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https://www.readbyqxmd.com/read/28644909/a-highly-efficient-synthesis-of-z-macrocycles-using-stereoretentive-ruthenium-based-metathesis-catalysts
#1
Tonia Sarah Ahmed, Robert H Grubbs
A highly efficient, Z-selective ring-closing metathesis system for the formation of macrocycles using a stereoretentive, ruthenium-based catalyst supported by a dithiolate ligand is reported. This catalyst is demonstrated to be remarkably active as observed in initiation experiments showing complete catalyst initiation at -20 °C within 10 min. Macrocyclization reactions generated Z-products from easily accessible diene starting materials bearing a Z-olefin moiety. This stereoretentive approach provides a more efficient and selective route to Z-macrocyles than in previously reported systems...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28643515/structures-of-degradation-products-and-degradation-pathways-of-aflatoxin-b1-by-high-voltage-atmospheric-cold-plasma-hvacp-treatment
#2
Hu Shi, Bruce R Cooper, Richard L Stroshine, Klein E Ileleji, Kevin Keener
High voltage atmospheric cold plasma (HVACP) is a novel non-thermal decontamination technology that has potential for use in the food industry. In this study, HVACP was applied to treat pure aflatoxin B1 (AFB1) powder on a glass slide. AFB1 was degraded by 76% using a 5 min HVACP treatment in air having 40% relative humidity. The degradation products of AFB1 were separated and their molecular formulas were elucidated using liquid chromatography time of flight mass spectrometry (HPLC-TOF MS). Six main degradation products were observed...
June 23, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28642777/transcriptome-analysis-of-genes-associated-with-the-artemisinin-biosynthesis-by-jasmonic-acid-treatment-under-the-light-in-artemisia-annua
#3
Xiaolong Hao, Yijun Zhong, Xueqing Fu, Zongyou Lv, Qian Shen, Tingxiang Yan, Pu Shi, Yanan Ma, Minghui Chen, Xueying Lv, Zhangkuanyu Wu, Jingya Zhao, Xiaofen Sun, Ling Li, Kexuan Tang
Artemisinin is a sesquiterpene lactone endoperoxide extracted from a traditional Chinese medicinal plant Artemisia annua. Artemisinin-based combination therapies (ACTs) are recommended as the best treatment of malaria by the World Health Organization (WHO). Both the phytohormone jasmonic acid (JA) and light promote artemisinin biosynthesis in A. annua. Interestingly, we found that the increase of artemisinin biosynthesis by JA was dependent on light. However, the relationship between the two signal pathways mediated by JA and light remains unclear...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28642632/mcl-plays-an-anti-inflammatory-role-in-mycobacterium-tuberculosis-induced-immune-response-by-inhibiting-nf-%C3%AE%C2%BAb-and-nlrp3-inflammasome-activation
#4
Qingwen Zhang, Xinru Jiang, Weigang He, Kailin Wei, Jinxia Sun, Xiangyang Qin, Yuejuan Zheng, Xin Jiang
Mycobacterium tuberculosis (Mtb) remains a significant menace to global health as it induces granulomatous lung lesions and systemic inflammatory responses during active tuberculosis (TB). Micheliolide (MCL), a sesquiterpene lactone, was recently reported to have a function of relieving LPS-induced inflammatory response, but the regulative role of MCL on the immunopathology of TB still remains unknown. In this experiment, we examined the inhibitory effect of MCL on Mtb-induced inflammatory response in mouse macrophage-like cell line Raw264...
2017: Mediators of Inflammation
https://www.readbyqxmd.com/read/28641489/screening-of-several-biological-activities-induced-by-different-sesquiterpene-lactones-isolated-from-centaurea-behen-l-and-rhaponticum-repens-l-hidalgo
#5
Abolfazl Shakeri, Elaheh Amini, Javad Asili, Milena Masullo, Sonia Piacente, Mehrdad Iranshahi
This study aims to evaluate the in vitro cytotoxic, in vitro and in ovo anti-angiogenic effects and antimicrobial activity of sesquiterpene lactones (SLs) from two plants Centaurea behen and Rhaponticum repens (L.). Five SLs, including cynaropicrin (1), 4β,15-dehydro-3-dehydrosolstitialin A (2), aguerin B (3), janerin (4), cebellin E (5), and a flavone hispidulin (6) were isolated from C. behen (compounds 1-3) and R. repens (compounds 4-6). Cynaropicrin (1) and aguerin B (3) were characterised by strong cytotoxic activities against A2780 cells with IC50 values of 1...
June 23, 2017: Natural Product Research
https://www.readbyqxmd.com/read/28638458/anti-metastatic-effect-of-semi-purified-nuphar-lutea-leaf-extracts
#6
Janet Ozer, Daniel Fishman, Brit Eilam, Avi Golan-Goldhirsh, Jacob Gopas
Nuphar lutea L. SM., leaf and rhizome extracts (NUP), contain nupharidines as active components. Nupharidines belong to the sesquiterpene lactones class of a naturally occurring plant terpenoids. This family of compounds has gained considerable interest for treating infection, inflammation and cancer. NF-κB is a central, downstream regulator of inflammation, cell proliferation and apoptosis. In our previous work we demonstrated strong inhibition of NF-κB activity and induction of apoptosis by NUP. In addition, NUP exhibited anti-inflammatory properties and partial protection from LPS-induced septic shock by modulating ERK pathway and cytokine secretion in macrophages...
2017: Journal of Cancer
https://www.readbyqxmd.com/read/28636402/a-chiral-pentenolide-based-unified-strategy-toward-dihydrocorynantheal-dihydrocorynantheol-protoemetine-protoemetinol-and-yohimbane
#7
Changmin Xie, Jisheng Luo, Yan Zhang, Lili Zhu, Ran Hong
An organocatalytic cross-aldol reaction of formaldehyde (formalin) with alkyl aldehydes, followed by the Z-selective Horner-Wadsworth-Emmons (HWE) reaction and immediate lactonization, afforded γ-alkylated pentenolides in good overall yields and excellent enantioselectivities. Based on this scalable sequence, five quinolizidine alkaloids were synthesized in a unified and concise manner. The development of an in situ activation of a tertiary amide to improve the efficiency of the Bischler-Napieraiski (B-N) reaction was also noteworthy due to the generality to sensitive substrates for a variety of target molecules...
June 21, 2017: Organic Letters
https://www.readbyqxmd.com/read/28636373/total-synthesis-of-the-marine-polyketide-gracilioether-f
#8
Ritabrata Datta, Subrata Ghosh
First asymmetric synthesis of the marine natural product (-)-gracilioether F is described from a D-mannitol derived known compound. The key step involves intramolecular 1, 4-conjugate addition of a hydroxymethyl radical generated from Ti (III) mediated ring opening of a terminal epoxy ring tethered to a butenolide to produce stereoselectively a five-membered ring fused bicyclic lactone, the core structure present in gracilioether F.
June 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28636136/capillary-zone-electrophorsis-for-the-analysis-of-naturally-occurring-2-hydroxycitric-acids-and-their-lactones
#9
B L Abhijith, Moolya Mohan, David Joseph, Simimole Haleema, Hassan Y Aboul-Enein, Ibrahim Ibnusaud
A simple capillary zone electrophoresis method with direct ultraviolet detection has been developed for the analysis of naturally occurring diastereomeric 2-hydroxycitric acid lactones. Using 50 mM sodium phosphate buffer of pH 7, a baseline resolution Rs > 3.0 was observed for all organic acids selected for the present study. This method was employed for the quantitative determination of title acids present in the plant sources namely G. cambogia fruit rinds and H. sabdariffa calyx. Conversion of 2-hydroxycitric acids to their lactones on heating above plant sources is deliberated...
June 21, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28635648/deoxyelephantopin-and-isodeoxyelephantopin-as-potential-anticancer-agents-with-effects-on-multiple-signaling-pathways
#10
REVIEW
Tahir Mehmood, Amara Maryam, Hamed A Ghramh, Muhammad Khan, Tonghui Ma
Cancer is the 2nd leading cause of death worldwide. The development of drugs to target only one specific signaling pathway has limited therapeutic success. Developing chemotherapeutics to target multiple signaling pathways has emerged as a new prototype for cancer treatment. Deoxyelephantopin (DET) and isodeoxyelephantopin (IDET) are sesquiterpene lactone components of "Elephantopus scaber and Elephantopus carolinianus", traditional Chinese medicinal herbs that have long been used as folk medicines to treat liver diseases, diabetes, diuresis, bronchitis, fever, diarrhea, dysentery, cancer, and inflammation...
June 21, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28633201/rapid-start-up-of-denitrifying-granular-sludge-by-dosing-with-semi-starvation-fluctuation-c-n-ratio-strategy
#11
Wenyu Niu, Jianbo Guo, Jing Lian, Yuanyuan Song, Caicai Lu, Haibo Li, Yi Han, Pengna Yin
This study cultivated denitrifying granular sludge in three UASB reactors by the semi-starvation fluctuation C/N ratio strategy (reactor 1 (R1): constant C/N ratio; R2: regular fluctuation C/N ratio; and R3: semi-starvation fluctuation C/N ratio (SSF)). Microbial aggregates appeared in R1, R2 and R3 on days 28, 14 and 6, respectively. Compared with the results in R1 and R2, the guanosine tetraphosphate (ppGpp) concentration was highest, the acyl homoserine lactones (AHLs) concentration quickly reached a certain threshold, and more protein (PN) of extracellular polymeric substances (EPS) secretion resulted in the rapid formation of denitrifying granular sludge in R3...
June 1, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28632154/synthesis-and-biodegradation-of-poly-l-lactide-co-%C3%AE-propiolactone
#12
Yuushou Nakayama, Kazuki Aihara, Zhengguo Cai, Takeshi Shiono, Chikara Tsutsumi
Although the copolymerizations of l-lactide (LA) with seven- or six-membered ring lactones have been extensively studied, the copolymerizations of LA with four-membered ring lactones have scarcely been reported. In this work, we studied the copolymerization of LA with β-propiolactone (PL) and the properties of the obtained copolymers. The copolymerization of LA with PL was carried out using trifluoromethanesulfonic acid as a catalyst and methanol as an initiator to produce poly(LA-co-PL) with Mn of ~50,000 and PL-content of 6-67 mol %...
June 20, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28630071/albumin-inhibits-pseudomonas-aeruginosa-quorum-sensing-and-alters-polymicrobial-interactions
#13
Allie Clinton Smith, Anne Rice, Bryan Sutton, Rebecca Gabrilska, Aimee K Wessel, Marvin Whiteley, Kendra P Rumbaugh
Polymicrobial interactions are complex and can influence the course of an infection, as is the case when two or more species exhibit a synergism that produces a disease state not seen with any of the individual species alone. Cell-to-cell signaling is key to many of these interactions, but little is understood about how the host environment influences polymicrobial interactions or signaling between bacteria. Chronic wounds are typically polymicrobial, with Staphylococcus aureus and Pseudomonas aeruginosa being the two most commonly isolated species...
June 19, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28629536/two-new-diterpenoid-lactones-isolated-from-andrographis-paniculata
#14
Gui-Yang Wang, Ting Wen, Fei-Fei Liu, Hai-Yan Tian, Fan Chun-Lin, Xiao-Jun Huang, Wen-Cai Ye, Ying Wang
In the present study, two new diterpenoid lactones, 3-deoxy-andrographoside (1) and 14-deoxy-15-methoxy-andrographolide (2), were isolated from the aerial parts of Andrographis paniculata. Their structures were elucidated by combination of NMR, MS, and chemical methods. The configurations of 1 and 2 were established based on the analysis of ROESY data and single crystal X-ray diffraction experiment.
June 2017: Chinese Journal of Natural Medicines
https://www.readbyqxmd.com/read/28628730/comparative-study-on-ambient-ionization-methods-for-direct-analysis-of-navel-orange-tissues-by-mass-spectrometry
#15
H Zhang, A Bibi, H Lu, J Han, H Chen
It is of sustainable interest to improve the sensitivity and selectivity of the ionization process, especially for direct analysis of complex samples without matrix separation. Herein, four ambient ionization methods including desorption atmospheric pressure chemical ionization (DAPCI), heat-assisted desorption atmospheric pressure chemical ionization (heat-assisted DAPCI), microwave plasma torch (MPT), and internal extractive electrospray ionization (iEESI) were employed for comparative analysis of the navel orange tissue samples by mass spectrometry...
June 19, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28627870/encapsulation-of-autoinducer-sensing-reporter-bacteria-in-reinforced-alginate-based-microbeads
#16
Ping Li, Mareike Müller, Matthew Wook Chang, Martin Frettlöh, Holger Schönherr
Quorum sensing, in which bacteria communities use signaling molecules for inter- and intracellular communication, has been intensively studied in recent decades. In order to fabricate highly sensitive easy-to-handle point of care biosensors that detect quorum sensing molecules, we have developed, as is reported here, reporter bacteria entrapped alginate-methacrylate (alginate-MA) hydrogel beads. The alginate-MA beads, which were obtained by electrostatic extrusion, were reinforced by photo-crosslinking to increase stability and thereby to reduce bacteria leaching...
June 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28627762/quantitative-nmr-approach-to-optimize-the-formation-of-chemical-building-blocks-from-abundant-carbohydrates
#17
Sebastian Meier, Samuel Elliot, Søren Tolborg, Irantzu Sadaba Zubiri, Esben Taarning
The future role of biomass-derived chemicals relies on the formation of diverse functional monomers in high yields from carbohydrates. Recently, it has become clear that a series of α-hydroxy acids, esters and lactones can be formed from carbohydrates in alcohols and water using tin-containing catalysts such as Sn-Beta. These compounds are potential building blocks for polyesters with additional olefin and alcohol functionalities. We employ an NMR approach to identify, quantify and optimize the formation these building blocks in the chemocatalytic transformation of abundant carbohydrates by Sn-Beta...
June 19, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28624619/quorum-sensing-signals-enhance-the-electrochemical-activity-and-energy-recovery-of-mixed-culture-electroactive-biofilms
#18
Shanshan Chen, Xianyue Jing, Jiahuan Tang, Yanlun Fang, Shungui Zhou
The impacts of exogenous or endogenous quorum sensing (QS) signaling molecules on mixed-culture electroactive biofilms (EABs), especially extracellular polymeric substances (EPS) and exoelectrogens using direct electron transfer mechanism inside EABs are poorly understood. This research focuses on the influence of acylhomoserine lactones (AHLs), the most common QS signaling molecules for gram negative bacteria, on mixed-culture EABs. Results indicated that both exogenous and endogenous AHLs played the role as regulators to improve the electrochemical activities of EABs...
June 13, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28622119/caffeine-adsorption-of-montmorillonite-in-coffee-extracts
#19
Takashi Shiono, Kenichiro Yamamoto, Yuko Yotsumoto, Aruto Yoshida
The growth in health-conscious consumers continues to drive the demand for a wide variety of decaffeinated beverages. We previously developed a new technology using montmorillonite (MMT) in selective decaffeination of tea extract. This study evaluated and compared decaffeination of coffee extract using MMT and activated carbon (AC). MMT adsorbed caffeine without significant adsorption of caffeoylquinic acids (CQAs), feruloylquinic acids (FQAs), dicaffeoylquinic acids (di-CQAs), or caffeoylquinic lactones (CQLs)...
June 16, 2017: Bioscience, Biotechnology, and Biochemistry
https://www.readbyqxmd.com/read/28621138/divergent-synthesis-of-solanidine-and-22-epi-solanidine
#20
Ling-Li Hou, Yong Shi, Zhi-Dan Zhang, Jing-Jing Wu, Qing-Xiong Yang, Wei-Sheng Tian
A divergent synthesis of solanidine and 22-epi-solanidine, two 25S natural steroidal alkaloids, from 25R-configured diosgenin acetate, is described. Initially, solanidine was synthesized through a series of transformations including a cascade ring-switching process of furostan-26-acid, an epimerization of C25 controlled by the conformation of six-membered lactone ring, an intramolecular Schmidt reaction, and an imine reduction/intramolecular aminolysis process. To address the epimerization issue during Schmidt reaction, an improved synthesis was developed, which also led to a synthesis of 22-epi-solanidine...
June 16, 2017: Journal of Organic Chemistry
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