高效液相色谱法测定马蹄香中马兜铃酸A含量

用高效液相分析方法,测定了马蹄香植物体不同部位中马兜铃酸A的含量。结果表明,马兜铃酸A主要存在于马蹄香的地下根及根茎部分,地上茎中含量极少,叶中不含马兜铃酸A。在根及根茎中马兜铃酸A的含量为0.165%～0.198%,茎中含量为0.012%～0.023%。与马兜铃科其他植物比较,马蹄香植物体中马兜铃酸A的含量较高。     

茉莉酸对拟南芥花粉育性的调控

概述了茉莉酸在调控拟南芥雄性器官正常发育过程中的作用.茉莉酸合成型突变体和不敏感型突变体coil均表现为雄性不育.文章对其机制进行了讨论.     

大黄酸和大黄素的热分析及其动力学研究

本文采用热重法(TG)和差热分析法(DTA)测定了大黄酸和大黄素的DTA,TG-DTG曲线。两者的DTA曲线中皆有两个较为明显的吸热峰,第一个在熔化过程中出现,第二个发生在热分解过程中并伴随有明显的失重现象。TG曲线均有一个失重平台,失重率在90%以上。用TG-DTG法对两者在非等温条件下进行热分解动力学研究,把从TG-DTG曲线中取得的数据和31个不同的方程采用Achar微分法和Madhusudanan-Krishnan-Ni-nan(MKN)积分法对其进行非等温分解动力学研究,得到动力学参数活化能(E和指前因子A)和分解动力学机理及方程。得出结论:大黄酸和大黄素的动力学方程为dα/dt=Aexp(-E/RT)3/2(1-α)4/3[1/(1-α)1/3-1]-1和dα/dt=Aexp(-E/RT)3/2(1-α)2/3[1/(1-α)1/3]-1,其分解等合3D抗理。二者的活化能E(kJ/mol)分别为117.6和86.79,lnA/s-1分别是36.72和27.44。     

黄芪甲苷对马兜铃酸诱导的巨噬细胞M1型极化的作用及机制研究

目的:探讨黄芪甲苷对马兜铃酸诱导的RAW264.7细胞向M1型极化的影响,并初步探索其可能的作用机制.方法:分别采用马兜铃酸和脂多糖(LPS)刺激RAW264.7细胞24h,伴或不伴黄芪甲苷进行药物干预处理.采用细胞计数检测试剂盒-8(CCK8)检测细胞活性变化,流式细胞仪检测巨噬细胞分型,酶联免疫吸附试验(ELISA...     

D-葡萄糖直接发酵产生维生素C前体——2-酮基-L-古龙酸的研究——Ⅱ.2,5-DKG产酸菌株发酵条件

本文研究了D-葡萄糖两步串联发酵中前一步菌株的发酵产酸条件。实验结果表明,在含有D-葡萄糖、适量的玉米浆、碳酸钙和磷酸盐的培养基中,摇瓶培养48小时,一株葡萄糖酸杆菌突变株SCB611可产生2,5-二酮基-D-葡萄糖酸25—30mg/ml,克分子转化率为25%左右;另一株欧文氏菌突变株SCB247可产生2,5-二酮基-D-葡萄糖酸45—50mg/ml,克分子转化率为40%。随发酵时间适当延长,2,5-二酮基-D-葡萄糖酸可逐渐增高。温度28℃,种龄15小时,接种量10%及良好的通气条件,有利于菌株产生2,5-二酮基-D-葡萄糖酸。     

腾冲嗜酸热两面菌伴侣素ATcpnβ底物结合特性研究

嗜酸嗜热古菌腾冲嗜酸热两面菌(Acidianus tengchongensis)来源的Ⅱ型伴侣素ATcpnβ已获得晶体结构解析,其顶端结构域突触下端相应于Ⅰ型伴侣素GroEL的重要底物结合位点处的氨基酸多为极性氨基酸,将其突变为疏水性氨基酸时,突变体对变性底物的捕获能力显著增强.表面等离子共振研究表明,ATcpnβ对于化学变性底物的再折叠中间体的其捕获作用不依赖于Mg2+/ATP.前期对该伴侣素冷冻电镜观察和结构解析表明,ATP的存在并不能驱动ATcpnβ从开放构型向闭合构型转变,但是表面等离子共振研究表明,ATcpnβ对热变性过程中已经聚集的底物的捕获作用依赖于Mg2+/ATP,说明Mg2+/ATP可以介导ATcpnβ顶端结构域一定的构象变化,引起顶端结构域疏水残基的进一步暴露,从而能够与大分子聚集体紧密结合.两个方面的研究均表明,伴侣素蛋白与变性底物的结合仍然以疏水相互作用为主,并且伴侣素蛋白与变性底物的结合受Mg2+/ATP的结合调控,与伴侣素蛋白疏水面的暴露程度相关.     

丹参酸甲对小鼠骨髓来源树突状细胞表型及其部分功能的影响

探讨丹参酸甲对小鼠骨髓来源树突状细胞(dendritic cells,DCs)表型及其部分免疫功能的影响,可为丹参酸甲的临床应用提供理论和实验依据。首先,分离培养小鼠骨髓细胞,并利用IL-4和GM-CSF诱生树突状细胞。随后,进行丹参酸甲体外处理,采用流式细胞术检测丹参酸甲对树突状细胞百分率、细胞表面分子(MHC-Ⅱ、CD80、CD86)表达水平及摄取能力的影响;采用ELISA检测各组DC与T细胞共培养后上清液中细胞因子的含量。结果显示:经10μg/mL丹参酸甲处理后,树突状细胞的百分率、FITC-Dextran阳性细胞的数量明显增加,而其表面分子MHC-Ⅱ~(high)/MHC-Ⅱ~(low)比例、MHC-Ⅱ~(high)和MHC-Ⅱ~(low)平均荧光强度、CD80和CD86的表达水平均显著降低。此外,丹参酸甲可增强DC诱导的T细胞分泌IL-10的能力,同时抑制T细胞分泌INF-γ的能力。以上结果说明,丹参酸甲可诱导骨髓细胞向DC分化;并可通过增强DC对抗原的摄取吞噬能力,下调成熟DC的表面标志物表达水平,抑制树突状细胞的成熟,减轻DC与T细胞相互作用介导的炎症反应。这为丹参酸甲在临床用于T细胞过度活化引发的免疫性疾病提供了依据。     

胸苷酸合成酶mRNA亲和多肽的鉴定及其对翻译过程的抑制作用

胸苷酸合成酶(thymidylate synthase, TS)是催化生物体内胸苷酸合成所必需的酶, 多年来一直作为肿瘤化疗的靶点. 研究表明, TS是一种RNA结合蛋白, 可以与其自身mRNA的2个位点结合, 使mRNA翻译受阻. 本文以mRNA体外展示技术进行了由大容量多肽库(>10¹³)中筛选胸苷酸合成酶mRNA亲和多肽的研究, 对随机库进行了12轮循环的选择及扩增. 结果表明, 与初始库相比, 经选择循环之后, 碱性氨基酸及芳香族的苯丙氨酸含量明显增加, 它们在TS RNA与蛋白质的相互作用中扮演着重要角色. 按其理化特性对每一随机位点的氨基酸进行分类, 并与初始库比较, 发现位点1, 12, 17和18具有明显的带正电荷的特性, 表明碱性侧链参与了与RNA的结合. 二级结构预测表明, 随着筛选的进行, 与TS mRNA 亲和的多肽显示出明显的螺旋倾向, 而且形成螺旋的区域富含碱性氨基酸. 凝胶迁移及体外翻译实验证实, 选择循环之后的多肽能够与TS mRNA高度亲和, 并能抑制TS mRNA的翻译. 本研究表明mRNA体外展示方法得到的亲和多肽可以用作新的TS RNA的翻译抑制剂, 并有可能成为一类新型的抗肿瘤药物.     

对香豆酸对慢性束缚应激诱导小鼠抑郁样行为的作用

目的:探索对香豆酸(p-CA)对慢性束缚应激(CRS)诱导小鼠抑郁样行为的作用。方法:实验分两批进行,第一批小鼠随机分成对照组(Control),慢性束缚应激组(CRS)和慢性束缚应激+p-CA组(CRS+p-CA),每组8只,其中慢性束缚应激小鼠每天接受4 h的束缚应激,连续束缚21 d,而对照组小鼠留在笼中不被打扰。第22日小鼠腹腔注射溶媒(10%吐温80)或p-CA(100mg/kg),注射后1 h进行自发活动测试(LMA),注射后4 h进行强迫游泳测试(FST),注射后24 h进行悬尾测试。第二批小鼠随机分成慢性束缚应激组(CRS),慢性束缚应激+ANA-12(原肌球蛋白激酶B拮抗剂)组(CRS+ANA-12)和慢性束缚应激+p-CA组(CRS+p-CA)慢性束缚应激+p-CA+ANA-12组(CRS+p-CA+ANA-12),每组8只,4组小鼠每天接受4 h的束缚应激,连续束缚21d。第22日小鼠腹腔注射溶媒(10%吐温80)或p-CA(100 mg/kg),ANA-12(0.5 mg/kg)在p-CA注射前30 min给药。注射后1 h进行自发活动测试(LMA),注射后2 ...     

Bile acid kinetics in man studied by radio thin-layer chromatography and densitometry coupling

A method based on coupling of the techniques of radioscanning a TLC plate and densitometry has been developed for the determination of pool sizes and fractional turnover rate of bile acids in man after intraduodenal administration of ¹⁴C-labelled acid. The validity of the method has been checked by comparison of the results obtained with those of an enzymatic spectrophotometric analysis, and a measurement of the radioactivity by liquid scintillation counting, after elution of the separated bile acid from a TLC plate. Advantages of the proposed method over the previous one include a reduced number of manipulations, the possibility of automation, a better reproducibility, and the possibility of elaborating the radiometric data obtained for the primary bile acid for better characterising its metabolism inside the enterohepatic circulation.     

Aristoloside,an aristolochic acid derivative from stems of Aristolochia manshuriensis

Aristoloside, a new companion aristolochic acid derivative isolated from stems of Aristolochia manshuriensis has been shown to be 6-O-β-d-glucopyranoside of aristolochic acid-D on chemical and physicochemical evidence. Three known acids, aristolochic acids I, IV (both as their corresponding methyl esters), and -D have also been characterized from stems of the plant.     

Separation of [1-H]cellooligosaccharides by thin-layer chromatography: Assay for cellulolytic enzymes

A thin-layer chromatographic method for the separation with high resolution of [1-³H]-celloligosaccharides on silica gel plates has been developed. Reducing end-labeled glucose through cellohexaose were separated on silica gel plates with three ascents of ethyl acetate:water:methanol (40:15:20; v:v) and each was extracted with an efficiency of 88 ± 3%. Separations of cellooligosaccharides using other adsorbents, solvents, and impregnants are also described. This thin-layer chromatographic method facilitated analysis of the activity of cellulolytic enzymes.     

Reverse-phase purification and silica gel thin-layer chromatography of porphyrin carboxylic acids

Thin-layer chromatography on silica gel 60 plates in the solvent N,N-dimethylformamide/methanol/ethylene glycol/glacial acetic acid/1-chlorobutane/chloroform (4/35/6/0.4/18/20 by volume) separates porphyrin carboxylic acids by the number of free carboxyl groups. Coproporphyrins I and III and isocoproporphyrin are separated in 30 min, other porphyrins in 15 min. The N,N-dimethylformamide and acetic acid in the solvent strongly increase porphyrin fluorescence on the plates. Fading and diffusion of the fluorescent patterns is prevented by storage of the plates in the cold and dark without oxygen and with desiccant. In a preliminary step, porphyrins are purified in high yields, concentrated, and deacidified rapidly (2 min) by reversephase chromatography on cartridges containing a C₁₈ spacer or on Amberlite XAD-2 columns. The methods are applied to urines of porphyria patients and for following porphyrin ester hydrolysis.     

离子交换层析结合反向色谱纯化聚二氨基丙酸

ε-聚赖氨酸生产菌株Streptomyces albulus PD-1可合成一种新型非蛋白质氨基酸均聚物聚二氨基丙酸,采用离子交换层析和反向色谱,对聚二氨基丙酸的分离纯化进行研究。离子交换层析柱选用DEAE-Sepharose Fast Flow填料,50 mmol/L磷酸盐缓冲液(p H 7.5)平衡上样,含0.5 mol/L Na Cl的磷酸盐缓冲液(p H 7.5)洗脱,收集洗脱液用分子筛Sephadex G-25除去磷酸盐缓冲液。然后用C18反相色谱进一步纯化,流动相为V(甲醇)/V(0.1%磷酸)=5/95。经过离子交换层析和反向色谱,纯化得到聚二氨基丙酸纯品,回收率为39.8%,样品纯度达98.4%,为后续的聚二氨基丙酸的深入研究奠定基础。     

A rapid preparative method for isolation of neutral and acidic glycosphingolipids by radial thin-layer chromatography

An efficient method to separate neutral and acidic glycosphingolipids (GSLs) from their mixtures within a short period (45-60 min) and with low consumption of solvents (chloroform-methanol-water, 60/35/8 (v/v/v); 250-500 ml) has been developed. This method utilizes a centrifugal thin-layer chromatograph (Chromatotron) and the GSL mixtures (30-400 mg) are applied to glass plates coated with a 1-mm layer of silica gel 60 PF-254. The method (radial thin-layer chromatography) is rapid and simple and the recovery of glycosphingolipids is high (70-80%).     

Enantiomeric resolution of amino acids by thin-layer chromatography

A simple and rapid method of separating optical isomers of amino acids on a reversed-phase TLC plate, without using impregnated plates or a chiral mobile phase, is described. Amino acids derivatized with 1-fluoro-2,4-dinitrophenyl-5- -alanine amide were spotted on a reversed phase pre-coated TLC plate. Enantiomers of glutamate and aspartate were separated most effectively with solvent consisting of 25% acetonitrile in triethylamine-phosphate buffer (50 mM, pH 5.5) (v/v). Separation of - and -serine was achieved with 30% of acetonitrile solvent. The enantiomers of threonine, proline and alanine were separated with 35% of acetonitrile solvent, and those of methionine, valine, phenylalanine and leucine with 40% of acetonitrile solvent. The possibility of using TLC for quantitative determination of amino acid enantiomers was shown by the quantitative recovery of - and -alanine from the TLC plate in the range of 0.56–4.48 nmol.