Proteomic characterization of donkey milk “caseome”

At present, compared with bovine milk, the characterization of donkey milk caseins is at a relatively early stage progress, and only limited data are related to its genetic polymorphism. In this work, the heterogeneity of donkey caseome was investigated using a proteomic approach, based on one- (PAGE, UTLIEF) and two-dimensional (PAGE → UTLIEF) electrophoresis, stained with either Coomassie Brilliant Blue or specific polyclonal antibodies, and structural MS analysis. These combined methodologies allowed the contemporary identification of donkey α_s1, α_s2, β and κ-CN with their related heterogeneity due to phosphorylation (α_s1, α_s2 and β-CN), glycosylation (κ-CN) and incorrect splicing of RNA in mRNA (deleted forms of α_s1-CN and β-CN). The results achieved showed 11 components for κ-CN, six phosphorylated components for β and α_s1-CN and three main phosphorylated components for α_s2-CN, each accounting for 10, 11 and 12 P/mole. At this regard, for the first time, the primary structure of the expressed protein corresponding to the only available donkey α_s2-CN cDNA sequence was determined. Furthermore β-CN was found in homozygous and heterozygous state for the occurrence of a genetic β-CN variant having a MW value 28 mass units higher than the common β-CN phenotype.     

Factors Controlling Stereoselectivity in the Koenigs-Knorr Type D-Mannopyranosylation

Abstract

The factors controlling stereoselectivity in the formation of cyclohexyl α- and β-D-mannopyranosides with D-mannosyl chloride, cyclohexanol and silver triflate (AgOTf), were examined. For the syntheses of β-D-mannopyranosides, dichloromethane (CH₂Cl₂) as solvent could be used only at low temperature, while the use of tetrahydrofuran (THF) as solvent proved to be effective at room temperature. Diallyl ether (All₂O) was effectively used in CH₂Cl₂ as an olefinic additive. Stereoselectivities in these reactions were changed by use of THF as an oxonium ion source and All₂O as an inhibitor to prevent complex formation of the silver ion with the allyloxy group of the glycosyl donor.     

Synthesis of New N-Sulfonyl Monocyclic β-Lactams and the Investigation of Their Antibacterial Activities

New monocyclic β-lactams 4–6 were synthesized by a ketene-imine [2+2] cycloaddition reaction. The prepared monocyclic β-lactams 4–6 were cleaved by ceric ammonium nitrate (CAN) to give NH-β-lactams 7–9. The NH-β-lactams were converted to N-sulfonyl β-lactams 10–21 by treatment with four different sulfonyl chlorides in the presence of Et₃N and 4-N,N-dimethylaminopyridine (DMAP). Some of these monocyclic β-lactams were active against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Rapid Separation of Testosterone and its Microsomal Metabolites by Reverse-Phase High Performance Liquid Chromatography

Abstract

High performance liquid chromatography has been used to separate testosterone from its oxidative metabolites (7α-, 16α -and 6 β-hydroxytestosterone and androstenedione) following in vitro incubation with rat liver microsomes. The separation was accomplished in less than 18 minutes on a radially compressed C₁₈ reverse-phase column using isocratic elution with tetra-hydrofuran: water (24/76, v/v).     

Ultrasound-assisted rapid synthesis of β-cyanoepoxides using hypervalent iodine reagents

An elegant approach for the rapid synthesis of β-cyanoepoxides 3 by the epoxidation of β-cyanostyrenes 1 with PIDA 2a is described. The epoxidation of β-cyanostyrenes 1 was performed with 1.2 equiv. of PIDA 2a in MeCN-H₂O (1:1) at room temperature in ultrasonic bath. The epoxidation reactions were completed in short reaction time and β-cyanoepoxides 3 were isolated in 69–94% yields.     

β-Secretase inhibition by C-methylisoflavones from Abronia nana

The methanol extract of Abronia nana suspension cultures were subjected to column chromatography to identify potential inhibitors of β-secretase, which is a major factor in Alzheimer’s disease development. Two new C-methylisoflavones boeravinone T (1) and U (4) were isolated with three knowns boeravinone B (2), J (3) and X (5). The half-maximal inhibitory concentration (IC₅₀) values of compounds 1–5 were 18.29, 8.57, 7.87, 12.02 and 5.30 μM, respectively. The most potent 5, non-competitively inhibited β-secretase [inhibition constant (K_i) = 3.79 μM]. Compounds 1–5 did not inhibit other proteases such as chymotrypsin, trypsin and elastase at concentrations up to 1 mM, indicating that they were relatively specific inhibitors of β-secretase. A free hydroxyl group at C-3 position of the C-methylisoflavone skeleton appeared to be responsible for the stronger inhibitory activity against β-secretase.     

Synthesis and Antimicrobial Evaluation of Novel N-Substituted β-Hydroxy Benzimidazole Sulfone Fluoroquinolones by Selective Oxidation Using Ticl4-H2O2

Abstract

The synthesis of N-substituted β-hydroxy benzimidazole sulfones containing 8-methoxy fluoroquinolone has been described and they were evaluated for antimicrobial activities. The compounds of N-substituted β-hydroxy benzimidazole sulfides (4a–e) and N-substituted β-hydroxy benzimidazole sulfones (5a–e) at C-7 of fluoroquinoline exhibited superior activity in vitro. 8-Methoxy fluoroquinolone carboxylic acid (1), reaction with piperizine in acetonitrile in presence of triethylamine under reflux gives 7-piperazinyl-8-methoxyfluoroquinolone (2). The latter is reacted with epichlorohydrine in presence of NaOH in acetone yielded N-substituted epoxide (3), which on treatment with 5-substituted-2-mercaptobenzimidazoles gives N-substituted β-hydroxy benzimidazole sulfides (4). Further, 4 on treatment with TiCl₄-H₂O₂ and in DCM yielded the corresponding N-substituted β-hydroxy benzimidazole sulfone (5).     

Synthesis,structure and olefin polymerization catalysis of nickel(II) complexes bearing N,O-chelate ligands

Four β-ketoimine ligands (two series) were prepared through traditional condensation reactions of β-diketones with 2,6-substituted anilines. Reaction took place only at the cyclohexanone carbonyl rather than at the acetyl or benzoyl carbonyl, even if more than two equivalents of the amines were added. Consequently, four new moisture- and air-stable bis(β-ketoamino)nickel(II) complexes, Ni[2–CH₃C(O)C₆H₈(=NAr)]₂ (Ar?=?2, 6-iPr₂C₆H₃, (1); Ar?=?2, 6-Me₂C₆H₃, (2) and Ni[2–PhC(O)C₆H₈(=NAr)]₂ (Ar?=?2, 6-iPr₂C₆H₃, (3); Ar?=?2, 6-Me₂C₆H₃, (4) were obtained and characterized. The solid-state structures of complex 1, 2 and 3 have been determined by single-crystal X-ray diffraction. Additionally, these complexes can be applied as highly active catalyst precursors for vinyl polymerization of norbornene (NBE) after activation with methylaluminoxane (MAO).     

High-Performance Liquid Chromatographic Determination of the Metabolites of the Potato Glycoalkaloids, α-Chaconine and α-Solanine,in Potato Tubers and Potato Products

Abstract

A high-performance liquid chromatographic method has been developed to separate and quantify the metabolites, γ-chaconine, β₁-and β₂-chaconine, γ-solanine and β₂-solanine, of the potato gly-coalkaloids α-chaconine and α-solanine in potatoes and potato products. A carbohydrate analysis column and a solvent system of tetrahydrofuran-water-acetonitrile (55:8:37) were employed for the separation. Flow rate was 1.1 ml/min and the compounds were monitored at 215 nm. β₂-chaconine (0.63 mg to 29.75 mg/100 g dried weight) was present in all samples whereas the other glycosides of α-chaconine were only detectable in the animal feed products. It appears that some of the animal feeds may contain trace amounts of γ-solanine and an unknown which maybe β₁-solanine. Limit of detection for all glycosides was 0.05 μg/μl. Elution time for all the lower glycosides of α-chaconine was 8 min versus 16 min for the α-solanine group. These metabolic compounds were confirmed using thin-layer chromatography.     

SYNTHESIS AND MOLECULAR STRUCTURE OF [Cu(μ-OC6H3-2,6-Me2)(thd)]2: A LIGAND-MEDIATED REDUCTION TO METALLIC COPPER

Abstract

The reaction between barium 2,6-dimethylphenoxide (1) and copper 2,2,6,6-tetramethylheptane-3,5-dionate gave the volatile β-diketonatoaryloxide [Cu(μ-OC₆H₃-2,6-Me₂)(thd)]₂ (2). The complex was characterized by elemental analysis, IR and ESR spectroscopy as well as single-crystal X-ray diffraction. It crystallises in the space group P2₁ /c with a = 6.602(2), b = 24.454(5), c = 12.391(4) Å, β = 95.49(2)°. TGA experiments at 1 atmosphere show that 2 is volatile and decomposes at 292°C to metallic copper by a ligand-mediated reduction.     

Complex Formation of Monomeric Phosphorus Oxoacids with Sodium Ion in Donnan Exclusion Chromatography

Abstract

A method for evaluation of stability constants of very unstable and labile complexes has been proposed by the use of Donnan exclusion chromatography. The stability constants of sodium complexes of monomeric phosphorus oxoacids have been evaluated to be log β₁ = -0.04 for phosphinate, log β₁ = 0.86 and log β₂ = 0.24 for hydrogen orthophosphate and log β₁ = 0.61 and log β₂ = 0.16 for phosphonate, respectively, at I = 1.00 (CH₃)₄NCl, t = 25.0° ± 0.1°C.     

Serine and Threonine Schiff Base Esters React with β-Anomeric Peracetates in the Presence of BF3·Et2O to Produce β-Glycosides

Improved procedures are reported for the glycosylation of L-serine and L-threonine utilizing activated Schiff base glycosyl acceptors, which are less expensive and more efficient alternatives to published methods. L-serine or L-threonine benzyl ester hydrochloride salts were reacted with the diarylketimine bis-(4-methoxyphenyl)-methanimine in CH₃CN at rt to form the more nucleophilic Schiff bases 3a and 3b in excellent yield. These Schiff bases exhibited ring-chain tautomerism in CDCl₃ as shown by ¹H NMR. Schiff bases 3a and 3b, acting as glycosyl acceptors, reacted at rt with simple sugar peracetate donors with BF₃·OEt₂ promotion to provide the corresponding L-serine and L-threonine O-linked glycosides in excellent yields and purities. The dipeptide ester Schiff base Ar₂C = N-Ser-Val-OCH₃ 3e also reacted to provide β-glycosides in excellent yields, and without epimerization. With microwave irradiation the reactions were complete in 2 to 5 min. To investigate this reaction further, classical AgOTf-promoted Koenigs-Knorr reaction of D-glucopyranosyl, lactosyl, and maltosyl bromides were examined, providing the β-glycosides with yields ranging from 35% to 68%. The difference in reactivity between α- and β-carbohydrate peracetate donors was remarkable. The less configurationally stable D-xylopyranosyl tetra-acetate (a pentose) showed no selectivity (αvsβ-configuration) toward the Schiff bases.     

Calix[4]arenes as molecules for second order nonlinear optics

Abstract

The synthesis of a novel class of molecules for second order nonlinear optics, i.e. calix[4]arenes with extended π-systems, is described. These compounds are obtained via Wittig-Horner reactions of the formylated calix[4]arenes 5 and 6 to give the stilbene derivatives 7–9, or by diazotization of calix[4]arene, 1, followed by alkylation to give the phenylazocalix[4]arenes 11 and 12. The molecular second order nonlinear optical properties (β_z) of these calix[4]arenes have been measured by electric field-induced second harmonic generation. The influence of different acceptors as well as the influence of the different conformations of the calix[4]arenes on β_z values were determined. Surprisingly, the wavelength of the charge-transfer band λ_max is lower when β_z increases upon increasing the number of acceptors.     

The Use of Chiral Auxiliaries Prepared from (-)-β-Pinene in Stereoselective Reduction of β-Ketobutyrates

Chiral auxiliaries previously prepared from (-)-β---pinene (3), alcohols 5a-e and 6, were transformed into β---ketobutyrates 7a-e and 8 respectively. These compounds were stereoselectively reduced by NaBH₄ in the presence of additives (MnCl₂ or CaCl₂), leading to the corresponding β-hydroxy butyrates 10a-e and 11 in good chemical yield and poor to moderate stereoselectivities (de 0%-60%). The configuration at the newly generated stereogenic center in 10a was determined to be S through its transformation into S-(+)-butanediol.     

The Effects of β-Cyclodextrin On the Fluorescence,Uv Absorption and Solubility of Selected Bimanes In Aqueous Solutions

Abstract

The effects of β-cyclodextrin were investigated on the fluorescence emission and excitation as well as on the UV absorption and solubility of certain bimanes in aqueous solution. Three syn-bimanes with differing water solubilities were examined, namely, syn-(CH₂OCOCH₃, CH₃) bimane, syn-(CH₃, CH₃) bimane, and syn-(C₆H₃, Cl) bimane. the anti-(CH₃, CH₃) bimane was also examined. In dilute solutions, the syn-(CH₃, CH₃) bimane and syn-(C₆H₃, Cl) bimane showed enhancement of their relative fluorescence intensities upon the addition of β-cyclodextrin as did anti-(CH₃, CH₃) bimane. Only the anti-(CH₃, CH₃) bimane showed significant changes in its UV absorption upon the addition of β-cyclodextrin. Both syn-(CH₂OCOCH₃, CH₃) bimane and syn-(CH₃, CH₃) bimane solubilities were increased in the presence of β-CD. the formation of β-cyclodextrin inclusion complexes is proposed as a possible interpretation of these observations.     

Highly Stereoselective Synthesis of a C2-Symmetric 2,2′-Bipyridine Derived from Glucose

2-Bromo-6-lithiopyridine adds stereoselectively to the β-face of 1,2;5,6-di-O-isopropylidene-α-D-glucofuranos-3-ulose (2) to provide compound 5 in 50% yield as a single diastereomer. Compound 5 can be coupled to form novel C₂-symmetric 2,2′-bipyridine 7, the first example of a C₂-symmetric bipyridine that derives chirality from glucose.     

Comparative QSAR: Radical Toxicity and Scavenging. Two Different Sides of the Same Coin

Abstract

From an analysis of the toxicity of phenols to rat embryos and anilines to embryo fibroblast cells a new type of toxicity is postulated for these classes of compounds. Substituents which increase the electron density on the aromatic ring as estimated by σ⁺ or ε_HOMO increase potency. It is postulated that it is the radical form of the phenols and the anilines that accounts for their toxicity. The results are compared with QSAR for radical scavengers and oxidoreductases acting on phenols, anilines and carbazoles.     

A Spectrophotometric Study of Complexation Between Nickel(II) and 4-(5′-Methyl-3′-Isoxazolylazo)Resorcinol

Abstract

The complexation equilibria between Ni(II) and 4-(5′-methyl-3′-isoxazolylazo)resorcinol have been spec-trophotometrically studied in a 20% (v/v) ethanol-water medium at 0.1M NaCIO₄ ionic strength and species NiHR (log β₁₁₁ = 14.83 ± 0.05), NiR (log β₁₀₁ = 9.32 ± 0.04) and NiR₂ (log β₁₀₂ = 17.84 ± 0.05) are established.     

Analogues of Moranoline and Mdl 73945. Methyl 6(5)-Deoxy-6(5)-(Morpholin-4-Yl)-α-D-Glycosides as Glucosidase Inhibitors

ABSTRACT

Methyl 2,3,4-tri-O-acetyl-6-O-(p-tolylsulfonyl)-α-D-glucopyranoside (6), or its iodo analogue 7, were subjected to nucleophilic displacement with morpholine to give 8, deacetylation of which gave methyl 6-deoxy-6-(morpholin-4-yl)-α-D-glucopyranoside (3). Similarly, 11, 12 and 21 were prepared. The 6-deoxy-6-iodo derivative 16 was subjected to nucleophilic displacement with morpholine and subsequent acetylation to give 15. Deacetylation of 15 gave 17. The kinetic studies for the inhibition of β-D-glucosidase from sweet almond and using o-nitrophenyl β-D-glucopyranoside as substrate exhibited a K _i value for 21 on the same order as 1-deoxynojirimycin whereas for 3, a K _i value of lesser order was observed.