A new flavan from the Drynaria bonii H. Christ rhizomes

In Vietnam, the medicinal plant Drynaria bonii H. Christ is used for the treatment of osteoporosis, bone fractures, and stimulate the growth of hair, treat tinnitus (Ho 2002; Loi 2004). In this article, experiments were designed to investigate the proliferation activity of ethanol, n-hexane, chloroform, ethyl acetate and methanol extracts from D. bonii rhizomes on MG-63 human osteoblast-like cells. The results showed that methanol and hexane extracts had the ability to proliferate MG-63 cells at the concentration varying from 0.1 to 0.01 μg/mL. In particular, at the concentration of 0.01 μg/mL, hexane and methanol extracts illustrated the highest proliferation ratio with 9.31% and 6.16%, respectively. By column chromatography, a new compound named drynaether A (1) and five known compounds uracil (2), 4′-hydroxy-7-methoxyflavan (3), kaempferol (4), indole-3-carboxylic acid (5) and protocatechuic acid (6) were isolated and identified from the methanol extract.     

A new dihydrofurocoumarin from the fruits of Pandanus tectorius Parkinson ex Du Roi

From the fruit of Pandanus tectorius Parkinson ex Du Roi, one new dihydrofurocoumarin, named pandanusin A (1) and 15 known compounds, including one furanocoumarin (2), two coumarins (3, 4), four lignans (5–8), one neolignan (9), two flavonoids (10, 11), three phenolics (12–14), one monoglyceride (15) and one monosaccharide (16) were isolated by various chromatography methods. Among them, compounds (3–5) were obtained from the Pandanus genus for the first time and compounds (9–14, 16) were reported from this species for the first time. Their structures were elucidated by HR–ESI–MS, NMR 1D and 2D experiments and comparison with previous reported data. The α-glucosidase inhibitory activity of all compounds was measured. The isolated compounds (1–12, 14) showed better α-glucosidase inhibitory activity (IC₅₀ = 42.2, 36.5, 84.7, 73.2, 40.8, 26.7, 76.5, 33.8, 68.1, 14.4, 22.1, 81.5, 43.8 μM, respectively) than the standard drug acarbose (IC₅₀ = 214.5 μM).     

An HPLC method with diode array detector for the simultaneous quantification of chloroquine and desethylchloroquine in plasma and whole blood samples from Plasmodium vivax patients in Vietnam,using quinine as an internal standard

A sensitive, simple method for quantification of chloroquine (CQ) and desethylchloroquine (MCQ) in whole blood and plasma from Plasmodium vivax patients has been developed using HPLC with diode array detection (DAD). Solid‐phase extraction on Isolute‐96‐CBA was employed to process 100 μL of plasma/whole blood samples. CQ, MCQ and quinine were separated using a mobile phase of phosphate buffer 25 mm , pH 2.60–acetonitrile (88:12, v/v) with 2 mm sodium perchlorate on a Zorbax SB‐CN 150 × 4.6 mm, 5 μm column at a flow rate of 1.2 mL/min, at ambient temperature in 10 min, with the DAD wavelength of 343 nm. The method was linear over the range of 10–5000 ng/mL for both CQ and MCQ in plasma and whole blood. The limit of detection was 4 ng/mL and limit of quantification was 10 ng/mL in both plasma and blood for CQ and MCQ. The intra‐, inter‐ and total assay precision were <10% for CQ and MCQ in plasma and whole blood. In plasma, the accuracies varied between 101 and 103%, whereas in whole blood, the accuracies ranged from 97.0 to 102% for CQ and MCQ. The method is an ideal technique with simple facilities and instruments, bringing about good separation in comparison with previous methods. © 2016 The Authors Biomedical Chromatography Published by John Wiley & Sons Ltd     

Magnetic “Molecular Oligomers” Based on Decametallic Supertetrahedra: A Giant Mn49 Cuboctahedron and its Mn25Na4 Fragment

Two nanosized Mn₄₉ and Mn₂₅Na₄ clusters based on analogues of the high‐spin (S=22) [Mn^III₆Mn^II₄(μ₄‐O)₄]¹⁸⁺ supertetrahedral core are reported. Mn₄₉ and Mn₂₅Na₄ complexes consist of eight and four decametallic supertetrahedral subunits, respectively, display high virtual symmetry (O_h), and are unique examples of clusters based on a large number of tightly linked high nuclearity magnetic units. The complexes also have large spin ground‐state values (Mn₄₉: S=61/2; Mn₂₅Na₄: S=51/2) with the Mn₄₉ cluster displaying single‐molecule magnet (SMM) behavior and being the second largest reported homometallic SMM.     

Binding of Chromium(III) to Transferrin Could Be Involved in Detoxification of Dietary Chromium(III) Rather than Transport of an Essential Trace Element

Cr^III binding to transferrin (Tf; the main Fe^III transport protein) has been postulated to mediate cellular uptake of Cr^III to facilitate a purported essential role for this element. Experiments using HepG2 (human hepatoma) cells, which were chosen because of high levels of the transferrin receptor, showed that Cr^III binding to vacant Fe^III‐binding sites of human Tf effectively blocks cellular Cr^III uptake. Through bio‐layer interferometry studies of the Tf cycle, it was found that both exclusion and efflux of Cr₂^IIITf from cells was caused by 1) relatively low Cr₂Tf affinity to cell‐surface Tf receptors compared to Fe₂Tf, and 2) disruption of metal release under endosomal conditions and post‐endosomal Tf dissociation from the receptor. These data support mounting evidence that Cr^III is not essential and that Tf binding is likely to be a natural protective mechanism against the toxicity and potential genotoxicity of dietary Cr through blocking Cr^III cellular accumulation.     

Primes dividing the degrees of the real characters

Let G be a finite group and let Irr(G) denote the set of all complex irreducible characters of G. The Ito–Michler Theorem asserts that if a prime p does not divide the degree of any χ Irr(G) then a Sylow p-subgroup P of G is normal in G. We prove a real-valued version of this theorem, where instead of Irr(G) we only consider the subset Irr_rv(G) consisting of all real-valued irreducible characters of G. We also prove that the character degree graph associated to Irr_rv(G) has at most 3 connected components. Similar results for the set of real conjugacy classes of G have also been obtained. Part of this paper was done while the second author visited the Mathematics Department of the Università di Firenze. He would like to thank the Department for its hospitality. The authors are also grateful to F. Lübeck for helping them with some computer calculations. The research of the first author was partially supported by MIUR research program “Teoria dei gruppi ed applicazioni”. This research of the second author was partially supported by the Spanish Ministerio de Educación y Ciencia proyecto MTM2004-06067-C02-01. The third author gratefully acknowledges the support of the NSA and the NSF.     

An Engineered OmpG Nanopore with Displayed Peptide Motifs for Single-Molecule Multiplex Protein Detection

Molecular detection via nanopore, achieved by monitoring changes in ionic current arising from analyte interaction with the sensor pore, is a promising technology for multiplex sensing development. Outer Membrane Protein G (OmpG), a monomeric porin possessing seven functionalizable loops, has been reported as an effective sensing platform for selective protein detection. Using flow cytometry to screen unfavorable constructs, we identified two OmpG nanopores with unique peptide motifs displayed in either loop 3 or 6, which also exhibited distinct analyte signals in single-channel current recordings. We exploited these motif-displaying loops concurrently to facilitate single-molecule multiplex protein detection in a mixture. We additionally report a strategy to increase sensor sensitivity via avidity motif display. These sensing schemes may be expanded to more sophisticated designs utilizing additional loops to increase multiplicity and sensitivity.     

Switchable Organocatalysis from N-heterocyclic Carbene-Carbodiimide Adducts with Tunable Release Temperature**

N-Heterocyclic carbenes (NHCs) are powerful organocatalysts, but practical applications often require in situ generation from stable precursors that “mask” the NHC reactivity via reversible binding. Previously established “masks” are often simple small molecules, such that the NHC structure is used to control both catalytic activity and activation temperature, leading to undesirable tradeoffs. Herein, we show that NHC-carbodiimide (CDI) adducts can be masked precursors for switchable organocatalysis and that the CDI substituents can control the reaction profile without changing the NHC structure. Large electronic variations on the CDI (e.g., alkyl versus aryl) drastically change the catalytically active temperature, whereas smaller perturbations (e.g., different para-substituted phenyls) tune the catalyst release within a narrower window. This control was demonstrated for three classic NHC-catalyzed reactions, each influencing the NHC-CDI equilibrium in different ways. Our results introduce a new paradigm for controlling NHC organocatalysis as well as present practical considerations for designing appropriate masks for various reactions.     

Ruthenium catalysts supported on TiO<Subscript>2</Subscript> prepared by sol–gel way for <Emphasis Type="Italic">p</Emphasis>-hydroxybenzoic acid wet air oxidation

The wet air oxidation of p-hydroxybenzoic acid, chosen as a model compound of olive mills wastewaters was carried out at 140 °C and 50 bar air over Ru catalysts supported on TiO₂ prepared by sol–gel method. These catalysts were characterized by means of N₂ adsorption–desorption, XRD and TEM. Optimization of the catalytic performances was obtained by studying some parameters such as the catalyst preparation method, the solvent evacuation way, the nature of the hydrolysis agent, the influence of the ruthenium salt used as the metal precursor (Ru(NO)(NO₃)₃ or Ru(acac)₃) and the catalyst pretreatment. The pre-calcination of the catalyst precursor at 300 °C under oxygen, before the reduction step under hydrogen, was detrimental to the activity. The results showed that the use of nitric acid as hydrolysis agent, drying under supercritical conditions and the use of Ru(NO)(NO₃)₃ leads to the more efficient catalyst with high TOC abatement.     

On The Effective Computation Of Łojasiewicz Exponents Via Newton Polyhedra

In this paper we give some conclusions on Newton non-degenerate analytic map germs on Kn (K = ? or ?), using information from their Newton polyhedra. As a consequence, we obtain the exact value of the Lojasiewicz exponent at the origin of Newton non-degenerate analytic map germs. In particular, we establish a connection between Newton non-degenerate ideals and their integral closures, thus leading to a simple proof of a result of Saia. Similar results are also considered to polynomial maps which are Newton non-degenerate at infinity.