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Chengwei Niu, Yuchen Sheng, Enyuan Zhu, Lili Ji, Zhengtao Wang
The rhizome of Dioscorea bulbifera Linn, traditionally used to treat thyroid disease and cancer in China, is reported to induce serious liver injury during clinical practice. Diosbulbin B (DB), a diterpene lactone, has been found to be the main toxic compound in D. bulbifera. The present study aims to investigate the protection of ferulic acid (FA) against DB-induced acute liver injury and its engaged mechanism. Mice were orally administered FA (20, 40, 80 mg/kg) once daily for 6 consecutive days; and then orally given DB (250 mg/kg) on the last day...
October 23, 2016: Bioscience Trends
Jing Qu, Shidong Deng, Li Li, Yunbao Liu, Yong Li, Shuanggang Ma, Xiaoguang Chen, Shishan Yu
Nine dimeric xanthanolides, pungiolides F-N, and five known analogues, pungiolides A-E, were isolated from fruits of Xanthium chinense. Their structures were elucidated through spectroscopic and electronic circular dichroism (ECD) analyses. Pungiolide F is a xanthanolide dimer with an acyclic linkage. Five of the dimers, pungiolides H, L, A, C and E, exhibited moderate cytotoxicities with IC50 values in the range of 0.90-6.84 μM using taxol as the positive control, which had, by comparison, IC50 values in the range of 0...
October 20, 2016: Phytochemistry
Dimitry A Chistiakov, Alexandra A Melnichenko, Alexander N Orekhov, Yuri V Bobryshev
In humans, three paraoxonase (PON1, PON2, and PON3) genes are clustered on chromosome 7 at a locus that spans a distance around 170 kb. These genes are highly homologous to each other and have a similar protein structural organization. PON2 is the intracellular enzyme, which is expressed in many tissues and organs, while two other members of PON gene family are produced by liver and associate with high density lipoprotein (HDL). The lactonase activity is the ancestral. Besides lactones and organic phosphates, PONs can hydrolyze and therefore detoxify oxidized low density lipoprotein and homocysteine thiolactone, i...
October 19, 2016: Biochimie
Michael Grigalunas, Olaf Wiest, Paul Helquist
Trisubstituted α-pyrones are obtained by a Pd-catalyzed three-component, single-flask operation via an α-arylation, subsequent α-alkenylation, alkene isomerization, and dienolate lactonization. A variety of coupling components under mild conditions afforded isolated yields of up to 93% of the pyrones with complete control of regioselectivity. Metal dependence was noted for three of the steps of the pathway. Utility of the pyrone products was demonstrated by further transformations providing convenient access to polyaromatic compounds, exhibiting broad molecular diversity...
October 21, 2016: Organic Letters
Xiangyi Zhang, Gavin O Jones, James L Hedrick, Robert M Waymouth
Ring-opening polymerization of lactones is a versatile approach to generate well-defined functional polyesters. Typical ring-opening catalysts are subject to a trade-off between rate and selectivity. Here we describe an effective catalytic system combining alkoxides with thioureas that catalyses rapid and selective ring-opening polymerizations. Deprotonation of thioureas by sodium, potassium or imidazolium alkoxides generates a hydrogen-bonded alcohol adduct of the thiourea anion (thioimidate). The ring-opening polymerization of L-lactide mediated by these alcohol-bonded thioimidates yields highly isotactic polylactide with fast kinetics and living polymerization behaviour, as evidenced by narrow molecular weight distributions (Mw/Mn < 1...
November 2016: Nature Chemistry
James M Cash, Mathew R Heal, Ben Langford, Julia Drewer
The atmospheric reactions leading to the generation of secondary organic aerosol (SOA) from the oxidation of isoprene are generally assumed to produce only racemic mixtures, but aspects of the chemical reactions suggest this may not be the case. In this review, the stereochemical outcomes of published isoprene-degradation mechanisms contributing to high amounts of SOA are evaluated. Despite evidence suggesting isoprene first-generation oxidation products do not contribute to SOA directly, this review suggests the stereochemistry of first-generation products may be important because their stereochemical configurations may be retained through to the second-generation products which form SOA...
October 20, 2016: Environmental Science. Processes & Impacts
Sheng-Yang Hsia, Yu-Hsuan Hsiao, Wen-Tai Li, Jung-Feng Hsieh
This study investigated the glucono-δ-lactone (GDL)-induced aggregation of isoflavones and soy proteins in soymilk. High-performance liquid chromatography (HPLC) analysis indicated that isoflavones mixed with β-conglycinin (7S) and glycinin (11S) proteins formed 7S-isoflavone and 11S-isoflavone complexes in soymilk supernatant fraction (SSF). Most of the soy protein-isoflavone complexes then precipitated into the soymilk pellet fraction (SPF) following the addition of 4 mM GDL, whereupon the pH value of the soymilk dropped from 6...
October 20, 2016: Scientific Reports
Nathan Line, Aaron Burns, Sean Butler, Jerry Cashbolm, Craig J Forsyth
Salvinorin A (1) is natural product that in humans is a hallucinogen which binds the human κ-opioid receptor. A total synthesis has been developed that parlays L-(+)-tartaric acid into that of (-)-1 via an unprecedented allylic dithiane intramolecular Diels-Alder reaction to obtain the trans-decalin scaffold. Tsuji allylation set the C9 quaternary center and a late-stage stereoselective chiral ligand-assisted addition of a 3-titanium furan upon a C12 aldehyde / C17 methyl ester established the furanyl lactone moiety...
October 18, 2016: Chemistry: a European Journal
You Jin Jang, Moon Jung Back, Zhicheng Fu, Joo Hyun Lee, Jong Hoon Won, Hae Chan Ha, Hae Kyung Lee, Ji Min Jang, Jong Min Choi, Dae Kyong Kim
Acute lung injury (ALI) is a respiratory failure disease and the major source of mortality in the critically ill patients. The main pathological changes involved in ALI include the excessive recruitment and activation of neutrophils by increased pro-inflammatory mediators. However, any specific therapy for ALI has not been developed. The objective of this study was to investigate protective effects of parthenolide, a sesquiterpene lactone produced in feverfew, on LPS-induced lung injury. In the present study, parthenolide treatment reduced infiltration of inflammatory cells, airway permeability and production of pro-inflammatory cytokines in LPS-induced ALI mouse model...
October 18, 2016: Archives of Pharmacal Research
Andrés Corral Lugo, Abdelali Daddaoua, Alvaro Ortega, Bertrand Morel, Ana Isabel Díez Peña, Manuel Espinosa-Urgel, Tino Krell
Quorum sensing systems are essential for bacterial communication. We report here the purification and characterization of the Pseudomonas aeruginosa LasR quorum sensing regulator purified from lysates of E. coli cultures grown in the absence of added acyl-homoserine lactones (AHL). We show by isothermal titration calorimetry that LasR recognizes different AHLs with an affinity of approximately 1 μM. The affinity of LasR for its cognate 3-Oxo-C12-AHL was similar to that of other AHLs, indicating that this regulator has not evolved to preferentially recognize its cognate AHL...
October 15, 2016: Protein Expression and Purification
Darja Kušar, Karin Šrimpf, Petra Isaković, Lina Kalšek, Javid Hosseini, Irena Zdovc, Tina Kotnik, Modest Vengušt, Gabrijela Tavčar-Kalcher
BACKGROUND: Bacterial intercellular communication, called quorum sensing, takes place via the production and collective response to signal molecules. In Gram-negative bacteria, like Pseudomonas aeruginosa, these signaling molecules are N-acylhomoserine lactones (AHLs). P. aeruginosa is a common cause of inflammation of the ear canal (otitis externa) in dogs. It employs quorum sensing to coordinate the expression of host tissue-damaging factors, which are largely responsible for its virulence...
October 18, 2016: BMC Veterinary Research
Feifei Cheng, Anzhou Ma, Guoqiang Zhuang, Rupert G Fray
In order to cope with pathogens, plants have evolved sophisticated mechanisms to sense pathogenic attacks and to induce defence responses. The N-acyl-homoserine lactone (AHL)-mediated quorum sensing in bacteria regulates diverse physiological processes including those involved in pathogenicity. In this work, we study the interactions between AHL-producing transgenic tobacco plants and Pseudomonas syringae pv. tabaci 11528 (P. syringae 11528). Both a reduced incidence of disease and decrease in the growth of P...
October 18, 2016: Molecular Plant Pathology
Eunchong Park, Ju Han Song, Myun Soo Kim, Su-Ho Park, Tae Sung Kim
CD4(+) T cell activation and adequate differentiation into effector T helper (Th) cells are crucial for mediating adaptive immune responses to cope with foreign pathogens. Despite the significant role of Th cells, excessive increases in their numbers result in inflammatory and autoimmune diseases. In this study, we investigated the effects of costunolide, a plant-derived natural compound with an anti-inflammatory activity, in regulating Th cells and the underlying mechanisms. Costunolide significantly decreased cell populations of differentiated Th1, Th2, and Th17 subsets under Th subset-polarizing conditions, while exerting statistically negligible effects on Treg cell differentiation...
October 15, 2016: International Immunopharmacology
Michel Fischer, Klaus Harms, Ulrich Koert
An efficient stereoselective synthetic approach to 7-20 oxa-bridged abietane type natural products is reported. Key steps are an asymmetric Mukaiyama aldol addition to construct the C3 stereocenter and an intramolecular organocatalyzed Stetter-type Michael addition followed by a Tishchenko reaction. An intramolecular lactone-enolate arylation delivers the tetracyclic skeleton. This synthetic strategy was applied for the first total synthesis of (+)-elevenol, an antihepatitis C active compound from Fluegga virosa, and the first total synthesis of (+)-przewalskin...
October 18, 2016: Organic Letters
Andrea Fiorani, Filbert Totsingan, Antonio Pollicino, Yifeng Peng, Maria Letizia Focarete, Richard A Gross, Mariastella Scandola
Oligo(Glu70 -co-Leu30 ), a peptide synthesized by protease catalysis, is functionalized at the N-terminus with a 4-pentenoyl unit and grafted to polyLSL[6'Ac,6″Ac], a glycopolymer prepared by ring-opening metathesis polymerization of lactonic sophorolipid diacetate. First, polyLSL[6'Ac,6"Ac] fiber mats are fabricated by electrospinning. Oxidation of the fiber mats and subsequent reaction with cysteamine lead to thiol-functionalized fiber mats with no significant morphology changes. Grafting of the alkene-modified oligopeptide to thiol-functionalized polyLSL[6'Ac,6″Ac] fiber mats is achieved via "thiol-ene" click reaction...
October 18, 2016: Macromolecular Bioscience
Yuan-Yuan Wang, Jun-Mian Tian, Cheng-Chen Zhang, Bo Luo, Jin-Ming Gao
Two picrotoxane sesquiterpene lactone glycosides, nepalactones A (1) and B (2), and one new coumarin, nepalarin (3), were isolated from the root barks of the poisonous plant Coriarianepalensis. Their structures were elucidated via HRESIMS and 1D and 2D NMR spectroscopic analyses, and further verified via transformation methods. In addition, compounds 1-3 and five semisynthetic congeners (1a-e) were assayed for the activity to induce neurite outgrowth in rat pheochromocytoma (PC12) cells. As a result, nepalactone A derivative 1c and nepalarin (3) significantly enhanced nerve growth factor (NGF)-mediated neurite outgrowth in PC12 cells...
October 12, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Bernd Schmidt, Felix Wolf, Christopher Ehlert
alpha-Methylene-gamma-butyrolactone and alpha-methylene-delta-valerolactone undergo Pd-catalyzed Matsuda-Heck couplings with arene diazonium salts to alpha-benzyl butenolides or pentenolides, respectively, or to alpha-benzylidene lactones. The observed regioselectivity is strongly ring size dependent, with six-membered rings giving exclusively alpha-benzyl pentenolides, whereas the fivemembered alpha-methylene lactone reacts to mixtures of regioisomers with a high proportion of E-alpha-benzylidene-gamma-butyrolactones...
October 17, 2016: Journal of Organic Chemistry
Jian-Song Li, Min-Na Du, Hui Zhang, Ji Zhang, Shao-Yong Zhang, Hai-Yan Wang, An-Liang Chen, Ji-Dong Wang, Wen-Sheng Xiang
Two new milbemycin derivatives, 27-methoxylmilbemycin α31 (1) and 27-oxomilbemycin α31 (2), were isolated from the genetically engineered strain Streptomyces bingchenggensis BCJ60. Their structures were determined by 1D NMR, 2D NMR and HR-ESI-MS spectral analysis, and comparison with previous reports. The acaricidal and nematocidal capacities of compounds 1 and 2 were evaluated against Tetranychus cinnabarinus and Bursaphelenchus xylophilus, respectively. The results showed that the two new macrocyclic lactones 1 and 2 possessed potent acaricidal and nematocidal activities...
October 16, 2016: Natural Product Research
Marion A David, Stéphane Orlowski, Roger K Prichard, Shaima Hashem, François André, Anne Lespine
Macrocyclic lactones (ML) are important anthelmintics used in animals and humans against parasite nematodes, but their therapeutic success is compromised by the spread of ML resistance. Some ABC transporters, such as p-glycoproteins (Pgps), are selected and overexpressed in ML-resistant nematodes, supporting a role for some drug efflux proteins in ML resistance. However, the role of such proteins in ML transport remains to be clarified at the molecular level. Recently, Caenorhabditis elegans Pgp-1 (Cel-Pgp-1) has been crystallized, and its drug-modulated ATPase function characterized in vitro revealed Cel-Pgp-1 as a multidrug transporter...
September 15, 2016: International Journal for Parasitology, Drugs and Drug Resistance
Andrew G Palmer, Arijit Mukherjee, Danielle M Stacy, Stephen Lazar, Jean-Michel Ané, Helen E Blackwell
Density-dependent phenotypic switching in bacteria, the phenomenon of quorum sensing (QS), is instrumental in many pathogenic and mutualistic behaviors. In many Gram-negative bacteria, QS is regulated by N-acylated-l-homoserine lactones (AHLs). Synthetic analogues of these AHLs hold significant promise for regulating QS at the host-symbiont interface. Regulation depends on refined temporal and spatial models of quorums under native conditions. Critical to this is an understanding of how the presence of these signals may affect a prospective host...
October 14, 2016: Chembiochem: a European Journal of Chemical Biology
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