarboxylato‐N1,O2)‐copper, the first time found in the nature, was isolated from a marine endophytic fungus Fusarium sp. ZZF51 from the South China Sea coast. Its structure was elucidated using spectroscopic methods and single crystal X‐ray diffraction analysis. The antimicrobial cytotoxicity experiments exhibited that ZZF51(A) had mutagenicity activities against four aerobic reference strains Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella enteritidis with respective MIC values of 12.5, 25, 12.5, and 50 µg/mL. The anti‐cancer tests showed that the compound had strong inhibitory activities against three human cancer lines KB, KBv200, and HepG2 with IC₅₀ values of 3.54, 3.68 and 25.12 µg/mL respectively. In the course of investigating the source of ZZF51(A) in biomass, it was found that the output of ZZF51(A) was largely influenced by the amount of CuCl₂ in the liquid medium, and the fungus (No. ZZF51) had two notable characteristics:endurance of high concentration Cu(II) ions and biosorption of Cu(II) ions.     

The 15N NMR study of silatranes

Various silatrane compounds were studied by means of ¹⁵N NMR spectroscopy. The quantum chemical calculations of some of the compounds were carried out using CNDO/2 method. The following correlations were obtained, i.e., ¹⁵N chemical shifts vary linearly with Taft's polar substituent constants (s) of the substituents R on the silicon atoms, and also with the net charge densities on the nitrogen atoms. From both experimental and theoretical aspects, it could be concluded that the SiN dative bonds in a series of silatrane compounds actually exist.     

Dioxopiperazine Alkaloids Produced by the Marine Mangrove Derived Endophytic Fungus Eurotium rubrum

Cultivation of the fungal strain Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus, resulted in the isolation of two new dioxopiperazine derivatives, namely, dehydrovariecolorin L ( 1 ) and dehydroechinulin ( 2 ), together with eight known dioxopiperazine compounds including variecolorin L ( 3 ), echinulin ( 4 ), isoechinulin A ( 5 ), dihydroxyisoechinulin A ( 6 ), preechinulin ( 7 ), neoechinulin A ( 8 ), neoechinulin E ( 9 ), and cryptoechinuline D ( 10 ). The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data as well as by comparison with literature. Compounds 1, 2, 9 , and 10 were investigated for their α,α‐diphenyl‐β‐picrylhydrazyl (DPPH) radical‐scavenging activity. In addition, the new compounds, 1 and 2 , were evaluated for their cytotoxic activity against the P‐388, HL‐60, and A549 cell lines.     

人工合成化合物S-A的核磁共振研究

利用核磁共振技术对人工合成化合物S-A的溶液行为进行了研究, 确定该化合物在氯仿溶剂中存在分子内氢键过程, 而该交换过程对核磁共振结果的影响异常明显. 针对以上现象, 通过外加试剂和改变温度的手段对样品体系或测试环境进行了调制, 提高了核磁共振谱图的信号质量和“可读性”.     

Probing platinum azido complexes by 14N and 15N NMR spectroscopy

Metal azido complexes are of general interest due to their high energetic properties, and platinum azido complexes in particular because of their potential as photoactivatable anticancer prodrugs. However, azido ligands are difficult to probe by NMR spectroscopy due to the quadrupolar nature of (14)N and the lack of scalar (1)H coupling to enhance the sensitivity of the less abundant (15)N by using polarisation transfer. In this work, we report (14)N and (15)N NMR spectroscopic studies of cis,trans,cis-[Pt(N(3))(2)(OH)(2)(NH(3))] (1) and trans,trans,trans-[Pt(N(3))(2)(OH)(2)(X)(Y)], where X=Y=NH(3) (2); X=NH(3), Y=py (3) (py=pyridine); X=Y=py (4); and selected Pt(II) precursors. These studies provide the first (15)N NMR data for azido groups in coordination complexes. We discuss one- and three-bond J((15)N,(195)Pt) couplings for azido and am(m)ine ligands. The (14)N(α) (coordinated azido nitrogen) signal in the Pt(IV) azido complexes is extremely broad (W(1/2)≈2124 Hz for 4) in comparison to other metal azido complexes, attributable to a highly asymmetrical electric field gradient at the (14)N(α) atom. Through the use of anti-ringing pulse sequences, the (14)N NMR spectra, which show resolution of the broad (14)N(α) peak, were obtained rapidly (e.g., 1.5 h for 10 mM 4). The linewidths of the (14)N(α) signals correlate with the viscosity of the solvent. For (15) N-enriched samples, it is possible to detect azido (15)N resonances directly, which will allow photoreactions to be followed by 1D (15)N NMR spectroscopy. The T(1) relaxation times for 3 and 4 were in the range 5.7-120 s for (15)N, and 0.9-11.3 ms for (14)N. Analysis of the (1)J((15)N,(195)Pt) coupling constants suggests that an azido ligand has a moderately strong trans influence in octahedral Pt(IV) complexes, within the series 2-pic相似文献   

Marine Algae Membrane Phospholipids Study by High Resolution 31P NMR

Abstract

Membrane phospholipids were extracted using a modified Folch, Lees and Sloane-Stanley method, from 21 different algae species covering three major divisions of the protista kingdom. In the modified method after chloroform/methanol (2:1 v/v) extraction and filtration, the solution was backwashed with K-EDTA, 0.6 M, instead of KCl, 1 M. Because algae samples are eavily loaded with cations that broaden NMR signals, the K-EDTA wash results in more highly resolved NMR signals. Following rotary evaporation, the crude algae lipid extract was dissolved in the chloroform-benzene(d6)/methanol-CsEDTA (2:l ml/ml) reagent and analyzed using a 500 MHz NMR spectrophotometer. Phospholipid chemical shifts were determined relative to standard phosphoric acid (85%), following the UIPAC convention. The internal reference used was phosphatidylcholine (PC, -0.84 δ) Division chlorophyta (8 sps.) yields phospholipid signals for phosphatidylglycerol (PG, 0.50), phosphatidic acid (PA, 0.25), cardiolipin (CL, 0.18), phosphatidylethanolamine (PE, 0.03), sphyngomyelin (SPH, -0.09), phosphatidylinositol (PI, -0.37) and PC; the lysoderivatives for lyso PG (LPG, 1.09) and lyso PC (LPC, -0.28), and one uncharacterized signal at 0.32. Phosphatidylserine (PS -0.05) and plasmalogens were not detected. Division rhodophyta (10 sps.) shows signal from PG, PA, CL, PE, SPH, PI, and PC; the lysoderivatives of lyso PA (LPA, 0.83), lyso PE (LPE, 0.43) and LPC; the plasmalogens PC plasmalogen (PC plas, -0.77), LPC plas (-0.20), and l-0-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (PAF-acether, -0.70); and an uncharacterized signal at -40 δ chemical shift. PS was not detected. Division Phaeophytas (3 sps.) showed signals for PG, PA, CL, PE, SPH, PI, and PC and lysoderivatives of LPG, LPA, LPE plas (0.53), LPE, LPC plas, and LPC. PS, PAF-acether and the uncharacterized signals at 0.32 δ and -0.40 δ were not detected.     

Epipyrone A,a Broad-Spectrum Antifungal Compound Produced by Epicoccum nigrum ICMP 19927

We have isolated a filamentous fungus that actively secretes a pigmented exudate when growing on agar plates. The fungus was identified as being a strain of Epicoccum nigrum. The fungal exudate presented strong antifungal activity against both yeasts and filamentous fungi, and inhibited the germination of fungal spores. The chemical characterization of the exudate showed that the pigmented molecule presenting antifungal activity is the disalt of epipyrone A—a water-soluble polyene metabolite with a molecular mass of 612.29 and maximal UV–Vis absorbance at 428 nm. This antifungal compound showed excellent stability to different temperatures and neutral to alkaline pH.     

Production and Properties of a Surface-Active Lipopeptide Produced by a New Marine Brevibacterium luteolum Strain

Microbial-derived surfactants are molecules of great interest due to their environmentally friendly nature and low toxicity; however, their production cost is not competitive when compared to synthetics. Marine microorganisms are exposed to extremes of pressure, temperature, and salinity; hence, they can produce stable compounds under such conditions that are useful for industrial applications. A screening program to select marine bacteria able to produce biosurfactant using low-cost substrates (mineral oil, sucrose, soybean oil, and glycerol) was conducted. The selected bacterial strain showed potential to synthesize biosurfactants using mineral oil as carbon source and was identified as Brevibacterium luteolum. The surface-active compound reduced the surface tension of water to 27 mN m^?1 and the interfacial tension (water/hexadecane) to 0.84 mN m^?1 and showed a critical micelle concentration of 40 mg L^?1. The biosurfactant was stable over a range of temperature, pH, and salt concentration and the emulsification index (E₂₄) with different hydrocarbons ranging from 60 to 79 %. Structural characterization revealed that the biosurfactant has a lipopeptide nature. Sand washing removed 83 % of crude oil demonstrating the potential of the biosurfactants (BS) for bioremediation purposes. The new marine B. luteolum strain showed potential to produce high surface-active and stable molecule using a low-cost substrate.     

NMR研究HDI与水的加成产物N-100结构

用NMR研究了六次甲基二异氰酸酯与水的加成产物N－100的结构．结果表明：N－100中含有脲基、缩二脲基、双缩二脲基、三聚体异氰脲基、异氰酸酯和氨基等基团，是一种以氢原子为交联点、胺和异氰酸酯为端基的具有复杂网络结构的多异氰酸酯．一维核磁谱及二维化学位移相关谱不但分辨出4种羰基，还确定了氮上5种不同取代结构的分子链连接情况．通过建立理论模型，准确地定量描述了N－100的网络结构．     

Reactions of organo-rhodium complexes with multidentate N,N and N,S-heterocycles and exchange studies by NMR

Dihalobridged binuclear complexes [Rh(diolefin)(μ-X)]₂ {diolefin = 1,5-cyclooctadiene (cod), X = Cl or Br; diolefin = norbornadiene (nbd), X = Cl}, undergo halide bridge cleavage reactions with multidentate N,N-heterocycles 1,3,5-tris(benzimidazolyl)benzene (L¹H₃), 1,3,5-tris(N-methylbenzimidazolyl)benzene (L²H₃) and N,S-heterocycle 1,3,5-tris(benzothiazolyl)benzene (L³H₃) to yield trinuclear heterocycle bridged complexes [{RhX(cod)}₃(μ-LH₃)] and [{RhCl(nbd)}₃(μ-LH₃)] (LH₃ = L¹H₃, L²H₃, L³H₃). ¹H NMR exchange measurements have shown resonances for olefinic protons 1″, 2″, 5″ and 6″ of cod at different chemical shifts, perhaps due to restricted Rh–N bond rotation. The olefinic and aliphatic protons would undergo exchange with each other and also with intermediate species. The exchange mechanism may be visualized to involve Rh–N bond breaking, rotation of the cod ligand of the T-shaped (three-coordinate) intermediate species followed by recomplexation. An alternate mechanism may be Rh–cod bond breaking at olefin positions 5″ and 6″, isomerisation of the T-complex such that 5″/6″ moves trans to X coupled with rotation of the heterocycle about the Rh–N bond (made easier by the reduced coordination number of the intermediate), followed by recoordination of 1″/2″ trans to N, followed by recomplexation. NMR signals from the intermediate species in one dimensional ¹H, ¹³C and 2D NMR spectra have supported the exchange of protons.     

四氟菊酯的核磁共振法分析

采用^1HNMR、^13C NMR、无畸变增强极化转移实验(DEPT)、^1H—^1H相关谱(COSY)、^1H检测异核多量子相关谱(HMQC)、^1H检测的异核多键相关谱(HMBC)等方法，对四氟菊酯的^1H和^13C NMR谱信号进行了归属；并用奥氏核效应(NOE)差谱法确定了该化合物的立体结构，为其结构鉴定和生产过程中的质量控制提供了重要依据。     

ErFe_(11)Ti化合物在流动氮气氛中的差热-热重分析

通过X射线衍射(XRD)、差热-热重(DTA-TG)联用仪以及磁测量等手段研究了ErFe11Ti化合物在流动氮气氛从室温(~300 K)到1473 K升温过程中成分、结构及居里温度等变化行为。结果表明,温度为600 K左右时,ErFe11Ti化合物吸氮反应最剧烈,吸氮以后化合物的居里温度TC有明显提高。当温度较高时,ErFe11Ti可能部分分解为Er-N,α-Fe(Ti)。α-Fe和Ti分别在860和1300 K左右发生吸氮反应,生成FeNy和Ti2N2。在整个升温过程中,DTA曲线未因样品升温至某成分的居里点发生而出现明显放热峰,这可能是因为样品的相变潜热较小所引起的。     

煤与催化裂化油浆共处理反应沥青性质分析

用1L高压反应釜通过煤与催化裂化油浆共处理制得了沥青并对沥青性质进行了分析研究。发现煤与油浆比例为1：1时，共处理沥青的针入度、软化点和延度三大指标符合国家高等级道路沥青标准，此时该沥青的饱和分较低，芳香分和沥青质适中，而胶质较多。