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Natural product chemistry

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https://www.readbyqxmd.com/read/28453309/combination-of-cyclodextrin-and-ionic-liquid-in-analytical-chemistry-current-and-future-perspectives
#1
Y H Boon, M Raoov, N N M Zain, S Mohamad, H Osman
The growth in driving force and popularity of cyclodextrin (CDs) and ionic liquids (ILs) as promising materials in the field of analytical chemistry has resulted in an exponentially increase of their exploitation and production in analytical chemistry field. Cyclodextrins belong to the family of cyclic oligosaccharides composing of α-(1,4) linked glucopyranose subunits and possess a cage-like supramolecular structure. This structure enables chemical reactions to proceed between interacting ions, radical or molecules in the absence of covalent bonds...
April 28, 2017: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/28443894/taste-and-smell-in-aquatic-and-terrestrial-environments
#2
REVIEW
E Mollo, M J Garson, G Polese, P Amodeo, M T Ghiselin
Covering: up to 2017The review summarizes results up to 2017 on chemosensory cues occurring in both aquatic and terrestrial environments. The chemicals are grouped by their physicochemical properties to compare their potential mobility in the different media. In contrast to what is widely asserted in the literature, the report emphasizes that living organisms encounter and sense molecules of various degrees of solubility and volatility both on land and in aquatic environments. The picture that emerges from the review suggests a substantial revision of the traditional definitions of the chemical senses based on their spatial range, which is currently orienting the literature on chemosensory signaling, in favor of a new vision based on the natural products that are the actual mediators of the chemosensory perceptions...
April 26, 2017: Natural Product Reports
https://www.readbyqxmd.com/read/28443507/synthesis-and-biological-activity-of-unnatural-enediynes
#3
Roberto Romeo, Salvatore V Giofrè, Maria A Chiacchio
The first reports of the natural enediyne anticancer antibiotics date back to the late 1980s; since then, a great deal of interest has been devoted to the chemistry, biology and potential medical applications of this family of compounds. The biological activity of enediynes is linked to the presence of a highly unsaturated hex-1-ene- 1,5-diyne system. The thermally induced transformation of this unit into a benzene  diradical (the Bergman cycloaromatization) is the key step of the antitumor properties of such compounds: 1,4-diaryl radicals are able to abstract H-atoms from the deoxyribose backbone of DNA, thus leading to DNA strand cleavage and ultimately cell death...
April 24, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/28436674/general-dialdehyde-click-chemistry-for-amine-bioconjugation
#4
Sina Elahipanah, Paul J O'Brien, Dmitry Rogozhnikov, Muhammad N Yousaf
The development of methods for conjugating a range of molecules to primary amine functional groups has revolutionized the fields of chemistry, biology, and material science. The primary amine is a key functional group and one of the most important nucleophiles and bases used in all of synthetic chemistry. Therefore, tremendous interest in the synthesis of molecules containing primary amines and strategies to devise chemical reactions to react with primary amines has been at the core of chemical research. In particular, primary amines are a ubiquitous functional group found in biological systems as free amino acids, as key side chain lysines in proteins, and in signaling molecules and metabolites and are also present in many natural product classes...
April 24, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28436651/synthesis-of-dicarba-closo-dodecaborane-1-carboxamides
#5
Matthias S Scholz, Lukas M Wingen
Amide bond formation is one of the most important chemical reactions. In peptide and organic chemistry, the application of amide coupling reagents is a routine strategy, but surprisingly not in carborane chemistry. Thus, we now report a fast, safe, and robust protocol to couple amines to m- and p-dicarba-closo-dodecaborane-1-carboxylic acids. The procedure comprises the activation of carboxylic acid with the coupling reagent (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)(dimethylamino)morpholinocarbenium hexafluorophosphate, extraction of the product using the hydrophobic nature of the cluster, and a straightforward chromatographic purification...
April 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28425517/diels-alder-reactions-of-graphene-oxides-greatly-enhanced-chemical-reactivity-by-oxygen-containing-groups
#6
Shaobin Tang, Weihua Wu, Liangxian Liu, Zexing Cao, Xiaoxuan Wei, Zhongfang Chen
Graphene oxides (GOs) or reduced GOs (rGOs) may offer extraordinary potential for chemical functionalization of graphene due to their unique electronic and structural properties. By means of dispersion-corrected density functional theory computations, we systematically investigated the Diels-Alder (DA) chemistry of GOs. Our computations showed that the dual nature of GOs as both a diene and a dienophile is stronger than that of pristine graphene. Interestingly, the interior bonds of a graphene surface modified by oxygen-containing groups could be functionalized by maleic anhydride (MA) and 2,3-dimethoxybutadiene (DMBD) through cycloaddition reactions, and the cycloaddition products of MA and DMBD are more favorable than the non-covalent complexes between these reagents and the GO surface...
April 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28424520/decarboxylative-alkenylation
#7
Jacob T Edwards, Rohan R Merchant, Kyle S McClymont, Kyle W Knouse, Tian Qin, Lara R Malins, Benjamin Vokits, Scott A Shaw, Deng-Hui Bao, Fu-Liang Wei, Ting Zhou, Martin D Eastgate, Phil S Baran
Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or reductions, has an essential role in the manipulation of organic matter. Despite its importance, olefin synthesis still relies largely on chemistry introduced more than three decades ago, with metathesis being the most recent addition. Here we describe a simple method of accessing olefins with any substitution pattern or geometry from one of the most ubiquitous and variegated building blocks of chemistry: alkyl carboxylic acids...
April 19, 2017: Nature
https://www.readbyqxmd.com/read/28422235/a-facile-mechanochemical-route-to-a-covalently-bonded-graphitic-carbon-nitride-g-c3n4-and-fullerene-hybrid-toward-enhanced-visible-light-photocatalytic-hydrogen-production
#8
Xiang Chen, Huanlin Chen, Jian Guan, Jieming Zhen, Zijun Sun, Pingwu Du, Yalin Lu, Shangfeng Yang
Graphitic carbon nitride (g-C3N4) as an emerging two-dimensional (2D) nanomaterial has been commonly used as a metal-free photocatalyst with potential applications in visible light photocatalytic water-splitting. However, the photocatalytic activity of g-C3N4 is quite low due to its relatively large band gap and the existence of contact resistance between the nanosheets. Herein we report for the first time the facile synthesis of a covalently bonded g-C3N4/C60 hybrid via a solid-state mechanochemical route and its application in photocatalytic hydrogen production under visible light...
April 19, 2017: Nanoscale
https://www.readbyqxmd.com/read/28415050/free-radicals-and-polyphenols-the-redox-chemistry-of-neurodegenerative-diseases
#9
REVIEW
Sonia Losada-Barreiro, Carlos Bravo-Díaz
The oxidation of bioorganic materials by air and, particularly, the oxidative stress involved in the cell loss and other pathologies associated with neurodegenerative diseases (NDs) are of enormous social and economic importance. NDs generally involve free radical reactions, beginning with the formation of an initiating radical by some redox, thermal or photochemical process, causing nucleic acid, protein and lipid oxidations and the production of harmful oxidative products. Physically, persons afflicted by NDs suffer progressive loss of memory and thinking ability, mood swings, personality changes, and loss of independence...
March 29, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28411483/guidelines-for-consistent-characterisation-and-documentation-of-plant-source-materials-for-studies-in-phytochemistry-and-phytopharmacology
#10
EDITORIAL
Christian Zidorn
Plants are still by far the most important source of natural products. For higher plants as source materials identification and documentation are less challenging than for many other groups of organisms such as microorganisms or marine invertebrates. Nonetheless, many studies in natural products chemistry and phytopharmacology involving higher plants are flawed because the plant material is erroneously assigned, inaccurately documented, untraceable, or not named in accordance with the rules of nomenclature...
April 12, 2017: Phytochemistry
https://www.readbyqxmd.com/read/28408902/the-naturally-occurring-host-defense-peptide-ll-37-and-its-truncated-mimetics-ke-18-and-kr-12-have-selected-biocidal-and-antibiofilm-activities-against-candida-albicans-staphylococcus-aureus-and-escherichia-coli-in-vitro
#11
Yu Luo, Denise T F McLean, Gerard J Linden, Danny F McAuley, Ronan McMullan, Fionnuala T Lundy
Amongst the recognized classes of naturally occurring antimicrobials, human host defense peptides are an important group with an advantage (given their source) that they should be readily translatable to medicinal products. It is also plausible that truncated versions will display some of the biological activities of the parent peptide, with the benefit that they are less costly to synthesize using solid-phase chemistry. The host defense peptide, LL-37, and two truncated mimetics, KE-18 and KR-12, were tested for their inhibitory effects and antibiofilm properties against Candida albicans, Staphylococcus aureus, and Escherichia coli, microorganisms commonly implicated in biofilm-related infections such as ventilator-associated pneumonia (VAP)...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28400233/identification-of-acylation-products-in-shape-chemistry
#12
Chaoqi Lin, Salomé Poyer, Loussiné Zargarian, Jean-Yves Salpin, Philippe Fossé, Olivier Mauffret, Juan Xie
SHAPE chemistry (selective 2'-hydroxyl acylation analyzed by primer extension) has been developed to specifically target flexible nucleotides (often unpaired nucleotides) independently to their purine or pyrimidine nature for RNA secondary structure determination. However, to the best of our knowledge, the structure of 2'-O-acylation products has never been confirmed by NMR or X-ray data. We have realized the acylation reactions between cNMP and NMIA under SHAPE chemistry conditions and identified the acylation products using standard NMR spectroscopy and LC-MS/MS experiments...
April 1, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28400186/photobiosynthesis-of-stable-and-functional-silver-silver-chloride-nanoparticles-with-hydrolytic-activity-using-hyperthermophilic-%C3%AE-glucosidases-with-industrial-potential
#13
Juscemácia N Araújo, Aryane Tofanello, Viviam M da Silva, Juliana A P Sato, Fabio M Squina, Iseli L Nantes, Wanius Garcia
The β-glucosidases are important enzymes employed in a large number of processes and industrial applications, including biofuel production from biomass. Therefore, in this study, we reported for the first time the photobiosynthesis of stable and functional silver/silver chloride nanoparticles (Ag/AgCl-NPs) using two hyperthermostable bacterial β-glucosidases with industrial potential. The syntheses were straightforward and rapid processes carried out by mixing β-glucosidase and silver nitrate (in buffer 10mM Tris-HCl, pH 8) under irradiation with light (over a wavelength range of 450-600nm), therefore, compatible with the green chemistry procedure...
April 8, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28398047/isoprene-peroxy-radical-dynamics
#14
Alexander P Teng, John D Crounse, Paul O Wennberg
Approximately 500 Tg of 2-methyl-1,3-butadiene (isoprene) is emitted by deciduous trees each year. Isoprene oxidation in the atmosphere is initiated primarily by addition of hydroxyl radicals (OH) to C4 or C1 in a ratio 0.57 ± 0.03 (1σ) to produce two sets of distinct allylic radicals. Oxygen (O2) adds to these allylic radicals either δ (Z or E depending on whether the allylic radical is cis or trans) or β to the OH group forming six distinct peroxy radical isomers. Due to the enhanced stability of the allylic radical, however, these peroxy radicals lose O2 in competition with bimolecular reactions...
April 11, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28397647/can-science-feed-on-a-crisis-expectations-the-pine-institute-and-the-decline-of-the-french-resin-industry
#15
Marcin Krasnodębski
Argument While science and economy are undoubtedly interwoven, the nature of their relationship is often reduced to a positive correlation between economic and scientific prosperity. It seems that the modern scholarship focusing on "success stories" tends to neglect counterintuitive examples such as the impact of economic crises on research. We argue that economic difficulties, under certain circumstances, may also lead to the prosperous development of scientific institutions. This paper focuses on a particular organism, the Pine Institute in Bordeaux in France...
March 2017: Science in Context
https://www.readbyqxmd.com/read/28397187/synthesis-of-ureas-from-co2
#16
REVIEW
Hua Wang, Zhuo Xin, Yuehui Li
Ureas are an important class of bioactive organic compounds in organic chemistry and exist widely in natural products, agricultural pesticides, uron herbicides, pharmaceuticals. Even though urea itself has been synthesized from CO2 and ammonia for a long time, the selective and efficient synthesis of substituted ureas is still challenging due to the difficulty of dehydration processes. Efficient and economic fixation of CO2 is of great importance in solving the problems of resource shortages, environmental issues, global warming, etc...
April 2017: Topics in Current Chemistry (Journal)
https://www.readbyqxmd.com/read/28394136/synthetic-functional-thymidine-derived-polydeoxyribonucleotide-analogues-from-a-six-membered-cyclic-phosphoester
#17
Yi-Yun Timothy Tsao, Karen L Wooley
A grand challenge that crosses synthetic chemistry and biology is the scalable production of functional analogues of biomacromolecules. We have focused our attention on the use of deoxynucleoside building blocks bearing non-natural bases to develop a synthetic methodology that allows for the construction of high molecular weight deoxynucleotide polymers. Our six-membered cyclic phosphoester ring-opening polymerization strategy is demonstrated, herein, by an initial preparation of novel polyphosphoesters, comprised of butenyl-functionalized deoxyribonucleoside repeat units, connected via 3',5'-backbone linkages...
April 10, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28393452/minimization-of-the-thiolactomycin-biosynthetic-pathway-reveals-that-the-cytochrome-p450-enzyme-tlmf-is-required-for-five-membered-thiolactone-ring-formation
#18
Xiaoyu Tang, Jie Li, Bradley S Moore
Thiolactomycin (TLM) belongs to a class of rare and unique thiotetronate antibiotics inhibiting bacterial fatty acid synthesis. Although this group of natural product antibiotics was first discovered over 30 years, the study of TLM biosynthesis remains in its infancy. We recently discovered the biosynthetic gene cluster (BGC) for TLM from the marine bacterium Salinispora pacifica CNS-863. Here, we report the investigation of TLM biosynthetic logic through mutagenesis and comparative metabolic analyses. Our results reveal that only four genes (tlmF, tlmG, tlmH, and tlmI) are required for the construction of the characteristic γ-thiolactone skeleton of this class of antibiotics...
April 10, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28391863/evaluation-of-new-natural-deep-eutectic-solvents-for-the-extraction-of-isoflavones-from-soy-products
#19
Sylwia Bajkacz, Jakub Adamek
Natural deep eutectic solvents (NADESs) are considered to be new, safe solvents in green chemistry that can be widely used in many chemical processes such as extraction or synthesis. In this study, a simple extraction method based on NADES was used for the isolation of isoflavones (daidzin, genistin, genistein, daidzein) from soy products. Seventeen different NADES systems each including two or three components were tested. Multivariate data analysis revealed that NADES based on a 30% solution of choline chloride: citric acid (molar ratio of 1:1) are the most effective systems for the extraction of isoflavones from soy products...
June 1, 2017: Talanta
https://www.readbyqxmd.com/read/28391700/effect-of-water-chemistry-and-hydrodynamics-on-nitrogen-transformation-activity-and-microbial-community-functional-potential-in-hyporheic-zone-sediment-columns
#20
Yuanyuan Liu, Chongxuan Liu, William C Nelson, Liang Shi, Fen Xu, Yunde Liu, Ailan Yan, Lirong Zhong, Christopher Thompson, James K Fredrickson, John M Zachara
Hyporheic zones (HZ) are active biogeochemical regions where groundwater and surface water mix. N transformations in HZ sediments were investigated in columns with a focus on understanding how the dynamic changes in groundwater and surface water mixing affect microbial community and its biogeochemical function with respect to N transformations. The results indicated that denitrification, DNRA, and nitrification rates and products changed quickly in response to changes in water and sediment chemistry, fluid residence time, and groundwater-surface water exchange...
April 18, 2017: Environmental Science & Technology
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