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Showing posts with label medicinal chemistry. Show all posts
Showing posts with label medicinal chemistry. Show all posts

Wednesday, 17 February 2016

The Medicinal Chemistry of Dengue Virus

Abstract Image



The dengue virus and related flaviviruses are an increasing global health threat. In this perspective, we comment on and review medicinal chemistry efforts aimed at the prevention or treatment of dengue infections. We include target-based approaches aimed at viral or host factors and results from phenotypic screenings in cellular assay systems for viral replication. This perspective is limited to the discussion of results that provide explicit chemistry or structure–activity relationship (SAR), or appear to be of particular interest to the medicinal chemist for other reasons. The discovery and development efforts discussed here may at least partially be extrapolated toward other emerging flaviviral infections, such as West Nile virus. Therefore, this perspective, although not aimed at flaviviruses in general, should also be able to provide an overview of the medicinal chemistry of these closely related infectious agents.


READ AT
http://pubs.acs.org/doi/full/10.1021/acs.jmedchem.5b01653


The Medicinal Chemistry of Dengue Virus

Medicinal Chemistry, Institute of Pharmacy and Molecular Biotechnology IPMB, Heidelberg University, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
§ Laboratory of Organic Synthesis, Institute of Chemistry of the Academy of Sciences of Moldova, Academiei 3, 2028 Chisinau, Moldova
J. Med. Chem., Article ASAP
DOI: 10.1021/acs.jmedchem.5b01653
Publication Date (Web): January 15, 2016
Copyright © 2016 American Chemical Society
*C. D. Klein, phone +49-6221-544875, e-mail c.klein@uni-heidelberg.de.
ACS Editors' Choice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

Biography
Mira A. M. Behnam studied pharmacy and biotechnology at The German University in Cairo, where she obtained her B.Sc. degree (2009) and M.Sc. degree (2011) in Pharmaceutical Chemistry in collaboration with Würzburg University. Since 2013, she is DAAD scholarship holder and Ph.D. candidate in the group of Prof. Christian Klein (Heidelberg University) working on the development of potent antiviral compounds against dengue and West Nile virus.
Biography
Christoph Nitsche studied chemistry and business administration. He obtained his Ph.D. on the development of dengue virus protease inhibitors under the guidance of Prof. Christian Klein at Heidelberg University with a scholarship from the German National Academic Foundation. Currently, he is working as a Feodor Lynen Fellow (Alexander von Humboldt-Foundation) in the laboratory of Prof. Gottfried Otting at the Australian National University. His present research focuses on novel NMR methods for drug discovery.
Biography
Veaceslav Boldescu studied pharmaceutical technology and obtained a Ph.D. in Technology of special products (pharmaceuticals) in 2008 under the guidance of Acad. Gheorghe Duca (Academy of Sciences of Moldova). He started his research pathway at the State University of Moldova and continued it at the Institute of Chemistry of the Academy of Sciences of Moldova, working in the Laboratory of Organic Synthesis lead by Prof. Fliur Macaev. His main research interests include development of new chemotherapeutic agents against infections such as tuberculosis and dengue.
Biography
Christian D. Klein studied pharmacy and obtained a Ph.D. in Pharmaceutical Chemistry in 2000 under the guidance of Profs. Ulrike Holzgrabe (University of Bonn) and A. J. Hopfinger (UIC, Chicago). Following postdoctoral work at ETH Zürich, he became an Emmy Noether junior group leader. Since 2007, he is professor of Pharmaceutical Chemistry at Heidelberg University. His main research interests are anti-infective compounds and fundamental questions in medicinal chemistry, such as the study of unusual binding modes and structural motifs.

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Wednesday, 16 October 2013

Microwave-assisted synthesis of N-heterocycles in medicinal chemistry


Med. Chem. Commun., 2013, 4,1323-1343
DOI: 10.1039/C3MD00152K, Review Article
Davide Garella, Emily Borretto, Antonella Di Stilo, Katia Martina, Giancarlo Cravotto, Pedro Cintas
Microwave-assisted synthesis of heterocycle libraries has given an impressive contribution to drug discovery and development.http://pubs.rsc.org/en/Content/ArticleLanding/2013/MD/C3MD00152K?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FMD+%28RSC+-+Med.+Chem.+Commun.+latest+articles%29#!divAbstract
 

Microwave-assisted synthesis of N-heterocycles in medicinal chemistry

 

 

 The syntheses of almost all N-heterocycles have now been successfully performed under microwave irradiation and have provided significant improvements in the reaction time and efficiency. The peculiar properties of dielectric heating give it the ability to strongly promote cyclocondensation, cycloaddition and selective N-heterocycle functionalisation and it has, therefore, very much caught the attention of the medicinal chemistry community. In this work, we present an overview of recent literature and technical advances in this research field with the aim of providing insight into the applications of microwave-assisted synthesis in the preparation of the main drug categories that contain N-heterocycle scaffolds.

Friday, 2 August 2013

COLUMN CHROMATOGRAPHY


A chemist in the 1950s using column chromatography. The Erlenmeyer receptacles are on the floor.
Column chromatography in chemistry is a method used to purify individual chemical compounds from mixtures of compounds. It is often used for preparative applications on scales from micrograms up to kilograms. The main advantage of column chromatography is the relatively low cost and disposability of the stationary phase used in the process. The latter prevents cross-contamination and stationary phase degradation due to recycling.
The classical preparative chromatography column, is a glass tube with a diameter from 5 mm to 50 mm and a height of 5 cm to 1 m with a tap and some kind of a filter (a glass frit or glass wool plug – to prevent the loss of the stationary phase) at the bottom. Two methods are generally used to prepare a column: the dry method, and the wet method.
  • For the dry method, the column is first filled with dry stationary phase powder, followed by the addition of mobile phase, which is flushed through the column until it is completely wet, and from this point is never allowed to run dry.
  • For the wet method, a slurry is prepared of the eluent with the stationary phase powder and then carefully poured into the column. Care must be taken to avoid air bubbles. A solution of the organic material is pipetted on top of the stationary phase. This layer is usually topped with a small layer of sand or with cotton or glass wool to protect the shape of the organic layer from the velocity of newly added eluent. Eluent is slowly passed through the column to advance the organic material. Often a spherical eluent reservoir or an eluent-filled and stoppered separating funnel is put on top of the column.
The individual components are retained by the stationary phase differently and separate from each other while they are running at different speeds through the column with the eluent. At the end of the column they elute one at a time. During the entire chromatography process the eluent is collected in a series of fractions. Fractions can be collected automatically by means of fraction collectors. The productivity of chromatography can be increased by running several columns at a time. In this case multi stream collectors are used. The composition of the eluent flow can be monitored and each fraction is analyzed for dissolved compounds, e.g. by analytical chromatography, UV absorption, or fluorescence. Colored compounds (or fluorescent compounds with the aid of an UV lamp) can be seen through the glass wall as moving bands.

    Overview


    Stationary phase

    The stationary phase or adsorbent in column chromatography is a solid. The most common stationary phase for column chromatography is silica gel, followed by aluminaCellulosepowder has often been used in the past. Also possible are ion exchange chromatographyreversed-phase chromatography(RP), affinity chromatography or expanded bed adsorption(EBA). The stationary phases are usually finely ground powders or gels and/or are microporous for an increased surface, though in EBA a fluidized bed is used. There is an important ratio between the stationary phase weight and the dry weight of the analyte mixture that can be applied onto the column. For silica column chromatography, this ratio lies within 20:1 to 100:1, depending on how close to each other the analyte components are being eluted.

    Mobile phase (eluent)

    The mobile phase or eluent is either a pure solvent or a mixture of different solvents. It is chosen so that the retention factor value of the compound of interest is roughly around 0.2 - 0.3 in order to minimize the time and the amount of eluent to run the chromatography. The eluent has also been chosen so that the different compounds can be separated effectively. The eluent is optimized in small scale pretests, often using thin layer chromatography (TLC) with the same stationary phase.
    There is an optimum flow rate for each particular separation. A faster flow rate of the eluent minimizes the time required to run a column and thereby minimizes diffusion, resulting in a better separation. However, the maximum flow rate is limited because a finite time is required for analyte to equilibrate between stationary phase and mobile phase, see Van Deemter's equation. A simple laboratory column runs by gravity flow. The flow rate of such a column can be increased by extending the fresh eluent filled column above the top of the stationary phase or decreased by the tap controls. Faster flow rates can be achieved by using a pump or by using compressed gas (e.g. air,nitrogen, or argon) to push the solvent through the column (flash column chromatography).
    The particle size of the stationary phase is generally finer in flash column chromatography than in gravity column chromatography. For example, one of the most widely used silica gel grades in the former technique is mesh 230 – 400 (40 – 63 µm), while the latter technique typically requires mesh 70 – 230 (63 – 200 µm) silica gel.

    A spreadsheet that assists in the successful development of flash columns has been developed. The spreadsheet estimates the retention volume and band volume of analytes, the fraction numbers expected to contain each analyte, and the resolution between adjacent peaks. This information allows users to select optimal parameters for preparative-scale separations before the flash column itself is attempted.



    An automated ion chromatography system.


    ,,,,,,,,,,,,, allow video to load.................. .................


    Typical set up for manual column chromatography

    CHECK THIS VIDEO

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    CHECK THIS VIDEO

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    Jumping Crystals








    Scientists from the United Arab Emirates and Russia examined light-induced jumping crystals by kinematic analysis
    Read more

    Tuesday, 30 July 2013

    Boron vapour trail leads to heterofullerenes

    borafullerene
    The simple route to borafullerenes could open up an interesting new avenue of heterofullerene research © Wiley-VCH
    A team of scientists has developed a simple way to synthesise heterofullerenes – fullerenes with atoms other than carbon in their structure – by exposing fullerenes to boron vapour during their growth. They found that atom exchange with a carbon takes place to form a derivative known as borafullerene. The team believes the process can be easily scaled up and applied to other all-carbon analogues including nanotubes or graphene.
    read all at

    Monday, 29 July 2013

    Nickel-Catalyzed Suzuki–Miyaura Couplings in Green Solvents

    Figure

    Nickel-Catalyzed Suzuki–Miyaura Couplings in Green Solvents

    Publication Date (Web): July 23, 2013 (Letter)
    DOI: 10.1021/ol401727y

    The nickel-catalyzed Suzuki–Miyaura coupling of aryl halides and phenol-derived substrates with aryl boronic acids using green solvents, such as 2-Me-THF and tert-amyl alcohol, is reported. This methodology employs the commercially available and air-stable precatalyst, NiCl2(PCy3)2, and gives biaryl products in synthetically useful to excellent yields. Using this protocol, bis(heterocyclic) frameworks can be assembled efficiently.

    Wednesday, 17 July 2013

    Building nanographene by organic synthesis



    Direct C-H coupling of pyrene makes nanographenes with defined shape and edge structures

    Direct C-H coupling of pyrene makes nanographenes with defined shape and edge structures

    Japanese scientists are making tiny fragments of graphene using direct
    cross-coupling of C-H bonds to determine what effect size and edge geometry
    have on the properties of carbon materials. By bolting together aromatic hydrocarbons, they can
    build nanographene fragments with defined shapes in an attempt to relate geometry to performance.
    Speaking at the RSC’s seventh International Symposium on Advancing the Chemical Sciences in Edinburgh, UK, Kenichiro Itami from Nagoya University explained .............read all at

    Tuesday, 16 July 2013

    A new labdane diterpene from Rauvolfia tetraphylla Linn. (Apocynaceae)

    A new labdane diterpene from Rauvolfia tetraphylla Linn. (Apocynaceae)
    A new labdane diterpene from Rauvolfia tetraphylla Linn. (Apocynaceae)

    Rauvolfia tetraphylla Linn. (syn. R. canescens L., family: Apocynaceae) holds an important position in the Indian traditional system of medicine, and has other immense applications. This particular plant is regarded as a rich source of a wide variety of important alkaloid constituents such as reserpine, reserpiline, raujemidine, isoreserpiline, deserpidine, aricine, ajmaline, ajmalicine, yohimbines, serpentine, sarpagine, vellosimine and tetrphylline. However, there is no report on the terpenoid constituent from this plant, and we report the isolation from the air-dried stems and branches of R. tetraphylla and structural elucidation of a new labdane diterpene, 3-hydroxy-labda-8(17),13(14)-dien-12(15)-olide (1; Fig. 1) bearing  an unusual -lactone moiety.
    Structure of labdane diterpene
    Fig. 1 Structure of labdane diterpene
    Goutam Brahmachari*, Lalan Ch. Mandal, Dilip Gorai, Avijit Mondal, Sajal Sarkar and Sasadhar Majhi
    Doi: 10.3184/174751911X13220462651507

    read all at

    Novel uses of nanoparticle catalytic systems

    Novel uses of nanoparticle catalytic systems
    Novel uses of nanoparticle catalytic systems

    Easily prepared and recoverable nanoparticles with a diameter of 10–40 nm, with a high surface area and stability may provide a catalytic system or the support for a catalyst.

    Thursday, 27 June 2013

    A molecular database for developing organic solar cells


    molecular_space_logo




    Harvard researchers have released a massive database of more than 2 million molecules that might be useful in the construction of solar cells that rely on organic compounds for construction of organic solar cells for the production of renewable energy. Developed as part of the Materials Genome Initiative launched by the White House’s Office of … more…

    http://www.kurzweilai.net/a-molecular-database-for-developing-organic-solar-cells?utm_source=KurzweilAI+Daily+Newsletter&utm_campaign=4fc1bf53a4-UA-946742-1&utm_medium=email&utm_term=0_6de721fb33-4fc1bf53a4-282116853





    Monday, 24 June 2013

    Lab Reproduction of Marine Compound with Antibiotic Properties




     
    Baringolin is a marine product with antibiotic properties. Image: IRB Barcelona
     

    Barcelona, Spain (Scicasts) – Bacterial resistance to drugs leads pharmaceutical labs to be in constant search for new antibiotics to treat the same diseases. For the last thirty years, the sea bottom has yielded a wealth of substances with properties of interest to the pharmaceutical industry.
     
    Isolated from a marine microorganism off the coast of Alicante by the company BioMar, baringolin shows promising antibiotic activity at a very low concentration. The Combinatorial Lab headed by Fernando Albericio at the Institute for Research in Biomedicine (IRB Barcelona), which collaborates with BioMar, has now synthesized this molecule and revealed its structure. Today's results open up the possibility to better understand how this substance works and to design derivatives to turn into a viable drug in the next 10 years. These findings are published in todays' online edition of the journal Angewandte Chemie.

    read all at

    http://scicasts.com/bioit/1858-drug-development/6186-lab-reproduction-of-marine-compound-with-antibiotic-properties

    From left to right, this image shows researchers Mercedes Alvárez, Xavier Just-Baringo and Fernando Albericio from the IRB Barcelona.
    (Photo Credit: IRB Barcelona)


    /files/Image/XavierJust.jpg

    Xavier Just, PhD student at IRB Barcelona, has reproduced the natural structure in the lab

     Reference article:
    Total Synthesis and Stereochemical Assignment of Baringolin
    Xavier Just-Baringo, Paolo Bruno, Lars K. Ottesen, Librada M. Cañedo, Fernando Albericio and Mercedes Álvarez.
    Angewandte Chemie (2013) http://dx.doi.org/10.1002/ange.201302372 (German Edition) http://dx.doi.org/10.1002/anie.201302372 (International Edition)



    Natural Products from St. John's Wort


    Natural Products from St. John's Wort

    Enatiomers (−)-hyperione A and (−)-hyperione B can be synthesised from a common precursor in ten steps
    Read more


    http://www.chemistryviews.org/details/ezine/1238795/Natural_Products_from_St__Johns_Wort.html



    doc b's CV