三唑基香豆素荧光性能的构效关系研究

采用分子力学MM2对15种三唑基香豆素化合物进行结构预优化。在B3LYP/6-31G(d,p)基组水平上对三唑基香豆素化合物进行构型全优化。通过线性回归分析建立了最优构效关系模型,获得了对三唑基香豆素化合物的荧光性能(Φ)影响较大的结构参数。结果表明,三唑环电荷(QTRIA)和分子表面积(S)是影响三唑基香豆素化合物荧光量子产生率最主要的两个原因,荧光量子产生率与QTRIA呈正相关,与S呈负相关。所得到的QSAR方程对该系列化合物的荧光量子产生率有较好的预测效果。     

三聚氯氰在荧光增白剂工业中的应用与展望

介绍用三聚氯氰合成的荧光增白剂,按其母体结构类型可分为以下几种:双三嗪氨基二苯乙烯类型、含三嗪基的香豆素类型、三嗪基芘类型、4-酰氨基-4’-三嗪氨基二苯乙烯类型。同时,简述了上述荧光增白剂的典型合成工艺及其主要用途。并预测今后十年内三聚氯氰在荧光增白剂中的消耗量仍以年均6%左右的速率递增。     

6,7-二羟基香豆素的研制

以苯醌和醋酐为原料,通过酰化反应制备了中间体1,2,4-三乙酰氧基苯,再与苹果酸发生环合反应制得6,7-二羟基香豆素。     

阳离子香豆素的合成及其对高得率浆的返黄抑制作用

以3-氨基酚和乙酰乙酸乙酯为原料,在Lewis酸的催化下,通过Pechmann法合成了 7-氨基-4-甲基香豆素。将阳离子醚化剂2,3-环氧丙基三甲基氯化铵与7-氨基-4-甲基香豆素反应,实现了7-氨基-4-甲基香豆素的阳离子化。通过红外光谱和核磁共振光谱对合成产物的结构进行表征;采用紫外光谱、荧光光谱探讨了其光学性质;采用紫外光加速老化实验检测了合成产物对纸张返黄的抑制效果。结果表明,该阳离子化的7-氨基-4-甲基香豆素的亲水性较好,能在较长时间内抑制纸张返黄。     

以香豆素为配体的三元稀土配合物的合成及发光性能的研究

以香豆素为主配体,邻菲罗啉、三苯基氧化磷、氨替吡啉、水这些中性配体作为第二配体,合成了不同稀土离子(Eu3+、Tb3+、Sm3、Dy3+)的配合物,通过元素分析、红外、紫外、荧光光谱等分析,表征了这些配合物的组成结构和发光性能.结果表明,在所合成的配合物中,香豆素与铕、邻菲罗啉形成的配合物发光强度最强,对其掺入不同比例的钆,发现可改变该配合物的发光强度.     

A New Mechanism for Hydroxyl Radical Production in Irradiated Nanoparticle Solutions

The absolute yield of hydroxyl radicals per unit of deposited X‐ray energy is determined for the first time for irradiated aqueous solutions containing metal nanoparticles based on a “reference” protocol. Measurements are made as a function of dose rate and nanoparticle concentration. Possible mechanisms for hydroxyl radical production are considered in turn: energy deposition in the nanoparticles followed by its transport into the surrounding environment is unable to account for observed yield whereas energy deposition in the water followed by a catalytic‐like reaction at the water‐nanoparticle interface can account for the total yield and its dependence on dose rate and nanoparticle concentration. This finding is important because current models used to account for nanoparticle enhancement to radiobiological damage only consider the primary interaction with the nanoparticle, not with the surrounding media. Nothing about the new mechanism appears to be specific to gold, the main requirements being the formation of a structured water layer in the vicinity of the nanoparticle possibly through the interaction of its charge and the water dipoles. The massive hydroxyl radical production is relevant to a number of application fields, particularly nanomedicine since the hydroxyl radical is responsible for the majority of radiation‐induced DNA damage.     

Determination of vanillin,ethyl vanillin,and coumarin in infant formula by liquid chromatography-quadrupole linear ion trap mass spectrometry

A simple, precise, accurate, and validated liquid chromatography-quadrupole linear ion trap mass spectrometry method was developed for the determination of vanillin, ethyl vanillin, and coumarin in infant formula samples. Following ultrasonic extraction with methanol/water (1:1, vol/vol), and clean-up on an HLB solid-phase extraction cartridge (Waters Corp., Milford, MA), samples were separated on a Waters XSelect HSS T3 column (150 × 2.1-mm i.d., 5-μm film thickness; Waters Corp.), with 0.1% formic acid solution-acetonitrile as mobile phase at a flow rate of 0.25 mL/min. Quanti?cation of the target was performed by the internal standard approach, using isotopically labeled compounds for each chemical group, to correct matrix effects. Data acquisition was carried out in multiple reaction monitoring transitions mode, monitoring 2 multiple reaction monitoring transitions to ensure an accurate identi?cation of target compounds in the samples. Additional identi?cation and con?rmation of target compounds were performed using the enhanced product ion modus of the linear ion trap. The novel liquid chromatography-quadrupole linear ion trap mass spectrometry platform offers the best sensitivity and speci?city for characterization and quantitative determination of vanillin, ethyl vanillin, and coumarin in infant formula and fulfills the quality criteria for routine laboratory application.     

Investigation of Biosynthetic Pathways to Hydroxycoumarins During Post‐Harvest Physiological Deterioration in Cassava Roots by Using Stable Isotope Labelling

Cassava (Manihot esculenta Crantz) is an important starch‐rich crop, but the storage roots only have a short shelf‐life due to post‐harvest physiological deterioration (PPD), which includes the over‐production and polymerisation of hydroxycoumarins. Key aspects of coumarin secondary‐metabolite biosynthesis remain unresolved. Here we exploit the accumulation of hydroxycoumarins to test alternative pathways for their biosynthesis. Using isotopically labelled intermediates (p‐coumarate‐2‐¹³C, caffeate‐2‐¹³C, ferulate‐2‐¹³C, umbelliferone‐2‐¹⁸O and esculetin‐2‐¹⁸O), we show that the major biosynthetic pathway to scopoletin and its glucoside, scopolin, in cassava roots during PPD is through p‐coumaric, caffeic and then ferulic acids. An alternate pathway through 2′,4′‐dihydroxycinnamate and umbelliferone leads to esculetin and esculin. We have used C¹⁸O₂‐carboxylate‐labelled cinnamic and ferulic acids, and feeding experiments under an atmosphere of ¹⁸O₂, to investigate the o‐hydroxylation and cyclisation steps. We demonstrate that the major pathway is through o‐hydroxylation and not via a proposed spirolactone‐dienone intermediate.     

One-Pot Synthesis of Coumarin–Indomethacin Hybrids as COX-2 Targeting Probes for Cancer Imaging

Facile synthesis of 6- or 7-substituted coumarin-indomathacin hybrids (Coum-IDM) has been developed for specific cyclooxygenase-2 (COX-2) binding along with their intrinsic fluorescent properties. A mild and rapid condensation/dehydrative cyclization of 2-hydroxy benzaldehyde with activated indomethacin was carried out in one step under ultrasound irradiation. Coum-IDM₄ was found to be the best of this series as it presented significant binding to COX-2 and exhibited higher fluorescent intensity in cancer cells than in normal cells. Therefore, in the light of drug development tools, this new hybrid system could be a potential targeted probe for COX-2-overexpressed inflammation and cancer-cell tracking.     

Small Molecule Inhibitors of White Spot Syndrome Virus: Promise in Shrimp Seedling Culture

Rapid production of prawn (Litopenaeus vannamei) under artificial pressure can result in a series of obvious challenges and is vulnerable to serious losses related to aquatic environmental issues and the unrestrained outbreak of white spot syndrome (WSS). However, to date, there are no therapeutic strategies to contain the spread of the virus. Here, we synthesized 27 coumarin derivatives and evaluated their anti-white spot syndrome virus (WSSV) activity in L. vannamei larvae. We demonstrated that electron-withdrawing and electron-giving substituent groups play an important role in reducing toxicity and WSSV replication, respectively. Two coumarin C2 (2-amino-5-oxo-4-(p-tolyl)-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile) and C7 (2-amino-4-(4-chlorophenyl)-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile) were regarded as the most promising anti-WSSV compounds with maximum antiviral response <5% and median effective concentration <10 mg/L. The mortality of WSSV-infected larvae decreased by more than 60% after exposure to C2 and C7. With continuous immersion of C2 and C7 exchange, the mortality further decreased to 40% at 120 h. Additionally, C2 and C7 are the relatively stable in aquacultural water, making these agents suitable for use in inhibiting WSSV horizontal transmission in static aquaculture systems. These results showed the marked advantages of using C2 and C7 in the shrimp industry, and suggest that they hold potential for the treatment and prevention of WSSV infection in shrimp seedling culture.