天然药物中乙酰胆碱酯酶抑制剂的快速发现

目的建立从天然药物中快速发现乙酰胆碱酯酶抑制剂的有效方法,为中药及其活性成分治疗阿尔茨海默病提供支持。方法通过Ellman比色法,对多种药用植物乙醇提取物的抗乙酰胆碱酯酶活性进行评价,筛选出活性较好的提取物样品,应用亲和超滤超高效液相色谱-四级杆-飞行时间串联质谱(UPLC-Q-TOF/MS)联用技术分离鉴定其中的活性成分。结果元胡、黄柏、钩藤、血三七具有较强的乙酰胆碱酯酶抑制活性。经过快速筛选,发现3-二氢异卡丹宾或者3-二氢卡丹宾、钩藤碱、异钩藤碱、柯诺辛或异柯诺辛可能为钩藤中的活性化合物。结论采用亲和超滤UPLC-Q-TOF/MS联用技术从天然药物中快速筛选出乙酰胆碱酯酶抑制剂,方法可行、快速,能够为治疗阿尔茨海默病的新药开发提供先导化合物。     

天然产物中先导化合物的快速发现技术

药物研究的历史表明，天然产物是新药发现的重要来源，提高天然产物的研究水平，提高从天然产物中发现先导化合物或药物的效率，需要技术的进步和研究方法的改进。本文根据应用现代天然产物分离提取技术和高通量药物筛选技术研究天然产物先导化合物的实际工作情况，探讨从天然产物中快速发现先导化合物的新策略和新方法，以推进活性化合物或药物先导化合物的发现进程，促进我国的创新药物研究。     

细胞膜色谱法与液相色谱-质谱联用筛选佛手的活性成分

目的从佛手中筛选对主动脉血管有舒张作用的有效成分。方法采用大鼠血管平滑肌细胞膜色谱模型(VSM/CMC)筛选,液相色谱-质谱(LC/MS)离线分析,并结合离体药理实验确定佛手舒张血管的有效成分。结果佛手柑内酯是佛手中作用于血管的活性成分,药理实验结果表明其具有舒张血管作用,化合物在VSM/CMC的保留特性和其药理作用有显著相关性。结论 VSM/CMC 模型可以反映化合物与细胞膜及膜蛋白(包括受体)的相互作用;VSM/CMC 和LC/MS技术联用,为从天然产物中快速寻找新的活性成分提供了途径。     

天然产物与创新药物研究开发

创新药物研究对医药产业的发展，保障人民身体健康具有重要的作用。药物分子设计和从天然产物中发现活性先导化合物进而研发创新药物是行之有效的重要途径。天然产物特有的化学结构复杂性和生物活性多样性，奠定了从天然产物中发现活性先导物进而研发创新药物的成功几率。据统计，1982-2002年间全球上市1000多种小分子药品中，55％系来自天然产物或其衍生物，     

葛根中黄嘌呤氧化酶抑制剂的筛选分离及质谱分析

目的建立液相色谱-高分辨质谱(UPLC-Q Exactive MS)和半制备液相色谱(Semi-preparative HPLC)联用技术对葛根药材中黄嘌呤氧化酶抑制剂进行快速筛选分离及鉴定的新方法。方法实验以黄嘌呤氧化酶作为生物靶分子,以超滤技术为研究手段筛选酶抑制剂,采用Semi-preparative HPLC技术分离纯化筛选所得到的活性成分,利用核磁共振波谱技术对单体活性成分进行进一步结构鉴定。结果从葛根药材中筛选并分离出5个纯度均大于90%的活性成分(葛根素、葛根素-6"-O-木糖苷、大豆苷、6"-O-乙酰基大豆苷和大豆苷元)。结论利用液相色谱-超滤-质谱-半制备高效液相色谱联用技术可以快速鉴定、筛选、分离葛根药材中活性化合物。此方法对于筛选黄嘌呤氧化酶酶抑制剂具有快速和灵敏等优势,为痛风等治疗药物的筛选与开发提供了科学有效的技术支持。     

鹰嘴豆中超氧化物歧化酶抑制剂的分离与鉴定

目的 以超氧化物歧化酶为作用靶点,快速筛选、分离纯化和鉴定超氧化物歧化酶抑制剂。方法 首先,利用超滤-质谱技术(UF-MS)对鹰嘴豆中具有超氧化物歧化酶抑制作用的活性成分进行筛选。然后,在活性指导下,应用半制备型液相色谱(Semi-preparative HPLC)结合高速逆流色谱(HSCCC)技术从鹰嘴豆中分离超氧化物歧化酶抑制剂,最后,运用质谱和核磁共振波谱数据对分离所得化学成分进行结构解析和鉴定。结果 从鹰嘴豆中成功分离纯化并鉴定出五个超氧化物歧化酶抑制剂(分别为大豆苷、大豆苷元、毛蕊异黄酮、后莫紫檀素、鹰嘴豆芽素A),其纯度均>90%。结论 采用超高分辨质谱-半制备液相色谱-高速逆流色谱联用技术可以快速筛选、分离纯化和鉴定鹰嘴豆中超氧化物歧化酶抑制剂,为鹰嘴豆抗炎活性研究及天然产物的开发和利用提供一定的理论支持。     

软珊瑚Sinularia papillosa的次生代谢产物研究

目的研究海洋动物软珊瑚Sinulariapapillosa的次生代谢产物,寻找药物先导化合物。方法利用柱层析和现代分离方法进行分离、纯化,结合波谱学(UV,IR,NMR,MS等)研究,鉴定其次生代谢产物的物质结构及其生理活性。结果从软珊瑚乙酸乙酯部分又分离得到2个白色无定型粉末状化合物,通过波谱分析确定其为:(1)孕甾-5,20-二烯-3β-醇-3-O-α-L-吡喃岩藻糖苷;(2)1-(17Z-二十四碳烯基)-甘油醚。结论化合物1和2均为首次从该属软珊瑚中分离到,对于珊瑚分类学和甾类化合物的生源学具有一定参考意义。     

天然产物中先导化合物的发现与优化

本文对从天然产物中发现先导化合物的思路及先导化合物的优化方法作了简单论述。指出从天然产物中发现有活性的化合物，将仍然是先导物发现甚至是创制药物的重要组成部分。     

抗HIV活性植物多酚类化合物的研究进展

以鞣质为代表的植物多酚类化合物是广泛存在于植物界的一大类次生代谢物，这类化合物具有广泛的生理活性。随着天然药物化学研究的深入开展，对植物多酚作为抗人免疫缺陷病毒(HIV)药物先导化合物进行了筛选，希望从中找到有效药物。     

高速逆流色谱分离纯化天然产物中生物碱类成分的应用进展

高速逆流色谱技术(HSCCC)是一种新型的液-液分配色谱技术。介绍了HSCCC在分离纯化天然产物方面的优势以及近年来该技术在分离纯化天然产物中生物碱成分的研究进展,包括高速逆流色谱技术分离纯化已知和未知天然产物生物碱类成分、筛选生物碱活性成分;对新近发展的pH-区带精制逆流色谱、正交轴逆流色谱等新型的高速逆流色谱技术在分离纯化天然产物中生物碱成分的应用状况,高速逆流色谱与其他各种分析检测技术的联用进行了综述。     

Quantitative 1H NMR: development and potential of a method for natural products analysis

Based on a brief revision of what constitutes state-of-the-art "quantitative experimental conditions" for (1)H quantitative NMR (qHNMR), this comprehensive review contains almost 200 references and covers the literature since 1982 with emphasis on natural products. It provides an overview of the background and applications of qHNMR in natural products research, new methods such as decoupling and hyphenation, and analytical potential and limitations, and compiles information on reference materials used for and studied by qHNMR. The dual status of natural products, being single chemical entities and valuable biologically active agents that need to be purified from complex matrixes, results in an increased analytical demand when testing their deviation from the singleton composition ideal. The outcome and versatility of reported applications lead to the conclusion that qHNMR is currently the principal analytical method to meet this demand. Considering both 1D and 2D (1)H NMR experiments, qHNMR has proved to be highly suitable for the simultaneous selective recognition and quantitative determination of metabolites in complex biological matrixes. This is manifested by the prior publication of over 80 reports on applications involving the quantitation of single natural products in plant extracts, dietary materials, and materials representing different metabolic stages of (micro)organisms. In summary, qHNMR has great potential as an analytical tool in both the discovery of new bioactive natural products and the field of metabolome analysis.     

Challenges and rewards of research in marine natural products chemistry in Brazil

Brazil is blessed with a great biodiversity, which constitutes one of the most important sources of biologically active compounds, even if it has been largely underexplored. As is the case of the Amazon and Atlantic rainforests, the Brazilian marine fauna remains practically unexplored in the search for new biologically active natural products. Considering that marine organisms have been shown to be one of the most promising sources of new bioactive compounds for the treatment of different human diseases, the 8000 km of the Brazilian coastline represents a great potential for finding new pharmacologically active secondary metabolites. This review presents the status of marine natural products chemistry in Brazil, including results reported by different research groups with emphasis on the isolation, structure elucidation, and evaluation of biological activities of natural products isolated from sponges, ascidians, octocorals, and Opistobranch mollusks. A brief overview of the first Brazilian program on the isolation of marine bacteria and fungi, directed toward the production of biologically active compounds, is also discussed. The current multidisciplinary collaborative program under development at the Universidade de S?o Paulo proposes to establish a new paradigm toward the management of the Brazilian marine biodiversity, integrating research on the species diversity, ecology, taxonomy, and biogeography of marine invertebrates and microorganisms. This program also includes a broad screening program of Brazilian marine bioresources, to search for active compounds that may be of interest for the development of new drug leads.     

A routine experimental protocol for qHNMR illustrated with Taxol

Quantitative 1H NMR (qHNMR) provides a value-added dimension to the standard spectroscopic data set involved in structure analysis, especially when analyzing bioactive molecules and elucidating new natural products. The qHNMR method can be integrated into any routine qualitative workflow without much additional effort by simply establishing quantitative conditions for the standard solution 1H NMR experiments. Moreover, examination of different chemical lots of taxol (paclitaxel) and a Taxus brevifolia extract as working examples led to a blueprint for a generic approach to performing a routinely practiced 13C-decoupled qHNMR experiment and for recognizing its potential and main limitations. The proposed protocol is based on a newly assembled 13C GARP broadband decoupled proton acquisition sequence that reduces spectroscopic complexity by removal of carbon satellites. The method is capable of providing qualitative and quantitative NMR data simultaneously and covers various analytes from pure compounds to complex mixtures such as metabolomes. Due to a routinely achievable dynamic range of 300:1 (0.3%) or better, qHNMR qualifies for applications ranging from reference standards to biologically active compounds to metabolome analysis. Providing a "cookbook" approach to qHNMR, acquisition conditions are described that can be adapted for contemporary NMR spectrometers of all major manufacturers.     

Communiols E-H: new polyketide metabolites from the coprophilous fungus Podospora communis

Communiols E-H (1-4), four new polyketide-derived natural products containing furanocyclopentane, furanocyclopentene, cyclopentene, or gamma-lactone moieties, have been isolated from two geographically distinct isolates of the coprophilous fungus Podospora communis. The structures of these compounds were determined by analysis of NMR and MS data.     

(Iso)-quinoline alkaloids from fungal fruiting bodies of Cortinarius subtortus

Chemical analysis of the fruiting bodies of the agaricoid fungus Cortinarius subtortus yielded three new natural products, two quinoline and one isocarbostyryl alkaloid. The structures of compounds 1- 3 were determined by analysis of NMR and MS data. Compound 1 exhibited inhibitory effects against the phytopathogenic fungus Colletotrichum coccodes. All three compounds displayed moderate antioxidant activity in a DPPH free radical scavenging bioassay.     

Antiinsectan decaturin and oxalicine analogues from Penicillium thiersii

Three new oxalicine and decaturin analogues (6-8) have been isolated from organic extracts of Penicillium thiersii, along with the known compounds oxalicines A and B. These compounds (4-8) are members of a group of unique natural products containing terpenoid and pyridine moieties. The structures of the new compounds were elucidated by analysis of NMR and MS data. Most of these metabolites exhibit potent antiinsectan activity against the fall armyworm (Spodoptera frugiperda).     

ChemGPS-NP: tuned for navigation in biologically relevant chemical space

Natural compounds are evolutionary selected and prevalidated by Nature, displaying a unique chemical diversity and a corresponding diversity of biological activities. These features make them highly interesting for studies of chemical biology, and in the pharmaceutical industry for development of new leads. Of utmost importance, for the discovery of new biologically active compounds, is the identification and charting of the corresponding biologically relevant chemical space. The primary key to this is the coverage of the natural products' chemical space. Here we introduce ChemGPS-NP, a new tool tuned for handling the chemical diversity encountered in natural products research, in contrast to previous tools focused on the much more restricted drug-like chemical space. The aim is to provide a framework for making compound classification and comparison more efficient and stringent, to identify volumes of chemical space related to particular biological activities, and to track changes in chemical properties due to, for example, evolutionary traits and modifications in biosynthesis. Physical-chemical properties not directly discernible from structural data can be discovered, making selection more efficient and increasing the probability of hit generation when screening natural compounds and analogues.     

Isoterchebulin and 4,6-O-isoterchebuloyl-D-glucose, novel hydrolyzable tannins from Terminalia macroptera

Two new hydrolyzable tannins, isoterchebulin (1) and 4,6-O-isoterchebuloyl-D-glucose (2), together with six known tannins, 3-8, were isolated from the bark of Terminalia macroptera. Their structures were elucidated by extensive 1D and 2D NMR studies, MS, and chemical transformations. Biological activities of all compounds were evaluated against the snail Biomphalaria glabrata, the bacteria Bacillus subtilis and Pseudomonas fluorescens, the nematode Caenorhabditis elegans, and four cancer cell lines (Hep G2, MCF-7/S, MDA-MB-231, and 5637 cells). All compounds except 3 showed antimicrobial activities against B. subtilis (MIC 8-64 microg/mL), whereas only 1 was active against C. elegans (100 microg/mL) and B. glabrata(LC(100) = 60 microg/mL). 3 and 8 were toxic against 5637 cells with LC(50) = 84.66 and 41.40 microM, respectively.     

Developing a drug-like natural product library

Addressing drug-like/lead-like properties of biologically active small molecules early in a lead generation program is the current paradigm within the drug discovery community. Lipinski's "rule of five" has become the most commonly used tool to assess the relationship between structures and drug-like properties. Sixty percent of the 126 140 unique compounds in The Dictionary of Natural Products had no violations of Lipinski's "rule of five". We have isolated 814 natural products based on their expected drug-like/lead-like properties to generate a natural product library (NPL) in which 85% of the isolated compounds had no Lipinski violations. The library demonstrates the feasibility of obtaining natural products known for rich chemical diversity with the required physicochemical properties for drug discovery. The knowledge generated in creation of the library of structurally characterized pure natural products may provide opportunities to front-load lead-like property space in natural product drug discovery programs.     

A new antifouling hexapeptide from a Palauan sponge,Haliclona sp

Bioassay-guided fractionation of an extract of the sponge Haliclona sp. provided a known hexapeptide, waiakeamide (1), and a new sulfone derivative (2). The structures of hexapeptides 1 and 2 were elucidated by extensive NMR analyses and the advanced Marfey's method with LC/MS. These compounds showed repellent activity against the blue mussel, Mytilus edulis galloprovincialis.