Template synthesis, spectroscopic studies and biological screening of macrocyclic complexes derived from thiocarbohydrazide and benzil

A novel series of complexes of the type [M(TML)X₂]; where TML is a tetradentate macrocyclic ligand; M = Co(II), Ni(II), Cu(II) or Zn(II); X = Cl⁻, CH₃COO⁻ or NO ₃ ⁻ have been synthesized by template condensation of benzil and thiocarbohydrazide in the presence of divalent metal salts in methanolic medium. The complexes have been characterized with the help of elemental analyses, conductance measurements, molecular weight determination, magnetic measurements, electronic, NMR, infrared and far infrared spectral studies. Electronic spectra along with magnetic moments suggest the six coordinate octahedral geometry for these complexes. The low value of molar conductance indicates them to be non-electrolytes. The biological activities of metal complexes have been tested in vitro against a number of pathogenic bacteria to assess their inhibiting potential.     

Conformational studies of 3,4-dideoxy furanoid sugar amino acid containing analogs of the receptor binding inhibitor of vasoactive intestinal peptide

Conformational analysis of vasoactive intestinal peptide (VIP) receptor binding inhibitor Leu¹-Met²-Tyr³-Pro⁴-Thr⁵-Tyr⁶-Leu⁷-Lys⁸1 by various NMR techniques and constrained molecular dynamics (MD) simulation studies revealed that the molecule had a turn structure involving its Tyr³-Pro⁴-Thr⁵-Tyr⁶ moiety with intramolecular hydrogen bond between Tyr⁶NH→Tyr³CO. In order to mimic the structure of 1, peptidomimetic analogs 2-4 were synthesized using conformationally constrained scaffolds of 3,4-dideoxy furanoid sugar amino acids (2S,5R)-ddSaa1 5 and its enantiomer (2R,5S)-ddSaa2 6. All these analogs displayed well defined three-dimensional structures akin to that found in 1. Peptides 2 and 3, which differed only in the sugar amino acid stereochemistry, show propensity of structures with identical intramolecular hydrogen bonds between ThrNH→MetCO. A similar structure with a hydrogen bond between TyrNH→MetCO was observed in 4.     

Synthesis and structural studies of complexes of Sb(III) and Bi(III) with thiosemicarbazones

Summary Several new complexes of Sb(III) and Bi(III) with thiosemicarbazones of furfuraldehyde, thiophene-2-carbaldehyde, indol-3-carbaldehyde and pyridine-2-carbaldehyde have been prepared and characterized by elemental analysis, conductivity, molecular weight determination and IR,¹H-and¹³C-NMR spectral studies. The ligands form complexes of the typeMX ₃ L[M=Sb(III) or Bi(III);X=chloride;L=ligand] which are found to be non-electrolytes inDMF. Spectral data indicate that the thiosemicarbazones act as bidentate ligands through the azomethine nitrogen and sulphur.

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Synthese und Strukturuntersuchungen an Komplexen von Sb(III) and Bi(III) mit Thiosemicarbazonen

Zusammenfassung Es wurden einige neue Komplexe von Sb(III) und Bi(III) mit Tiosemicarbazonen von Furfural, Thiophen-2-carbaldehyd, Indol-3-carbaldehyd und Pyridin-2-carbaldehyd hergestellt und mittels Elementaranalyse, Leitfähigkeitsmessungen, Molekulargewichtsbestimmungen und IR-,¹H- bzw.¹³C-NMR-Spektroskopie charakterisiert. Die Komplexe sind vom TypMX ₃ L[M=Sb(III) oder Bi(III);X=Chlorid;L=Ligand] und sind inDMF Nichtelektrolyten. Die spektroskopischen Daten zeigen, daß die Thiosemicarbazone als zweizähnige Liganden über den Azomethin-Stickstoff und Schwefel wirken.

     

High-Performance Thin-Layer Chromatographic Determination of Itopride Hydrochloride in its Pharmaceutical Preparation and in the Bulk Drug

JPC – Journal of Planar Chromatography – Modern TLC - A normal-phase high-performance thin-layer chromatographic (HPTLC) method has been established for quantitative estimation of...     

Spectrophotometric determination of vanadium using variamine blue and its application to synthetic, environmental and biological samples

A simple, rapid and accurate spectrophotometric method is described for the determination of trace amounts of vanadium using variamine blue (VB) as a chromogenic reagent. The method is based on the oxidation of variamine blue to form a violetcolored species on reaction with vanadium(V), having an absorption maximum at 570 nm. Beer’s law is obeyed in the range of 0.1–2.0 μg ml^?1. The molar absorptivity and Sandell’s sensitivity were found to be 1.65 × 10⁴ l mol^?1 cm^?1 and 0.003 μg cm^?2, respectively. Optimum reaction conditions were evaluated in order to delimit the linear range. The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of vanadium in steel, pharmaceutical, environmental, and biological samples.     

Determination of rhodium in water samples using cloud point extraction (CPE) coupled with flame atomic absorption spectrometry (FAAS)

Cloud point extraction was applied as a method for preconcentration of rhodium after formation of a complex with 2-propylpiperidine-1-carbodithioate (2-PPC), and later determined by flame atomic absorption spectrometry using TritonX-114 as surfactant. Rhodium was complexed with 2-PPC in an aqueous phase and kept for 15 min in a thermostatted bath at 40 °C. Separation of the two phases was accomplished by centrifugation for 15 min at 4000 rpm. The chemical variables affecting the cloud point extraction were optimized and successfully applied to rhodium determination in various water samples. Under optimized conditions, the preconcentration system (100 mL sample) permitted an enhancement factor of 50. The detection limits obtained under optimal conditions was 0.052 ng mL⁻¹. The extraction efficiency was investigated at different rhodium concentrations (7.0–42.0 μg mL⁻¹), and good recoveries (96.42–99.14%) were obtained using this method. It has been applied to the determination of rhodium in water and was compared with reported methods in terms of Student’s ‘t’-test and variance ratio ‘f’-test.     

Preconcentration of trace metals on Amberlite XAD-4 resin coated with dithiocarbamates and determination by inductively coupled plasma-atomic emission spectrometry in saline matrices

Preconcentration of Cd(II), Cu(II), Mn(II), Ni(II), Pb(II) and Zn(II) in saline matrices on Amberlite XAD-4 resins coated with ammonium pyrrolidine dithiocarbamate (APDC) and piperidine dithiocarbamate (pipDTC) and subsequent determination by inductively coupled plasma atomic emission spectrometry were studied. Parameters such as effect of pH, effect of HNO(3) concentration on elution of metals from resin were studied. The results show that Amberlite XAD-4 coated with APDC was more efficient in the recovery of metal ions compared with Amberlite XAD-4 coated with pipDTC, in the concentration range of 0.1-200 mug l(-1), for 1 g of Amberlite XAD-4 coated resin. The detection limits for Cd(II), Cu(II), Mn(II), Ni(II), Pb(II), Zn(II) are 0.1, 0.4, 0.3, 0.4, 0.6, 0.5 mug l(-1), respectively, for resin coated with APDC and 0.7, 1.0, 0.8, 0.9, 1.7 and 1.2 mug l(-1) for resin coated with pipDTC. The effect of diverse ions on the determination of aforesaid metals was studied. The method was applied for the determination of trace metal ions in artificial sea water and natural water samples. The results were compared with extraction AAS method.     

A Highly stereospecific and efficient synthesis of homopentafluoro- phenylalanine

A short and efficient synthesis of homopentafluorophenylalanine (6) from oxazolidine aldehyde 1 in 57% overall yield and in > 98% ee is described. The enantiomeric excess of the product was determined by 19F NMR analysis of the coupling product derived from 5 and L-Ser(O-t-Bu)-OCH3, by comparison to a dipeptide obtained from racemic 5.     

Efficient oxidizing methods for the synthesis of oxandrolone intermediates

Mild, efficient and eco-friendly oxidation of 17alpha-methylandrostan-3beta-17beta-diol (1) has been studied with three different reagents viz. pentavalent iodine reagent 2-iodoxy benzoic acid (IBX) in DMSO at 65 degrees C, sodium hypochlorite and H2O2/Na2WO4 under phase transfer conditions to give 17beta-hydroxy-17alpha-methylandrostan-3-one (mestanolone 2), a drug intermediate as oxidized product. The H2O2/Na2WO4/PTC gave mestanolone in high yield and purity whereas sodium hypochlorite/PTC system yielded some chlorinated material along with the mestanolone. However, 1 with 2.5 equivalent of IBX gave 17beta-hydroxy-17alpha-methyl-Delta1-androsten-3-one (3) under the similar reaction conditions in good yield and single step reaction.     

Production of ethanol from cellulosic biomass by Clostridium thermocellum SS19 in submerged fermentation

Carotenogenesis of the lactose-negative yeast Rhodotorula rubra GED5 was studied by cocultivation with Kluyveromyces lactis MP11 in whey ultrafiltrate (WU) (35, 50, and 70 g of lactose/L). Maximum yields of cell mass (24.3 g/L) and carotenoids (10.2 mg/L of culture fluid or 0.421 μ g/g of dry cells) were obtained by growing the microbial association in WU (50 g of lactose/L) in a fermentor with an airflow rate of 0.8 L/(L·min), agitation of 220 rpm, and temperature of 30°C. The identified carotenoid pigments—β-carotene, torulene, and torularhodin—reached maximum concentrations (133, 26.9, and 222.3 μg/g of dry cells, respectively) on d 5 for torulene and d 6 for β-carotene and torularhodin.