Two-dimensional electrophoresis and peptide mass fingerprinting of bacterial outer membrane proteins.

Many bacterial outer membrane proteins (OMPs) are missing from two-dimensional (2-D) gel proteome maps. Recently, we developed a technique for 2-D electrophoresis (2-DE) of Escherichia coli OMPs using alkaline pH incubation for isolation of OMPs, followed by improved solubilization conditions for array by 2-DE using immobilized pH gradients. In this report, we expanded our study, examining protein components from the outer membranes of two enteric bacteria, Salmonella typhimurium and Klebsiella pneumoniae (also known as Klebsiella aerogenes), as well as the unrelated, free-living alpha-proteobacteria Caulobacter crescentus. Patterns of OMPs expression appeared remarkably conserved between members of the Enterobacteriaceae, while C. crescentus was unique, displaying a greater number of clusters of higher-molecular-weight proteins (>80 kDa). Peptide mass fingerprinting (PMF) was used for protein identification, and despite matching across-species boundaries, proved useful for first-pass protein assignment of enteric OMPs. In contrast, identification of C. crescentus OMPs was successful only when searching against its recently completed genome. For all three microorganisms examined, the majority of proteins identified on the 2-D gel appear localized to the outer membrane, a result consistent with our previous finding in Escherichia coli. In addition, we discuss some of the benefits and limitations of PMF in cross-species searching.     

Simultaneous LC Estimation of Glimepiride and Metformin in Glimepiride Immediate Release and Metformin Sustained Release Tablets

In the present study, a simple, rapid and precise liquid chromatographic method was developed and validated for the simultaneous determination of glimepiride and metformin in sustained release formulation. The separation was achieved on a Nucleosil 100-5SA column, 250 × 4.6 mm i.d., 5 μm using a mobile phase composed of 1.7 % ammonium dihydrogen phosphate buffer pH 3.0: acetonitrile (70:30 v/v).The instrumental settings were a flow rate of 1.0 ml min⁻¹ and a detector wavelength of 230 nm. The retention time of glimepiride and metformin were 5.1 and 11.3, respectively. The developed method was validated in terms of specificity, sensitivity, linearity, range, accuracy, precision and ruggedness. The proposed method was successfully applied to the sustained release pharmaceutical dosage form for the simultaneous determination of glimepiride and metformin without any interference by excipients.

     

Synthesis, complexation studies and biological applications of some novel stilbenophanes, indolophanes and bisindolostilbenophanes via McMurry coupling

Various types of stilbenophanes, indolophanes and bisindolostilbenophanes were synthesized by intra-, inter- and tandem intra-, intermolecular McMurry coupling. Some of the indolophanes and bisindolostilbenophanes exhibited significant activity against the growth of various bacteria. Complexation of some of the cyclophanes with TCNQ has also been studied.     

Differentiation of isomeric 2-aryldimethyltetrahydro-5-quinolinones by electron ionization and electrospray ionization mass spectrometry

A series of isomeric 2-aryl-6,6-dimethyltetrahydro-5-quinolinones (set I) and 2-aryl-7,7-dimethyltetrahydro-5-quinolinones (set II) were studied under positive ion electron ionization (EI) and electrospray ionization (ESI) techniques. Under EI conditions, the molecular ions were found to be less stable in set I isomers, and they resulted in abundant fragment ions, i.e., [M-CH(3)](+), [M-CO](+.), [M-HCO](+), [M-(CH(3),CO)](+), and [M-(CH(3),CH(2)O)](+), when compared with set II isomers. In addition, the set I isomers showed specific fragment ions corresponding to [M-OH](+) and [M-OCH(3)](+). The retro-Diels-Alder (RDA) product ion was always higher in set II isomers. The ESI mass spectra produced [M + H](+) ions, and their decomposition showed favorable loss of CH(3) radical, CH(4) and C(2)H(6) molecules in set I isomers. The set II isomers, however, showed predominant RDA product ions, and specific loss of H(2)O. The selectivity in EI and ESI was attributed to the instability of set I isomers by the presence of a gem-dimethyl group at the α-position, and it was supported by the data from model compounds without a gem-dimethyl group. Density functional theory (DFT) calculations successfully corroborated the fragmentation pathways for diagnostic ions. This study revealed the effect of a gem-dimethyl group located at the α-position to the carbonyl having aromatic/unsaturated carbon on the other side of the carbonyl group.     

Robust sliding mode control for a class of nonlinear systems using inertial delay control

This paper proposes a robust sliding mode control strategy for an uncertain nonlinear system subjected to time-varying disturbance. The class of system considered includes state-dependent nonlinearity in the input vector (in addition to the plant matrix). The control scheme uses inertial delay control to estimate the lumped uncertainty. The proposed control enforces sliding without using the discontinuous control and without requiring the knowledge of uncertainties or their bounds. The overall stability of the system is proved. The effectiveness of the proposed strategy is verified for model following and robust performance, by simulation of an illustrative example and an application to inverted pendulum system.     

Unique copper–salen complex: an efficient catalyst for N-arylations of anilines and imidazoles at room temperature

We have reported here the catalytic activity of a unique Cu–salen type complex in N-arylation of anilines with arylboronic acids in water. The protocol is found to be applicable for a wide range of electronically diversified arylboronic acids and anilines with excellent yields of the isolated product. Further the scope of this protocol has been extended to the synthesis of various N-aryl imidazoles in iso-propanol.     

A Rapid HPTLC Method for Standardization of Ficus bengalensis Linn.

JPC – Journal of Planar Chromatography – Modern TLC - Because of the increasing importance of Ficus bengalensis as a potent antidiabetic herbal drug, detailed chemical and analytical...     

Simultaneous Determination of Etodolac and Acetaminophen in Tablet Dosage Form by RP-LC

A simple, specific, precise and accurate reverse phase liquid chromatographic (RP-LC) method has been developed for the simultaneous determination of etodolac and acetaminophen in tablet dosage form. The chromatographic separation was achieved on a BDS Hypersil C18, 100 mm × 4.6 mm, 5 μm column at a detector wavelength of 274 nm using an isocratic mobile phase consisting of a mixture of 0.05% aqueous orthophosphoric acid and acetonitrile in the ratio of 50:50 (v/v) at a flow rate of 1.0 mL min^?1. The retention times for etodolac and acetaminophen were found to be 1.32 and 4.24 min, respectively. The method was validated for the parameters like specificity, linearity, precision, accuracy and robustness. The method was found to be specific and stability indicating as no interfering peaks of impurities, degradent and excipients were observed. The square of correlation coefficients (R ²) for etodolac and acetaminophen were 0.9996 and 0.9998 while percentage recoveries were 101.32 and 100.94%, respectively. Intra- and inter-day relative standard deviations for both the components were <2.0%. The proposed RP-LC method can be applied for the routine analysis of commercially available formulations of these drugs either as such or in combination.     

Synthesis of Biaryl Derivatives of Spirofurochromanone in Water and Their Anticancer Activity

Russian Journal of General Chemistry - Biaryl derivatives of spirofurochromanones have been synthesised from 4-bromophenyl derivatives of spirofurochromanones upon catalysis by Pd/C in water....