离子液体1-烯丙基-3-甲基咪唑分离毛竹半纤维素研究

以毛竹为原料,通过1-烯丙基-3-甲基咪唑室温离子液体([Amim]Cl)直接分离半纤维素,并利用红外光谱检测、热动力学分析、中性糖成分检测、糖醛酸含量测定和一维核磁共振成像等分析手段证明氯化1-烯丙基-3-甲基咪唑离子液体可直接分离毛竹半纤维素。所得组分中不含有木质素杂质但混有少量纤维素和果胶质,毛竹半纤维素结构是以(1→4)-β-D-木聚糖为主链,以阿拉伯糖和4-O-甲基-α-D-葡糖醛酸为侧链的木聚糖,其中阿拉伯糖以C-3位与木聚糖主链相连,4-O-甲基-α-D-葡糖醛酸则以O-2位与木糖主链相连。     

一种螺旋甾碱烷型糖苷生物碱及其制备方法与用途

正申请号:CN201710086724.6申请日:017.02.17公开(公告)号:CN106939031A本发明提供了一种螺旋甾碱烷型糖苷生物碱(3β,5α,22α,25R)螺旋甾碱烷-3-O-β-D-吡喃葡萄糖基-(1→2)-O-β-D-吡喃葡萄糖基-(1→4)-β-D-吡喃半乳糖苷及其制备方法与用途,该螺旋甾碱烷型糖苷生物碱对人肺腺癌细胞A549、人大细胞肺癌细胞H460和人肺鳞癌细胞SK-MES-1均具有抑制作用,且对A549细胞的半抑制     

苎麻水溶性碳水化合物的分离和分析

用冷、热水分级抽提苎麻水溶性碳水化合物，然后分离出多糖、低聚糖和单糖。苎麻水溶性多糖和低聚糖用酸水解成单糖，再将水解所得的中性糖和酸性糖分别制备成糖腈乙酰酯和二硫缩醛硅烷化衍生物，作气相色谱分析。分析结果表明，苎麻水溶性多糖的糖基主要是D-半乳糖、L-鼠李糖、D-葡萄糖、L-阿拉伯糖、D-甘露糖和D-半乳糖醛酸。此外，尚有少量的L-岩藻糖、L-来苏糖、D-木糖和D-半乳糖醛酸甲酯。苎麻低聚糖的糖基组成与苎麻水溶性多糖的相似。苎麻游离单糖主要有D-赤鲜糖和七碳糖，还有少量的D-半乳糖、L-阿拉伯糖和D-半乳糖醛酸。     

荷叶中黄酮类化合物的缓蚀性理论研究

用DFT中的B3LYP方法,在3-21G和6-311G水平上,研究荷叶黄酮类分子的分子结构及电子结构,并用Fukui指数分析活性。综合结论：槲皮素3-O-D-吡喃木糖基（1→2）-β-D-吡喃半乳糖苷、异鼠李素、槲皮素-3-丙酯、紫云英苷、山奈酚和异鼠李素-3-O-β-D-葡萄糖苷与金属吸附作用较强。Fukui指数表明：分子的亲核进攻和亲电进攻点主要位于羰基氧原子和与独立苯环连接的羟基氧原子上。     

乌龙茶的醇类香味形成机理

在我们对乌龙茶（水仙与毛蟹──是茶树的两种名品种）的香味形成机理作研究的过程中，我们分离并鉴定出了香叶醇、芳樟醇、2-苯乙醇、苄醇、芳樟醇氧化物Ⅰ与Ⅱ（反式-与顺式-芳樟醇3，6-氧化物）的主要醇类香味前驱体（1-7），并与β-樱草糖苷一样的水杨酸甲酯（6-O-β-D-吡喃木糖基-β-D-吡喃糖苷），以酶法水解（用Yabukita栽培种制得的丙酮粉末）得出，随后采用气相色谱与气相色谱-质谱联用分析法。芳樟醇氧化物Ⅳ（顺式-芳樟醇3，7-氧化物）与（Z）-3-己烯醇的香味前驱体（8与9）罕见地分别以6-O-β-D-芹菜呋喃糖基-β-D-吡喃葡糖与β-D-吡喃葡糖的形式被分离出。作为一个初始实验，我们亦认日本绿茶生产用的Yabukita栽培种的新鲜茶叶作提纯并对其特性描述为一种新的糖苷酶（β-樱草糖苷）。这一糖苷酶经证实为与茶叶中醇类香味形成有关系的主要糖苷酶之一。这是迄今为止提纯出的第二个β-樱草糖苷的标样。从新鲜乌龙茶叶（水仙栽培种）中作的糖苷酶的提纯亦完成了一项发现，即樱草糖苷的活性很近似于Yabukita栽培种。     

2-氯-4-硝基苯基-β-D-吡喃岩藻糖苷的合成

2-氯-4-硝基苯基糖苷是一类重要的糖基酶底物试剂,在相关酶抑制剂制备、酶生物活性研究中有着广泛的应用.以D-半乳糖为原料,通过4步反应得到中间体D-岩藻糖;再经乙酰化制备1,2,3,4-三-O-乙酰基-α,β-D-吡喃岩藻糖,溴代反应获得1-溴-2,3,4-三-O-乙酰基-α-D-吡喃岩藻糖,通过溴代糖与2-氯4-硝基苯酚偶联,立体选择性获得2-氯-4-硝基苯-2,3,4-三-O-乙酰基-β-D-吡喃岩藻糖基糖苷,最后脱除乙酰基保护得标题化合物.该化合物可以作为一种新型的β-D-岩藻糖苷酶底物试剂,用于酶活性测试,其合成方法未见文献报道.     

2,3,4,6-四-O-乙酰基-1-巯基-吡喃葡萄糖的合成

以无水α-D-葡萄糖为原料通过四步反应完成2,3,4,6-四-O-乙酰基-1-巯基-吡喃葡萄糖的合成.首先用α-D-葡萄糖和乙酸酐合成1,2,3,4,6-五-O-乙酰基-β-D-吡喃葡萄糖(Ⅰ),再由(Ⅰ)和溴素、冰醋酸制得2,3,4,6-四-O-乙酰-α-D-溴代吡喃葡萄糖(Ⅱ),然后用(Ⅱ)和硫脲制得2-S-(2,3,4,6-四-O-乙酰基-β-D-吡喃葡萄糖基)-2-异硫脲氢溴酸盐(Ⅲ),最后加入氯仿和偏重亚硫酸钠制得最终产物2,3,4,6-四-O-乙酰基-1-巯基-吡喃葡萄糖(Ⅳ).通过FTIR、元素分析、1HNMR、13C-NMR等手段对产物结构进行了表征.     

瓜尔胶酶解法制备半乳甘露低聚糖及其产物表征

用β-甘露聚糖酶水解瓜尔胶制备了半乳甘露低聚糖(Galacto-mannan-oligosaccharides,GMOS),用时间飞行质谱(MALDI-TOF)、13CNMR表征了产物结构.以底物酶解率为指标,通过L16(43)正交实验,确定在底物质量分数为0.3%、50℃下的最佳酶解条件为:pH值7.0、酶解时间10 h、加酶量40 U·(g瓜尔胶)-1.MALDI-TOF 质谱分析证明,GMOS主要由2～10个单糖组成;13CNMR分析证明,GMOS主链的D-甘露糖基C6上通过糖苷键连接有1个半乳糖残基支链.     

含D-乙酰氨基葡萄糖的酰氨基硫脲合成及表征

以D-氨基葡萄糖盐酸盐为起始原料,经过酰化、氯代和异硫氰酸酯化制得中间体2-乙酰氨基-3,4,6-三-O-乙酰基-2-脱氧-β-D-吡喃糖基异硫氰酸酯,再与各种酰肼反应,得到了12种新型的标题化合物。产物结构均经IR、1HNMR和ESI-MS确认。所得糖基衍生物构型未发生变化,均为β型。     

苎麻葡甘聚糖的提纯和分析

用不同浓度的碱溶液分级抽提苎麻半纤维素。用气相色谱法分析其糖基组成,并将其中葡萄糖和甘露糖基含量较高的组分用氢氧化钡溶液进一步分级,得四个不同的多糖组分。糖基分析表明,其中有两个多糖组分主要由D-葡萄糖及D-甘露糖组成,但两者有不同的比旋光度,且红外光谱也有所不同,是两种链结构存在着某些差异的葡萄甘露聚糖。     

三氮唑核苷的合成

肌苷与醋酐〔n(肌苷 )∶n(醋酐 ) =1 0 0∶2 .18〕在催化剂对甲基苯磺酸的催化作用下制得 1,2 ,3,5 O 四乙酰 β D 呋喃核糖 (Ⅰ) ,收率为 84%。1,2 ,4 三氮唑 3 羧酸甲酯与N ,O 二 (三甲基硅烷基 )乙酰胺在乙腈中硅烷化反应后 ,直接与Ⅰ在催化剂CF3SO2 OSi(CH3) 3的作用下缩合〔n(1,2 ,4 三氮唑 3 羧酸甲酯 )∶n(Ⅰ)∶n(催化剂 ) =1∶1∶2〕制得 1 (2 ,3,5 三 O 乙酰基 β D 呋喃核糖基 ) 1,2 ,4 三氮唑 3 羧酸甲酯 (Ⅱ) ,收率为 83 4% ,Ⅱ经氨解制得三氮唑核苷。总收率为 5 5 6 %。     

Study on extraction kinetics of α-cyclopentylmandelic acid enantiomers with hydroxyethyl-β-cyclodextrin as chiral selector

In this work,the kinetic study on reactive extraction ofα-cyclopentylmandelic acid(α-CPMA)enantiomers was performed in a Lewis cell using hydroxyethyl-β-cyclodextrin(HE-β-CD)as chiral selector.The enantioselective complexation equilibrium between HE-β-CD andα-CPMA enantiomers was studied by phase solubility method.The important process parameters affecting the initial extraction rate were separately studied and the reaction rate equations were deduced.The optimal conditions for kinetic study were as follows:stirring speed of 75 r·min~(-1),interfacial area of 12.56 cm~2,pH of 2.5,initial HE-β-CD concentration of 0.05 mol·L~(-1),initialα-CPMA concentration of 5 mmol·L~(-1),and temperature of 278 K.The reaction has been found to be first order inα-CPMA and second order in HE-β-CD with the forward rate constants of 2.056×10~(-3)m~6·mol~(-2)·s~(-1)and 1.459×10~(-3)m~6·mol~(-2)·s~(-1)for(S)-α-CPMA and(R)-α-CPMA,respectively.The complexation equilibrium constants were evaluated as 61 L·mol~(-1) and 117 L·mol~(-1)for(S)-α-CPMA and(R)-α-CPMA,and the intrinsic enantioselectivity is estimated as 1.92.     

PP/Mg(OH)_2阻燃复合材料流变行为的研究

用日本岛津ＡＧ－２０００型毛细管流变仪，在几个温度下，研究了ＰＰ和ＰＰ／Ｍｇ（ＯＨ）２阻燃复合材料的流变行为。研究结果表明：ＰＰ／Ｍｇ（ＯＨ）２阻燃复合材料熔体流变行为同ＰＰ一样，仍属于非牛顿型假塑性行为；在２００℃温度，相同剪切速率下，ＰＰ和ＰＰ／Ｍｇ（ＯＨ）２阻燃复合材料的粘流活化能十分接近，１０３Ｓ－１剪切速率下，ＰＰ／Ｍｇ（ＯＨ）２阻燃复合材料熔体粘流活化能为３．７１４Ｋｃａｌ／ｍｏｌ，与ＰＰ相差只有０．０３７Ｋｋｃａ／ｍｏｌ，挤出胀大比为１．２９，低于ＰＰ。     

Preparation of regioisomers of structured TAG consisting of one mole of CLA and two moles of caprylic acid

TAG (MLM) with medium-chain FA (MCFA) at the 1,3-positions and long-chain FA (LCFA) at the 2-position, and TAG (LMM) with LCFA at the 1(3)-position and MCFA at 2,3(1)-positions are a pair of TAG regioisomers. Large-scale preparation of the two TAG regioisomers was attempted. A commercially available FFA mixture (FFA-CLA) containing 9-cis, 11-trans (9c, 11t)- and 10t,12c-CLA was selected as LCFA, and caprylic acid (C₈FA) was selected as MCFA. The MLM isomer was synthesized by acidolysis of acyglycerols (AG) containing two CLA isomers with C₈FA: A mixture of AG-CLA/C₈ FA (1∶10, mol/mol) and 4 wt% immobilized Rhizomucor miehei lipase was agitated at 30°C for 72 h. The ratio of MLM to total AG was 51.1 wt%. Meanwhile, LMM isomer was synthesized by acidolysis of tricaprylin with FFA-CLA: A mixture of tricaprylin/FFA-CLA (1∶2, mol/mol) and 4 wt% immobilized R. miehei lipase was agitated at 30°C for 24 h. The ratio of LMM to total AG was 51.8 wt%. MLM and LMM were purified from 1,968 and 813 g reaction mixtures by stepwise short-path distillation, respectively. Consequently, MLM was purified to 92.3% with 49.1% recovery, and LMM was purified to 93.2% with 52.3% recovery. Regiospecific analyses of MLM and LMM indicated that the 2-positions of MLM and LMM were 95.1 mol% LCFA and 98.3 mol% C₈ FA, respectively. The results showed that a process comprising lipase reaction and short-path distillation is effective for large-scale preparation of high-purity regiospecific TAG isomers.     

海因类化合物的研究(Ⅰ)

本文合成了1，3－双（β－环氧丙基）－5，5－二甲基海因化合物。讨论了原料的配比、反应温度、溶剂等因素对海因化合物的影响，并用红外、核磁和端基分析、元素分析等手段对产物进行了分析。当环氧氯丙烷／海因摩尔比为2：1异丙醇作溶剂，反应温度低于100℃并在氮气保护下，可以获得目标产物。     

含能配合物Ni（C5N5O5H-4）2（by）2的晶体结构和热分解性能

培养了含能配合物Ni(C5N5O5H42)(by2)(by=吡啶)晶体,用X射线单晶衍射法测定了其分子结构。其晶体属于单斜晶系,空间群为P21/C,a=9.0070(18)nm,b=10.002(2)nm,c=19.445(4)nm,β=93.69(3),V=1748.1(6)nm3,μ=0.633mm-1,Z=4,S=1.00,最终残差因子[I>2σ(I)]R1=0.0530,WR2=0.1162,对于全部数据R1=0.0965,WR2=0.1358。用DSC、TG-DTG对该配合物的热分解过程进行了研究。结果表明,该配合物的热分解过程仅由1个剧烈的放热峰组成,剩余残渣量约5.508%。用Kissinger法和Ozawa-Doyle法计算出配合物热分解过程中的表观活化能和指前因子分别为224.30kJ/mol和7.32×1019s-1。     

氨基-β-环糊精-单壁碳纳米管-二茂铁修饰电极对抗坏血酸的电化学行为研究

合成制备了氨基-β-环糊精(NH2-β-CD),然后通过主客体反应将NH2-β-CD与二茂铁(Fc)形成稳定的包合物,再与单壁碳纳米管(SWCNTs)复合后得到NH2-β-CD/Fc/SWCNTs复合膜修饰电极。通过循环伏安法研究该修饰电极对抗坏血酸(AA)的电催化行为。结果表明,在pH7.0的磷酸盐缓冲溶液(PBS)中,电位范围在-0.2～0.6V内,峰电流的变化值与抗坏血酸的浓度在1×10-5～1×10-3mol/L范围内成良好的线性关系,检出限为3.6×10-7mol/L。当用于模拟样品的测定,加标回收率为98.3%～100.8%,效果良好。     

Revisiting the Mechanism of β-O-4 Bond Cleavage During Acidolysis of Lignin. Part 3: Search for the Rate-Determining Step of a Non-Phenolic C6-C3 Type Model Compound

Abstract

The rate-determining step of a C₆-C₃ dimeric non-phenolic β-O-4 type lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol (veratrylglycerol-β-guaiacyl ether, VG), was evaluated under acidolysis conditions (0.2 mol/l HBr in 82% aqueous 1,4-dioxane at 85°C) by comparing the disappearances between VG and the corresponding compound labeled at the β-position of VG, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)(2–²H)propane-1,3-diol. The disappearance of VG occurred more rapidly than that of the latter compound, and a primary kinetic isotope effect was clearly observed. This result indicates that the C-H bond at the β-position of VG is broken in the rate-determining step. Two possible mechanisms are presented as the rate-determining step: (1) A base abstracts the β-proton of a benzyl cation-type intermediate produced from VG affording an enol ether compound, 2-(2-methoxyphenoxy)-3-(3,4-dimethoxyphenyl)prop-2-en-1-ol; (2) The hydride transfers from the β- to the α-position of the benzyl cation. It was confirmed that both mechanisms certainly exist and that the latter seems to contribute more than has generally been considered.     

2-二乙硫基亚甲基-3-羰基(羟基)丁酸乙酯与吲哚及其衍生物的(脱硫)偶联反应

在回流条件下,二甲亚砜(DMSO)作溶剂,在20 mol％联萘酚酸存在下,2-二乙硫基亚甲基-3-羰基丁酸乙酯与吲哚及其衍生物能有效地进行脱硫偶联反应,高产率地生成β-吲哚基-β-乙硫基不饱和羰基化合物.在相同条件下,2-二乙硫基亚甲基-3-羟基丁酸乙酯与吲哚及其衍生物能有效地进行偶联反应,高产率地生成α-吲哚基二硫缩烯酮.该反应具有催化剂经济易得及其用量少、反应条件温和、环境友好和易操作等优点.     

Structural basis of Bcl-xL recognition by a BH3-mimetic α/β-peptide generated by sequence-based design

The crystal structure of a complex between the prosurvival protein Bcl-x(L) and an α/β-peptide 21-mer is described. The α/β-peptide contains six β-amino acid residues distributed periodically throughout the sequence and adopts an α-helix-like conformation that mimics the bioactive shape of the Puma BH3 domain. The α/β-peptide forms all of the noncovalent contacts that have previously been identified as necessary for recognition of the prosurvival protein by an authentic BH3 domain. Comparison of our α/β-peptide:Bcl-x(L) structure with structures of complexes between native BH3 domains and Bcl-2 family proteins reveals how subtle adjustments, including variations in helix radius and helix bowing, allow the α/β-peptide to engage Bcl-x(L) with high affinity. Geometric comparisons of the BH3-mimetic α/β-peptide with α/β-peptides in helix-bundle assemblies provide insight on the conformational plasticity of backbones that contain combinations of α- and β-amino acid residues. The BH3-mimetic α/β-peptide displays prosurvival protein-binding preferences distinct from those of Puma BH3 itself, even though these two oligomers have identical side-chain sequences. Our results suggest origins for this backbone-dependent change in selectivity.