Simultaneous separation and determination of Tarabine PFS and Adriblastine using micellar electrokinetic chromatography and high performance liquid chromatography. Application to some biological fluids

The simultaneous determination of Tarabine PFS and Adriblastine by two independent techniques, viz. micellar electrokinetic chromatography (MEKC) and high performance liquid chromatography (HPLC), has been studied. For MEKC analysis, separations and identifications were accomplished using uncoated fused-silica capillaries and injections were performed in the hydrodynamic mode. The running buffer consisted of 0.05 M borate/phosphate pH 8.70, with 0.10 M SDS at an operating voltage of 15.0 kV and the temperature held at 25.0 degrees C. Under these conditions, the migration times of Tarabine PFS and Adriblastine were 2.70 and 6.40 min, respectively. Calibration curves were established for 0.010-0.300 microg/mL (r = 0.99) Tarabine PFS and 8.000-120.0 microg/mL (r = 0.99) Adriblastine. The limit of detection (LOD) was estimated and found to be 0.003 and 3.000 microg/mL of Tarabine PFS and Adriblastine, respectively. The limit of quantitation (LOQ) was found to be 0.009 and 8.000 microg/mL of Tarabine PFS and Adriblastine, respectively. For HPLC analysis, separations and determinations were performed on teicoplanin stationary phase with reversed mobile phase containing methanol:buffer pH 4.05 (20.0:80.0%, v/v) at 285 nm. Calibration curves were established for 3.000-90.00 microg/mL (r = 0.99) Tarabine PFS and for 10.00-120.0 microg/mL (r = 0.99) Adriblastine. LOD and LOQ were estimated and found to be 0.950 and 2.050 microg/mL of Tarabine PFS and 3.130 and 9.250 microg/mL of Adriblastine, respectively. Both MEKC and HPLC methods were applied for the simultaneous determination of analytes in urine samples. It was found that 8.00-10.0% (Tarabine PFS) and 13.0-15.0% (Adriblastine) of the injected dose was recovered in urine samples with 99.5-102% recovery.     

Reaction between 2,2′ -dithiodianiline and acetylenic ketones or esters. A new synthesis of 4H-1,4-benzothiazines

The title compounds ( 3a-c ) together with the benzothiazolines ( 4b-c ) were obtained by reaction between 2,2′ -dithiodianiline ( 1 ) and acetylenic ketone ( 2a ) or esters ( 2b-c ). A possible pathway involving the formation and subsequent cyclization to 3 of enamine intermediates A and/or B , is suggested.     

Crystal structure of the 2:1 inclusion compound between deoxycholic acid and quadricyclane

The 2:1 inclusion compound formed between deoxycholic acid (C₂₄H₄₀O₄,M _r=392.58) and quadricyclane (C₇H₈,M _r=92.14) crystallizes in space groupP2₁2₁2₁ witha=27.150(7),b=13.359(3),c=14.161(4) Å,Z=4. The structure was refined toR=0.08₆ andR _w=0.08₈ for 2079 observed reflections withI>2.5(I). The crystal packing is very similar to that found in the norbornadiene-deoxycholic acid inclusion compound and is characterized by an assembly of antiparallel pleated bilayers, formed by molecules of deoxycholic acid held together through hydrogen bonds. Quadricyclane occupies approximately the same position of norbornadiene and its atoms give rise to good van der Waals interactions with some methyl groups of deoxycholic acid. Supplementary Data relating to the article are deposited with the British Library as Supplementary Publication No. SUP 82006 (14) pages. To obtain copies, see page ii of this issue.     

Heavy metal biosorption by bacterial cells

Microbial biomass provides available ligand groups on which metal ions bind by different mechanisms. Biosorption of these elements from aqueous solutions represents a remediation technology suitable for the treatment of metal-contaminated effluents. The purpose of the present investigation was the assessment of the capability of Brevibacterium sp. cells to remove bivalent ions, when present alone or in pairs, from aqueous solutions, using immobilized polyacrylamide cells of the microorganism in a flow-through system. The biosorption capacity of Brevibacterium cells was studied for lead, cadmium and copper. The metal cell binding capacity followed the order Cu > Pb > Cd, based on estimated q_max. These values, expressed as mmol metal/g dry weight cells, were 0.54 for Cu, 0.36 for Pb and 0.14 for Cd. Polyacrylamide-gel immobilized cells were effective in Pb, Cu and Cd removal. Lead removal was not affected by the presence of Cd and Cu; lead instead inhibited Cd and Cu removal. The desorption of the metal, by fluxing a chelating solution, restored the metal binding capacity of the cells, thus affording the multiple use of the same biomass in the remediation treatment. Received: 31 July 1997 / Revised: 22 December 1997 / Accepted: 30 December 1997     

LC Analysis of Oxytetracycline and Chlortetracycline: Application for In Vitro Bio-Equivalence Study of Veterinary Medicines

A liquid chromatographic method has been applied for the analysis of two antibiotics widely used in the veterinary field, oxytetracycline dihydrate and chlortetracycline hydrochloride in premixes for medicated feeding stuffs for veterinary use. In particular, the validated method was employed to study the releasing profile of each drug from two formulations, a commercially available and a new formulation, having different excipient composition. The dissolution profiles obtained from the chromatographic analysis allowed to verify the in vitro bio-equivalence of the commercial and the new formulations for oxytetracycline and chlortetracycline.     

Bio-Guided Fractionation of Stem Bark Extracts from Phyllanthus muellarianus: Identification of Phytocomponents with Anti-Cholinesterase Activity

A combination of flash chromatography, solid phase extraction, high-performance liquid chromatography, and in vitro bioassays was used to isolate phytocomponents endowed with anticholinesterase activity in extract from Phyllanthus muellarianus. Phytocomponents responsible for the anti-cholinesterase activity of subfractions PMF1 and PMF4 were identified and re-assayed to confirm their activity. Magnoflorine was identified as an active phytocomponent from PMF1 while nitidine was isolated from PMF4. Magnoflorine was shown to be a selective inhibitor of human butyrylcholinesterase—hBChE (IC₅₀ = 131 ± 9 μM and IC₅₀ = 1120 ± 83 μM, for hBuChE and human acetylcholinesterase—hAChE, respectively), while nitidine showed comparable inhibitory potencies against both enzymes (IC₅₀ = 6.68 ± 0.13 μM and IC₅₀ = 5.31 ± 0.50 μM, for hBChE and hAChE, respectively). When compared with the commercial anti-Alzheimer drug galanthamine, nitidine was as potent as galanthamine against hAChE and one order of magnitude more potent against hBuChE. Furthermore, nitidine also showed significant, although weak, antiaggregating activity towards amyloid-β self-aggregation.     

Inelastic neutron scattering study of water in hydrated LTA-type zeolites

The vibrational dynamics of water molecules encapsulated in synthetic Na-A and Mg-exchanged A zeolites were studied versus temperature by inelastic neutron scattering (INS) measurements (30-1200 cm(-1)) as a function of the induced ion-exchange percentage by using the indirect geometry tof spectrometer TOSCA at the ISIS pulse neutron facility (RAL, UK). The experimental INS spectra were compared with those of ice Ih to characterize the structural changes induced by confinement on the H2O hydrogen-bonded network. We observed, after increasing the Mg2+ content, a tendency of water molecules to restore the bulklike arrangements together with more hindered dynamics. These results are confirmed by the analysis of the evaluated one-phonon amplitude-weighted proton vibrational density of states aimed, in particular, to follow the evolution of the water molecules librational mode region.     

Characterization of blue decorated Renaissance pottery fragments from Caltagirone (Sicily,Italy)

Renaissance blue decorated pottery fragments from the archaeological site of Caltagirone (Sicily, Italy) were analysed by scanning electron microscopy – energy dispersive X-ray spectrometry (SEM/EDS). The samples were dated back to 16th century AD on the basis of archaeological observations. The micro-chemical analyses were performed on the ceramic body and the surface decorated layer of the samples. Particularly, the investigation was addressed the characterization of the coating blue decorations. The obtained results allowed us to clearly identify smalt as pigment. Also the presence of arsenic (As) was revealed and the Co/As ratio values were calculated and related to the different process used for the pigment preparation. Further spectroscopic analyses, performed through X-ray absorbance spectroscopy (XAS), carried out at the Co K-edge, confirmed the micro-analytical results and permitted us to identify the oxidation form and the local environment of cobalt atoms. PACS  81.05.Mh; 82.80.-d; 68.37.Hk     

Enantioselective Extraction of Dinitrophenyl Amino Acids Mediated by Lipophilic Deoxyguanosine Derivatives: Chiral Discrimination by Self-Assembly

The transfer of potassium salts of dinitrophenyl amino acids from water to chloroform by the lipophilic guanosine derivative 1 takes place enantioselectively. Depending on the K⁺: 1 ratio, G-quartets of 1 self-assemble into octamers ( O ) or polymers.