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Natural product chemistry

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https://www.readbyqxmd.com/read/28652644/the-development-of-alkoxide-directed-metallacycle-mediated-annulative-cross-coupling-chemistry
#1
Glenn C Micalizio, Haruki Mizoguchi
Alkoxide-directed metallacycle-mediated cross-coupling is a rapidly growing area of reaction methodology in organic chemistry. Over the last decade, developments have resulted in > thirty new and highly selective intermolecular (or "convergent") C-C bond-forming reactions that have established powerful retrosynthetic relationships in stereoselective synthesis. While early studies were focused on developing transformations that forge a single C-C bond by way of a functionalized and unsaturated metallacyclopentane intermediate, recent advances mark the ability to employ this organometallic intermediate in additional stereoselective transformations...
April 2017: Israel Journal of Chemistry
https://www.readbyqxmd.com/read/28650492/exploiting-the-biosynthetic-machinery-of-streptomyces-pilosus-to-engineer-a-water-soluble-zirconium-iv-chelator
#2
Tomas Richardson-Sanchez, William Tieu, Michael P Gotsbacher, Thomas J Telfer, Rachel Codd
The water solubility of a natural product-inspired octadentate hydroxamic acid chelator designed to coordinate Zr(iv)-89 has been improved by using a combined microbiological-chemical approach to engineer four ether oxygen atoms into the main-chain region of a methylene-containing analogue. First, an analogue of the trimeric hydroxamic acid desferrioxamine B (DFOB) that contained three main-chain ether oxygen atoms (DFOB-O3) was generated from cultures of the native DFOB-producer Streptomyces pilosus supplemented with oxybis(ethanamine) (OBEA), which competed against the native 1,5-diaminopentane (DP) substrate during DFOB assembly...
June 26, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28650175/bioactive-peptide-natural-products-as-lead-structures-for-medicinal-use
#3
Tam Dang, Roderich D Süssmuth
The need for new drugs for the treatment of various diseases is enormous. From the previous century until the present, numerous peptide and peptide-derived natural products have been isolated from bacteria and fungi. Hence, microorganisms play a pivotal role as sources for novel drugs with an emphasis on anti-infective agents. Various disciplines from biology, chemistry, and medicine are involved in early stages of the search for peptide natural products including taxonomy, microbiology, bioanalytics, bioinformatics, and medicinal chemistry...
June 26, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28650100/tautomerization-and-dissociation-of-molecular-peptide-radical-cations
#4
REVIEW
Xiaoyan Mu, Tao Song, Chi-Kit Siu, Ivan K Chu
Radical-mediated dissociations of peptide radical cations have intriguing unimolecular gas phase chemistry, with cleavages of almost every bond of the peptide backbone and amino acid side chains in a competitive and apparently "stochastic" manner. Challenges of unraveling mechanistic details are related to complex tautomerizations prior to dissociations. Recent conjunctions of experimental and theoretical investigations have revealed the existence of non-interconvertible isobaric tautomers with a variety of radical-site-specific initial structures, generated from dissociative electron transfer of ternary metal-ligand-peptide complexes...
June 26, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/28648259/semisynthesis-and-spectral-characterization-of-5-methylpyranopelargonidin-and-4-methylfuropelargonidin-and-their-separation-and-detection-in-strawberry-fruit-wine
#5
Ondřej Kurka, Lukáš Kučera, Helena Pelantová, Marek Kuzma, Vladimír Havlíček, Petr Bednář
Condensation of anthocyanins and their aglycons with small organic molecules yields more stable natural dyes, e.g. pyranoanthocyanins arising spontaneously in various food products. Reaction of pelargonidin with acetone produces two isomeric anthocyanidin dyes - 5-methylpyranopelargonidin and 4-methylfuropelargonidin. A robust semipreparative liquid chromatographic method was developed to isolate both derivatives from a simple aged solution of pelargonidin in methanol: acetone: 37% aqueous hydrochloric acid (1:1:0...
June 17, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28648054/practical-singly-and-doubly-electrophilic-aminating-agents-a-new-more-sustainable-platform-for-carbon-nitrogen-bond-formation
#6
Padmanabha V Kattamuri, Jun Yin, Surached Siriwongsup, Doo-Hyun Kwon, Daniel H Ess, Qun Li, Guigen Li, Muhammed Yousufuddin, Paul F Richardson, Scott C Sutton, László Kürti
Given the importance of amines in a large number of biologically active natural products, active pharmaceutical ingredients, agrochemicals and functional materials, the development of efficient CN bond-forming methods with wide substrate scope continues to be at the frontiers of research in synthetic organic chemistry. Here, we present a general and fundamentally new synthetic approach for the direct, transition metal-free preparation of symmetrical and unsymmetri-cal diaryl-, arylalkyl- and dialkylamines that relies on the facile single or double addition of readily available C-nucleophiles to the nitrogen atom of bench-stable electrophilic aminating agents...
June 26, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28647090/natural-product-inspired-compound-collections-evolutionary-principle-chemical-synthesis-phenotypic-screening-and-target-identification
#7
REVIEW
Luca Laraia, Herbert Waldmann
Natural products have been an excellent and abundant source of therapeutics for many decades. To expand on their success, and explore areas of chemical space not covered by biosynthesis, the synthesis of natural product-inspired compound collections has emerged as a viable strategy. Herein we describe the principles behind biology-oriented synthesis and related approaches, the requirements for development of novel chemistry and how phenotypic screens are a very fruitful way to explore the bioactivity of compounds made using these approaches...
March 2017: Drug Discovery Today. Technologies
https://www.readbyqxmd.com/read/28644617/dynamic-covalent-chemistry-of-carbon-dioxide-opportunities-to-address-environmental-issues
#8
Jean Septavaux, Geoffroy Germain, Julien Leclaire
Extraction and purification of basic chemicals from complex mixtures has been a persistent issue throughout the development of the chemical sciences. The chemical industry and academic research have grown over the centuries by following a deconstruction-reconstruction approach, reminiscent of the metabolism process. Chemists have designed and optimized extraction, purification, and transformation processes of molecules from natural deposits (fossil fuels, biomass, ores), in order to reassemble them into complex adducts...
June 23, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28641826/the-chemical-history-of-morphine-an-8000-year-journey-from-resin-to-de-novo-synthesis
#9
Karolina Brook, Jessica Bennett, Sukumar P Desai
Evidence of human use of opium dates back as far as the sixth millennium BCE. Ancient societies through the Renaissance period created a variety of opium products, proliferating its common use and subsequent addiction. Because the active moiety was not known at this time, the potency of these opium concoctions could neither be predicted nor controlled. The first step in identifying opium's active ingredient, morphine, was its chemical isolation in the early 1800s by Wilhelm Sertürner. The subsequent elucidation of morphine's chemical formula and Sir Robert Robinson's derivation of morphine's structural formula, which won him the 1947 Nobel Prize in Chemistry, round out 150 years of the incremental advances in our chemical understanding of morphine...
April 2017: Journal of Anesthesia History
https://www.readbyqxmd.com/read/28641414/review-of-studies-in-natural-products-chemistry-volume-48-bioactive-natural-products-studies-in-natural-products-chemistry-volume-48-bioactive-natural-products-edited-by-atta-ur-rahman-elsevier-2016-470-pp-295-00-isbn-9780444636027
#10
https://www.readbyqxmd.com/read/28638140/imaging-dynamic-fingerprints-of-competing-e2-and-sn2-reactions
#11
Eduardo Carrascosa, Jennifer Meyer, Jiaxu Zhang, Martin Stei, Tim Michaelsen, William L Hase, Li Yang, Roland Wester
The competition between bimolecular nucleophilic substitution and base-induced elimination is of fundamental importance for the synthesis of pure samples in organic chemistry. Many factors that influence this competition have been identified over the years, but the underlying atomistic dynamics have remained difficult to observe. We present product velocity distributions for a series of reactive collisions of the type X(-) + RY with X and Y denoting the halogen atoms fluorine, chlorine and iodine. By increasing the size of the residue R from methyl to tert-butyl in several steps, we find that the dynamics drastically change from backward to dominant forward scattering of the leaving ion relative to the reactant RY velocity...
June 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28637365/insight-into-the-c-f-bond-mechanism-of-molecular-analogs-for-antibacterial-drug-design
#12
Junna Liu, Biyu Lv, Huaqing Liu, Xin Li, Weiping Yin
The activities of biological molecules usually rely on both of intra-molecular and intermolecular interactions between their function groups. These interactions include interonic attraction theory, Van der Waal's forces and the function of geometry on the individual molecules, whether they are naturally or synthetic. The purpose of this study was to evaluate the antibacterial activity of C-F bond compound using combination of experiments verification and theoretical calculation. We target on the insect natural products from the maggots of Chrysomyis megacephala Fabricius...
June 21, 2017: Natural Product Research
https://www.readbyqxmd.com/read/28636605/catalytic-allylic-oxidation-of-internal-alkenes-to-a-multifunctional-chiral-building-block
#13
Liela Bayeh, Phong Q Le, Uttam K Tambar
The stereoselective oxidation of hydrocarbons is one of the most notable advances in synthetic chemistry over the past fifty years. Inspired by nature, enantioselective dihydroxylations, epoxidations and other oxidations of unsaturated hydrocarbons have been developed. More recently, the catalytic enantioselective allylic carbon-hydrogen oxidation of alkenes has streamlined the production of pharmaceuticals, natural products, fine chemicals and other functional materials. Allylic functionalization provides a direct path to chiral building blocks with a newly formed stereocentre from petrochemical feedstocks while preserving the olefin functionality as a handle for further chemical elaboration...
June 21, 2017: Nature
https://www.readbyqxmd.com/read/28636366/oxygenation-via-c-h-c-c-bond-activation-with-molecular-oxygen
#14
Yu-Feng Liang, Ning Jiao
The selective oxidation of organic molecules is a fundamentally important component of modern synthetic chemistry. In the past decades, direct oxidative C-H and C-C bond functionalization has proved to be one of the most efficient and straightforward methods to synthesize complex products from simple and readily available starting materials. Among these oxidative processes, the use of molecular oxygen as a green and sustainable oxidant has attracted considerable attention because of its highly atom-economical, abundant, and environmentally friendly characteristics...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28636311/insights-into-integrated-lead-generation-and-target-identification-in-malaria-and-tuberculosis-drug-discovery
#15
John Okombo, Kelly Chibale
New, safe and effective drugs are urgently needed to treat and control malaria and tuberculosis, which affect millions of people annually. However, financial return on investment in the poor settings where these diseases are mostly prevalent is very minimal to support market-driven drug discovery and development. Moreover, the imminent loss of therapeutic lifespan of existing therapies due to evolution and spread of drug resistance further compounds the urgency to identify novel effective drugs. However, the advent of new public-private partnerships focused on tropical diseases and the recent release of large data sets by pharmaceutical companies on antimalarial and antituberculosis compounds derived from phenotypic whole cell high throughput screening have spurred renewed interest and opened new frontiers in malaria and tuberculosis drug discovery...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28634235/mechanistic-elucidation-of-the-mycofactocin-biosynthetic-radical-s-adenosylmethionine-protein-mftc
#16
Bulat Khaliullin, Richard Ayikpoe, Mason Tuttle, John A Latham
Ribosomally synthesized and posttranslationally modified peptide (RiPP) pathways produce a diverse array of natural products. A subset of these pathways depend on radical S-adenosylmethionine (RS) proteins to modify the RiPP-produced peptide. Mycofactocin biosynthesis is one example of an RS protein-dependent RiPP pathway. Recently, it has been shown that MftC catalyzes the oxidative decarboxylation of the C-terminal tyrosine (Tyr30) on the mycofactocin precursor peptide MftA; however, this product has not been verified by techniques other than MS...
June 20, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28633438/sandpuma-ensemble-predictions-of-nonribosomal-peptide-chemistry-reveals-biosynthetic-diversity-across-actinobacteria
#17
Marc G Chevrette, Fabian Aicheler, Oliver Kohlbacher, Cameron R Currie, Marnix H Medema
Summary: Nonribosomally synthesized peptides (NRPs) are natural products with widespread applications in medicine and biotechnology. Many algorithms have been developed to predict the substrate specificities of nonribosomal peptide synthetase adenylation (A) domains from DNA sequences, which enables prioritization and dereplication, and integration with other data types in discovery efforts. However, insufficient training data and a lack of clarity regarding prediction quality have impeded optimal use...
June 19, 2017: Bioinformatics
https://www.readbyqxmd.com/read/28630318/reducing-secondary-organic-aerosol-formation-from-gasoline-vehicle-exhaust
#18
Yunliang Zhao, Rawad Saleh, Georges Saliba, Albert A Presto, Timothy D Gordon, Greg T Drozd, Allen H Goldstein, Neil M Donahue, Allen L Robinson
On-road gasoline vehicles are a major source of secondary organic aerosol (SOA) in urban areas. We investigated SOA formation by oxidizing dilute, ambient-level exhaust concentrations from a fleet of on-road gasoline vehicles in a smog chamber. We measured less SOA formation from newer vehicles meeting more stringent emissions standards. This suggests that the natural replacement of older vehicles with newer ones that meet more stringent emissions standards should reduce SOA levels in urban environments. However, SOA production depends on both precursor concentrations (emissions) and atmospheric chemistry (SOA yields)...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28629133/propolis-diterpenes-as-a-remarkable-bio-source-for-drug-discovery-development-a-review
#19
REVIEW
Noushin Aminimoghadamfarouj, Alireza Nematollahi
Propolis is one of the complex, but valuable, bio-sources for discovering therapeutic compounds. Diterpenes are organic compounds composed of four isoprene units and are known for their biological and pharmacological characteristics, such as antibacterial, anticancer, and anti-inflammatory activities. Recently, advancements have been made in the development of antibacterial and anticancer leads from propolis-isolated diterpenes, and scrutiny of these compounds is being pursued. Thus, this review covers the progress in this arena, with a focus on the chemistry and biological activities of propolis diterpenes...
June 17, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28619619/flavin-catalyzed-redox-tailoring-reactions-in-natural-product-biosynthesis
#20
REVIEW
Robin Teufel
Natural products are distinct and often highly complex organic molecules that constitute not only an important drug source, but have also pushed the field of organic chemistry by providing intricate targets for total synthesis. How the astonishing structural diversity of natural products is enzymatically generated in biosynthetic pathways remains a challenging research area, which requires detailed and sophisticated approaches to elucidate the underlying catalytic mechanisms. Commonly, the diversification of precursor molecules into distinct natural products relies on the action of pathway-specific tailoring enzymes that catalyze, e...
June 12, 2017: Archives of Biochemistry and Biophysics
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