Reversed-phase high performance liquid chromatographic method for the determination of lansoprazole, omeprazole and pantoprazole sodium sesquihydrate in presence of their Acid-induced degradation products

A simple sensitive, selective and accurate reversed-phase high performance liquid chromatographic method was developed and validated for the quantitative determination of lansoprazole, omeprazole and pantoprazole sodium sesquishydrate in the presence of their acid-induced degradation products. The three compounds were monitored at 280 nm using Nova-Pak C(18) column and a mobile phase consisting of 0.05 M potassium dihydrogen phosphate : methanol : acetonitrile (5 : 3 : 2 v/v/v). Linearity ranges were 2-20 mug ml(-1), 2-36 mug ml(-1) and 0.5-20 mug ml(-1) for lansoprazole, omeprazole and pantoprazole, respectively. The corresponding recoveries were 100.61+/-0.84%, 100.50+/-0.80% and 99.78+/-0.88%. The minimum detection limits were 0.55, 0.54 and 0.03 mug ml(-1) for lansoprazole, omeprazole and pantoprazole, respectively. The method could be successfully applied to the determination of pure, laboratory prepared mixtures and pharmaceutical dosage forms. The results obtained were compared with the reported methods for lansoprazole and pantoprazole or the official U.S.P method for omeprazole.     

Synthesis and characterization of silver(I) coordination networks bearing flexible thioethers: anion versus ligand dominated structures

This report describes the synthesis and X-ray characterization of a series of L(n)AgX complexes wherein Ln = PhS(CH2)nSPh (n = 2, 4, 6, 10) and X = CF3SO3-, CF3COO-, CF3CF2COO-, CF3CF2CF2COO-, NO3-, and ClO4-. This study was undertaken in order to rationalize the structure of the coordination networks formed as a function of the anion coordinating strength and the ligand structure. The following complexes were examined: with L(2), CF3SO3- (1), CF3COO- (2), ClO4- (3); L4, CF3SO3- (4), CF3COO- (5), CF3CF2COO- (6), CF3CF2CF2COO- (7); L6, CF3COO-.H2O (8), CF3CF2COO- (9), CF3CF2CF2COO- (10); and L10, NO3- (11). The anions selected are classified in three groups of increasing coordinating strength: perchlorates, fluorosulfonates, and perfluorocarboxylates. Except in two cases, all complexes form 2D-coordination networks. The 2D-network in 1 (L2, CF3SO3-) is made up of Ag(I) and L2, while the anion is only a terminal co-ligand that completes the trigonal coordination around Ag(I). In 4 (L4, CF3SO3-), a 1D-coordination polymer, [Ag-L4-]infinity, is observed where the anions are coordinated to Ag(I) in a trigonal fashion. The perfluorocarboxylates form tetrameric units in a zigzag shape, but only with the L4 ligand. In these (6 and 7), the silver-silver distances are very short, especially those of the central bond, indicating the presence of weak Ag-Ag interactions. Dimers, with short silver-silver distances, are observed with ligands L2 and L6 and perfluorocarboxylates. In 8 (L6, CF3COO-.H2O), a 3D channel-like structure is built through water molecules that connect adjacent layers. An unusual stoichiometry is noted in 3 (L2, ClO4-, acetone); Ag:L is 4:2.5. In 11 (L10 and NO3-), the nitrate acts as a bidentate ligand and an [Ag-NO3-]infinity chain is formed. Adjacent chains are linked by the L10 ligands into a 2D-coordination network.     

Synthesis of new anthracene derivatives

An efficient synthesis is described for hexabromoanthracenes 3 and 4 by direct bromination of 9,10-dibromoanthrecene 2. Whereas base-induced elimination of hexabromide 3 with t-BuOK gave 2,3,9,10-tetrabromoanthracene 5, the reaction of hexabromide 4 with DBU afforded 1,3,9,10-tetrabromoanthracene 6 as the sole product. Tetrabromide 5 was also obtained by aromatization of 1,4-dinitroxy-2,3,9,10-tetrabromo-1,2,3,4-tetrahydroanthracene 17. Efficient and convenient synthetic routes are described for the preparation of dinotroxy 17, dimethoxy 23, and dihydroxides 18 and 19 with silver-induced substitution of hexabromides 3 and 4. The hydroxy compounds 19 and 18 were converted to diepoxide 20 and monoepoxide 21, respectively, with sodium methoxide. Base-promoted aromatization of dimethoxide 23 afforded dibromomonomethoxides 26 and 27. Bromoanthracenes and isomeric arene oxides constitute valuable precursors for the preparation of functionalized substituted anthracene derivatives that are difficult to prepare by other routes.     

Synthesis of a new intercalating nucleic acid analogue with pyrenol insertions and the thermal stability of the resulting oligonucleotides towards DNA over RNA

Abstract  

A new intercalating nucleic acid monomer Y was obtained via alkylation of pyren-1-ol with (S)-(+)-2-(2,2-dimethyl-1,3-dioxolan-4-yl)ethanol under Mitsunobu conditions followed by hydrolysis with 80% aqueous acetic acid to give a diol which was tritylated with 4,4′-dimethoxytrityl chloride followed by treatment with 2-cyanoethyltetraisopropylphosphordiamidite in the presence of N,N′-diisopropylammonium tetrazolide. In this way the monomer Y was obtained as its dimethoxytrityl-protected phosphoramidite building block for standard DNA synthesis. The corresponding oligonucleotides from Y have nearly identical hybridization properties with those of intercalating nucleic acid (INA) where neighboring oxygen and carbon atoms are interchanged in the linker. The synthesis of monomer Y avoids the use of allergic intermediates which are a problem in the synthesis of INA.     

Transfer Hydrogenation of Acetophenone Catalyzed by in situ Generated 2,6-Bis(5-thioxo-4,5-dihydro-1,2,4-triazole- 3-yl)pyridine-ruthenium(II) Complexes

2,6-Bis(5-thioxo-4,5-dihydro-1,2,4-triazole-3-yl)pyridines (3, 4) were used for the first time as ligand in ruthenium catalyzed transfer hydrogenation of acetophenone. The in situ prepared three-component system Ru(II)/tridentate triamine ligands (3a—3d, 4a—4d) and KOH catalysed the transfer hydrogenation reaction of acetophenone in good yields under mild conditions.     

Identities for the Hankel transform and their applications

In the present paper the authors show that iterations of the Hankel transform with Kν-transform is a constant multiple of the Widder transform. Using these iteration identities, several Parseval-Goldstein type theorems for these transforms are given. By making use of these results a number of new Goldstein type exchange identities are obtained for these and the Laplace transform. The identities proven in this paper are shown to give rise to useful corollaries for evaluating infinite integrals of special functions. Some examples are also given as illustration of the results presented here.     

Formal verification of tail distribution bounds in the HOL theorem prover

Tail distribution bounds play a major role in the estimation of failure probabilities in performance and reliability analysis of systems. They are usually estimated using Markov's and Chebyshev's inequalities, which represent tail distribution bounds for a random variable in terms of its mean or variance. This paper presents the formal verification of Markov's and Chebyshev's inequalities for discrete random variables using a higher‐order‐logic theorem prover. The paper also provides the formal verification of mean and variance relations for some of the widely used discrete random variables, such as Uniform(m), Bernoulli(p), Geometric(p) and Binomial(m, p) random variables. This infrastructure allows us to precisely reason about the tail distribution properties and thus turns out to be quite useful for the analysis of systems used in safety‐critical domains, such as space, medicine or transportation. For illustration purposes, we present the performance analysis of the coupon collector's problem, a well‐known commercially used algorithm. Copyright © 2008 John Wiley & Sons, Ltd.     

A new approach to the characterization of the nano-surface structure by using factor analysis

The study provides a new approach to explore the existence of a nanostructure on the benzoic acid-modified glassy carbon electrode (BA-GC) system by applying factor analysis with varimax rotation of factors. The infrared spectra (IR) spectra of the bare glassy carbon electrodes (GC) and the BA-GC electrode systems with benzoic acid-nanofilm (BA-FILM) were obtained by using 10 different surface modification experiments. The IR data of the bare GC, BA-GC and BA-FILM were categorized into three series corresponding to the GC, BA-GC and BA-FILM. The factor analysis method was separately applied to each group to extract the factor loadings. By making use of these loadings, the rotated factor loadings corresponding to the first two factors were computed to estimate the relationship among and within groups. The results provided by the factor analysis method indicate the existence of the BA-FILM on the BA modified glassy carbon electrode.     

Controlling double-cavity optical switching in a K-type multilevel system including spontaneously generated coherence

A composite system consisting of a K-type atomic medium and a double optical cavity configuration is considered to study the phenomenon of atomic optical bistability (AOB) in the mean field approximation. The controllability of this phenomenon achieved by additional electromagnetic fields not circulating in the cavities is studied. Also, the effect of spontaneously generated coherence due to the quantum interference in decaying nearby levels on the multi-branched AOB is discussed. The system displays a new class of bifurcations.     

Antifungal Activity of Soft Tissue Extract from the Garden Snail Helix aspersa (Gastropoda,Mollusca)

Gastropods comprise approximately 80% of molluscans, of which land snails are used variably as food and traditional medicines due to their high protein content. Moreover, different components from land snails exhibit antimicrobial activities. In this study, we evaluated the antifungal activity of soft tissue extracts from Helix aspersa against Candida albicans, Aspergillus flavus, and Aspergillus brasiliensis by identifying extract components using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Two concentrations of three extracts (methanol, acetone, and acetic acid) showed antifungal activity. Both acetone (1 g/3 mL) and acetic acid extracts (1 g/mL) significantly inhibited C. albicans growth (p = 0.0001, 5.2 ± 0.2 mm and p = 0.02, 69.7 ± 0.6 mm, respectively). A. flavus and A. brasiliensis growth were inhibited by all extracts at 1 g/mL, while inhibition was observed for acetic acid extracts against A. brasiliensis (p = 0.02, 50.3 ± 3.5 mm). The highest growth inhibition was observed for A. flavus using acetic acid and acetone extracts (inhibition zones = 38 ± 1.7 mm and 3.1 ± 0.7 mm, respectively). LC-MS-MS studies on methanol and acetone extracts identified 11-α-acetoxyprogesterone with a parent mass of 372.50800 m/z and 287.43500 m/z for luteolin. Methanol extracts contained hesperidin with a parent mass of 611.25400 m/z, whereas linoleic acid and genistein (parent mass = 280.4 and 271.48900 m/z, respectively) were the main metabolites.