吡啶二甲酰胺基桥联双β-环糊精手性固定相的制备和评价

基于吡啶-2,3-二甲酸和6-氨基-β-环糊精的缩合反应,合成了桥联β-环糊精,将其键合到硅胶表面,制备了一种新型的吡啶二甲酰胺基桥联双β-环糊精手性固定相(PyCDP).以黄烷酮类、三唑类、氨基酸类、β-受体阻滞剂类共38种手性药物和农药作探针,系统评价了此固定相的手性色谱性能,并采用自制的天然环糊精固定相(CDCS...     

Boron nitride nanosheet-assisted matrix solid-phase dispersion microextraction of alkaloids from lotus plumule by high-performance liquid chromatography coupled with ultraviolet detection and ion mobility quadrupole time-of-flight mass spectrometry

A boron nitride nanosheet (BNNS)-assisted matrix solid-phase dispersion method was established to microextract alkaloids from medicinal plants. The target compounds were identified by high-performance liquid chromatography coupled with ultraviolet detection and ion mobility quadrupole time-of-flight mass spectrometry. During the experimental process, several important parameters, including the type of dispersant, the amount of dispersant, the grinding time, and the type of elution solvent, were optimized. Finally, the BNNSs were chosen as the best dispersant, and their microcosmic morphologies were identified by scanning electron microscopy and transmission electron microscopy. Because of the special property of BNNSs, the cost of this experiment was greatly reduced, especially in elution volume, sample amount (50 mg), and extraction time (2 min). Under the best conditions, 50 mg of sample powder was dispersed with 50 mg of BNNSs, the grinding time was 120 s, the mixed powder was eluted with 200 μL of methanol, and good linearity (r² > 0.9993) and satisfactory recoveries (80–100%) were obtained. The inter- and intraday precisions were acceptable, with RSDs lower than 2.01 and 4.84%, respectively. The limits of detection ranged from 2.54 to 15.00 ng/mL, and the limits of quantitation were 8.47 to 50.00 ng/mL. The proposed method was successfully applied for the determination of liensinine, isoliensinine, and neferine in lotus plumule.     

Meso-四（对甲基苯基）卟啉及其钴配合物的光学性能与生物应用

对meso-四(对甲基苯基)卟啉(TMPP)和meso-四(对甲基苯基)卟啉钴(TMPP-Co)的溶剂化效应及其水相体系下的发光机理进行了细致地研究。发现TMPP在与钴离子配位后发光强度明显下降;TMPP-Co的溶剂化效应不仅与溶剂极性有关,还与Co离子的轴向配位有关;TMPP与TMPP-Co在水相条件下及在甘油中的发光强度呈现先上升后下降的趋势。此外,TMPP-Co产生单线态氧的能力较强;通过制备TMPP-TAT-NPs纳米粒子成功实现对细胞的染色,并局域在细胞溶酶体上。     

MALDI-TOF质谱和电子光谱技术研究人血清铁蛋白释放铁的动力学

采用MALDI-TOF质谱技术研究血清混合蛋白质的组成,用电子光谱技术分析人血清铁蛋白(Serumferritin,SF)释放铁的动力学过程和规律.结果表明,在人血清中,以Na₂S₂O₄为电子供体时,SF释放铁的速率极快,无法采用常规分光光度法进行检测;以抗坏血酸为电子供体时,SF以一级反应动力学方式释放铁,认为人血清中其它蛋白质协助或参与调控铁蛋白进行快速释放铁反应,从而满足人体对铁的需求.     

表面活性剂对气-液界面纳米颗粒吸附规律的影响

通过测定及分析纳米颗粒和表面活性剂-纳米颗粒复配体系在自由吸附过程与动态收缩过程中表面张力的变化,总结了纳米颗粒在气-液界面的吸附排布规律以及表面活性剂对其吸附规律的影响.实验结果表明,自由吸附过程中,随矿化度增加、阳离子活性剂浓度增加,平衡表面张力降低,这与颗粒吸附密度增加及颗粒润湿性改变有关.浓度低于临界胶束浓度(CMC)时,阳离子活性剂体系与混合体系的表面张力差异证明了阳离子活性剂可以通过静电作用吸附于纳米颗粒表面,进而部分溶解于水相;而阴离子活性剂与纳米颗粒相互作用力较弱,对表面张力影响较小.纳米颗粒体系在液滴收缩过程中,表面张力从自由吸附平衡态进一步降低大约9 m N/m,说明自由吸附过程中纳米颗粒不能达到紧密排布;同时表面张力呈现为缓慢降低、快速降低和达到平衡三部分,表面压缩模量可达70 m N/m,满足了液膜Gibbs稳定准则,这将有助于提高泡沫或者乳液稳定性.纳米颗粒-表面活性剂体系在液滴收缩过程中表面张力降低值随活性剂浓度增加而减小;表面压缩模量由高到低依次为:纳米颗粒>阳离子活性剂-纳米颗粒>阴离子-纳米颗粒>表面活性剂.     

Recent advances on discovery of enzyme inhibitors from natural products using bioactivity screening

The essence of enzymes is to keep the homeostasis and balance of humans by catalyzing metabolic responses and modulating cells. Suppression of an enzyme slows the progress of some diseases, making it a therapeutic target. Therefore, it is important to develop enzyme inhibitors by proper bioactivity screening strategies for the future treatment of some major diseases. In this review, we summarized the recent (2015–2020) applications of several screening strategies (electrophoretically mediated microanalysis, enzyme immobilization, affinity chromatography, and affinity ultrafiltration) in finding enzyme inhibitors from certain species of bioactive natural compounds of plant origin (flavonoids, alkaloids, phenolic acids, saponins, anthraquinones, coumarins). At the same time, the advantages and disadvantages of each strategy were also discussed, and the future possible development direction in enzyme inhibitor screening has been prospected. To sum up, it is expected to help readers select suitable screening strategies for enzyme inhibitors and provide useful information for the study of the biological effects of specific kinds of natural products.     

Palladium-catalyzed asymmetric allylic C–H alkylation of 1,4-dienes and glycine Schiff bases

A highly regio-and enantioselective allylic C–H alkylation of 1,4-dienes with glycine Schiff bases has been established by chiral palladium-phosphoramidite catalysis. This reaction can proceed under mild conditions and tolerate a wide scope of 1,4-dienes,delivering structurally diverse chiral β-branched α-amino acid surrogates in moderate to high yields and with high levels of regio-, Z/E-, diastereo-and enantioselectivities.     

放疗绝对剂量的数学算法模型

本文提出一种通过物理模型计算放疗过程中每一个组织深度处绝对剂量的算法,它可代替蒙特卡罗仿真的部分工作且耗费时间更少.这个算法是基于对照射野内X射线产生电子的能量注量的积分运算,并考虑了射线的能谱及二次散射线,得到了后向散射对表面剂量的贡献比例,同时得到前向散射、后向散射及原射线剂量贡献的关系.比较了二次光子和二次电子的三维能谱,得出该能谱是粒子注量关于粒子能量和粒子运动方向的函数.为了得到每一深度处的光子注量,计算了有连续能谱的X射线的期望质量衰减系数.上述算法计算得到的绝对剂量与蒙特卡罗方式仿真的结果趋势一致,两者的差异在于算法未考虑高于二次的散射线.最后将算法应用到非均匀模体剂量计算,能准确反映其中剂量分布特点且具有较小的误差.     

Access to chiral homoallylic vicinal diols from carbonyl allylation of aldehydes with allyl ethers via palladium-catalyzed allylic C-H borylation

Chiral homoallylic vicinal diols are found in many bioactive compounds and are among the most versatile functional groups in organic chemistry. Here, we describe an asymmetric carbonyl allylation of aldehydes with allyl ethers proceeding via allylic C-H borylation enabled by palladium and chiral phosphoric acid sequential catalysis, providing facile access to homoallylic vicinal anti-diols in high yields and with excellent stereoselectivity. This protocol enables the total synthesis of aigialomycin D to be finished within 7 steps.