海南桉叶活性物质的应用研究进展

综述了桉叶提取物的一般应用研究进展及其生物活性物质(芦丁、槲皮素等)在医药领域作为药物前体物的的应用研究进展,展望了桉叶在环境减毒领域的应用前景,并介绍了桉叶活性物质的常见提取方法.     

桉树制化学机械浆适应性研究

本文对７年生尾叶桉和雷林壹号桉的材性、化学组分及制碱性亚钠化学机械浆适应性进行了初步研究。除雷林壹号桉抽出物较高外，两个树种材性特征较为接近，属硬质中密度材种，尾叶桉制化学机械浆质量优于雷林壹号桉。两者经合适的工艺制浆，可以用来生产本色和漂白化学机械浆，作为定向培育纸浆材要求两者比较，种植尾叶桉更为经济合理。     

桉树制化学机械浆适应性研究

本文对７年生尾叶桉和雷林壹号桉的材性、化学组分及制碱性亚钠化学机械浆适应性进行了初步研究。除雷林壹号桉抽出物较高外．两个树种材性特征较为接近，属硬质中密度材种，尾叶桉制化学机械浆质量优于雷林壹号桉。两者经合适的工艺制浆，可以用来生产本色和漂白化学机械浆，作为定向培育纸浆材要求两者比较，种植尾叶桉更为经济合理。     

速生桉叶去除水中六价铬

考察了桉叶的烘干温度、叶片颗粒大小、烘干和储存时间对速生桉叶处理含Cr(Ⅵ)废水的影响,同时还研究了速生桉叶对Cr(Ⅵ)去除的吸附等温模型、动力学和热力学特性.结果表明:颗粒越小越有利于去除Cr(Ⅵ);叶片越新鲜,Cr(Ⅵ)的去除效果越好.速生桉叶颗粒大小为3 mm×3 mm,在105℃下干燥120 min后,对50 ...     

微波辅助提取巨尾桉叶多糖及其抗氧化性研究

以巨尾桉叶为原料,开展了微波辅助水提法提取巨尾桉叶多糖的工艺优化研究,建立了葡萄糖为标准品测定多糖的定量分析方法,考察了巨尾桉叶多糖的抗氧化性。实验结果表明,测定波长为489 nm下的标准曲线方程为:y=0.014 5x+0.000 8;巨尾桉叶多糖提取的优化工艺为:微波功率为480 W,液固比为45∶1 m L/g,提取时间为7 min,多糖提取率为9.17%;巨尾桉叶多糖对DPPH·和过氧化氢的清除率分别为70.05%和84.7%。     

微波辅助提取巨尾桉叶多糖及其抗氧化性研究

以巨尾桉叶为原料,开展了微波辅助水提法提取巨尾桉叶多糖的工艺优化研究,建立了葡萄糖为标准品测定多糖的定量分析方法,考察了巨尾桉叶多糖的抗氧化性。实验结果表明,测定波长为489 nm下的标准曲线方程为:y=0.014 5x+0.000 8;巨尾桉叶多糖提取的优化工艺为:微波功率为480 W,液固比为45∶1 m L/g,提取时间为7 min,多糖提取率为9.17%;巨尾桉叶多糖对DPPH·和过氧化氢的清除率分别为70.05%和84.7%。     

两种桉叶挥发油含量和化学成分周年变化

为了探索窿缘桉和尾叶桉叶挥发油含量和化学成分的周年变化规律,采用水蒸气蒸馏法提取其挥发油,采用GC-MS法分析挥发油化学成分,并以挥发油提取率为指标,确定桉叶的最佳采收期。结果表明,窿缘桉叶挥发油含量周年变化显著,5、9、10月份含量最高,为最佳采收期;尾叶桉叶挥发油含量周年变化较小,4、5、7月份含量相对较高,适宜采收。窿缘桉叶挥发油主要成分为α-蒎烯、β-蒎烯、桉树脑,含量变化显著。尾叶桉叶挥发油主要成分为α-蒎烯、桉树脑、冰片和α-松油醇,含量变化显著。不同时期桉叶挥发油化学成分含量有很大的差异。     

海南枝叶浸提物的抗菌及降解双酚A研究

研究了海南桉叶浸提物的抗菌特性。发现采用乙醇浸提可以得到较高的收率及较好的抗菌效果，乙醇浸提物对金黄色葡萄球菌的青霉素效价约为670U·mL^-1。桉叶的甲醇和乙醇浸提物对双酚A具有极强的降解能力。     

赤桉和本泌桉叶精油的化学成分研究

用水蒸气蒸馏法提取了赤桉叶和本泌桉叶精油,通过气相色谱-质谱(GC-MS)联用法分析鉴定了二者的化学成分及质量分数。赤桉叶精油共鉴定出57种化合物,占总离子流出峰面积的94.81%,主要成分为w(1,8-桉叶油素)=50.17%,其后依次是w(α-蒎烯)=8.53%、w(蓝桉醇)=5.65%、w(乙酸松油酯)=3.69%、w(α-松油醇)=3.58%;本泌桉叶精油共鉴定出45种化合物,占总离子流出峰面积的90.93%,主要成分为w(α-蒎烯)=31.00%、w(蓝桉醇)=15.34%、w(香树烯)=13.80%和w(表蓝桉醇)=4.86%。     

影响尾叶桉酶解木素制备的因素研究

系统地研究了球磨预处理时间、纤维素酶用量、酶解时间、底物浓度等因素对尾叶桉原料酶解的影响,并提出一个适宜的分离层叶桉酶解木素的方法。     

Fabrication of antibacterial silver nanoparticle‐modified chitosan fibers using Eucalyptus extract as a reducing agent

Green chemical method could be a promising route to achieve large scale synthesis of nanostructures for biomedical applications. Here, we describe a green chemical synthesis of silver nanoparticles (Ag NPs) on chitosan‐based electrospun nanofibers using Eucalyptus leaf extract. A series of silver salt (AgNO₃) amounts were added to a certain composition of chitosan/polyethylene oxide aqueous acetic acid solution. The solutions were then electrospun to obtain nanofibrous mats and then, morphology and size of nanofibers were analyzed by scanning electron microscopy (SEM). Incubation of AgNO₃‐containing mats into Eucalyptus leaf extract led to the formation of Ag NP clusters with average diameter of 91 ± 24 nm, depicted by SEM and transmission electron microscopy. Surface enhanced Raman spectroscopy also confirmed formation of Ag NPs on the nanofibers. The mats also showed antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria with bigger inhibition zone for extract‐exposed mats against S. aureus. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42133.     

桉木枝桠材混合制浆性能实验

桉木是一种速生树种,其性能适合制浆造纸。实验将桉木按照一定比例均匀混入杨木枝桠材中进行磨浆,通过实验验证添加桉木后对制浆性能的影响。实验表明,桉木添加后浆料性能有所变化,消耗有所降低,桉木作为制浆原材料制浆能缓解制浆原料紧张,降低制浆成本,推广价值高,有很好的发展前途。     

桉树生物质能源的优势、现状和潜力

桉树是我国南方最重要的速生商品林树种,也是优良的能源树种.桉树因为有高效的光合作用机制,因此其人工林是世界上生长最快、生物量最大的一种人工林生态体系.桉树是有一种水分适应机制,为其提供很强的抗旱能力且能够通过树叶减少每单位叶面积的养分分配来适应恶劣环境;它还是一种典型的外生菌根植物, 因此桉树耐贫瘠能力强.桉树的天然分布区澳大利亚的自然条件多种多样,因此桉树有适应各种不同气候和地理条件的繁多种类,包括抗盐碱、耐水浸、抗风和耐寒性等特点.作为能源树种,桉树还具有以下优点:易于管理,养护成本低,易繁殖, 其大量的宿芽构成了强大的萌蘖能力,富含芳香油,抗病,抗虫.桉树能源利用的方式主要有:桉叶油,生物柴油;桉树全树的热值均高,是能源的好材料;炭化利用;液化利用.目前我国桉树人工林已达180万公顷,且每年以大于 10 % 的速度在增长.桉树的迅速发展,无论在科研、生产技术上以及产业等各方面均成熟;本文还重点介绍了澳大利亚桉树生物质能源利用的现状,在此基础上判断,我国桉树生物质能的利用条件也已经成熟.     

巨尾桉单宁的提取分离及其抗菌抗氧化性能

采用超声波辅助法提取了巨尾桉叶中的单宁,大孔树脂吸附法纯化了粗提物,考察了提取物对8种常见菌种的抑制作用和对H2O2、DPPH.和.OH的清除作用。结果表明,巨尾桉单宁的提取得率为4.01%;经树脂分离纯化后单宁质量分数达到53.12%;巨尾桉单宁对除大肠杆菌外的供试菌种均有较强的抑制作用,纯化后的单宁对金黄色葡萄球菌、酵母菌和痢疾杆菌的最低抑菌质量浓度(MIC)均为1.0 g/L,对蜡状芽孢杆菌和沙门氏菌的抑制作用优于阳性对照物;粗提物、纯化物在质量浓度为0.50 g/L时对H2O2有最大清除率,分别为80.00%、89.12%,其IC50分别为0.11、0.12 g/L;抗坏血酸、粗提物和纯化物均在质量浓度为1.50 g/L时对DPPH.有最大清除率,分别为98.43%、88.97%和92.21%。在清除.OH体系中,粗提物、纯化物均在质量浓度为4.00 g/L时有最大清除率,分别为87.52%和94.32%,各试样对.OH的清除能力依次为抗坏血酸>纯化物>粗提物。     

巨尾桉单宁的纯化工艺及其抗氧化抑菌性能

利用NKA-9大孔树脂纯化了巨尾桉树皮和树叶中的单宁,并采用二苯基苦基肼自由基(DPPH·)和羟基自由基(·OH)的清除作用评价了其抗氧化性,采用滤纸片扩散法测定了其对5种常见食源性致病菌的抑菌作用。结果表明,在上样质量浓度0.8 g/L、上样量10 mL、体积分数80%乙醇解吸液用量为3倍柱体积(BV)的动态纯化条件下,树皮单宁纯化物中单宁的质量分数为47.82%;在上样质量浓度0.5g/L、上样量10mL、体积分数80%解吸液用量3BV的动态纯化条件下,树叶单宁纯化物中单宁的质量分数为37.00%。树皮和树叶中单宁纯化物对DPPH·的半抑制浓度(IC50)分别为0.0121和0.0168g/L;当单宁质量浓度为0.6 g/L时,对·OH的清除作用相当于V_C的2.55和2.19倍。树皮和树叶中单宁纯化物对大肠杆菌、金黄色葡萄球菌、痢疾杆菌、沙门氏菌、蜡状芽孢杆菌的抑制作用均强于粗提物,且对痢疾杆菌的抑菌圈直径分别达13.25、12.50 mm。     

Vertebrate Herbivory on Eucalyptus—Identification of Specific Feeding Deterrents for Common Ringtail Possums (Pseudocheirus peregrinus) by Bioassay-Guided Fractionation of Eucalyptus ovata Foliage

Factors determining the acceptance of Eucalyptus ovata foliage by common ringtail possums (Pseudocheirus peregrinus) were studied. Bioassay-guided fractionation was used with foliage from both browser-susceptible and browser-resistant trees to identify the chemical components underlying the resistance. In foliage from browser-resistant trees, the deterrent principles were contained in the base-soluble fraction of the chloroform extract. Further fractionation of this material yielded polar and nonpolar fractions that contained acylphloroglucinol derivatives, and from the polar fraction we isolated macrocarpal G. Addition of this compound to an artificial diet at a concentration of 2.1% of dry matter resulted in a 90% reduction of voluntary food intake compared with solvent-treated controls. This is the first time that a specific compound in Eucalyptus has been shown to inhibit feeding of any marsupial folivore.     

Development of the ultrasonic conditions as an advanced technique for extraction of phenolic compounds from Eucalyptus robusta

This study is designed to develop ultrasonic conditions as an advanced technique for optimal recovery of phenolics and antioxidants from Eucalyptus robusta leaf and to evaluate the impact of solvents, temperature, sonication time and power on ultrasound-assisted extraction of these compounds. Temperature has the greatest impact on the total phenolic content (TPC) yield followed by time and power. A yield of 163.68 ± 2.13 mg GAE/g of TPC is observed using 250 W ultrasonic power for 90 min at 60°C with water. This study validates UAE as an efficient, green, and sustainable technique for extracting phenolics from E. robusta.     

Thermal and morphological study of polyurethanes based on Eucalyptus tar pitch and castor oil

This article presents the results of the synthesis and characterization of environmentally friendly polyurethanes based on renewable polyols, and specially highlights the use of Eucalyptus tar pitch, a byproduct of the charcoal making industry in Brazil, to obtain PUs. Eucalyptus tar pitch and castor oil PUs synthesized with MDI in THF, catalyzed by dibutyltin dilaurate, were prepared with NCO/OH equal to 1, and vacuum cured. The addition of Eucalyptus tar pitch to the formulation of PUs showed a tendency to increase the formation of rigid segments, and consequently, to modify thermal stability. SEM micrographs confirm this behavior, displaying different materials. Homogeneous polyurethane elastomers become rigid and acquire lamella structure with the addition of biopitch, as confirmed by tensile strength assays. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3287–3291, 2004     

Jensenone: Biological Reactivity of a Marsupial Antifeedant from Eucalyptus

The resistance of Eucalyptus to browsing mammals has been related to the level and type of formylated phloroglucinol compounds (FPCs) present in the leaf. The antifeedant activity of FPCs appears to depend on their aldehyde groups, but little else is known of their mode of action. We have sought to elucidate this further by examining the biological reactivity and disposition of jensenone, a model FPC. Neither jensenone nor any metabolites were detected in urine or feces of marsupial brushtail or ringtail possums that had ingested up to 725 mg x kg(-0.75). When jensenone was incubated in rat gastrointestinal segments in vitro, it rapidly disappeared. Jensenone also reacted rapidly with glutathione, cysteine, glycine, ethanolamine, and trypsin, and more slowly with acetylcysteine and albumin. Sideroxylonal, a more complex FPC, exhibited the same reactivity. Torquatone, a related compound that lacks both aldehyde groups and antifeedant activity, was unreactive. Mass spectroscopic analysis indicated that the adducts were Schiff bases formed between the aldehyde groups of FPCs and amine groups of the conjugating molecules. Successive adducts were formed with the two aldehyde groups of jensenone, and the four groups of sideroxylonal. The jensenone bis-glutathione adduct appeared to cyclize to the disulfide form. These findings suggest that the antifeedant effects of FPCs are due to their facile binding to amine groups on critical molecules in the gastrointestinal tract, leading to a loss of metabolic function. The consequent toxic reaction, probably involving chemical mediators such as 5-hydroxytryptamine (5HT), may cause colic, nausea, and a general malaise, resulting in anorexia.