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https://www.readbyqxmd.com/read/28821153/combination-of-microsized-mineral-particles-and-rosin-as-a-basis-for-converting-cellulosic-fibers-into-sticky-superhydrophobic-paper
#1
Xiaoyan Yu, Peiwen Bian, Yang Xue, Xueren Qian, Haipeng Yu, Wenshuai Chen, Xiaohai Hu, Peng Wang, Dong Wu, Qinghui Duan, Limei Li, Jing Shen, Yonghao Ni
The unique features of cellulosic paper including flexibility, biodegradability, and low cost enables it as a versatile, sustainable biomaterial for promising applications. In the paper industry, microsized mineral particles are widely used in the production of printing/writing paper grades, while rosin derived from trees is the earliest internal sizing agent for paper hydrophobication. On the basis of existing commercial practices associated with the use of mineral particles and rosin in paper production, we present a process concept of converting cellulosic fibers (paper-grade pulp) into "sticky" superhydrophobic paper involving the use of microsized mineral particles and rosin (a tree-derived natural product, mainly a mixture of resin acids, especially abietic acid with chemical formula of C19H29COOH)...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821110/unraveling-the-reaction-mechanism-of-silver-ions-reduction-by-chitosan-from-so-far-neglected-spectroscopic-features
#2
Ana Patrícia Carapeto, Ana Maria Ferraria, Ana Maria Botelho do Rego
Metallic silver nanoparticles were synthesized in aqueous solution using chitosan, as both reducing and stabilizing agent, and AgNO3 as silver precursor aiming the production of solid ultra-thin films. A systematic characterization of the resulting system as a function of the initial concentrations was performed. The combination of UV-vis absorption - and its quantitative analysis - with X-ray photoelectron spectra, light scattering measurements and atomic force microscopy allowed obtaining a rational picture of silver reduction mechanism through the identification of the nature of the formed reduced/oxidized species...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821095/an-o-acetyl-glucomannan-from-the-rhizomes-of-curculigo-orchioides-structural-characterization-and-anti-osteoporosis-activity-in-vitro
#3
Xueqian Wang, Mengliu Zhang, Dawei Zhang, Shumei Wang, Chunyan Yan
Osteoporosis is characterized by a reduction in bone mass and bone mineral density, which weakens the bone. Due to the side effects associated with drugs that are currently used to treat this disease, an increasing number of studies have focused on the research of effective ingredients derived from natural products. In particular, polysaccharides extracted from Chinese herbal medicines have received increasing attention. In this study, we isolated a homogeneous polysaccharide (COP90-1) from the dried rhizomes of Curculigo orchioides, a famous traditional Chinese medicine that is widely used in China, and determined its structure using the combined methods of chemical and spectral analyses...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821080/investigation-of-chitosan-s-antibacterial-activity-against-vancomycin-resistant-microorganisms-and-their-biofilms
#4
Eduardo M Costa, Sara Silva, Mariana Veiga, Sandra Vicente, Freni K Tavaria, Manuela E Pintado
Vancomycin-resistant microorganisms are a hurdle that traditional antibiotics struggle to overcome. These difficulties have led to search for new solutions based on natural products. Chitosan has been recognized as an effective antibacterial agent against a vast array of microorganisms including antibiotic resistant ones. As such, this work aimed to evaluate chitosan as an alternative to traditional antibiotics in the management/control of two vancomycin-resistant microorganisms, VRSA and VREF, in planktonic and sessile settings...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28821071/on-the-use-of-ion-crosslinked-nanocellulose-hydrogels-for-wound-healing-solutions-physicochemical-properties-and-application-oriented-biocompatibility-studies
#5
Alex Basu, Jonas Lindh, Eva Ålander, Maria Strømme, Natalia Ferraz
Calcium ion-crosslinked nanofibrillated cellulose (NFC) hydrogels were investigated as potential materials for wound healing dressings. The physicochemical properties of the hydrogels were examined by rheology and water retention tests. Skin cells and monocytes were selected for application-oriented biocompatibility studies. The NFC hydrogels presented entangled fibrous networks and solid-like behavior. Water retention tests showed the material´s potential to maintain a suitable moist environment for different type of wounds...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28820585/chemo-enzymatic-assembly-of-isotopically-labeled-folates
#6
Antonio Angelastro, William Michael Dawson, Louis Y P Luk, E Joel Loveridge, Rudolf K Allemann
Pterin-containing natural products have diverse functions in life but an efficient and easy scheme for their in vitro synthesis is not available. Here, we report a chemo-enzymatic 14-step, one-pot synthesis that can be used to generate 13C- and 15N-labeled dihydrofolates (H2F) from glucose, guanine and p-aminobenzoyl-L-glutamic acid. This synthesis stands out from previous approaches to produce H2F in that the average yield of each step is >91% and it requires only one single purification step. The use of a one-pot reaction allowed us to overcome potential problems with individual steps during the synthesis...
August 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28820583/processing-2-methyl-l-tryptophan-through-tandem-transamination-and-selective-oxygenation-initiates-indole-ring-expansion-in-the-biosynthesis-of-thiostrepton
#7
Zhi Lin, Jia Ji, Shuaixiang Zhou, Fang Zhang, Jiequn Wu, Yinlong Guo, Wen Liu
Thiostrepton (TSR), an archetypal member of the family of ribosomally synthesized and post-translationally modified thiopeptide antibiotics, possesses a biologically important quinaldic acid (QA) moiety within the side-ring system of its characteristic thiopeptide framework. QA is derived from an independent L-Trp residue; however, its associated transformation process remains poorly understood. We here report that during the formation of QA, the key expansion of an indole to a quinoline relies on the activities of the pyridoxal-5'-phosphate-dependent protein TsrA and the flavoprotein TsrE...
August 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28820534/the-ligand-effect-on-the-oxidative-addition-of-dioxygen-to-gold-i-hydride-complexes
#8
Carlo Alberto Gaggioli, Leonardo Belpassi, Francesco Tarantelli, Jeremy N Harvey, Paola Belanzoni
The ligand effect on the recently uncovered feasible oxidative addition reaction of O2 on [LAuH] complexes has been investigated for a series of fifteen ligands. The activation barriers of this spin-forbidden reaction have been estimated at the minimum energy crossing points (MECP, relativistic scalar level) between the adiabatic triplet (reactants spin state) and singlet (product spin state) potential energy surfaces (PES) and calculated at the transition states by including Spin-Orbit Coupling (SOC) effects, as applied for the mechanistic study of this reaction in a previous study by us [Chem...
August 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28820533/actinomycetes-still-a-source-of-novel-antibiotics
#9
REVIEW
Olga Genilloud
Covering: 2006 to 2017Actinomycetes have been, for decades, one of the most important sources for the discovery of new antibiotics with an important number of drugs and analogs successfully introduced in the market and still used today in clinical practice. The intensive antibacterial discovery effort that generated the large number of highly potent broad-spectrum antibiotics, has seen a dramatic decline in the large pharma industry in the last two decades resulting in a lack of new classes of antibiotics with novel mechanisms of action reaching the clinic...
August 18, 2017: Natural Product Reports
https://www.readbyqxmd.com/read/28820528/deciphering-the-photosensitization-mechanisms-of-hypericin-towards-biological-membranes
#10
Hugo Gattuso, Marco Marazzi, François Dehez, Antonio Monari
Resorting to state-of-the art molecular modeling and simulation techniques we provide full characterization of the photophysical properties of the naturally occurring hypericin chromophore, currently used in photodynamic therapy. In particular, we reveal the different photophysical pathways leading to intersystem-crossing and hence, triplet manifold population that is necessary for the subsequent production of singlet oxygen. In particular we identify an extended region of quasi-degeneracy between the first singlet excited state and three triplet state surfaces...
August 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28820497/anesthetic-agents-of-plant-origin-a-review-of-phytochemicals-with-anesthetic-activity
#11
REVIEW
Hironori Tsuchiya
The majority of currently used anesthetic agents are derived from or associated with natural products, especially plants, as evidenced by cocaine that was isolated from coca (Erythroxylum coca, Erythroxylaceae) and became a prototype of modern local anesthetics and by thymol and eugenol contained in thyme (Thymus vulgaris, Lamiaceae) and clove (Syzygium aromaticum, Myrtaceae), respectively, both of which are structurally and mechanistically similar to intravenous phenolic anesthetics. This paper reviews different classes of phytochemicals with the anesthetic activity and their characteristic molecular structures that could be lead compounds for anesthetics and anesthesia-related drugs...
August 18, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28820476/biosynthesis-of-s-adenosylmethionine-by-magnetically-immobilized-escherichia-coli-cells-highly-expressing-a-methionine-adenosyltransferase-variant
#12
Chunli Yin, Tao Zheng, Xin Chang
S-Adenosylmethionine (SAM) is a natural metabolite having important uses in the treatment of various diseases. To develop a simple and effective way to produce SAM, immobilized Escherichia coli cells highly expressing an engineered variant of methionine adenosyltransferase (MAT) were employed to synthesize SAM. The recombinant I303V MAT variant was successfully produced at approximately 900 mg/L in a 10-L bioreactor and exhibited significantly less product inhibition and had a four-fold higher specific activity (14...
August 18, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28820436/minimal-pruning-and-reduced-plant-protection-promote-predatory-mites-in-grapevine
#13
Theresa Pennington, Christian Kraus, Ekatarina Alakina, Martin H Entling, Christoph Hoffmann
Improving natural pest control by promoting high densities of predatory mites (Acari: Phytoseiidae) is an effective way to prevent damage by pest mites (e.g., Eriophyidae, Tetranychidae) and other arthropod taxa that can cause serious damage to vineyards. Here, we investigate the influence of innovative management on predatory mite densities. We compare (i) full versus reduced fungicide applications and (ii) minimal pruning versus a traditional trellis pruning system in four fungus-resistant grapevine varieties...
August 18, 2017: Insects
https://www.readbyqxmd.com/read/28820277/natural-phospholipids-occurrence-biosynthesis-separation-identification-and-beneficial-health-aspects
#14
Abdelmoneim H Ali, Xiaoqiang Zou, Sherif M Abed, Sameh A Korma, Qingzhe Jin, Xingguo Wang
During the last years, phospholipids (PLs) have attracted great attention because of their crucial roles in providing nutritional values, technological and medical applications. There are considerable proofs that PLs have unique nutritional benefits on human health, such as reducing cholesterol absorption, improving liver functions, and decreasing the risk of cardiovascular diseases. PLs are the main structural lipid components of cell and organelle membranes in all living organisms, and therefore, they occur in all organisms and the derived food products...
August 18, 2017: Critical Reviews in Food Science and Nutrition
https://www.readbyqxmd.com/read/28820264/iridium-catalyzed-enantioselective-silylation-of-unactivated-c-sp3-h-bonds
#15
Bo Su, John F Hartwig
We report highly enantioselective silylations of unactivated, primary C(sp3)-H bonds. The reactions form dihydrobenzosiloles in high yields with excellent enantioselectivities by functionalization of enantiotopic methyl groups under mild conditions. The reaction is catalyzed by an iridium complex generated from [Ir(COD)OMe]2 and chiral dinitrogen ligands that were recently developed by our group. The C-Si bonds in the enantioenriched dihydrobenzosiloles were further transformed to C-Cl, C-Br, C-I and C-O bonds in final products...
August 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28820140/clarity-of-objectives-and-working-principles-enhances-the-success-of-biomimetic-programs
#16
Jonas Wolff, David Wells, Chris Reid, Sean John Blamires
Biomimetics, the transfer of functional principles from living systems into product designs, is increasingly being utilized by engineers. Nevertheless, recurring problems must be overcome if it is to avoid becoming a short-lived fad. Here we assess the efficiency and suitability of methods typically employed by examining three flagship examples of biomimetic design approaches from different disciplines: (1) the creation of gecko-inspired adhesives; (2) the synthesis of spider silk, and (3) the derivation of computer algorithms from natural self-organizing systems...
August 18, 2017: Bioinspiration & Biomimetics
https://www.readbyqxmd.com/read/28819995/the-effect-of-different-fish-feed-compositions-on-%C3%AE-13-c-and-%C3%AE-15-n-signatures-of-sea-bass-and-its-potential-value-for-tracking-mariculture-derived-nutrients
#17
Henrik Kusche, Nicola Hillgruber, Yvonne Rößner, Ulfert Focken
Increasing demand for fish and seafood calls for an expansion of aquaculture production. At the same time, the status of the marine environment must not be jeopardised. Stable isotopes are potential markers for tracking feed-based nutrient flows from aquaculture into marine biota. Here, we demonstrate how four experimental diets (main protein components: fishmeal, soya protein concentrate, wheat gluten, and Jatropha kernel meal) and a commercial diet induce characteristic δ(13)C and δ(15)N signals in sea bass (Dicentrarchus labrax) during nine weeks of laboratory feeding under replicate conditions...
August 18, 2017: Isotopes in Environmental and Health Studies
https://www.readbyqxmd.com/read/28819971/a-radical-based-synthesis-of-lingzhiol
#18
Lea-Marina Mehl, Martin E Maier
The polycyclic natural product lingzhiol [(±)-1] was synthesized from dimethoxytetralone 8 via cyclization of an intermediate benzylic radical, generated from spiroepoxide 14, onto an alkynyl substituent generating the tetracyclic compound 13 with an exocyclic double bond. After oxidative cleavage of the double bond of 13 and reduction of the keto function of 23, the correct diastereomer 12-syn was converted to lingzhiol (1) via known steps. In a similar manner, lingzhiol analog 39 was synthesized from 5-methoxy-tetralone (27)...
August 18, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28819677/direct-analysis-of-terpenes-from-biological-buffer-systems-using-sesi-and-ir-maldesi
#19
Milad Nazari, Alexandra A Malico, Måns Ekelöf, Sean Lund, Gavin J Williams, David C Muddiman
Terpenes are the largest class of natural products with a wide range of applications including use as pharmaceuticals, fragrances, flavorings, and agricultural products. Terpenes are biosynthesized by the condensation of a variable number of isoprene units resulting in linear polyisoprene diphosphate units, which can then be cyclized by terpene synthases into a range of complex structures. While these cyclic structures have immense diversity and potential in different applications, their direct analysis in biological buffer systems requires intensive sample preparation steps such as salt cleanup, extraction with organic solvents, and chromatographic separations...
August 17, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28819559/growth-inhibitory-efficacy-of-natural-products-in-a-model-for-triple-negative-molecular-subtype-of-clinical-breast-cancer
#20
Nitin Telang
Global gene expression profiling identifies predictive and prognostic biomarkers and rationalizes breast cancer subtype-targeted treatment. The Anthracyclin/Taxol and survival pathway specific small molecular inhibitors, constitute current treatment options. These options are associated with acquired tumor resistance and emergence of drug-resistant cancer stem cells. Dietary supplements and constitutive bioactive phytochemicals with relatively low systemic toxicity may provide testable alternatives for current therapy...
September 2017: Biomedical Reports
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