A new eco-friendly strategy for the synthesis of novel antimicrobial spiro-oxindole derivatives via supramolecular catalysis

Novel spiro-oxindole derivatives were synthesised by one-pot multicomponent reaction using isatins, urea and 1,3-dicarbonyls. β-Cyclodextrin, an oligosaccharide, catalysed the reaction and can be reused for further reaction after recovery. This developed synthetic route is environmentally benign in which water is used as solvent to produce excellent yields of products. The synthesised compounds were evaluated for their antimicrobial activities against two bacteria and two fungi. All the synthesised spiro-oxindoles exhibit significant antimicrobial activity.     

Interaction of Globular Plasma Proteins with Water‐Soluble CdSe Quantum Dots

The interactions between water‐soluble semiconductor quantum dots [hydrophilic 3‐mercaptopropionic acid (MPA)‐coated CdSe] and three globular plasma proteins, namely, bovine serum albumin (BSA), β‐lactoglobulin (β‐Lg) and human serum albumin (HSA), are investigated. Acidic residues of protein molecules form electrostatic interactions with these quantum dots (QDs). To determine the stoichiometry of proteins bound to QDs, we used dynamic light scattering (DLS) and zeta potential techniques. Fluorescence resonance energy transfer (FRET) experiments revealed energy transfer from tryptophan residues in the proteins to the QD particles. Quenching of the intrinsic fluorescence of protein molecules was noticed during this binding process (hierarchy HSA<β‐Lg <BSA, lower binding affinity for hydrophobic protein molecules). Upon binding with QD particles, the protein molecules underwent substantial conformational changes at the secondary‐structure level (50 % helicity lost), due to loss in hydration.     

Determination of memantine in rat plasma by HPLC-fluorescence method and its application to study of the pharmacokinetic interaction between memantine and methazolamide

A sensitive high-performance liquid chromatographic method with fluorescence detection was developed to determine memantine (MT) in rat plasma. The method consists of pre-column labeling of MT with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) and a clean-up step with solid-phase extraction. A good separation of DIB-MT was achieved within 12 min on an octadecylsilica (ODS) column (150 × 4.6 mm i.d.; 5 μm) with a mobile phase of acetonitrile-water (70:30, v/v). The calibration curve prepared with fluoxetine as an internal standard showed good linearity in the range of 10-400 ng/mL (r = .999). The limits of detection and quantitation at signal-to-noise ratios of 3 and 10 were 2.0 and 6.6 ng/mL, respectively. The method was shown to be reliable with precisions of <5% for intra-day and <9% for inter-day as relative standard deviation. The fluorescence property and reaction yield of authentic DIB-MT were also examined. The proposed method was successfully applied to study the pharmacokinetic interaction between MT and methazolamide.     

Rapid and simultaneous determination of lead and sulphur in galena by means of ethylenediaminetetra-acetic acid

Summary A convenient method for the rapid, accurate and simultaneous estimation of lead and sulphur (after oxidising to sulphate level) in the same solution has been proposed. The results obtained are in good agreement with those obtained by classical procedures. The method is useful particularly in the analysis of galena.

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Zusammenfassung Es wird ein Verfahren zur gleichzeitigen Bestimmung von Blei und Schwefel (nach Oxydation zu Sulfat) beschrieben. Das Verfahren ist schnell und genau und liefert Ergebnisse, die mit denjenigen klassischer Methoden gut übereinstimmen. Es eignet sich besonders für die Analyse von Bleiglanz.

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Thanks are due to Director, Geology and Mining, U.P. for providing laboratory facilities.     

Kinetics and mechanisms of oxidations by metal ions. Part IX(1) Oxidation of phenylphosphinic acid by chromic acid in perchlorate medium

Summary The kinetics of chromic acid oxidation of phenylphosphinic acid to phenylphosphonic acid has indicated the formation of an anhydride between HCrO ₄ ^– and phenylphosphinic acid in its active PhP(OH)₂ and inactive PhPH(O)OH forms. The ambiguity about the reactive form of phenylphosphinic acid arises from the fact that protonation of the anhydride leads to the same transition state which disproportionates in the rate-determining step to phosphonium ion and chromium(IV). These, through different reactions in the fast step, yield phenylphosphonic acid and chromium(III) as the final products. That HCrO ₄ ^– is the reactive species of chromium(VI) is confirmed by the fact that k₀ is independent of the inital [Cr^VI] where k₀ is defined by the Equation k₀=k_obs[Cr^VI]/[HCrO ₄ ^– ]; k_obs is the pseudo first-order rate constant with respect to chromium(VI) ([Phenyl-phosphinic acid][Cr^VI]).The plot between k₀ and [H⁺] passes through the origin indicating that the reaction does not occur in the absence of H⁺-ions. Furthermore, the plot between log k₀ and –H₀, the Hammett acidity function, is linear with a slope value of 1.02±0.02 confirming the protonation of the anhydride prior to its rate-limiting disproportionation.The equilibrium constant for the anhydride formation and the composite rate constant kK, K is the protonation constant of anhydride, are reported. The equilibrium constant is almost independent of temperature.Sen Gupta and Chakaladar⁽³⁾ reported values of 8.5, 9.2, 11, 12 and 13, respectively, at 26°, 30.4°, 36°, 39.4° and 46° C. The uncertainty limits were not reported. Nevertheless it is apparent from the data that the values are not greatly influenced by temperature. The statistical mean is 11±2 dm³ mol^–1, in fair agreement with our values.     

Kinetics and mechanisms of oxidation by metal ions,part XII [1] oxidation of formaldehyde by alkaline osmium(VIII)

The stopped-flow measurements on the disappearance of alkaline osmium(VIII) at 402 nm indicated a first-order dependence each in [Os(VIII)] and [HCHO]. The pseudo first-order rate constant k_obs ([HCHO] ? [Os(VIII)]) decreased with increasing [OH^?]. The ionic strength, however, had no effect on k_obs. The rapid scan spectra of the reaction mixture indicated the formation of an inert complex which absorbs at 319 nm. Therefore the rate determining step is considered to involve the bimolecular collision between OsO₄(OH) and hydrated formaldehyde. The values of the rate limiting constant k and the equilibrium constant K_ha for the formation of the alkoxide ion from the reaction of hydrated formaldehyde with OH^? are evaluated. The equilibrium constant K_ha, within the experimental limits, is independent of temperature. The pK_a value, calculated from K_ha, is 13.62 ± 0.05 which is in good agreement with the pK_a value 13.27 for formaldehyde. The activation parameters, ΔH? = 40 ± 2 kJ mol^?1 and ΔS? = ?51 ± 6 JK^?1 mol^?1, for the rate limiting constant k are determined.     

Direct rapid gravimetric determination of magnesium in limestones, dolomites etc.

Ohne Zusammenfassung     

Mammary gland tumor promotion in F1 generation offspring from male and female rats exposed to soy isoflavones for a lifetime

The effect of dietary isoflavones in the form of NOVASOY (NS) was investigated on methylnitrosourea-initiated mammary gland cancer in F1 generation female Sprague Dawley rats from parents who had undergone lifetime exposure to variable levels of dietary NS. In comparison to NS-free dietary groups, lifetime exposure of F1 rats to 40 and 1000 mg/kg diets of NS reduced tumor latency, but did not significantly affect tumor incidence, tumor size, or tumor multiplicity. A significantly lower tumor multiplicity was, however, observed in rats fed the soy-based, NS-free diet compared to the casein-based, NS-free diet. An evaluation of a dose-response relationship pointed towards a biphasic effect, with a trend showing lower tumor incidence, lower tumor multiplicity, and lower tumor size in rats fed 1000 mg/kg diet NS compared to 40 mg/kg diet NS; however, the data failed to achieve statistical significance. Histologically, tumor type significantly differed according to the administered basal diet variety and NS dose. Our data and that of others provide conflicting evidence for chemopreventive effects of soy isoflavones on mammary gland tumor induction. We suggest standardization of interlaboratory experimental approaches for establishing low dose-response relationships for soy and its isoflavones to aid in risk assessment.     

Study of the Gelation and Rheological Behavior of Carboxymethyl Cellulose-Polyacrylamide Graft Copolymer Hydrogel

This research article deals with the synthesis of carboxymethyl cellulose-g-polyacrylamide copolymer and its suitability for the development of hydrogel system using cross-linker. The hydrogels were prepared using different concentrations of synthesized graft copolymer and chromium(III) acetate cross-linker. The gelation and rheological behaviors of this gel system were thoroughly studied. It was experimentally observed that the prepared hydrogels exhibit an acceptable gel strength and gelation time. The graft polymeric gel using 10,000 ppm copolymer and 2000 ppm chromium(III) acetate cross-linker could be deformed up to 7690% without tearing of the gel network in the range of 0.1–10,000% strain. These observations show the potential of the developed hydrogel system for its application as sealant during water shutoff jobs in oil reservoir.