植物络合素分析方法进展

植物络合素是植物体内合成的一类具有很强络合重金属能力的小分子多肽,它们在植物重金属解毒机制中扮演着极为重要的角色。由于植物络合素具有用于植物修复重金属污染的环境的潜力,探索植物络合素的结构、种类和解毒机理成为近年的研究热点。简要评述了植物络合素的分离、检测、表征和定量等方法。     

新型绿色植物生长调节剂——芸苔素内酯的研究进展*

芸苔素内酯是一种新型绿色环保植物生长调节剂,具有促进植物生长、提高植物抗逆抗病能力、改善植物生长品质等多方面功能,被视为第六类植物生长激素。概述了芸苔素内酯的研究进展,介绍了芸苔素内酯在农业生产中的应用,为推动芸苔素内酯的广泛使用提供参考。     

重量法测定含硫湿法磷酸中单质硫的含量北大核心CSCD

硫是化肥中的有益中量元素,它在土壤中能被微生物分解,通过土壤进入植物体内,是氨基酸、蛋白质和原生质等物质的组成元素,参与植物细胞内的氧化还原反应,形成具有特殊机能的谷胱甘肽、维生素B1、维生素H、异硫氰酸等,间接参与碳水化合物的代谢、叶绿素的生成,具有调节植物生长的作用,是植物生长发育必需的营养元素之一.若硫含量较低,一般会在作物生长初期显示出与缺少氮素相似的症状,降低作物吸收营养的能力,影响作物的产量[1].     

具有生物活性的植物内生真菌次生代谢产物

植物内生真菌是指那些在其生活史中的某一段时期生活在植物组织内,对植物组织没有引起明显病害症状的真菌.植物内生真菌几乎在所有植物中存在,它们种类繁多,分布广泛,在长期的自然选择下与寄主植物形成和谐的共生关系,使其产生的次生代谢产物十分丰富,这对农业、医药行业等的发展都具有着巨大的潜在价值.本文对近年来从65种植物中分离获...     

信息与服务

整形素是对植物各种生理过程和形态发生过程具有深刻影响的一类新型合成生长调节剂。它具有多种生物活性:可促进植物离体部分愈伤组织的形成,从而可用于植物组织培养;可用于进行植物无性繁殖,用于调整花期,诱发单性结实;消除某些植物的向光性和向地性。     

植物如何对抗过强的日光

植物在进行光合作用时,如何防止接受日光过强导致的危险,是一个具有实际意义的问题。Lawrence国家实验室的化学家G.R.Fleming和植物生物学家K.K.Niyogi最近用超快速光谱学和植物遗传学方法找到了它的答案。植物通过光合作用产生化学能。在过强的日光下,为了避免叶绿素和其他光合作用色素发生氧化型损坏,植物具有保护自己的能力,这是二三十年以前就已经知道了的事情。但是对于这种保护过程的生物物理机制,即反馈失活机制却一直不甚了解。现在的答案是,起保护效应的分子是一种名为玉米黄质(zeaxanthin)的类胡萝卜素的物质。利用飞秒光谱技…     

石墨炉原子吸收光谱法测定土壤中重金属铅、镉的方法改进

土壤重金属污染是生态环境污染中最为常见也是最严重的一种污染,土壤中的重金属具有难降解、易积累和毒性大等特点,它在土壤中不断积累,进而通过食物链被植物和其他生物体吸收、富集,直接影响植物、动物甚至人类的健康[1-4]。     

吲哚乙酸的间接光度分析法研究

吲哚乙酸(IAA)是一种植物生长激素,具有重要的生理功能,调节和控制着植物体内的核酸蛋白质和酶的合成,以及植物生长发育等各种生命现象,如发芽、生根、细胞生长、器官分化、开化结果、落叶、休眠等。研究吲哚乙酸分析测试方法对了解植物生长发育过程和规律有十分重要的意义。由于植物中吲哚乙酸的含量极低,吲哚乙酸含量的测定一般都使用高效液相色谱法[1]、放射免疫法[2]。我们对吲哚乙酸的电化学分析法做了初步的研究[3],本文提出具有快速、简便、灵敏的光度分析法。在pH=2的硫酸溶液中研究了磷钼黄与吲哚乙酸的反应动力学及反应机理,探…     

福林法测定骆驼蓬不同部位中多酚含量

植物多酚是一类具有良好的抗氧化性,可抑制动脉硬化、降低血压、抗癌、抗衰老和提高免疫力等功效的物质,目前关于植物多酚的测定方法有气相色谱法、液相色谱法、高锰酸钾法、分光光度法和原子吸收光谱法等。骆驼蓬是蒺藜科骆驼蓬属多年生草本植物,多生于路旁、戈壁滩等干旱处,是新疆有毒植物之一,也是维吾尔药用植物之一;其含     

植物源性食品中化学性危害物质的色谱-质谱检测技术研究进展

植物源性食品中的化学性危害物质威胁人们的健康和生命。现阶段植物源性食品中的化学性危害物质具有品类多、残留量低、存在未知潜在风险等特点,检测难度较大。因此,开发植物源性食品中化学性危害物质的高通量、高灵敏度的检测技术具有重要意义。色谱-质谱联用技术具有灵敏度高、选择性好、检测通量高等优点,在植物源性食品化学性危害物质的检测中得到了广泛应用。该文主要综述了色谱-质谱检测技术在植物源性食品化学性危害物质分析中的研究进展,包括植物源性食品中主要化学性危害物质的种类及检测概况、相关的样品前处理方法及发展趋势以及基于色谱-质谱的检测技术研究现状,探讨了不同检测技术的优势及存在的问题,并对其未来发展趋势进行了展望,以期为植物源性食品中化学性危害物质筛查研究提供参考。     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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%).     

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.     

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.