Spectroscopic and electrical characterization of <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">γ</Emphasis>-bisdiphenylene-<Emphasis Type="Italic">β</Emphasis>-phenylallyl radical as an organic semiconductor

The semiconductor properties of the earliest known stable radical, α,γ-bisdiphenylene-β-phenylallyl radical (Koelsch radical, 1^?) were assessed using spectroscopic and electrical techniques. This radical undergoes reversible redox processes, and it has low redox potentials. In addition, 1^? possesses long wavelength absorption bands, owing to the existence of a singly-occupied molecular orbital whose energy level lies between those of the HOMO and LUMO. A spin-coated thin-film of 1^? displays photocurrent and an electron mobility of 6.3 × 10^?7 cm² V^?1 s^?1 on a trially-fabricated organic field effect transistor.     

Single-Step Partial Purification of Intracellular <Emphasis Type="Italic">β</Emphasis>-Galactosidase from <Emphasis Type="Italic">Kluyveromyces lactis</Emphasis> Using Microemulsion Droplets

Partial purification of β-galactosidase from the crude extract of Kluyveromyces lactis was carried out using water-in-isooctane microemulsions formed by the anionic surfactant, sodium di-ethylhexyl sulfosuccinate (Aerosol OT). In order to obtain the crude extract, yeast cells of K. lactis were disrupted by a cell disrupter and separated. The purification of β-galactosidase from the extract by a recently developed one-step reversed micellar (i.e., microemulsion-based) extraction method was then tested, by measuring total protein mass and enzyme activity in the product stream and by analyzing its composition using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography. Effects of salt concentration, protein concentration, and pH on the extraction were investigated. Using this approach, a 5.4-fold purification of β-galactosidase was achieved with 96 % total activity recovery, using a feed containing crude extract and 50 mM K-phosphate buffer (pH 7.5) and 50 mM KCl. Gel filtration chromatography showed that the single extraction was successful at removing low molecular weight impurity proteins (molecular weight (MW)?<?42 kDa) from the crude extract.     

<Emphasis Type="Italic">N</Emphasis>′-tetrazolylmethoxyl derivatives of <Emphasis Type="Italic">N</Emphasis>-methyldiazene <Emphasis Type="Italic">N</Emphasis>-oxides

A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups.     

Immobilisation of <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> α-amylase and <Emphasis Type="Italic">Aspergillus niger</Emphasis> glucoamylase enzymes as cross-linked enzyme aggregates

Cross-linked enzyme aggregates (CLEA) of Aspergillus oryzea α-amylase (AoAA) and Aspergillus niger glucoamylase (AnGA) were prepared using glutaraldehyde and dextran polyaldehyde as cross-linkers. The maximum activity recoveries for glutaraldehyde cross-linking were 21.8 % and 41.2 %, respectively. The addition of a proteic feeder (bovine serum albumin) exhibited a negative effect on the activity recoveries for both enzymes. Dextran polyaldehyde was used as a cross-linking agent instead of glutaraldehyde to reduce the activity losses. As a result, an activity recovery of 60.0 % was obtained for Aspergillus oryzea α-amylase. On the other hand, no activity recovery was observed for Aspergillus niger glucoamylase due to the latter enzyme’s affinity for dextran.     

Directed Aminomethylation of Pyrrole,Indole, and Carbazole with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-Tetramethylmethanediamine

Catalytic aminomethylation of pyrrole and indole with N,N,N′,N′-tetramethylmethanediamine in the presence of 5 mol % of ZrOCl₂·8H₂O proceeds selectively at the positions 2, 5 of pyrrole and 1, 3 of indole. Carbazole under the same conditions affords 3-formyl-9-aminomethyl derivative. The reaction in the presence of 5 mol % of K₂CO₃ occurs as monoaminomethylation: for pyrrole at the position 2, for indole at the position 3, and for carbazole at the nitrogen atom of the substrate. Water-soluble 1,1′-(1H-pyrrole-2,5-diyl)bis(N,N-dimethylmethanamine) exhibits a fungistatic activity with respect to phytopathogenic fungi Rhizoctonia solani.     

Expression of a Glucose-tolerant β-glucosidase from <Emphasis Type="Italic">Humicola grisea</Emphasis> var. <Emphasis Type="Italic">thermoidea</Emphasis> in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

A β-glucosidase gene (bgl4) from Humicola grisea var thermoidea was successfully expressed in Saccharomyces cerevisiae. The recombinant protein (BGL4 ^Sc ) was initially detected associated with yeast cells and later in the culture medium. BGL4 ^Sc showed optimal pH and temperature of 6.0 and 40 °C, respectively, and an apparent molecular mass of 57 kDa. The enzyme showed activity against cellobiose and synthetic substrates, and was inhibited more than 80% by Fe²⁺, Cu²⁺, Zn²⁺, and Al³⁺. Using p-nitrophenyl-β-d-glucopyranoside (pNPG) as substrate, BGL4 ^Sc presented a V _max of 6.72 μmol min⁻¹ mg total protein⁻¹ and a K _m of 0.16 mM under optimal conditions. Most important, BGL4 ^Sc is resistant to inhibition by glucose and the calculated K _i value for this sugar is 70 mM. This feature prompts BLG4 ^Sc as an ideal enzyme to be used in the saccharification process of lignocellulosic materials for ethanol production.     

Recognition of <Emphasis Type="Italic">R</Emphasis>- and <Emphasis Type="Italic">S</Emphasis>-Isomers of α-Alanine by Chiral Nanotubes

DFT PBE/3ζ study of relative stability of the R- and S-isomers of α-alanine in open carbon nanotubes with chirality indices (5,5), P,M-(5,1) and P,M-(5,2) has shown that the encapsulated molecule of the amino acid notably changes its geometrical and electronic characteristics. Besides, for the clusters α-alanine@nano (5,2) the most stable are practically degenerate in energy adducts S-alanine@P-(5,2) and R-alanine@М-(5,2). All this indicates the ability of chiral nanotubes to recognize encapsulated molecules of the R- and S-isomers.     

Synthesis of 20<Emphasis Type="Italic">S</Emphasis>-protopanaxadiol <Emphasis Type="Italic">β</Emphasis>-D-galactopyranosides

20S-Protopanaxadiol (3β,12β,20S-trihydroxydammar-24-ene) 3-, 12-, and 20-O-β-D-galactopyranosides were synthesized for the first time. Condensation of 12β-acetoxy-3β,20S-dihydroxydammar-24-ene (1) and 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosylbromide (α-acetobromogalactose) (2) under Koenigs–Knorr conditions with subsequent removal of the protecting groups resulted in regio- and stereoselective formation of 20S-protopanaxadiol 3-O-β-D-galactopyranoside, an analog of the natural ginsenoside Rh₂. Glycosylation of 12β,20S-dihydroxydammar-24-en-3-one (5) by 2 with subsequent treatment of the reaction products with NaBH₄ in isopropanol and deacetylation with NaOMe gave 20S-protopanaxadiol 12- and 20-O-β-Dgalactopyranosides.     

10<Emphasis Type="Italic">α</Emphasis>-Hydroxy-<Emphasis Type="Italic">β</Emphasis>-isomorphine,a by-product of the synthesis of 10<Emphasis Type="Italic">α</Emphasis>-hydroxymorphine

Abstract  A new compound was isolated from the reaction mixture after O-demethylation of 6-O-acetyl-10α-acetoxycodeine with boron tribromide. The structure of this compound, 10α-hydroxy-β-isomorphine, was elucidated by spectral data, and its spatial arrangement was deduced from an NOE experiment. Capillary zone electrophoresis was used for separation of morphine and its 10-hydroxy analogues. Graphical abstract        

Synthesis of <Emphasis Type="Italic">α</Emphasis>-chloropyridine derivatives of <Emphasis Type="Italic">γ</Emphasis>-aminobutyric acid

The sodium salt of N-(6-chloronicotinoyl)-γ-aminobutyric acid, a structural analog of the known nootropic and vasidilating drug picamilon, was synthesized via Schotten–Baumann acylation of γ-aminobutyric acid with 6-chloronicotinoyl chloride and subsequent neutralization of the N-(6-chloronicotinoyl)-γ-aminobutyric acid that was obtained in >60% yield.     

Purification and Characterization of Thermostable α-Galactosidase from <Emphasis Type="Italic">Aspergillus terreus</Emphasis><Subscript>GR</Subscript>

An extracellular thermostable α-galactosidase producing Aspergillus terreus _GR strain was isolated from soil sample using guar gum as sole source of carbon. It was purified to apparent homogeneity by acetone precipitation, gel filtration followed by DEAE-Sephacel chromatographic step. The purified enzyme showed a single band after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the purified enzyme after SDS-PAGE was 108 kDa. The enzyme showed optimum pH and temperature of 5.0 and 65 °C, respectively, for artificial substrate pNPαGal. α-Galactosidase from A. terreus _GR is found to be thermostable, as it was not inactivated after heating at 65 °C for 40 min. The K _m for pNPαGal, oNPαGal, raffinose, and stachyose are 0.1, 0.28, 0.42, and 0.33 mM, respectively. Inhibitors such as 1,10-phenanthroline, phenylmethylsulfonyl fluoride, ethylenediaminetetraacetic acid, mercaptoethanol, and urea have no effect, whereas N-bromosuccinamide inhibited enzyme activity by 100%. Among metal ions tested, Mg²⁺, Ni²⁺, Ca²⁺, Co²⁺, and Mn²⁺ had no effect on enzyme activity, but Ag⁺, Hg²⁺, and Cu²⁺ have inhibited complete activity.     

1,3-Diamino-2-Hydroxypropane-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-Tetraacetic Acid: Crystal and Molecular Structures

The synthesis, IR spectroscopic study, and X-ray diffraction analysis (CIF file CCDC no. 1574078) are carried out for 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid (I). The structural units of a crystal of compound I are (H_4.5HPdta)^0.5– anions, (H_5.5HPdta)^0.5+ cations, and molecules of water of crystallization joined by a branched network of hydrogen bonds: strong intermolecular O–H…O and intramolecular N–H…O bonds.     

Complex formation of magnesium and calcium ions with trimethylenediamine-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>’,<Emphasis Type="Italic">N</Emphasis>’-tetraacetic acid

Stability constants and heat effects of the formation reactions of magnesium and calcium trimethylenediaminetetraacetates at 298.15 K and ionic strength of 0.1, 0.5, and 1.0 (mol/L KNO₃) have been determined by means of potentiometry and calorimetry. Standard thermodynamic parameters (log K⁰, Δ_rG⁰, Δ_rH⁰, and Δ_rS⁰) of the studied equilibriums have been determined.     

Synthesis and characterization of some <Emphasis Type="Italic">o</Emphasis>,<Emphasis Type="Italic">o</Emphasis>′-dihydroxyazo dyes and their metal complexes

The synthesis and characterization of azo dyes containing o,o′-dihydroxy groups and their azo-metal(II) [Cu, Co, Ni, Zn] chelates by ¹H N.M.R., IR, AAS, UV–VIS, magnetic susceptibility and thin-layer chromatography techniques are reported. The stochiometry of the azo-metal chelates was determined by the spectroscopic titration method to be 1:2 (ML₂). The synthesized azo dyes and azo-metal chelate dyes were applied on wool fabric. Fastness to light and washing were measured.     

Porcine pancreatic α-amylase inhibitors from <Emphasis Type="Italic">Euonymus laxiflorus</Emphasis> Champ.

Twenty-six samples of indigenous medicinal plants were collected in Dak Lak Province of Vietnam and evaluated for α-amylase inhibitory activity. Of these samples, trunk bark extract from Euonymus laxiflorus Champ. (ELC extract) showed the greatest α-amylase inhibitory activity with the smallest 50 % inhibitory concentration (IC₅₀) of 6.6 ± 0.6 µg/mL against porcine pancreatic α-amylase. This extract possessed strong inhibitory activity against human saliva α-amylase and slightly lower activity against Bacillus subtilis α-amylase, with IC₅₀ values of 4.2 ± 0.2 and 27.8 ± 1.8 µg/mL, respectively. ELC extract was found to be strongly thermostable, retaining 72–100 % relative activity even after heating at 100 °C for 5 min to 2 h. This extract was also stable at various pH values. These results suggest that ELC extract may be a good candidate for treatment of non-insulin-dependent diabetes mellitus (NIDDM) and obesity.     

An efficient synthesis of <Emphasis Type="Italic">β</Emphasis>-methoxycarbonyl-<Emphasis Type="Italic">γ</Emphasis>-butyrolactones

β-Methoxycarbonyl-γ-butyrolactones bearing a γ-aromatic substituent were prepared via copper-catalyzed reductive aldol addition/lactonization domino reactions of ketones with α,β-unsaturated dicarboxylate esters and a silane under ambient temperature. The reaction has advantage of using readily available reagents, mild conditions and high efficiency.     

<Emphasis Type="Italic">β</Emphasis>-Chloro-<Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">β</Emphasis>-unsaturated carbonyls as convenient precursors of highly substituted benzenes

The Diels–Alder reactions of three β-chloro-α,β-unsaturated carbonyl compounds 1–3 with different dienes were carried out to afford highly functionalized cyclohexenes 4–9, bearing quaternary centers, in good yields. These cycloadducts (CAs) undergo dehydrochlorination with subsequent aromatization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene DBU to produce new substituted benzenes 11–14. Compound 10 is the product of lactonization and removal of an HCl molecule from compound 7. All products were characterized by NMR, IR, elementary analysis and some of them by MS. Structure assignments of isomers were carried out on the basis of NMR chemical shifts and coupling constants using 1D, 2D and heteronOe NMR techniques.     

Theoretical and experimental NMR studies of the Swern oxidation of methyl 6<Emphasis Type="Italic">α</Emphasis>,7<Emphasis Type="Italic">β</Emphasis>-dihydroxyvouacapan-17<Emphasis Type="Italic">β</Emphasis>-oate

This work describes the synthesis of new derivatives of 6α,7β-dihydroxyvouacapan-17β-oic acid (1) employing the Swern method for the oxidation of C-6 and C-7 of methyl 6α,7β-di-hydroxyvouacapan-17β-oate (2) and the formation of methyl 6,7-dioxovouacapan-17β-oate (3). NMR structural studies associated with theoretical calculations of reaction intermediates and products are also reported. The mixture of methyl 7β-hydroxy-6-oxovouacapan-17β-oate (4; 21%) and methyl 6α-hydroxy-7-oxovouacapan-17β-oate (5; 79%) was the product from the first step of the oxidation of 2. The lower energy of 5, calculated by HF/6-31G* and DFT/BLYP/6-31G* methods, reinforces the thermodynamic control proposed for the reaction. After further Swern oxidation of the mixture of 4 and 5, the isomeric form methyl 6-hydroxy-7-oxovouacap-5-en-17β-oate (6) was obtained. Theoretical calculations indicate a lower energy for the mono-enol 6 than the 1,2-diketo 3 and the other mono-enol methyl 7-hydroxy-6-oxovouacap-7-en-17β-oate (7).