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David W Shaffer, Indrani Bhowmick, Arnold L Rheingold, Charlene Tsay, Brooke N Livesay, Matthew P Shores, Jenny Y Yang
We describe the structural and electronic impacts of modifying the bridging atom in a family of Co(ii) pincer complexes with the formula Co(t-Bu)2P(E)Py(E)P(t-Bu)2Br2 (Py = pyridine, E = CH2, NH, and O for compounds 1-3, respectively). Structural characterization by single crystal X-ray diffraction indicates that compounds 1 and 3 are 5-coordinate complexes with both bromides bound to the Co(ii) ion, while compound 2 is square planar with one bromide in the outer coordination sphere. The reduction potentials of 1-3, characterized by cyclic voltammetry, are consistent with the increasing electron-withdrawing character of the pincer ligand as the linker (E) between the pyridine and phosphine arms becomes more electronegative...
October 24, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Yana K Rennie, Patrick J McIntyre, Tito Akindele, Richard Bayliss, Andrew G Jamieson
Inhibition of protein kinases using ATP-competitive compounds is an important strategy in drug discovery. In contrast, the allosteric regulation of kinases through the disruption of protein-protein interactions has not been widely adopted, despite the potential for selective targeting. Aurora-A kinase regulates mitotic entry and mitotic spindle assembly, and is a promising target for anti-cancer therapy. The microtubule-associated protein TPX2 activates Aurora-A through binding to two sites. Aurora-A recognition is mediated by two motifs within the first 43 residues of TPX2, connected by a flexible linker...
October 24, 2016: ACS Chemical Biology
Petra Břehová, Markéta Šmídková, Jan Skácel, Martin Dračínský, Helena Mertlíková-Kaiserová, Monica P Soto Velasquez, Val J Watts, Zlatko Janeba
Bordetella pertussis adenylate cyclase toxin (ACT) and Bacillus anthracis edema factor (EF) are key virulence factors with adenylate cyclase (AC) activity that substantially contribute to the pathogenesis of whooping cough and anthrax, respectively. There is an urgent need to develop potent and selective inhibitors of bacterial ACs with prospects for the development of potential antibacterial therapeutics and to study their molecular interactions with the target enzymes. Novel fluorescent 5-chloroanthraniloyl-substituted acyclic nucleoside phosphonates (Cl-ANT-ANPs) were designed and synthesized in the form of their diphosphates (Cl-ANT-ANPpp) as competitive ACT and EF inhibitors with sub-micromolar potency (IC50 values: 11-622 nm)...
October 24, 2016: ChemMedChem
Xueling Feng, Kaihuan Zhang, Peng Chen, Xiaofeng Sui, Mark A Hempenius, Bo Liedberg, G Julius Vancso
Highly swellable, dual-responsive hydrogels, consisting of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) based poly(ionic liquid)s (PILs) are formed by photo-polymerization. PFS chains bearing cross-linkable vinylimidazolium (VIm) side groups are copolymerized with NIPAM in aqueous solutions under ultraviolet light (λ = 365 nm) in the presence of a photoinitiator. The PFS-PILs serve as a macro-cross-linker and also provide redox responsiveness. The swelling ratio, morphology, and lower critical solution temperature (LCST) of the hydrogels are studied as a function of the PNIPAM/PFS ratio...
October 24, 2016: Macromolecular Rapid Communications
Huining Chai, Qingfu Wang, Tingting Liu, Zhengkun Yu
Dinuclear ruthenium(ii)-NNN pincer complexes bearing a π linker-supported bis(pyrazolyl-imidazolyl-pyridine) ligand were synthesized and structurally characterized, and they exhibited excellent catalytic activity for the transfer hydrogenation of ketones in refluxing isopropanol, reaching TOF values up to 1.3 × 10(6) h(-1). Compared with the corresponding mononuclear Ru(ii)-NNN pincer complexes, the bimetallic complexes could be applied at concentrations as low as 0.03 mol% Ru and demonstrated remarkably enhanced catalytic activity in the transfer hydrogenation reactions of ketones...
October 24, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Wen-Jing Shi, Pui-Chi Lo, Shirui Zhao, Roy C H Wong, Qiong Wang, Wing-Ping Fong, Dennis K P Ng
An efficient ferrocenyl BODIPY based dark quencher has been developed and employed to construct a FRET-based fluorescent probe that contains a biotin moiety as a potential directing ligand for cancer cells and a glutathione-cleavable disulfide linker connecting the quencher and a distyryl BODIPY fluorophore. This molecular probe is deactivated in the native form through FRET followed by intramolecular charge transfer due to the ferrocenyl unit. However, upon interaction with glutathione in phosphate buffered saline and inside cancer cells, the fluorescence emission is significantly increased due to detachment of the fluorophore from the quencher...
October 24, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Nilgun Isik Reed, You-Zhi Tang, Joel McIntosh, Yibing Wu, Kathleen S Molnar, Annafelicia Civitavecchia, Dean Sheppard, William F DeGrado, Hyunil Jo
One small molecule inhibitor of αvβ1 integrin, c8, shows antifibrotic effects in multiple in vivo mouse models. Here we synthesized c8 analogues and systematically investigate their structure-activity relationships (SAR) in αvβ1 integrin inhibition. N-Phenylsulfonyl-l-homoproline analogues of c8 maintained excellent potency against αvβ1 integrin while retaining good selectivity over other RGD integrins. In addition, 2-aminopyridine or cyclic guanidine analogues were shown to be equally potent to c8. A rigid phenyl linker increased the potency compared to c8, but the selectivity over other RGD integrins diminished...
October 13, 2016: ACS Medicinal Chemistry Letters
Larisa Kordyukova
Two enveloped virus families, Orthomyxoviridae and Paramyxoviridae, comprise a large number of dangerous pathogens that enter the host cell via fusion of their envelope with a target cell membrane at acidic or neutral pH. The Class I prototypic glycoproteins responsible for this reaction are the Influenza virus haemagglutinin (HA) protein or paramyxovirus fusion (F) protein. X-ray crystallography and cryoelectron microscopy data are available for the HA and F ectodomains in pre- and post-fusion conformations, revealing similar spiky architectures, albeit with clear differences in the details...
October 20, 2016: Virus Research
Nicola J Stagg, Ben-Quan Shen, Flavia Brunstein, Chunze Li, Amrita V Kamath, Fiona Zhong, Melissa Schutten, Bernard M Fine
Antibody drug conjugates (ADC) consist of potent cytotoxic drugs conjugated to antibodies via chemical linkers, which enables specific targeting of tumor cells while reducing systemic exposure to the cytotoxic drug and improving the therapeutic window. The valine citrulline monomethyl auristatin E (vcMMAE, conventional linker-drug) ADC platform has shown promising clinical activity in several cancers, but peripheral neuropathy (PN) is a frequent adverse event leading to treatment discontinuation and dose reduction...
October 20, 2016: Regulatory Toxicology and Pharmacology: RTP
Jianfang Li, Chunjuan Wang, Die Hu, Fengjiao Yuan, Xueqing Li, Shihan Tang, Minchen Wu
A family 27 carbohydrate-binding module of a Thermotoga maritima β-mannanase (TmCBM27) was chosen from the carbohydrate-active enzyme database by computer-aided design, possessing the lowest binding free energy with mannopentaose. To improve the enzymatic properties of a glycoside hydrolase family 5 β-mannanase from Aspergillus usamii (AuMan5A), two fusion β-mannanases, AuMan5A-F-M and AuMan5A-R-M, were designed by fusing a TmCBM27 into its C-terminus linked with a flexible peptide F (GGGGS)3 and rigid peptide R (EAAAK)3...
October 20, 2016: Journal of Bioscience and Bioengineering
Arash Asfaram, Mehrorang Ghaedi, Kheibar Dashtian
Magnetite (Fe3O4 nanoparticles (NPs)) HKUST-1 metal organic framework (MOF) composite as a support was used for surface imprinting of gallic acid imprinted polymer (HKUST-1-MOF-Fe3O4-GA-MIP) using vinyltrimethoxysilane (VTMOS) as the cross-linker. Subsequently, HKUST-1-MOF-Fe3O4-NPs-GA-MIP characterized by FT-IR, XRD and FE-SEM analysis and applied for fast and selective and sensitive ultrasound assisted dispersive magnetic solid phase microextraction of gallic acid (GA) by UV-Vis (UA-DMSPME-UV-Vis) detection method...
January 2017: Ultrasonics Sonochemistry
Konstantin Huhn, Robert Lämmer, Hanna Zimmermann, Alexandra Lämmer, Anne Waschbisch, Kathrin Utz, René Markus Gieß, Friedemann Paul, Ralf A Linker, De-Hyung Lee
BACKGROUND: Multiple Sclerosis (MS) is a chronic inflammatory disease of the CNS typically affecting younger adults and resulting in neuro-axonal degeneration already at early stages of the disease. Less is known about the effects of a later disease onset (LOMS, onset >50years of age). Analysis of retinal layers by optical coherence tomography (OCT) is a non-invasive method to investigate retinal and neuro-axonal degeneration. We applied OCT to detect differences in retinal damage depending on a later disease manifestation...
November 15, 2016: Journal of the Neurological Sciences
Pedro G Carranza, Pablo R Gargantini, César G Prucca, Alessandro Torri, Alicia Saura, Staffan Svärd, Hugo D Lujan
During evolution, parasitic microorganisms have faced the challenges of adapting to different environments to colonize a variety of hosts. Giardia lamblia, a common cause of intestinal disease, has developed fascinating strategies to adapt both outside and inside its host's intestine, such as trophozoite differentiation into cyst and the switching of its major surface antigens. How gene expression is regulated during these adaptive processes remains undefined. Giardia lacks some typical eukaryotic features, like canonical transcription factors, linker histone H1, and complex promoter regions; suggesting that post-transcriptional and translational control of gene expression is essential for parasite survival...
October 19, 2016: International Journal of Biochemistry & Cell Biology
Anastasia V Nuzhdina, Alexey S Morozov, Maria N Kopitsyna, Elena N Strukova, Daria S Shlykova, Ivan V Bessonov, Elena S Lobakova
Novel quaternized polyethyleneimine and cross-linked polyethyleneimine derivatives have been synthesized using both traditional and microwave-assisted techniques to create antimicrobial coatings, with octyl, dodecyl, or hexadecyl bromides as alkylating agent and various bifunctional electrophiles as cross-linkers. Quaternization has been performed using methyl iodide or dimethyl sulfate; it has been shown that methyl iodide has no advantages over dimethyl sulfate. Antimicrobial activity of the polymers against Gram-positive (S...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Chiaki Yoshikawa, Jun Qiu, Yoshihisa Shimizu, Chih-Feng Huang, Onko-Jan Gelling, Edith van den Bosch
Biofouling, an undesired adsorption of biological material to otherwise inert surfaces, is detrimental in medical, pharmaceutical, and other sectors. Concentrated polymer brushes (CPB) confer non-biofouling properties on modified surfaces but are cumbersome to fabricate. Here, a simple and versatile method of fabricating non-biofouling coatings for various substrates was developed using CPB-modified silica nanoparticles (SiPs). Concentrated poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) brushes were grafted on SiPs by surface-initiated atom transfer radical polymerization...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Bangrong Cai, Aimei Liao, Kyung-Ku Lee, Jae-Sam Ban, Hyun-Sam Yang, Young Jun Im, ChangJu Chun
A series of methotrexate-diosgenin conjugates was designed and synthesized to enhance the passive internalization of methotrexate (MTX) into transport-resistant cells. The inhibitory effects of these conjugates on dihydrofolate reductase (DHFR), and their anti-proliferation behaviors against a transport-resistant breast cancer cell line, MDA-MB-231, were investigated. All of the synthesized conjugates retained an ability to inhibit DHFR after the diosgenin substitution. The MTX conjugates were much more potent against methotrexate-resistant MDA-MB-231 cells than MTX...
October 19, 2016: Steroids
Hung-Yi Liu, Tanja Greene, Tsai-Yu Lin, Camron S Dawes, Murray Korc, Chien-Chi Lin
: The complex network of biochemical and biophysical cues in the pancreatic desmoplasia not only presents challenges to the fundamental understanding of tumor progression, but also hinders the development of therapeutic strategies against pancreatic cancer. Residing in the desmoplasia, pancreatic stellate cells (PSCs) are the major stromal cells affecting the growth and metastasis of pancreatic cancer cells by means of paracrine effects and extracellular matrix protein deposition. PSCs remain in a quiescent/dormant state until they are 'activated' by various environmental cues...
October 18, 2016: Acta Biomaterialia
Weidan Na, Qing Liu, Bowen Sui, Tianyu Hu, Xingguang Su
A novel and effective fluorescence strategy was developed for sensitive and selective detection of acid phosphatase (ACP). A förster resonance energy transfer (FRET) biosensor was established by attaching nile red (NR) to graphene quantum dots (GQDs) via lecithin/β-Cyclodextrin (lecithin/β-CD) complex as the linker. The introduction of lecithin/β-CD would brought GQDs-NR pair close enough through both electrostatic interaction and hydrophobic interaction, thereby making the FRET occur and thus resulting in the fluorescence quenching of GQDs (donor) and meanwhile the fluorescence enhancement of NR (acceptor)...
December 1, 2016: Talanta
Manel Moussa, Valérie Pichon, Clarisse Mariet, Thomas Vercouter, Nathalie Delaunay
Ion imprinted polymers (IIPs) specific to lanthanides were synthesized using neodymium ions (Nd(3+)) as template ions. Nd(3+) ions form binary complex ions with 5,7-dichloroquinoline-8-ol (DCQ) or vinylpyridine (VP), or ternary complex ions with both DCQ and VP in 2-methoxyethanol, before copolymerization in the presence of styrene and divinylbenzene as monomer and cross-linker, respectively. DCQ was expected to be trapped in the synthesized polymers pores. The template ion removal was then optimized. For the first time, the DCQ leakage was determined by HPLC-UV during the template removal and the sedimentation steps before solid-phase extraction (SPE) packing...
December 1, 2016: Talanta
Sandeep Pallerla, Ted Gauthier, Rushikesh Sable, Seetharama D Jois
Doxorubicin (DOX) belongs to the anthracycline class of drugs that are used in the treatment of various cancers. It has limited cystostatic effects in therapeutic doses, but higher doses can cause cardiotoxicity. In the current approach, we conjugated a peptidomimetic (Arg-aminonaphthylpropionic acid-Phe, compound 5) known to bind to HER2 protein to DOX via a glutaric anhydride linker. Antiproliferative assays suggest that the DOX-peptidomimetic conjugate has activity in the lower micromolar range. The conjugate exhibited higher toxicity in HER2-overexpressed cells than in MCF-7 and MCF-10A cells that do not overexpress HER2 protein...
October 10, 2016: European Journal of Medicinal Chemistry
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