活性天然产物靶标蛋白的鉴定

天然产物是创新药物的重要来源,确定活性天然产物的靶标蛋白和作用机制是新药开发的关键.在本篇综述中,对近二十年来在活性天然产物靶标鉴定领域出现的新技术和新方法进行简要的回顾和总结,通过实例重点介绍化学蛋白质组学和生物物理学方法在天然产物靶标蛋白鉴定方面的应用,讨论各种策略的优势和不足,并对其适用范围,应用前景和发展趋势作了前瞻性的展望.     

多环型Xanthone类天然产物的合成研究进展

多环型xanthone类天然产物是一类具有高度氧化态和六环骨架结构的天然产物.目前分离得到的此类化合物主要来源于放线菌.由于这类化合物具有结构特独、广泛的抗细菌活性、一定程度的抗真菌活性以及良好的抗肿瘤活性,吸引了大量有机合成和药物化学等领域学者的关注.近十年来,相关的生物和化学合成以及药物化学研究报道明显增多,主要总结了多环型xanthone类天然产物的合成研究进展.     

毛细管电泳结合高效液相色谱-质谱用于天然产物活性成分的筛选

发展了毛细管电泳(CE)和高效液相色谱-质谱(HPLC-MS)相结合的用于天然产物中活性成分筛选和鉴定的方法。该方法中,用HPLC半制备柱对天然产物粗提物进行分离纯化,再用CE对HPLC纯化后的组分进行活性测试。根据HPLC-MS/MS提供的二级质谱数据,即可确定活性成分的化学结构。以乙酰胆碱酯酶为实验模型,对我们发展的筛选方法进行了验证。从黄连粗提物中确定了药根碱、巴马汀等7种活性成分,并通过CE测定了它们的半抑制率(IC₅₀)值。与传统的天然产物分离纯化和活性筛选方法相比,该方法具有简单、微量、快速、准确的优点。本文建立的方法为天然产物粗提物中活性成分的筛选提供了新技术。     

绝对构型的测定

几乎所有具有生理活性的天然产物在其分子中都是含有不对称碳原子的。一般说来,这些具有生理活性的天然产物,它们的结构一经解决以后,人们就可从事于这些化合物的合成,不过要在这些化合物的绝对构型确定以后,才能真正地合成出和天然产物完全相同的物质。如果合成物与天然物的绝对构型不同,则合成物往往会失去或减低应有的生理活性。一个具有旋光活性的天然产物,如果它的绝对构型尚未解决,就不能说它的结构已经完全确定。本篇所述有旋光活性的     

倍半萜生物碱Dendrobine的全合成研究进展

石斛碱(Dendrobine)是一类从传统中药金钗石斛中分离得到的具有Picrotoxane倍半萜碳骨架的生物碱类天然产物.由于该化合物具有多环稠合和七个连续立体中心的结构特点,以及镇痛和退热等药理活性,引起了众多有机合成化学家和药物化学家的关注.五十年来,天然产物Dendrobine的药理活性研究和化学合成不断涌现,主要总结了天然产物Dendrobine的生源途径和合成研究进展.     

活性天然产物和结构多样性类天然产物的合成

天然产物骨架的复杂性和丰富的官能团化赋予了天然产物类化合物独有的生物学活性,因此天然产物作为药物研究的先导化合物有其无法替代的独特性质,比如紫杉醇、红霉素和利福霉素帮助科学家们理解重要的生物过程。以往化学家对天然产物独有情钟,但仅仅以合成天然产物本身为最终目的。今天,化学家们开始利用传统的合成方法来制备结构多样性的类天然产物化合物。这种利用合成手段制备的小分子化合物在生物学的基础研究和药物研究中将起到关键的作用。     

5′位羟基异戊烯基查尔酮类天然产物的合成及其抗菌活性研究

首次合成了Bartericin A (1), 2’,6’-二羟基-5’-(2’’-羟基-3’’-甲基-3’’-丁烯基)-4’-甲氧基查尔酮(2), Xanthohumol D (3)和Angusticornin B (4) 4个羟基异戊烯基查尔酮类天然产物.为了探讨天然产物中不同官能团对其核心骨架结构抗菌活性的影响,设计合成了衍生物6.所合成的目标产物和未知中间体化合物经过1H NMR、13C NMR、IR、HRMS进行了确证.选取大肠杆菌[CMCC(B)44102]、绿脓杆菌[CMCC(B)10104]、金黄色葡萄球菌[CMCC(B)260003]和枯草芽孢杆菌[CMCC(B)63 501],采用稀释点样法对所合成的4个天然产物及1个新型衍生物进行了抗菌活性评估.结果显示,天然产物1、4和衍生物6对革兰氏阳性菌金黄色葡萄球菌和枯草芽孢杆菌表现出了一定的抑制活性.天然产物3对枯草芽孢杆菌表现出了较为明显的抑制活性,但对其他3种菌株无抑制活性(最小抑菌浓度>200μg/mL).     

高通量天然产物化学和毛细管核磁共振探头技术的应用

介绍了近几年为高通量药物筛选构建大型天然产物样品库的高通量天然产物化学,即多通道平行高效液相制备和平行液质联用分析技术;详细介绍了核磁共振新技术即体积小和质量灵敏度高的毛细管核磁共振探头技术,该探头技术的成功应用使得天然产物样品库中活性化合物的结构鉴定所需样品量降低到前所未有的微克级水平;展望了源于中药的天然产物作为小分子探针开展脑功能方面的化学基因组学研究。     

有机锡化合物在天然产物合成中的应用

综述了有机锡化合物在不同对称合成天然产物中的应用。有机锡化合物应用于天然产物的不对称合成,反应条件温和、活性高,有很高的立体选择性和区域选择性,有广阔的应用前景。     

含连续全碳季碳手性中心天然产物的全合成研究进展

连续全碳季碳手性中心是活性天然产物中常见且具有合成挑战性的结构单元.本文首先介绍了本研究组在含连续全碳季碳手性中心天然产物的全合成研究进展;随后对含多个(≥3)连续全碳季碳手性中心天然产物的合成策略进行分类;最后以Waihoensene和Crinipellins家族天然产物的全合成研究为例,结合其他课题组报道的全合成研究,对比分析相关合成方法学及合成策略的优势和不足.     

Resistance distance

The theory of resistive electrical networks is invoked to develop a novel view: if fixed resistors are assigned to each edge of a connected graph, then the effective resistance between pairs of vertices is a graphical distance. Several theorems concerning this novel distance function are established.Research supported by the Robert A. Welch Foundation of Houston, Texas, TX, USA.     

Si-Zr-C-O纤维的耐高温抗氧化性能研究

以聚硅碳硅烷(PSCS)与乙酰丙酮锆为原料合成聚锆碳硅烷(PZCS),采用先驱体转化法制备了Si-Zr-C-O纤维.通过元素分析、扫描电镜(SEM)、X射线衍射(XRD)和俄歇电子能谱(AES)等分析测试手段研究了Si-Zr-C-O纤维的组成结构及其耐高温抗氧化性能.结果表明:Si-Zr-C-O纤维的元素组成为SiC1.24HxO0.56Zr0.0129,平均强度2.5GPa,平均直径11μm,纤维表面光滑平坦,没出现孔洞、裂纹、沟槽等缺陷,直径均匀.该纤维耐超高温性能良好,在1450和1600℃处理后,强度保留率分别为72%和36%,1800℃处理后Si-Zr-C-O纤维的化学式为SiC0.99HxO0.1Zry,纤维氧含量大大降低;纤维抗氧化性能良好,空气中1000℃热处理20h后,强度保留率为71.2%,热处理100h后,强度保留率为50%.     

Targeting Antibiotic Resistance

Finding strategies against the development of antibiotic resistance is a major global challenge for the life sciences community and for public health. The past decades have seen a dramatic worldwide increase in human‐pathogenic bacteria that are resistant to one or multiple antibiotics. More and more infections caused by resistant microorganisms fail to respond to conventional treatment, and in some cases, even last‐resort antibiotics have lost their power. In addition, industry pipelines for the development of novel antibiotics have run dry over the past decades. A recent world health day by the World Health Organization titled “Combat drug resistance: no action today means no cure tomorrow” triggered an increase in research activity, and several promising strategies have been developed to restore treatment options against infections by resistant bacterial pathogens.     

Resistance distance local rules

In [D.J. Klein, Croat. Chem. Acta. 75(2), 633 (2002)] Klein established a number of sum rules to compute the resistance distance of an arbitrary graph, especially he gave a specific set of local sum rules that determined all resistance distances of a graph (saying the set of local sum rules is complete). Inspired by this result, we give another complete set of local rules, which is simple and also efficient, especially for distance-regular graphs. Finally some applications to chemical graphs (for example the Platonic solids as well as their vertex truncations, which include the graph of Buckminsterfullerene and the graph of boron nitride hetero-fullerenoid B ₁₂ N ₁₂) are made to illustrate our approach.     

Heat Resistance of Polyamidobenzimidazoles

Thermal degradation of polymers based on polyamidobenzimidazoles was studied in relation to the monomeric units structure and mole fraction of the initial monomers.     

Resistance distance and Laplacian spectrum

The resistance distance r _ij between two vertices v _i and v _j of a (connected, molecular) graph G is equal to the resistance between the respective two points of an electrical network, constructed so as to correspond to G, such that the resistance of any two adjacent points is unity. We show how the matrix elements r _ij can be expressed in terms of the Laplacian eigenvalues and eigenvectors of G. In addition, we determine certain properties of the resistance matrix R=||r _ij ||. AcknowledgementsThis research was supported by the Natural Science Foundation of China and Fujian Province, and by the Ministry of Sciences, Technologies and Development of Serbia, within Project no. 1389. The authors thank Douglas J. Klein (Galveston) for useful comments.     

Electrochemical Method to Characterize Multidrug Resistance

Multidrug resistance（MDR） is a main factor to make the failure of chemotherapy. It is closely related to the over-expression of P-glycoprotein（P-gp）, multidrug resistance protein（MRP） and breast cancer resistance protein（BCRP）. Herein we reported a novel method to characterize MDR, taking advantage of the electrochemical properry of chemotherapeutic drugs. Meanwhile, the definition of accumulation phase and retention phase has been improved. Furthermore, with specific modulators introduced to inhibit the relevant efflux pumps, the exact protein that mainly works in the cells employed in this study can be identified.     

Insulin Resistance Associated Genes and miRNAs

Type 2 diabetes mellitus is the result of resistance to insulin function along with inadequate insulin secretion, leading to a number of dysfunctions characterized by hyperglycemia, and it is associated with microvascular, macrovascular, and neuropathic complications. There is compelling evidence that the decline in both insulin sensitivity and insulin secretion has a genetic component. In addition, increasing evidence suggests that microRNAs (miRNAs) as key regulators of gene expression play significant roles in insulin production, secretion, and function that regulate the function of insulin-target tissues. The current review demonstrates the candidate genes and the related miRNAs involved in molecular pathogenesis of insulin resistance in type 2 diabetes mellitus. In doing so, it provides an opportunity for more focused investigations that may identify the genes and miRNAs with a role in the pathogenesis of type 2 diabetes mellitus and its treatment.