PMP柱前衍生反相高效液相色谱—紫外检测法结合离子色谱—脉冲安倍法测定不同产地泽泻多糖的单糖组成

本文建立了1-苯基-3-甲基-5-吡唑啉酮(PMP)柱前衍生高效液相色谱-紫外检测法结合离子色谱-脉冲安倍法测定泽泻中10种单糖含量的测定方法，并比较了不同产地泽泻多糖中的单糖组成差异。经测定泽泻多糖中含有葡萄糖、半乳糖、半乳糖醛酸和阿拉伯糖，其中葡萄糖含量最高，说明泽泻多糖是以葡聚糖为主的杂多糖。不同产地泽泻多糖中葡萄糖、半乳糖、半乳糖醛酸含量差异显著(P<0.05),葡萄糖含量由高到低依次为广泽泻(166.940～264.724 mg/g)、川泽泻(82.647～155.019 mg/g)和建泽泻(51.148～97.746 mg/g);广泽泻多糖中半乳糖含量(3.511～3.840 mg/g)显著高于川泽泻(1.193～1.797 mg/g,P<0.01)和建泽泻(低于定量限);仅有广泽泻中半乳糖醛酸含量(1.342～1.823 mg/g)高于方法定量限。广泽泻中葡萄糖、半乳糖、半乳糖醛酸摩尔比为60.13∶1∶0.40,川泽泻中葡萄糖、半乳糖摩尔比为1545.05∶1,建泽泻多糖中几乎都是葡萄糖，葡萄糖占比在上述产地多糖中依次增加，三种单糖的杂合程度依次减弱。研究结...     

中药大黄多糖中单糖组成的毛细管区带电泳分析

以1-苯基-3-甲基-5-吡唑啉酮(PMP)为单糖的衍生化试剂,建立毛细管区带电泳(CZE)同时分离分析8种常见还原单糖PMP衍生物的方法。将该方法用于中药大黄多糖(RTP)的单糖组成及其摩尔比率的测定。结果表明,在pH 10.8和150 mmol/L硼砂缓冲溶液、10kV分离电压、25℃柱温的优化条件下,8种单糖衍生物实现了良好的分离,并证实RTP由阿拉伯糖、葡萄糖、半乳糖、葡萄糖醛酸和半乳糖醛酸5种单糖组成,其摩尔比为8.01∶5.01∶30.30∶1.00∶1.56;样品测定回收率为96.4%~105.3%。该方法灵敏、快速、准确,可用于中药RTP的组成分析。     

高效液相色谱法分析新型细菌多糖中单糖和糖醛酸组成

建立了柱前1-苯基-3-甲基-5-吡唑啉酮(PMP)衍生-高效液相色谱法,分离检测新型细菌多糖中5种单糖及糖醛酸组成的分析方法。新型细菌多糖中加入单糖内标木糖后,经3mol/L三氟乙酸水解,再用PMP进行衍生化,采用XBridgeTMC18柱(250×4.6mm,5μm),以50mmol/L KH2PO4溶液(pH=5.5)和乙腈为流动相,在245nm波长检测。定量分析结果表明,该多糖由甘露糖、葡萄糖醛酸、葡萄糖、半乳糖和岩藻糖组成,其质量比为1.77∶0.44∶8.52∶1.32∶1.67。该方法重现性良好,能够快速对多糖样品进行组成分析。     

毛细管电泳紫外检测法同时分析樟芝多糖水解液中8种单糖

本文报道了同时分析D-木糖、阿拉伯糖、葡萄糖、鼠李糖、D-甘露糖、半乳糖、D-葡萄糖醛酸和D-半乳糖醛酸8种单糖的毛细管电泳紫外检测方法。利用本研究所建立的方法,可以同时检测樟芝多糖水解液中的8种单糖,方法的检测限为0.11～0.22μg/mL,回收率在88%～104%之间,相对标准偏差(RSD)小于3%。本研究为分析表征樟芝多糖提供了一种可靠的方法。     

HPLC衍生化法分析决明子多糖水解产物中单糖组分及其多糖组成特征的研究

分别利用分光光度法和1-苯基-3-甲基-5-吡唑啉酮(PMP)衍生化/HPLC法分析了12批不同批次药材的决明子多糖及其水解产物中的单糖组分,以水解的单糖组分建立了决明子多糖的HPLC指纹图谱,并研究了决明子多糖的组成特征。结果表明,经过纯化的决明子多糖含量在93.41%~98.57%之间,以甘露糖为参照峰建立了12批药材的指纹图谱,相似度在0.963~0.999之间,多糖水解产物中单糖组分的含量在1.617~304.5 mg/g之间,7个共有峰组分含量大小分布均依次为:甘露糖木糖半乳糖葡萄糖阿拉伯糖葡萄糖醛酸氨基半乳糖,显示了决明子多糖的基本组成结构特征,12批药材的决明子多糖中各单糖的平均摩尔比为甘露糖∶木糖∶半乳糖∶葡萄糖∶阿拉伯糖∶葡萄糖醛酸∶氨基半乳糖=43.0∶24.2∶15.4∶5.6∶5.5∶3.4∶2.9。指纹图谱相似度分析和多糖的组成特征分析对市售药材的分析鉴定结果一致,可作为决明子多糖结构分析及其质量控制的依据。     

柱前衍生化-HPLC法分析不同产地厚朴叶多糖的单糖组成

建立了1-苯基-3-甲基-5-吡唑啉酮(PMP)柱前衍生化-高效液相色谱法(HPLC)同时测定厚朴叶多糖中的6种单糖含量的方法。采用Phenomenex(4.6 mm×250 mm, 4μm)为色谱柱，流动相为0.2%磷酸溶液-乙腈(体积比为82∶18),流速为1.0 mL/min,检测波长为245 nm,柱温为35℃。结果显示，基于HPLC法所建立的单糖检测方法，6种单糖成分在各自线性范围内线性关系良好(R²≥0.9994),平均加标回收率为97.17%～100.22%,相对标准偏差(RSD,n=6)为1.67%～2.82%。16批不同产地厚朴叶单糖组成相似，主要是由葡萄糖、甘露糖、半乳糖、鼠李糖和阿拉伯糖组成。主成分分析结果显示，湖北和重庆样品间的单糖组成得到明显区分。该试验所建立的方法操作简便，重复性和准确度高，适用于厚朴叶多糖中单糖成分的含量测定。     

气相色谱-质谱联用同时分析新型细菌多糖中的单糖和糖醛酸

对纯化的新型细菌多糖进行酸水解,用乙硫醇-三氟乙酸和醋酐-吡啶体系先后对酸水解物进行衍生,与之前报道不同的是糖醛酸得到有效衍生化。以木糖为内标,采用气相色谱-质谱联用(GC-MS)定量分析该多糖酸水解物中单糖和糖醛酸衍生物发现,该多糖的糖链由岩藻糖、葡萄糖、葡萄糖醛酸和半乳糖组成,其相对物质的量比为1.50:1.0:0.79:2.06;中性糖比例与糖醇乙酸酯化分析岩藻糖、葡萄糖和半乳糖的相对物质的量比(1.76:1.0:1.98)接近;糖醛酸咔唑法与该方法分析葡萄糖醛酸的含量分别为16.19%和14.85%。以上结果表明所建立的衍生化方法及GC-MS同时定量分析多糖酸水解物中单糖和糖醛酸的方法可行。此外还对葡萄糖醛酸的质谱裂解机理进行了阐述。     

柱前衍生化-高效液相色谱法分析缅甸刺梧桐胶多糖的单糖组成

利用1-苯基-3-甲基-5-吡唑啉酮柱前衍生化-高效液相色谱法,优化10种常见单糖的色谱分离条件,并用于不同等级的自制刺梧桐胶多糖的单糖组成分析。对自制刺梧桐胶多糖的单糖组成分析结果表明,自制刺梧桐胶多糖由葡萄糖醛酸(GlcUA)、鼠李糖(Rha)、半乳糖醛酸(GalUA)、半乳糖(Gal)、阿拉伯糖(Ara)和岩藻糖(Fuc) 6种单糖组成,平均物质的量比为1∶3.30∶1.62∶2.45∶0.08∶0.03。对不同等级的刺梧桐胶多糖的分析鉴定结果表明,不同等级的刺梧桐胶多糖的单糖组成均含Rha、GalUA、GlcUA、Gal 4种单糖组分,其中Ara在缅甸A、B级中没有检测出来,Fuc在缅甸D级中没有检测出来。方法学结果显示:10种单糖在各自线性范围内线性关系良好,相关系数r≥0.9992,6种单糖加标回收率在96.80%～101.26%之间,相对标准偏差小于3%。该方法简单、准确灵敏,可用于刺梧桐胶多糖的单糖组成分析。     

不同加工方式对鹿茸中水溶性多糖含量及单糖组成的影响

采用水提醇沉法提纯鹿茸中的水溶性多糖，苯酚-硫酸法测定其含量；多糖经水解、衍生后通过UPLC分析不同加工方式及不同部位鹿茸中单糖组成及含量的差异。结果表明，煮炸茸蜡片、粉片、纱片、骨片中水溶性多糖含量分别为1.74、1.67、1.03和1.13 g/kg，冻干茸为2.77、3.07、1.22和3.20 g/kg；排血茸4个部位水溶性多糖含量依次为1.55、1.78、0.96和0.77 g/kg，带血茸为1.69、1.64、1.01和1.31 g/kg。不同加工方式鹿茸中水溶性多糖单糖组成均检出甘露糖、氨基葡萄糖、核糖、葡萄糖醛酸、半乳糖醛酸、氨基半乳糖、葡萄糖和半乳糖8个组分，对于同一部位，煮炸茸单糖含量低于冻干茸，排血茸单糖（氨基葡萄糖和氨基半乳糖除外）含量低于带血茸；对于同一加工方式不同部位，表现出蜡片、粉片高于纱片、骨片。研究加工方式对鹿茸中水溶性多糖含量及单糖组成的影响，以期为鹿茸加工及其产品开发提供理论参考。     

基于高效阴离子色谱-脉冲安培法优化阿拉伯木聚精单精组成分析

以大粒车前子来源阿拉伯木聚糖为研究对象,采用完全酸水解结合高效阴离子色谱-脉冲安培法测定单糖组成,系统优化酸的种类和浓度、水解温度和时间、水解后样品放置时间等水解条件.结果表明,将车前子多糖置于2 mol/L H2 SO4、120℃常压油浴条件下水解2 h时,效果较好,但水解后稀释液放置时间不宜超过6 h.大粒车前子多糖主要由阿拉伯糖(8.89%)和木糖(41.52%)组成,同时检测出半乳糖醛酸(0.73%)、葡萄糖醛酸(3.44%)和微量的半乳糖、葡萄糖,结果重现性良好.利用上述最优条件水解黍子壳、燕麦麸皮和青稞来源阿拉伯木聚糖并分析单糖组成,均获得较好结果.本研究为分析各种来源阿拉伯木聚糖的单糖组成提供了参考.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.