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Natural product chemistry

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https://www.readbyqxmd.com/read/29234008/a-modular-synthesis-of-tetracyclic-meroterpenoid-antibiotics
#1
Raphael Wildermuth, Klaus Speck, Franz-Lucas Haut, Peter Mayer, Bianka Karge, Mark Brönstrup, Thomas Magauer
Stachyflin, aureol, smenoqualone, strongylin A, and cyclosmenospongine belong to a family of tetracyclic meroterpenoids, which, by nature of their unique molecular structures and various biological properties, have attracted synthetic and medicinal chemists alike. Despite their obvious biosynthetic relationship, only scattered reports on the synthesis and biological investigation of individual meroterpenoids have appeared so far. Herein, we report a highly modular synthetic strategy that enabled the synthesis of each of these natural products and 15 non-natural derivatives...
December 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/29229334/broad-range-chemical-profiling-of-natural-deep-eutectic-solvent-extracts-using-a-high-performance-thin-layer-chromatography-based-method
#2
Xiaojie Liu, Samantha Ahlgren, Henrie A A J Korthout, Luis F Salomé-Abarca, Lina M Bayona, Robert Verpoorte, Young Hae Choi
Natural deep eutectic solvents (NADES) made mainly with abundant primary metabolites are being increasingly applied in green chemistry. The advantages of NADES as green solvents have led to their use in novel green products for the food, cosmetics and pharma markets. However, one of the main difficulties encountered in the development of novel products and their quality control arises from their low vapour pressure and high viscosity. These features create the need for the development of new analytical methods suited to this type of sample...
December 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29222333/structural-determinants-of-bacterial-lytic-polysaccharide-monooxygenase-functionality
#3
Zarah Forsberg, Bastien Bissaro, Jonathan Gullesen, Bjørn Dalhus, Gustav Vaaje-Kolstad, Vincent G H Eijsink
Bacterial lytic polysaccharide monooxygenases (LPMO10s) use redox chemistry to cleave glycosidic bonds in the two foremost recalcitrant polysaccharides found in nature, namely cellulose and chitin. Analysis of correlated mutations revealed that the substrate-binding and copper-containing surface of LPMO10s comprises a network of coevolved residues and interactions, whose roles in LPMO functionality are unclear. Here, we mutated a subset of these correlated residues in a newly characterized C1/C4-oxidizing LPMO10 from Micromonospora aurantiaca (MaLPMO10B) to the corresponding residues in strictly C1-oxidizing LPMO10s...
December 8, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29219064/natural-product-formulations-for-prevention-and-treatment-of-alzheimer-s-disease-a-patent-review
#4
Rumiana Koynova, Boris Tenchov
INTRODUCTION: Although considerable efforts have been made to develop effective therapeutic agents for Alzheimer's disease (AD), neither a consensus concerning the pathogenesis of the disease nor a successful therapy for its treatment is available. The natural product chemistry brings tremendous diversity and abundant resource for medical needs. OBJECTIVES: The present review summarizes recent patents on natural extracts and derived drugs as agents for prevention and treatment of AD...
December 7, 2017: Recent Patents on Drug Delivery & Formulation
https://www.readbyqxmd.com/read/29214119/interested-consumers-awareness-of-harmful-chemicals-in-everyday-products
#5
Sabrina Hartmann, Ursula Klaschka
Background: Everyday products can contain a multitude of harmful substances unnoticed by most consumers, because established risk communication channels reach only part of the society. The question is, whether at least interested and informed consumers are able to use risk communication tools and assess harmful chemicals in products. Results: An online survey investigated the awareness of 1030 consumers on harmful substances in everyday items. Participating consumers' education level, knowledge in chemistry, and motivation were above society's average...
2017: Environmental Sciences Europe
https://www.readbyqxmd.com/read/29210664/advances-in-the-discovery-of-anthraquinone-based-anticancer-agents
#6
Alexander Tikhomirov, Alexander Shtil, Andrey Shchekotikhin
BACKGROUND: The anthracene-9,10-dione (anthraquinone) derivatives represent an exceptionally valuable class in anticancer drug development. An outstanding antitumor potency of the anthracycline antibiotics attracted the attention of medicinal chemists since the discovery of these chemotypes. The prominent anthraquinone-based drugs doxorubicin, mitoxantrone as well as more recent epirubicin, idarubicin, and valrubicin are successfully used in chemotherapy of hematological malignancies and solid tumors...
December 6, 2017: Recent Patents on Anti-cancer Drug Discovery
https://www.readbyqxmd.com/read/29200283/in-vitro-biosynthetic-studies-of-bottromycin-expand-the-enzymatic-capabilities-of-the-ycao-superfamily
#7
Christopher J Schwalen, Graham A Hudson, Simone Kosol, Nilkamal Mahanta, Gregory L Challis, Douglas A Mitchell
The bottromycins belong to the ribosomally synthesized and posttranslationally modified peptide (RiPP) family of natural products. Bottromycins exhibit unique structural features, including a hallmark macrolactamidine ring and thiazole heterocycle for which divergent members of the YcaO superfamily have been biosynthetically implicated. Here we report the in vitro reconstitution of two YcaO proteins, BmbD and BmbE, responsible for the ATP-dependent cyclodehydration reactions that yield thiazoline- and macrolactamidine-functionalized products, respectively...
December 4, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29199255/-diversity-of-secondary-metabolites-from-some-medicinal-plants-and-cultivated-lichen-mycobionts
#8
Takao Tanahashi
 Studies on the structural determination, biosynthesis, and biological activities of secondary metabolites from natural sources are significant in the field of natural products chemistry. This review focuses on diverse secondary metabolites isolated from medicinal plants and cultivated mycobionts of lichens in our laboratory. Monoterpene-tetrahydroisoquinoline glycosides and alkaloids isolated from Cephaelis acuminata and Alangium lamarckii gave important information on the biosynthesis of ipecac alkaloids...
2017: Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan
https://www.readbyqxmd.com/read/29194882/burchard-franck-1926-2017
#9
Lutz F Tietze
Burchard Frank, Emeritus Professor of Organic Chemistry at the University of Münster, passed away on February 21, 2017. He was an internationally recognized natural-product chemist, who made important contributions to the field of biomimetic transformations of alkaloids, as well as the areas of pigments and toxins, and porphyrinoids.
November 30, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29191021/dealkanative-main-group-couplings-across-the-peri-gap
#10
Laurence J Taylor, Michael Bühl, Brian A Chalmers, Matthew J Ray, Piotr Wawrzyniak, John C Walton, David B Cordes, Alexandra M Z Slawin, J Derek Woollins, Petr Kilian
Here, we highlight the ability of peri-substitution chemistry to promote a series of unique P-P/P-As coupling reactions, which proceed with concomitant C-H bond formation. This dealkanative reactivity represents an interesting and unexpected expansion to the established family of main-group dehydrocoupling reactions. These transformations are exceptionally clean, proceeding essentially quantitatively at relatively low temperatures (70-140 °C), with 100% diastereoselectivity in the products. The reaction appears to be radical in nature, with the addition of small quantities of a radical initiator (azobisisobutyronitrile) increasing the rate dramatically, as well as altering the apparent order of reaction...
November 30, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29186119/genetically-programmed-chiral-organoborane-synthesis
#11
S B Jennifer Kan, Xiongyi Huang, Yosephine Gumulya, Kai Chen, Frances H Arnold
Recent advances in enzyme engineering and design have expanded nature's catalytic repertoire to functions that are new to biology. However, only a subset of these engineered enzymes can function in living systems. Finding enzymatic pathways that form chemical bonds that are not found in biology is particularly difficult in the cellular environment, as this depends on the discovery not only of new enzyme activities, but also of reagents that are both sufficiently reactive for the desired transformation and stable in vivo...
November 29, 2017: Nature
https://www.readbyqxmd.com/read/29178779/synthesis-of-bis-phosphate-iminoaltritol-enantiomers-and-structural-characterization-with-adenine-phosphoribosyltransferase
#12
Lawrence D Harris, Rajesh K Harijan, Rodrigo G Ducati, Gary B Evans, Brett M Hirsch, Vern L Schramm
Phosphoribosyl transferases (PRTs) are essential in nucleotide synthesis and salvage, amino acid and vitamin synthesis. Transition state analysis of several PRTs has demonstrated ribocation-like transition states with a partial positive charge residing on the pentose ring. Core chemistry for synthesis of transition state analogues related to the 5-phospho--D-ribosyl 1-pyrophosphate (PRPP) reactant of these enzymes could be developed by stereospecific placement of bis-phosphate groups on an iminoaltritol ring...
November 27, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/29171235/-research-on-anticancer-activity-of-isocorydine-and-its-derivatives
#13
Qian Yan, Ru-Xia Li, Ai-Yi Xin, Jun-Xi Liu, Wen-Guang Li, Duo-Long Di
Isocorydine and its analogs were extracted from Dicranostigma leptopodum and Stephania yunnanensis through the method of natural products chemistry. Its derivatives were prepared by chemical structure modifications from isocorydine. MTT method was used to study the inhibitory effect of those compounds on the growth of HepG2, HeLa and MGC-803 cancer cell lines in vitro. The results showed that isocorydine and its analogs all have the growth inhibition for those cancer cell lines. This paper investigated the structure-activity relationship of isocorydine and its derivatives with anticancer activity in the aspect of stereochemical structure, functional groups positions of the compounds and the electron density of aromatic rings based on the single crystal diffraction structure and the molecular docking of EGFR and isocorydine...
August 2017: Zhongguo Zhong Yao za Zhi, Zhongguo Zhongyao Zazhi, China Journal of Chinese Materia Medica
https://www.readbyqxmd.com/read/29168493/site-selective-oxidation-amination-and-epimerization-reactions-of-complex-polyols-enabled-by-transfer-hydrogenation
#14
Christopher K Hill, John F Hartwig
Polyoxygenated hydrocarbons that bear one or more hydroxyl groups comprise a large set of natural and synthetic compounds, often with potent biological activity. In synthetic chemistry, alcohols are important precursors to carbonyl groups, which then can be converted into a wide range of oxygen- or nitrogen-based functionality. Therefore, the selective conversion of a single hydroxyl group in natural products into a ketone would enable the selective introduction of unnatural functionality. However, the methods known to convert a simple alcohol, or even an alcohol in a molecule that contains multiple protected functional groups, are not suitable for selective reactions of complex polyol structures...
December 2017: Nature Chemistry
https://www.readbyqxmd.com/read/29167789/radical-sam-enzymes-in-the-biosynthesis-of-ribosomally-synthesized-and-post-translationally-modified-peptides-ripps
#15
REVIEW
Alhosna Benjdia, Clémence Balty, Olivier Berteau
Ribosomally-synthesized and post-translationally modified peptides (RiPPs) are a large and diverse family of natural products. They possess interesting biological properties such as antibiotic or anticancer activities, making them attractive for therapeutic applications. In contrast to polyketides and non-ribosomal peptides, RiPPs derive from ribosomal peptides and are post-translationally modified by diverse enzyme families. Among them, the emerging superfamily of radical SAM enzymes has been shown to play a major role...
2017: Frontiers in Chemistry
https://www.readbyqxmd.com/read/29164866/electrochemical-analysis-of-enzyme-based-on-the-self-assembly-of-lipid-bilayer-on-an-electrode-surface-mediated-by-hydrazone-chemistry
#16
Juan Zhang, Xiaonan Wang, Tingjun Chen, Chang Feng, Genxi Li
In this work, a new strategy for electrochemical analysis of enzyme has been proposed based on a self-assembled lipid bilayer on an electrode surface mediated by hydrazone chemistry. Taking aldolase as an example, the enzyme can catalyze the formation of products containing carbonyl groups. These groups can react with hydrazine groups of the functional lipid derivative, resulting in the self-assembly of lipid bilayer on a guanidinium modified electrode surface. The lipid bilayer will then prevent the movement of hydrophilic electrochemical probes...
November 22, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29161811/coordination-structure-and-fragmentation-chemistry-of-the-tripositive-lanthanide-thio-diglycolamide-complexes
#17
Xiuting Chen, Qingnuan Li, Yu Gong
Tripositive Ln(TMTDA)33+ complexes (Ln = La-Lu except Pm, TMTDA= tetramethyl 3-thio-diglycolamide) were observed in the gas phase by electrospray ionization (ESI) of LnCl3 and TMTDA mixtures. Collision induced dissociation (CID) was employed to investigate their fragmentation chemistry, which revealed the influence of metal center as well as ligand on the ligated complexes. Ln(TMTDA)2(TMTDA-45)3+ resulting from Ccarbonyl-N bond cleavage of TMTDA and hydrogen transfer was the major CID product for all Ln(TMTDA)33+ except Eu(TMTDA)33+ which predominantly formed charge reducing product EuII(TMTDA)22+ via electron transfer from TMTDA to Eu3+...
November 22, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29161031/computational-exploration-of-concerted-and-zwitterionic-mechanisms-of-diels-alder-reactions-between-1-2-3-triazines-and-enamines-and-acceleration-by-hydrogen-bonding-solvents
#18
Yun-Fang Yang, Peiyuan Yu, Kendall N Houk
The mechanisms of Diels-Alder reactions between 1,2,3-triazines and enamines have been explored with density functional theory computations. The focus of this work is on the origins of the different reactivities and mechanisms induced by substituents and by hexafluoroisopropanol (HFIP) solvent. These inverse electron-demand Diels-Alder reactions of triazines have wide applications in bioorthogonal chemistry and natural product synthesis. Both concerted and stepwise cycloadditions are predicted, depending on the nature of substituents and solvents...
November 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29158402/structural-insights-into-enzymatic-4-2-aza-cycloaddition-in-thiopeptide-antibiotic-biosynthesis
#19
Dillon P Cogan, Graham A Hudson, Zhengan Zhang, Taras V Pogorelov, Wilfred A van der Donk, Douglas A Mitchell, Satish K Nair
The [4+2] cycloaddition reaction is an enabling transformation in modern synthetic organic chemistry, but there are only limited examples of dedicated natural enzymes that can catalyze this transformation. Thiopeptides (or more formally thiazolyl peptides) are a class of thiazole-containing, highly modified, macrocyclic secondary metabolites made from ribosomally synthesized precursor peptides. The characteristic feature of these natural products is a six-membered nitrogenous heterocycle that is assembled via a formal [4+2] cycloaddition between two dehydroalanine (Dha) residues...
November 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29155200/recent-advances-on-polysaccharides-lipids-and-protein-based-edible-films-and-coatings-a-review
#20
REVIEW
Bilal Hassan, Shahzad Ali Shahid Chatha, Abdullah Ijaz Hussain, Khalid Mahmood Zia, Naseem Akhtar
Food is a vital product for the survival of human beings and with passage of time quality concerns of consumers are rising. Edible films and coatings are thin layers applied on food products to protect them and improve their quality. Films/coatings are prepared from naturally occurring renewable sources (polysaccharides, proteins, lipids and composites) which we can eat without disposing them. These films are environment friendly and contain antioxidants, anti-browning agents and colorants. Various methods (spraying, brushing, electro-spraying) are used to apply a coating on food material to protect them from microbial growth, prolonging their shelf life and improving other quality aspects like sensory attributes, appearance, originality and freshness of ingredients...
November 16, 2017: International Journal of Biological Macromolecules
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