天然单萜柠檬烯的微生物转化

天然单萜柠檬烯资源丰富,价格便宜,在日用化工和医药行业已得到重要的应用。近几十年来,以柠檬烯为起始原料的新产品的研究与开发一直受到关注。大量文献报道了微生物能够对柠檬烯进行生物转化,得到系列在化妆品、食品、医药、有机合成等领域有重要应用价值的含氧衍生物。本文系统地综述了柠檬烯的微生物转化菌株和所得到转化产物的结构,分析了微生物对柠檬烯的主要转化途径以及影响微生物转化效率的主要因素。柠檬烯经微生物转化所得到的产物具有区域和立体选择性,并且难以通过人工合成方法得到。对生物转化过程进行系统优化,将有可能实现有用化合物的工业化生产。此外,在转化过程中诱导的高活性酶,尤其是单加氧酶和羟化酶的研究与应用也展现了诱人的前景。     

天然单萜与亲烯体反应研究进展

综述了α-蒎烯、β-蒎烯、柠檬烯等常见天然单萜与亲烯体马来酸酐、丙烯酸类、苯乙烯类以及含腈化合物发生的烯反应、Diels-Alder加成、共聚等反应,归纳了反应条件对反应产物及组成的影响,简要介绍了各种产物的应用现状和前景。     

镍催化杂芳烃的非天然戊烯基化及环状单萜化反应（英文）

萜类化合物,如半萜类和单萜类,是天然产物中种类最繁多、结构最多样的一类,广泛存在于植物和海洋生物中,在人类的日常生活中具有重要的应用价值.自然界中,二甲基烯丙基焦磷酸酯(DMAPP)和异戊烯基焦磷酸酯(IPP)在各种酶的作用下经过偶联、重排、环化以及异构化等反应合成萜类化合物.传统的人工方法大多依赖于过渡金属催化的异戊烯基以及反异戊烯基前体的反应,该反应不仅需要当量的金属试剂,且反应过程中也会产生当量的副产物,不符合绿色环保以及原子经济性原则.异戊二烯作为一种廉价易得的大宗化学品,其高附加值转化一直是学术界和工业界关注的焦点.但由于异戊二烯具有反应活性低以及区域选择性调控难的特点,氢芳基化产物最多可达到十四种异构体.此外,异戊二烯容易发生二聚、三聚以及调聚等反应,产生复杂产物.上述问题使得异戊二烯的高附加值转化具有很大挑战性.在前期关于异戊二烯氢官能团化以及手性二聚研究的基础上,本文提出了一种以异戊二烯为原料,通过接力催化策略,在杂芳环中引入非天然戊烯基和环状单萜骨架的方法.具体而言,使用廉价金属镍作为催化剂,小位阻的氮杂环卡宾作为配体,在当量碱的条件下,通过马氏加成得到异戊二烯4,3...     

在线二维集束毛细管柱-高气压光电离-飞行时间质谱用于单萜类化合物的快速测量

单萜类化合物是大气中生物源挥发性有机物（BVOCs）的一个主要组分，具有同分异构体种类多、寿命短、浓度低、时空变化快等特点。将集束毛细管柱（MCC）和高气压光电离-飞行时间质谱仪（HPPI-TOF MS）相结合，搭建MCC-HPPI-TOF MS联用装置，并开发一种二维GC-MS快速在线检测方法，用于单萜同分异构体的快速定性和定量分析。实验结果表明，在无任何样品预富集的前提下，该方法可在180 s内实现α-蒎烯、β-蒎烯、α-萜烯、γ-萜烯、3-蒈烯及柠檬烯等6种单萜同分异构体的在线检测，检出限（LODs）低至μg/m³量级。该方法已经用于松树和柏树枝叶释放出的单萜化合物的快速在线分析，展示了其在环境监测、过程分析等领域复杂混合物样品在线检测的能力和应用前景。     

单萜烯可持续聚合物的研究进展

随着人们对化石燃料等不可再生资源需求的不断增长,每年有大量的聚合物以塑料的形式被使用,大多数聚合物来自化石燃料,因此有必要寻找可再生的新型材料。与传统的石油基高分子材料不同,生物基高分子材料是利用可再生的生物资源合成的一类绿色环保聚合物材料,具有来源绿色、价廉易得、易于降解的特点。其中,萜烯以及萜类化合物具有独特的手性骨架和活性位点,有助于替代化石能源制造可再生和可持续的材料,减轻环境负担,进而拓展其在生物医药、包装涂料、食品工业等领域中的应用。本文主要综述了单萜烯,如蒎烯、柠檬烯和月桂烯的聚合过程和方法,并讨论了其在不同的催化体系、温度等方面对聚合过程的影响,所得聚合物在生产生活中的应用和单体在未来可利用的方向。     

用反相液相色谱法从肖石蚕五蕊花中分离环烯醚单萜类化合物

天然产物单萜类中除熟知精油中的普通单萜外,环烯醚单萜类(iridoids)则鲜为人知。自1963年Briggs等提出iridoids一词到七十年代才引起人们的重视和兴趣,这不仅由于这类单萜是许多民间药用植物的活性成分,而且还提供了萜类和生物碱结构间的联     

大环酮的微生物转化

微生物转化在有机合成上有着独特的地位。虽然甾族化合物的微生物转化应用得非常广泛,但有关大环化合物的微生物转化很少报导,而大环酮又是名贵的麝香系列香料。因此本实验意欲筛选使大环酮发生转化的微生物,同时也希望这些反应能在麝香酮的合成上代替有关化学反应。我们选择了三组典型的催化不同类型反应的微生物。     

柠檬烯和柠檬烯氧化物与硫酸的非均相反应动力学

主要对天然挥发性有机物柠檬烯和柠檬烯氧化物在30%-80% (w)硫酸表面的非均相吸收反应进行了研究, 借以评估天然挥发性有机物与大气环境中的酸性气溶胶的反应活性. 采用自行搭建的配以单光子激光电离飞行时间质谱的湿壁流动反应管的设备对柠檬烯及其氧化物在硫酸表面的非均相吸收动力学进行了测定,计算了稳态摄取系数(γ). 实验结果表明, 柠檬烯氧化物在硫酸表面比只含有双键的柠檬烯的反应活性高, 室温下柠檬烯氧化物在30%-50% (w)硫酸上对应的稳态摄取系数是(7.100±0.023)×10^-5-(8.150±0.162)×10^-3. 此外, 还利用气相色谱-质谱(GC-MS)联用和电喷雾电离质谱(ESI-MS)对柠檬烯氧化物与硫酸的体相反应产物进行了研究, 产物包括单萜烯、松油醇、水合萜二醇和水合萜二醇二硫酸酯. 其中, 水合萜二醇二硫酸酯作为有机硫酸酯的一种, 能够改变气溶胶的吸湿性, 增强云凝结核的活性, 对于大气中灰霾的形成可能有明显的促进作用.     

咪唑修饰硅胶负载乙酰丙酮钴(Ⅱ)催化分子氧氧化单萜烯研究

采用3-氯丙基三甲氧基硅烷和咪唑对硅胶表面进行修饰(SiIm), 通过咪唑环中π电子与钴离子空d轨道之间的纵轴配位作用制得非均相负载催化剂Co(acac)₂/SiIm, 用IR, UV-Vis和ICP-AES对其结构进行表征. 在乙腈溶剂中, 催化剂催化分子氧氧化单萜烯得到了相应的氧化产物. 研究表明, 负载催化剂具有良好的催化氧化性能, 获得了较高的反应转化率和产物选择性, 其中柠檬烯和α-蒎烯的氧化以环氧产物为主, 而β-蒎烯的氧化则以烯丙位氧化产物为主. 另外, 对反应机理和竞争反应进行了简单的阐述.     

松脂的催化歧化反应产物的气相色谱-质谱分析

采用气相色谱-质谱技术对松脂的催化歧化新工艺的反应产物进行分析,共分离出45个峰,鉴定出其中的38个化合物,并发现松脂歧化产物中歧化松节油的主要成分为对伞花烃,含量为16.26%;歧化松香的主要成分为脱氢枞酸和氢化树脂酸,其含量分别为41.58%和21.43%。在此基础上对松脂歧化反应过程进行了初步探讨,认为松脂原料中的酸性物质发生分子间氢转移反应,萜烯烃的存在促进了脱氢反应的进行;在树脂酸提供的酸性环境下松脂原料中中性油的主要成分双环单萜烯发生开环异构形成单环单萜烯,单环单萜烯再进行催化脱氢转化为对伞花烃。分析结果表明,直接以松脂为原料进行催化歧化反应可同时获得特级歧化松香和高含量的对伞花烃。     

Evaluation of the activity of the sponge metabolites avarol and avarone and their synthetic derivatives against fouling micro- and macroorganisms

The sesquiterpene hydroquinone avarol (1) was isolated from the marine sponge Dysidea avara, whereas the corresponding quinone, avarone (2), was obtained by oxidation of avarol, and the significantly more lipophilic compounds [3'-(p-chloro-phenyl)avarone (3), 3',4'-ethylenedithioavarone (4), 4'-isopropylthioavarone (5), 4'-tert-butylthioavarone (6), 4'-propylthioavarone (7), 4'-octylthioavarone (8)] were obtained by nucleophilic addition of thiols or p-chloroaniline to avarone. All these compounds were tested, at concentrations ranging from 0.5 to 50 microg/mL, for their effect on the settlement of the cyprid stage of Balanus amphitrite, for toxicity to both nauplii and cyprids and for their growth inhibitory activity on marine bacteria (Cobetia marina, Marinobacterium stanieri, Vibrio fischeri and Pseudoalteromonas haloplanktis) and marine fungi (Halosphaeriopsis mediosetigera, Asteromyces cruciatus, Lulworthia uniseptata and Monodictys pelagica).     

In-vitro antibacterial properties of crude aqueous and n-hexane extracts of the husk of Cocos nucifera

The increasing numbers of cases of antibiotic resistance among pathogenic bacteria such as Vibrio species poses a major problem to the food and aquaculture industries, as most antibiotics are no longer effective in controlling pathogenic bacteria affecting these industries. Therefore, this study was carried out to assess the antibacterial potentials of crude aqueous and n-hexane extracts of the husk of Cocos nucifera against some selected Vibrio species and other bacterial pathogens including those normally implicated in food and wound infections. The crude extracts were screened against forty-five strains of Vibrio pathogens and twenty-five other bacteria isolates made up of ten Gram positive and fifteen Gram negative bacteria. The aqueous extract was active against 17 of the tested bacterial and 37 of the Vibrio isolates; while the n-hexane extract showed antimicrobial activity against 21 of the test bacteria and 38 of the test Vibrio species. The minimum inhibitory concentrations (MICs) of the aqueous and n-hexane extracts against the susceptible bacteria ranged between 0.6-5.0 mg/mL and 0.3-5.0 mg/mL respectively, while the time kill study result for the aqueous extract ranged between 0.12 Log?? and 4.2 Log?? cfu/mL after 8 hours interaction in 1 x MIC and 2 x MIC. For the n-hexane extract, the log reduction ranged between 0.56 Log?? and 6.4 Log?? cfu/mL after 8 hours interaction in 1 x MIC and 2 x MIC. This study revealed the huge potential of C. nucifera extracts as alternative therapies against microbial infections.     

Pyrolysis mass spectrometry for distinguishing potential hoax materials from bioterror agents

Pyrolysis mass spectrometry (PyMS) was investigated as a rapid tool to distinguish potential bioterror hoax materials from samples containing pathogenic bacteria. A pyrolysis time-of-flight (TOF) mass spectrometer equipped with an alternative ionization technique, metastable atom bombardment (MAB), was used to produce sample spectra. These spectra were analyzed by principal component and discriminant analysis for pattern recognition. Materials investigated were two strains of Vibrio parahaemolyticus, one of which produced the tdh toxin, two Salmonella enterica serotypes, a biological mosquito control product containing spores of Bacillus thuringiensis, and several white to off-white powders (which could be used as hoax materials), such as flour, corn starch, methyl cellulose, and xanthan gum. PyMS distinguished bacterial samples from hoax materials. Furthermore, pattern analysis differentiated Vibrios from Salmonellae, Salmonella enterica Anatum from S. enterica Heidelberg, and the two V. parahaemolyticus strains from each other. The B. thuringiensis mixture was distinguished from other bacteria and powders, suggesting that PyMS with pattern recognition may differentiate samples containing pathogens, including Bacillus spp., from nonbiological agents and that it can be a rapid method for detection of bacteria. MS data acquisition took only 7 min for each sample.     

海洋真菌Hypoxylor oceanicum对1,2,3,4-四氢萘的转化及其产物测定

南海海洋真菌Hypoxylon oceanicum(326#)以葡萄糖(10g／L)、蛋白胨(2g／L)、酵母膏(1g／L)、20％的人工海水为培养基,在培养液中添加200mg／L的1,2,3,4-四氢萘,培养7d,对转化产物进行提取,经GC—MS和NMR检测,发现转化产物中有1个主要氧化产物3,4-dihydro-4-hydroxy-1(2H)—naphthalenone,占96．16％。另外3个氧化产物为：3,4-dihvdro-1(2H)—naphthalenone,1,2．3,4-tetrahydro-1-naphthalenol和1,2,3,4-tetrahydro-1,2-naphlhalenediol。该微生物催化氧化反应发生在四氢萘的非活性的饱和碳上,显示出海洋真菌Hypoxylon oceanicum(326#）具有独特的生物氧化机制。     

Bioreduction of Acetophenone Derivatives by Red Marine Algae Bostrychia radicans and B. tenella,and Marine Bacteria Associated

The biocatalytic reduction of acetophenone derivatives was exploited by using algal biomass from Bostrychia radicans and B. tenella producing exclusively (S)‐2‐phenylethanols with high enantiomeric excess (>99% ee). Bacterial populations associated with algal biomass were identified as the Bacillus genus. This report deals with the first investigations involving the use of marine bacteria associated with B. radicans and B. tenella marine algae for the biocatalytic reduction of acetophenone derivatives.     

Whole cell immobilised biosensors for toxicity assessment of a wastewater treatment plant treating phenolics-containing waste

Wastewater treatment plants dealing with industrial wastes are often susceptible to overload of toxic influent that can partially or completely destroy treatment for extended periods. An obvious candidate for monitoring toxicity in such wastewater systems is bioluminescent bacteria. However, the natural bioluminescent bacteria can be particularly sensitive to some industrial wastes and therefore their response to normal operational conditions does not reflect the status of the microbial community responsible for treatment. Moreover, the salt dependence of the marine bioluminescent bacteria, and the temperature sensitivity of some strains, further complicate their use. Here we describe the construction of whole cell genetically modified bioluminescent biosensors and their immobilisation for use in monitoring the toxicity of a complex industrial wastewater containing phenolic materials. A hand-held luminometer was designed for laboratory or field use, and the immobilisation system designed with several things in mind: the geometry of the instrument; the need for containment of GM bacteria; the maximisation of the bioavailability of the wastewater to the biosensor. The performance of a candidate GM sensor was compared with Vibrio fischeri in liquid culture and after immobilisation in thin films of poly(vinyl alcohol) (PVA) cryogels. The biosensors were tested against pure phenol and 3-chlorophenol as a reference toxic chemical known to be much more toxic to bacteria than phenol. The biosensors were then tested with the phenolics-containing industrial wastewater. The immobilisation system proved to operate predictably with pure toxicants, and was able to discriminate toxicity of various zones within the wastewater treatment plant.     

Antibacterial ultrafiltration membrane with silver nanoparticle impregnation by interfacial polymerization for ballast water

Interfacial polymerization technology was employed to immobilize silver (Ag) nanoparticles on the surface of commercial polyethersulfone (PES) membrane to develop antibacterial and antifouling ultrafiltration membrane. Ag nanoparticles were prepared from the reduction of silver nitrate (AgNO₃) by sodium borohydride in the presence of polyethyleneimine (PEI) as the stabilizer. The encapsulated Ag nanoparticles in the PEI solution were embedded into the PEI membrane when trimesoyl chloride solution was used to crosslink the PEI solution with the PES membrane, forming Ag-polyamide (PA) networks through the interfacial polymerization reaction. Experimental results showed that the membrane prepared with 50 mmol/L of AgNO₃ and 20 mmol/L of PEI had the optimized antibacterial effect against Escherichia coli. Bacterial concentration and species were also investigated. Exiguobacterium aestuarii and Staphylococcus aureus which are gram-positive bacteria, needed significantly more time for the Ag-PA/PES membrane to kill the bacteria completely when compared to E.coli and Vibrio coralliilyticus which are gram-negative bacteria. This study showed that Ag nanoparticles impregnated in membrane surfaces were 100% effective in killing various types of marine bacteria and bacteria in the seawater collected off Sentosa Island in Singapore. These membranes exhibit excellent antibacterial and antifouling properties which can be used to kill bacteria in ballast water and seawater.     

Synthesis and Biological Activity of Acrylate Copolymers Containing 3-Oxo-N-allyl-1,2-benzisothiazole-3(2H)-carboxamide Monomer as a Marine Antifouling Coating

A type of grafted acrylate copolymer resins, containing 3-oxo-N-allyl-1,2-benzisothiazole-2(3H)-carboxamide monomer and heterocyclic monomers, was synthesized through the copolymeri- zation of methyl methacrylate (MMA) and butyl acrylate (BA) with functional monomers. The structures of the monomers and copolymers were validated by infrared (IR) and ¹H nuclear magnetic resonance (NMR) spectroscopies. The inhibitory activities of the copolymers on algae, bacteria, and barnacle larvae were measured, and the antifouling potencies against marine macrofouling organisms were investigated. The results showed that the grafted resin had significant inhibitory effects on the growth of three marine algae (Isochrysis galbana, Nannochloropsisoculata, and Chlorella pyrenoidosa), and three bacteria (Vibrio coralliilyticus, Staphylococcus aureus,and Vibrio parahaemolyticus). The target copolymers also showed excellent inhibition of the survival of barnacle larvae. Additionally, the release rate of the antifoulant and the results of the marine field tests indicated that the grafted copolymers had outstanding antifouling potency against the attachment of marine macrofouling organisms.     

Overview of the inactivation by 254 nm ultraviolet radiation of bacteria with particular relevance to biodefense

Abstract Our goal was to ultimately predict the sensitivity of untested bacteria (including those of biodefense interest) to ultraviolet (UV) radiation. In this study, we present an overview and analysis of the relevant 254 nm data previously reported and available in the literature. The amount of variability in this data prevented us from determining an "average" response for any bacterium. Therefore, we developed particular selection criteria to include the data in our analysis and suggested future guidelines for reporting UV sensitivity results. We then compiled a table of the sensitivity to 254 nm UV for 38 bacteria and three bacterial spores. The UV sensitivity was quite similar (within 10%) among the spores of Bacillus anthracis (strains Vollum 1B and Sterne), Bacillus subtilis, and Bacillus megaterium. These data indicate that spores of B. subtilis and B. megaterium could be adequate simulants of B. anthracis spores in UVC experiments. Spores of B. anthracis, B. subtilis and B. megaterium were 5-10 times more resistant to UV than were their corresponding vegetative cells. The vegetative cells of B. anthracis showed similar UV sensitivity to those of Burkholderia pseudomallei, Shigella sonnei, and a wild-type strain of Escherichia coli. Yersinia enterocolitica and Vibrio cholerae appeared more sensitive to UV and Salmonella typhi slightly more resistant to UV than E. coli. The sensitivity (at 254 nm) of all vegetative bacteria ranged from 11 to 80 Jm(2) for a 1 Log(10) kill and from 25-200 Jm(2) for 4 Log(10) kill.     

A biocompatible micro cell culture chamber (microCCC) for the culturing and on-line monitoring of eukaryote cells

We have previously shown that a polymeric (PMMA) chip with medium perfusion and integrated heat regulation provides sufficiently precise heat regulation, pH-control and medium exchange to support cell growth for weeks. However, it was unclear how closely the cells cultured in the chip resembled cells cultured in the culture flask. In the current study, gene expression profiles of cells cultured in the chip were compared with gene expression profiles of cells cultured in culture flasks. The results showed that there were only two genes that were differently expressed in cells grown in the cell culture chip compared to cell culture flasks. The cell culture chip could without further modification support cell growth of two other cell lines. Light coming from the microscope lamp during optical recordings of the cells was the only external factor identified, that could have a negative effect on cell survival. Low grade light exposure was however compatible with optical recordings as well as cell viability. These results strongly indicate that a cell culture chip could be constructed that allowed for on-line optical recording of cellular events without affecting the cell culturing condition compared to cell cultured in culture flasks incubated in a dark and CO2 conditioned incubator.