989 resultados para Ethanol


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Two new phenoxynaphthacenequinone derivatives, 6-[4-(2-(4-hydroxyphenyl)isopropyl)phenoxy] -5,12-naphthacenequinone (7) and 6-[4-(potassium sulfophenylazo)phenoxy]-5,12-naphthacenequinone (8), were synthesized, and their photochromism in solution was investigated and compared with that of 6-phenoxy-5,12-naphthacenequinone (1). On the basis of the spectral data and the selective irreversible reaction of ammonia with the colored phenoxy-ana-naphthacenequinone, the concentrations of the ana forms at the photostationary state (PSS), achieved by 365 nm UV irradiation, and the molar extinction coefficients of the pure ana forms at 481-482 nm of compounds 1, 7 and 8 in dimethylsulfoxide (DMSO) were found to be 83 mol.% and 1.70x10(4) mol(-1) dm(3) cm(-1), 82 mol.% and 1.62x10(4) mol(-1) dm(3) cm(-1) and 16 mol.% and approximately 1.34x10(4) mol(-1) dm(3) cm(-1) respectively; the absorption spectra of the colored ana forms of 7 and 1 in DMSO were estimated; the rate;constants of photoconversion induced by 365 nm light were obtained. The results show the strong effect of the structure of the phenoxynaphthacenequinones on their photochromism in solution. In addition to DMSO solution, compound 7 exhibited normal photochromism in toluene, benzene, chloroform and a DMSO-ethanol mixed solvent, but not in dimethylformamide (DMF) in which a photoinduced reaction occurred between 7 and DMF or impurities.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The melting behavior of poly(methyl methacrylate)-grafted nascent polyethylene reactor powder by plasma irradiation was studied by differential scanning calorimetry (DSC). The grafting yield ranged hom 11 to 190%. Grafting was found to lower both melting point and heat of fusion during the first run of DSC determination. The heat of fusion was used to calculate the apparent grafting yield of the samples. There was little strain induced by plasma-irradiated grafting on the surface of the polyethylene crystals. A method to determine the covalent grafting yield in the graft copolymer systems was developed. (C) 1995 John Wiley & Sons, Inc.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Two M(n+)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol systems for the simultaneous determination of the valence states of Cr and Fe using factor analysis were studied. (1) At pH 4.0, Cr(III) and Cr(VI) react with the reagent to form stable complexes and a slight difference in the wavelengths of maximum absorption (lambda(max.)) between the two complexes is observed when the sodium lauryl sulfate, which also acts as a solubilizing and sensitizing agent, is added, viz., 590 nm for Cr(III) and 593 nm for Cr(VI) complexes. (2) In the presence of ethanol, both Fe(II) and Fe(III) form 1:2 complexes with the reagent at pH 2.5-3.5 and the lambda(max.) of the Fe(II) and Fe(III) complexes is at 557 and 592 nm, respectively. In the target transformation factor analysis, the K coefficients calculated from the standard mixtures by classical least-squares analysis and a non-zero intercept added to each wavelength are used as the target vector instead of the pure component standards; this can decrease the analysis errors introduced by the interaction between the two species and by deviations from Beer's law.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The complexation of acenaphthene and fluoranthene with beta-cyclodextrin (CD) in aqueous solutions in the presence and absence of ethanol was investigated by means of the time-resolved fluorescence technique. The appearance of a longer lifetime component and the increase of its fraction relative to that of the shorter lifetime component with increasing CD concentration demonstrate the formation of inclusion complex between the guest molecule and CD. The formation constants for complexation were derived from the pre-exponential factor A(i) of fluorescence decay curves. The presence of ethanol in the reaction systems enhanced the inclusion to a large extent.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Thin films of PSt/PMAA and PEO-PSt-PEO block polymers were deposited on a polystyrene substrate by solution adsorption (with or without solvent treatment), and the film surfaces were characterized by means of XPS. Direct solvent - casting of PEO-PSt-PEO from benzene solutions resulted in PSt-rich surfaces, whereas PMAA richer surfaces were obtained for PSt/PMAA films cast from DMF solutions. Moreover, solvent treatment after casting had profound effect on the film surface composition. Treatment with water markedly increased the surface concentration of polar PEO segments. In the case of PSt-PMAA block polymers, the PSt content on the surface increased in the order of water < ethanol < cyclohexane < petroleum ether, the last-named giving films with almost pure PSt surface. It is well worth noticing that the bulk composition had little to do with the surface composition for both PSt/PMAA and PEO-PSt-PEO block polymers within the composition range investigated when subsequent solvent treatment was applied.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Agaro-oligosaccharides were hydrolytically obtained from agar using hydrochloric acid, citric acid, and cationic exchange resin (solid acid). The FT-IR and NMR data showed that the hydrolysate has the structure of agaro-oligomers. Orthogonal matrix method was applied to optimize the preparation conditions based on alpha-naphthylamine end-labeled HPLC analysis method. The optimal way for oligosaccharides with different degree of polymerization (DP) was achieved by using solid acid degradation, which could give high yield and avoid solution neutralization process. Agaro-oligosaccharides with high purity were consequently obtained by activated carbon column isolation. Furthermore, the antioxidant and alpha-glucosidase inhibitory activity of three fractions were also investigated. The result indicated that 8% ethanol-eluted fraction showed highest activity against alpha-glucosidase with IC50 of 8.84 mg/mL, while 25% ethanol-eluted fraction possessed excellent antioxidant ability.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Among marine bacteria isolated from the cytotoxic sponge Hymeniacidon perleve, one strain NJ6-3-1 classified as Pseudomonas sp. showed both cytotoxic and antimicrobial activities. Fatty acid analysis indicated that the bacterial strain consists mainly of C16:1, C16:0, C18:1, C18:0, C15:0, C14:0. One unusual 9,10-cyclopropane-C17:0 fatty acid and C26:0 also constitute major components, as well as the existence of squalene, the precursor of triterpenoids. The major metabolites in the culture broth were identified as alkaloids, including diketopiperazines and indole compounds, namely 3,6-diisopropylpiperazine-2,5-dione, 3-benzyl-3-isopropylpiperazine-2,5-dione, 3,6-bis-(2-methylpropyl)-piperazine-2,5-dione, indole-3-carboxaldehyde, indole-3-carboxylic acid methyl ester, indole-3-ethanol, and quinazoline-2,4-dione.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Scanning tunneling microscope was used to investigate the in vitro assembly of R-phycoerythrin (R-PE) from the marine red alga Polysiphonia urceolata. The results showed that R-PE molecules assembled together by disc-to-disc while absorbing on HOPG surface, which just looked like the rods in the phycobilisomes. When the water-soluble R-PE was dissolved in 2% ethanol/water spreading solution, they could form monolayer film at the air/water interface. Similar disc-to-disc array of R-PE was constituted in the two-dimensional Langmuir-Blodgett film by the external force. It could be concluded that, apart from the key role of time linker polypeptides, the in vivo assembly of phycobiliproteins into phycobilisomes is also dependent on the endogenous properties of phycobiliprotein themselves.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We investigated chemical constituents and the antifeedant, antibacterial, and antilarval activities of EtOH (ethanol) extracts of the South China Sea seagrass Enhalus acoroides. Eleven pure compounds including four flavonoids and five steroids were obtained. Among these compounds, three flavonoids were antifeedant against second-instar larvae of Spodoptera litura, two flavonoids had antibacterial activity towards several marine bacteria, and one flavonoid showed strong antilarval activity against Bugula neritina larvae. This is the first description of isolation and bioactivity of secondary metabolites from E. acoroides.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

以奥利亚罗非鱼(Oreochromis aureus)为实验对象,设计了3种不同的摄食类型,分别是鲜活饵料组、饥饿3周后饱食投喂组和人工饲料组。鲜活饵料组投喂冰冻赤子爱胜蚓,利用蚯蚓体内丰富的营养成分和活性物质,以期获得奥利亚罗非鱼良好的生长状况;饥饿后饱食组是指饥饿3周后,以人工饲料饱食投喂2周,用于研究饥饿与补偿生长获得快速生长时血液理化指标的变化情况;人工饲料组作为对照组。纯淡水条件下养殖,水温25±2℃。测定了奥利亚罗非鱼在3种摄食类型饲喂下某些血液生理生化指标变化的情况,并将指标变化情况与增重率做相关性分析,试图找出能够反映奥利亚罗非鱼生长性能的血液生理生化指标。 研究结果表明,奥利亚罗非鱼在饥饿3周后获得了补偿生长,补偿生长时的增重率和特定生长率显著高于人工饲料组(P<0.05),高于鲜活饵料组,但差别不显著;相关性分析研究表明血清总蛋白、胆固醇、四碘甲状腺原氨酸(T4)与增重率极显著相关(P<0.01),血红蛋白显著相关(P<0.05),红细胞、白细胞、碱性磷酸酶高度相关(相关系数为0.580、0.551和0.557),因此,建议血清总蛋白、胆固醇和血红蛋白可作为能够反映罗非鱼生长性能的新指标。 根据序列设计引物,PCR反应条件:变性温度:95 ℃,3 min;退火温度:57℃,20 sec;延伸温度:72℃,5 min,共36个循环,从牙鲆、黑鲪和鲈鱼中克隆出胰岛素样生长因子(IGF-Ⅰ)部分序列,首次证实了IGF-Ⅰ在3种海水鱼中的存在。 利用蛋氨酸与ZnSO4•7H2O,在pH 5.5、80℃下,反应1小时,采用蛋氨酸与硫酸锌2:1的配料比,合成出了产物蛋氨酸螯合锌,蛋氨酸螯合锌外观白色,粉状,室温下微溶于水,不溶于乙醇,并用原子吸收光谱法测定其含锌量为15%,螯合率为88.2%。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

海藻是海洋生物中的一大类群,由于其特殊的生活环境,能够代谢产生大量结构独特多变和活性特殊多样的代谢产物,是化学和生物活性多样性研究的重要对象之一。我国海域辽阔,海藻资源丰富,为寻找结构新颖、生理活性独特的先导化合物,加强对海藻资源的开发利用,本论文对中国沿海的三种海洋红藻进行了化学成分和生物活性研究,同时对山东青岛海域生物量丰富的一种海洋红藻松节藻进行了动物体内抗糖尿病活性研究。 利用正相硅胶柱色谱、Sephadex LH-20柱色谱以及反相HPLC和重结晶等现代分离手段,对山东青岛沿海的红藻扇形叉枝藻(Gymnogongrus flabelliformis)进行了系统的化学成分研究,从中得到单体化合物26个,通过波谱学方法(IR、MS、NMR等)鉴定了他们的结构,分别为(3R,6R,7E)-(+)-3-O-phenylacetyl- 4,7-megastigmadiene-9-one(1),(3R,7E)-(-)-3-O-phenylacetyl-5,7-megastigmadiene -9-one(2),(3S,6R,7E)-(+)-3-hydroxyl-4,7-megastigmadien-9-one(3),(3S,5R,6S,7E)- (-)-3-hydroxy-5,6-epoxy-7-megastigmene-9-one(4),(3S,5S,6R,7E)-(+)-3-hydroxy- 5,6-epoxy-7-megastigmene-9-one(5),Dehydrovomifoliol(6),(3R)-(-)-4-[(2R,4S)-4- acetoxy-2-hydroxy-2,6,6-trimethylcyclohexylidene]-3-buten-2-one(7),2,3,3′-三溴-4,4′,5,5′-四羟基-1′-乙氧甲基双苯基甲烷(8),2,2′,3,3′-四溴-4,4′,5,5′-四羟基双苯基甲烷(9),3-溴-4,5-二羟基苯甲醛(10),2,3-二溴-4,5-二羟基苯甲基甲醚(11),2,3-二溴-4,5-二羟基苯甲醇(12),N, N-二甲基酪胺(13),4-羟基苯甲酸乙酯(14),4-羟基苯甲基乙醚(15),4-羟基苯乙基乙酯(16),4-羟基苯乙酸甲酯(17),4-羟基苯甲醛(18),豆甾-4-烯-3-酮(19),胆甾-4-烯-3-酮(20),胆甾醇(21),尿嘧啶(22),尿嘧啶核苷(23),腺嘌呤核苷(24),丁二酸(25),5-羟基-4-甲基-5-戊基-2,5-二氢呋喃-2-酮(26)。其中化合物1、2为新化合物,化合物3为新天然产物,所有化合物均为首次从该属海藻中分离得到。通过 MTT 法对部分单体化合物进行了肿瘤细胞毒活性筛选, 结果表明,化合物8、9、10、12对筛选的所有细胞株均有较强细胞毒活性,化合物11对人肺癌细胞株(A549)、人肝癌细胞株(Bel 7402)、人结肠癌细胞株(HCT-8)有一定细胞毒活性。通过研究单体化合物对小鼠腹腔巨噬细胞TNF-分泌的影响,对其进行抗炎活性筛选,结果表明,化合物8、9、11、13、17、23、24、25对小鼠腹腔巨噬细胞TNF-分泌表现出明显的抑制作用。 从采自山东荣成镆铘岛的红藻小珊瑚藻(Corallina pilulifera)的乙酸乙酯萃取物中分离得到16个单体化合物,通过波谱学方法鉴定化合物结构14个(另外2个正在鉴定中),分别为2α-乙氧酰基-2β-羟基-A-降胆甾-5-烯-4-酮(27),胆甾-4-烯-3-酮(28),胆甾醇(29),3β-羟基-胆甾-5,24(28)-二烯-7-酮(30),2α-羟基-胆甾-4-烯-3-酮(31),6α-羟基-胆甾-4-烯-3-酮(32),3β-羟基-胆甾-5-烯-7-酮(33),(E)-phytol epoxide(34),Phytenal(35),3,7,11,15- tetramethyl-hexadec-2-en-1-oll(Phytol)(36),Loloilide(37),(3S,5R,6S,7E)-(-)-3-hydroxy-5,6-epoxy-7- megastigmene-9-one(38),Dehydrovomifoliol(39),4-羟基苯甲醛(40)。其中,化合物 31为新天然产物,化合物27为首次从植物中分离得到,所有化合物均为首次从该种海藻中分离得到。通过 MTT 法对分离得到的单体化合物进行了肿瘤细胞毒活性筛选,化合物27和化合物32对筛选的所有肿瘤细胞株均有细胞毒活性,且化合物27对人胃癌细胞株(BGC-823)、人结肠癌细胞株(HCT-8)和人卵巢癌细胞株(A2780)具有中等强度抑制活性。化合物28、化合物31和化合物33对人肝癌细胞株(Bel 7402)、人结肠癌细胞株(HCT-8)和人卵巢癌细胞株(A2780)有一定细胞毒活性。 从采自广西北海涠洲岛的多管藻Polysiphonia sp.的乙酸乙酯萃取物中分离得到6个单体化合物,通过波谱学方法鉴定化合物结构5个(另外1个仍在鉴定),分别为胆甾醇(41),3,7,11,15-tetramethyl-hexadec-2-en-1-ol(Phytol)(42),3-吲哚甲醛(43),4-羟基苯甲醛(44),4-羟基苯甲酸(45)。 对山东青岛沿海的松节藻 (Rhodomela confervoides) 乙醇提取物进行了初步的体内抗糖尿病活性研究,采用链脲佐菌素诱导的2型糖尿病(STZ-DM)大鼠模型对其进行体内降糖实验,结果发现,松节藻乙醇提取物在糖尿病大鼠体内不仅具有显著的降血糖作用,且呈现良好的量–效关系,而且能够纠正糖尿病引发的物质代谢紊乱,增加体重,提高试验动物的成活率,因此具有良好的应用开发前景。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We studied the morphology of three rare haptorid ciliates, using live observation and silver impregnation: Apertospathula verruculifera n. sp., Longispatha elegans n. gen., n. sp., and Rhinothrix porculus (Penard, 1922) n. gen., n. comb. Simple ethanol fixation (50-70%, v/v) is recommended to reveal the ciliary pattern of "difficult" ciliates, such as R. porculus, by protargol impregnation. The three genera investigated have a distinct feature in common, viz., a lasso-shaped oral bulge and circumoral kinety, where the right half is slightly to distinctly longer than the left and the circumoral kinety is open ventrally. Thus, they are united in a new spathidiid family, the Apertospathulidae n. fam., which probably evolved from a Bryophyllum-like ancestor by partial reduction of the oral bulge and circumoral kinety. Apertospathula verruculifera has a wart-like process, the palpus dorsalis, at the anterior end of the dorsal brush. The right branch of the circumoral kinety is only slightly longer than the left one. Longispatha elegans has a straight oral bulge and circumoral kinety, the right branch of which extends to the posterior end of the body while the left branch ends in the anterior third of the body. Rhinothrix porculus, a curious ciliate with a snout-like dorsal elongation of the oral bulge, the palpus oralis, has a highly characteristic ciliary pattern: the oral pattern is as in Longispatha, but the bulge and circumoral kinety extend spirally to the posterior end of the body while the somatic kinetics course meridionally. This is achieved by inserting some shortened kinetics in the curves of the oral bulge.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

2,3,6-Tribromo-4,5-dihydroxybenzyl ethyl ether (1), a new bromophenol, was isolated from the ethanol extract of marine red alga Symphyocladia latiuscula, with a known compound, 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether ( 2). Their structures were elucidated by spectroscopic analysis, including high-resolution mass spectroscopy, and 1 and 2-dimensional NMR techniques. Compounds 1 and 2 showed inhibitory activity against Staphyloccocus aureus with IC50 102 and 50 mu g/mL, respectively.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Polysaccharides from Ulva pertusa were isolated and prepared by extraction in hot water and precipitation by ethanol. The water-soluble polysaccharides were chemically well defined, containing 47.0% total carbohydrate, 23.2% uronic acids, 17.1% sulfate groups, 1.0% N and 29.9% ash. Gas chromatography analysis demonstrated that the neutral sugars were mainly composed of rhamnose, xylose and glucose and smaller amounts of mannose, galactose and arabinose. The FTIR and C-13-NMR spectra indicated that basic repeating units of the polysaccharides were (beta-D-GlcpA-(1->4)-alpha-L-Rhap 3S) and (alpha-L-IdopA-(1->4)-alpha-L-Rhap 3S). Fifty ICR mice were used to study the effect of water-soluble polysaccharides from Ulva pertusa on the level of plasma lipids, with inositol niacinate as positive control. The results indicated that the polysaccharides significantly lowered the contents of plasma total cholesterol, low-density lipoprotein cholesterol, triglyceride and markedly increased the contents of serum high-density lipoprotein cholesterol, compared with the hyperlipidemia control group (p<0.01). Moreover, administration of polysaccharides significantly decreased the atherogenic index. The present results suggest that the polysaccharides from Ulva pertusa have great potential for preventing ischemic cardiovascular and cerebrovascular diseases.