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Natural product chemistry

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https://www.readbyqxmd.com/read/29053243/identification-of-the-biosynthetic-pathway-for-the-antibiotic-bicyclomycin
#1
Jon Patteson, Wenlong Cai, Rachel A Johnson, Kevin Santa Maria, Bo Li
Diketopiperazines (DKPs) are a large group of natural products with diverse structures and biological activities. Bicyclomycin is a broad-spectrum DKP antibiotic with unique structure and function: it contains a highly oxidized bicyclic [4.2.2] ring and is the only known selective inhibitor of the bacterial transcription termination factor, Rho. Here, we identify the biosynthetic gene cluster for bicyclomycin containing six iron-dependent oxidases. We demonstrate that the DKP core is made by a tRNA-dependent cyclodipeptide synthase, and hydroxylations on two unactivated sp3 carbons are performed by two mononuclear iron, α-ketoglutarate-dependent hydroxylases...
October 20, 2017: Biochemistry
https://www.readbyqxmd.com/read/29053214/herbicide-discovery-in-light-of-rapidly-spreading-resistance-and-ever-increasing-regulatory-hurdles
#2
Bodo Peters, Harry J Strek
According to the UN the global population is expected to grow to almost 10 billion people in 2050. This means that the demand for food, feed and fiber will double while at the same time agriculture is being challenged by a scarcity of water, global warming, less land available for farming, protection of natural habitats, demand for biodiversity on farms and other factors. In addition crop protection products are under pressure from rapidly spreading resistance and increasing regulatory requirements. Many regulatory bodies are also moving away from a risk assessment approach to a more hazard-based approach to grant registrations...
October 20, 2017: Pest Management Science
https://www.readbyqxmd.com/read/29052423/streamlined-total-synthesis-of-trioxacarcins-and-its-application-to-the-design-synthesis-and-biological-evaluation-of-analogues-thereof-discovery-of-simpler-designed-and-potent-trioxacarcin-analogues
#3
K C Nicolaou, Pengxi Chen, Shugao Zhu, Quan Cai, Rohan D Erande, Ruofan Li, Hongbao Sun, Kiran Kumar Pulukuri, Stephan Rigol, Monette Aujay, Joseph Sandoval, Julia Gavrilyuk
A streamlined total synthesis of the naturally occurring antitumor agents trioxacarcins is described, along with its application to the construction of a series of designed analogues of these complex natural products. Biological evaluation of the synthesized compounds revealed a number of highly potent, and yet structurally simpler, compounds that are effective against certain cancer cell lines, including a drug-resistant line. A novel one-step synthesis of anthraquinones and chloro anthraquinones from simple ketone precursors and phenylselenyl chloride is also described...
October 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29036919/a-two-step-bioconversion-process-for-canolol-production-from-rapeseed-meal-combining-an-aspergillus-niger-feruloyl-esterase-and-the-fungus-neolentinus-lepideus
#4
Elise Odinot, Frédéric Fine, Jean-Claude Sigoillot, David Navarro, Oscar Laguna, Alexandra Bisotto, Corinne Peyronnet, Christian Ginies, Jérôme Lecomte, Craig B Faulds, Anne Lomascolo
Rapeseed meal is a cheap and abundant raw material, particularly rich in phenolic compounds of biotechnological interest. In this study, we developed a two-step bioconversion process of naturally occurring sinapic acid (4-hydroxy-3,5-dimethoxycinnamic acid) from rapeseed meal into canolol by combining the complementary potentialities of two filamentous fungi, the micromycete Aspergillus niger and the basidiomycete Neolentinus lepideus. Canolol could display numerous industrial applications because of its high antioxidant, antimutagenic and anticarcinogenic properties...
October 14, 2017: Microorganisms
https://www.readbyqxmd.com/read/29035261/the-effect-of-acidification-on-the-bioavailability-and-electrochemical-lability-of-zinc-in-seawater
#5
Ja-Myung Kim, Oliver Baars, François M M Morel
A poorly studied but potentially important consequence of the CO2-induced acidification of the surface ocean is a possible change in the bioavailability of trace metals, which play a critical role in the productivity and population dynamics of marine ecosystems. We report laboratory and field experiments designed to compare quantitatively the effects of acidification on the bioavailability of Zn, a metal essential to the growth of phytoplankton and on the extent of its complexation by model and natural ligands...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29031541/how-to-boost-marine-fungal-research-a-first-step-towards-a-multidisciplinary-approach-by-combining-molecular-fungal-ecology-and-natural-products-chemistry
#6
Marlis Reich, Antje Labes
Marine fungi have attracted attention in recent years due to increased appreciation of their functional role in ecosystems and as important sources of new natural products. The concomitant development of various "omic" technologies has boosted fungal research in the fields of biodiversity, physiological ecology and natural product biosynthesis. Each of these research areas has its own research agenda, scientific language and quality standards, which have so far hindered an interdisciplinary exchange. Inter- and transdisciplinary interactions are, however, vital for: (i) a detailed understanding of the ecological role of marine fungi, (ii) unlocking their hidden potential for natural product discovery, and (iii) designing access routes for biotechnological production...
October 11, 2017: Marine Genomics
https://www.readbyqxmd.com/read/29027977/participation-of-the-halogens-in-photochemical-reactions-in-natural-and-treated-waters
#7
REVIEW
Yi Yang, Joseph J Pignatello
Halide ions are ubiquitous in natural waters and wastewaters. Halogens play an important and complex role in environmental photochemical processes and in reactions taking place during photochemical water treatment. While inert to solar wavelengths, halides can be converted into radical and non-radical reactive halogen species (RHS) by sensitized photolysis and by reactions with secondary reactive oxygen species (ROS) produced through sunlight-initiated reactions in water and atmospheric aerosols, such as hydroxyl radical, ozone, and nitrate radical...
October 13, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29024398/high-throughput-feasible-screening-tool-for-determining-enzyme-stabilities-against-organic-solvents-directly-from-crude-extracts
#8
Severin Wedde, Christian Kleusch, Daniel Bakonyi, Harald Gröger
Biotransformations in organic chemistry frequently suffer from limitations caused by low water-solubility of substrates and product inhibition. Both, usually are addressed by the addition of organic co-solvents, which often accompanies at the expense of enzyme stability. A common method for measuring enzyme stabilities is the determination of the enzyme´s melting temperature (Tm). However, today´s methods are limited to the application of purified enzymes. Herein, we describe for the first time an easy and fast (<1h) high-throughput-feasible method to determine enzyme stabilities directly from crude extracts...
October 12, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/29018267/current-landscape-and-future-prospects-of-antiviral-drugs-derived-from-microbial-products
#9
REVIEW
Naoki Takizawa, Manabu Yamasaki
Viral infections are a major global health threat. Over the last 50 years, significant efforts have been devoted to the development of antiviral drugs and great success has been achieved for some viruses. However, other virus infections, such as epidemic influenza, still spread globally and new threats continue to arise from emerging and re-emerging viruses and drug-resistant viruses. In this review, the contributions of microbial products isolated in Institute of Microbial Chemistry for antiviral research are summarized...
October 11, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/29016146/effect-of-aldehyde-and-carboxyl-functionalities-on-the-surface-chemistry-of-biomass-derived-molecules
#10
Basar Caglar, J W Niemantsverdriet, C J Weststrate
The adsorption and decomposition of acetaldehyde and acetic acid were studied on Rh(100) to gain insight into the interaction of aldehyde and carboxyl groups of biomass-derived molecules with the surface. Temperature-programmed reaction spectroscopy (TPRS) was used to monitor gaseous reaction products, whereas Reflection absorption infrared spectroscopy (RAIRS) was used to determine the nature of surface intermediates and reaction paths. The role of adsorbate interactions in oxygenate decomposition chemistry was also investigated by varying the surface coverage...
October 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28989658/efficient-syntheses-of-crinine-and-aspidospermidine-and-the-formal-synthesis-of-minfiensine-by-enantioselective-intramolecular-dearomative-cyclization
#11
Kang Du, He Yang, Pan Guo, Liang Feng, Guangqing Xu, Qinghai Zhou, Lung Wa Chung, Wenjun Tang
Polycyclic alkaloids bearing all-carbon quaternary centers possess a diversity of biological activities and are challenging targets in natural product synthesis. The development of a general and asymmetric catalytic method applicable to the efficient syntheses of a series of complex polycyclic alkaloids remains highly desirable in synthetic chemistry. Herein we describe an efficient palladium-catalyzed enantioselective dearomative cyclization which is capable of synthesizing two important classes of tricyclic nitrogen-containing skeleton, chiral dihydrophenanthridinone and dihydrocarbazolone derivatives bearing all-carbon quaternary centers, in excellent yields and enantioselectivities...
September 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28983993/synthesis-and-demonstration-of-the-biological-relevance-of-sp-3-rich-scaffolds-distantly-related-to-natural-product-frameworks
#12
Daniel J Foley, Philip G E Craven, Patrick M Collins, Richard G Doveston, Anthony Aimon, Romain Talon, Ian Churcher, Frank von Delft, Stephen P Marsden, Adam Nelson
The productive exploration of chemical space is an enduring challenge in chemical biology and medicinal chemistry. Natural products are biologically relevant, and their frameworks have facilitated chemical tool and drug discovery. A "top-down" synthetic approach is described that enabled a range of complex bridged intermediates to be converted with high step efficiency into 26 diverse sp(3) -rich scaffolds. The scaffolds have local natural product-like features, but are only distantly related to specific natural product frameworks...
October 6, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28981209/enantioselective-br%C3%A3-nsted-acid-catalysis-as-a-tool-for-the-synthesis-of-natural-products-and-pharmaceuticals
#13
Jérémy Merad, Claudia Lalli, Guillaume Bernadat, Julien Maury, Géraldine Masson
Synthesis of biologically active molecules (whether at laboratory or industrial scale) remains a highly appealing area of modern organic chemistry. Nowadays, the need to access original bioactive scaffolds goes together with the desire to improve synthetic efficiency while reducing the environmental footprint of chemical activities. Long neglected in the field of total synthesis, enantioselective organocatalysis has recently emerged as an eco-friendly and indispensable tool for the construction of relevant bioactive molecules...
October 5, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28974426/enriching-the-biological-space-of-natural-products-through-real-time-biotransformation-monitoring-the-nmr-tube-bioreactor
#14
Alexandra V Chatzikonstantinou, Maria V Chatziathanasiadou, Enrico Ravera, Marco Fragai, Giacomo Parigi, Ioannis P Gerothanassis, Claudio Luchinat, Haralambos L Stamatis, Andreas G Tzakos
BACKGROUND: Natural products offer a wide range of biological activities, but they are not easily integrated in the drug discovery pipeline, beacuse of their inherent scaffold intricacy and the associated complexity in their synthetic chemistry. Enzymes may be used to perform regioselective and stereoselective incorporation of functional groups in the natural product core, avoiding harsh reaction conditions, several protection/deprotection and purification steps. METHODS: Herein we developed a three step protocol carried out inside an NMR-tube...
September 30, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28971770/marine-natural-product-bis-indole-alkaloid-caulerpin-chemistry-and-biology
#15
Jignesh Lunagariya, Poonam Bhadja, Shenghui Zhong, Rohit Vekariya, Shihai Xu
Marine bis-indole alkaloids comprise a large and increasingly growing class of secondary metabolites, and continue to deliver a great variety of structural templates. The alkaloids derived from marine resources play a crucial role in medicinal chemistry and as chemical agents. In particular, bis-indole alkaloid caulerpin isolated from marine green algae Caulerpa and a red algae Chondria armata at various places around the world, and tested against several therapeutic areas such as anti-diabetic, antinociceptive, anti-inflammatory, anti-tumor, anti-larvicidal, anti-herpes, anti-tubercular, anti-microbial and immunostimulating activity as well as means of other chemical agents...
September 27, 2017: Mini Reviews in Medicinal Chemistry
https://www.readbyqxmd.com/read/28971198/polyethyleneimine-methylphosphonate-towards-the-design-of-a-new-class-of-macromolecular-actinide-chelating-agents-in-the-case-of-human-exposition
#16
Florian Lahrouch, Oleksandr Sofronov, Gaëlle Creff, André Rossberg, Christoph Hennig, Christophe Den Auwer, Chirstophe Di Giorgio
The use of uranium and to a minor extent plutonium as fuel for nuclear energy production or as components in military applications is under increasing public pressure. Uranium is weakly radioactive in its natural isotopy but its chemical toxicity, combined with its large scale industrial utilization, makes it a source of concern in terms of health impact for workers and possibly the general population. Plutonium is an artificial element that exhibits both chemical and radiological toxicities. So far, uranium (under its form uranyl, U(vi)) or plutonium (as Pu(iv)) decorporation or protecting strategies based on molecular design have been of limited efficiency to remove the actinide once incorporated after human exposure...
October 17, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28968091/a-boron-protecting-group-strategy-for-1-2-azaborines
#17
Andrew W Baggett, Shih-Yuan Liu
Upon reaction with either molecular oxygen or di-tert-butylperoxide in the presence of a simple copper(I) salt and an alcohol, a range of 1,2-azaborines readily exchange B-alkyl or B-aryl moieties for B-alkoxide fragments. This transformation allows alkyl and aryl groups to serve for the first time as removable protecting groups for the boron position of 1,2-azaborines during reactions that are not compatible with the easily modifiable B-alkoxide moiety. This reaction can be applied to synthesize a previously inaccessible BN isostere of ethylbenzene, a compound of interest in biomedical research...
October 11, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28967942/the-chemistry-and-biology-of-guanidine-natural-products
#18
REVIEW
Roberto G S Berlinck, Ariane F Bertonha, Mirelle Takaki, Julie P G Rodriguez
Covering: 2015 and 2016The chemistry and biology of natural guanidines isolated from microbial culture media, from marine invertebrates, as well as from terrestrial plants and animals, are reviewed. Emphasis is directed to the biosynthesis, total synthesis, ecological roles as well as on the evolution of guanidines isolated from natural sources.
October 2, 2017: Natural Product Reports
https://www.readbyqxmd.com/read/28966345/cements-in-the-21-st-century-challenges-perspectives-and-opportunities
#19
Joseph J Biernacki, Jeffrey W Bullard, Gaurav Sant, Nemkumar Banthia, Kevin Brown, Fredrik P Glasser, Scott Jones, Tyler Ley, Richard Livingston, Luc Nicoleau, Jan Olek, Florence Sanchez, Rouzbeh Shahsavari, Paul E Stutzman, Konstantine Sobolev, Tracie Prater
In a book published in 1906, Richard Meade outlined the history of portland cement up to that point(1). Since then there has been great progress in portland cement-based construction materials technologies brought about by advances in the materials science of composites and the development of chemical additives (admixtures) for applications. The resulting functionalities, together with its economy and the sheer abundance of its raw materials, have elevated ordinary portland cement (OPC) concrete to the status of most used synthetic material on Earth...
July 2017: Journal of the American Ceramic Society
https://www.readbyqxmd.com/read/28964679/reactive-indoor-air-chemistry-and-health-a-workshop-summary
#20
REVIEW
J R Wells, C Schoemaecker, N Carslaw, M S Waring, J E Ham, I Nelissen, P Wolkoff
The chemical composition of indoor air changes due to the reactive nature of the indoor environment. Historically, only the stable parent compounds were investigated due to their ease of measurement by conventional methods. Today, however, scientists can better characterize oxidation products (gas and particulate-phase) formed by indoor chemistry. An understanding of occupant exposure can be developed through the investigation of indoor oxidants, the use of derivatization techniques, atmospheric pressure detection, the development of real-time technologies, and improved complex modeling techniques...
September 23, 2017: International Journal of Hygiene and Environmental Health
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