Determination of 3,7-dimethyl-1-(5-oxohexyl)-xanthine (pentoxifylline) and its 3,7-dimethyl-1-(5-hydroxyhexyl)-xanthine metabolite in the plasma of patients with multiple diseases using high-performance liquid chromatography

Pharmacokinetic studies of pentoxifylline in elderly patients with multiple diseases are described. Because of the low plasma levels of pentoxifylline and its hydroxy metabolite a new high-performance liquid chromatographic method was established. Under our chromatographic conditions, piracetam, a nootropic drug, can be easily separated from simultaneously applied pentoxifylline and its metabolite. Piracetam shows no appreciable ultraviolet absorption above 230 nm and cannot be detected at 268 nm.     

Mild Template Synthesis of (2,8-Dithio-3,7-diaza-4,6-dimethyl-5-oxanonanedithioamido-1,9)copper(II) in Cu2[Fe(CN)6] Gelatin-Immobilized Matrices

Complexation process in Cu₂[(Fe(CN)₆] gelatin-immobilized matrices in contact with aqueous solutions of dithiooxamide H₂N–C(S)–C(S)–NH₂ and ethanal H₃C–CHO at pH > 10 were studied. The template synthesis was shown to occur under these specific conditions to yield the Cu(II) chelate with tetradentate (N,N,S,S)-ligand (2,8-dithio-3,7-diaza-4,6-dimethyl-5-oxanonanedithioamide-1,9) with a metal : ligand ratio of 1 : 1. Dithiooxamide and ethanal therein act as ligand syntones. The reaction scheme was suggested. It was established that this tetradentate ligand is not formed in the absence of Cu(II) in a solution in contact with the matrix. Moreover, the attempts made to obtain the title compound through the reactions of known copper(II) dithiooxamide complexes with ethanal failed.     

Some reactions of 3,7-dimethyl-2,3-epoxyoctanal and its derivatives

The oxide of citral (3,7-dimethyl-2,3-epoxioctanal) readily enters into the Knoevenagel condensation with the formation of the corresponding epoxydienecarboxylic acid. The epoxidation and addition of dichlorocarbene to similar epoxydienes proceeds at the double bond which does not adjoin the epoxide ring. The condensation of the acetal of citral oxide with ketones with the formation of 1,3-dioxolanes proceeds with the participation of the epoxide ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 453–455, April, 1986.     

Extraction of Palladium(II) and Platinum(IV) from Hydrogen Chloride Solutions with 3,7-Dimethyl-5-thianonane-2,8-dione and Complexation of This Reagent with the Platinum Metals

Extraction of palladium(II) and platinum(IV) from acidic chloride solutions with solutions of 3,7-dimethyl-5-thianonane-2,8-dione in toluene and chloroform and complexation of this reagent with platinum metals in aqueous acetone were studied by ^1Hand ^13C NMR and IR spectroscopy. The possibility of extractive separation of palladium(II) from platinum(IV) and their separation from Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with solutions of 3,7-dimethyl-5-thianonane-2,8-dione in organic solvents was studied. The apparent concentration constants of extraction of palladium(II) and platinum(VI) with 3,7-dimethyl-5-thianonane-2,8-dione and the corresponding thermodynamic parameters were determined.     

Luminescent amphiphilic nanogels by terpyridine-Zn(II) complexation of polymeric micelles

In this work, we investigated terpyridine (tpy)/Zn(II) complexation for the crosslinking of polymeric micelles of the branched poly(ethylene oxide)–poly(propylene oxide) block copolymer Tetronic® 1107 (T1107) in water and produce physically stable amphiphilic luminescent nanogels. Nanoparticles displayed a size of 235 ± 25 and 318 ± 57 nm before and after Zn(II) crosslinking, respectively, as measured by dynamic light scattering. High-resolution scanning electron microscopy analysis revealed the multimicellar nature of the crosslinked nanoparticles. In addition, Zn(II) complexation prevented nanoparticle disassembly after extreme dilution below the critical micellar concentration and reduced the minimum concentration required for the reverse thermal gelation of concentrated aqueous T1107 systems. The cell compatibility and uptake were initially assessed in the murine macrophage cell line RAW 264.7. Results showed that complexation increases the cell compatibility of the nanoparticles with respect to the non-complexed counterparts. In addition, non-crosslinked nanoparticles accumulated in the cell membrane, while the complexed ones were internalized, as observed by confocal laser scanning fluorescence microscopy. Then, the antiproliferative activity of the crosslinked nanoparticles was confirmed in the rhabdomyosarcoma cell line Rh30; their inhibitory concentration 50 (IC₅₀) being 101 μg/mL (6.7 μM). Finally, the encapsulation and release of the hydrophobic antiretroviral efavirenz was characterized in vitro. Complexation slightly reduced the release kinetics with respect to the pristine nanoparticles. Overall results demonstrate the promise of this simple modification strategy to produce amphiphilic nanogels with a set of advantageous physicochemical, optical, and biological properties.     

Synthesis, Characterization and Antibacterial Activity of Some Transition Metal cis-3,7-dimethyl-2,6-octadiensemicarbazone Complexes

The synthesis and characterization of some transition metal cis-3,7-dimethyl-2,6-octadiensemicarbazone (CDOSC) complexes are reported. The ligand CDOSC yields: [ML₂ Cl₂] and [ML₂ Cl₂] Cl type complexes, where M = Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II, L = CDOSC. Structures of the complexes were determined using elemental analysis, molar conductivity, magnetic measurements, i.r. and electronic, as well as n.m.r spectra. CDOSC acts as a bidentate ligand in all the complexes. All the newly synthesized metal complexes, as well as the ligand, were screened for their antibacterial activity. All the complexes exhibit strong inhibitory action against Gram (+) bacteria Staphylococcus aureus and Gram (−) bacteria Escherichia coli. The antibacterial activities of the complexes are stronger than those of the ligand CDOSC itself.     

Molecular and crystal structure of 3,7-di(2-propenyl)-1,5-diphenyl-3,7-diazabicyclo[3.3.1]-nonan-9-one complexed with copper(II) chloride

We have investigated the molecular and crystal structure of 3, 7-di(2-propenyl)-1, 5-diphenyl-3, 7-diazabicyclo[3.3.1]nonan-9-one complexed with copper(II) chloride. We have shown for the first time that the reason for the distortion of the coordination polyhedron of the metal is the interaction of the substituents at the nitrogen atoms with the halogen atoms.Communication 2 in the series Complexing properties of 3,7-diazabicyclo[3.3.1]nonanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 770–774, June, 1996. Original article submitted April 13, 1996.Deceased.     

Synthesis of (2,4-dimethyl-3-carbethoxy-5-pyrrolyl) succinic acid and its derivatives

-Pyrrolylsuccinic and (2,4-dimethyl-3-carbethoxy-5-pyrrolyl)succinic anhydrides were obtained by the reaction of pyrrole and 2,4-dimethyl-3-carbethoxypyrrole with maleic anhydride. (2,4-Dimethyl-3-carbethoxy-5-pyrrolyl)succinic acid and its imides and dialkylamides were synthesized by hydrolysis and aminolysis of the anhydrides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1523–1524, November, 1972.     

Thermal decomposition of poly(2-vinylpyridine): Effect of complexation with copper chloride

The thermal decomposition of complexes between poly(2-vinylpyridine) (P2VPy) and copper chloride was investigated by several techniques, including thermogravimetric analysis and mass spectrometry. P2VPy was selected as the host polymer for two reasons: its ability to form complexes with copper compounds which are soluble in high concentrations, and because it forms essentially no char upon pyrolysis. The decomposition mechanism of P2VPy changes significantly upon complexation with copper compounds. P2VPy was initially thought to be an ideal ligand for the pyrolytic formation of pure copper owing to its low carbon yield upon thermal decomposition. The presence of copper chloride during polymer decomposition alters the decomposition mechanism of the polymer and accounts for significant yields of carbonaceous char. The magnitude of this effect is dependent upon the quantity of copper present. Polymer char yields as high as 41 wt% have been obtained when each pyridine moiety is complexed by CuCl₂. Studies based on the model compound Cu(2-picoline)₂Cl₂ indicate that the diffusion length of released volatiles plays a significant role in the observed decomposition mechanisms.     

Stereochemistry of (3E)-3,7-dimethyl-3-octene-1,2,6,7-tetraol isolated from Passiflora quadrangularis

3,7-Dimethyl-3(E)-octene-1,2,6,7-tetraol, a monoterpene recently isolated from Passiflora quadrangularis fruit pulp, has been established to be a 12:42:14:32 mixture of (2R,6R)-, (2R,6S)-, (2S,6R)- and (2S,6S)-stereoisomers, in that order, by HPLC analysis of the corresponding tri-(R)-MTPA ester in comparison with stereochemically defined synthetic samples.     

Soft template synthesis of (2,8-dithio-3,7-diaza-5-oxanonandithioamide-1,9) nickel(II) and (2,7-dithio-3,6-diazaoctadien-3,5-dithioamide-1,8)nickel(II) using a nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix

Complexing processes leading under specific conditions to nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix systems in contact with aqueous-alkaline solutions (pH12) containing dithiooxamide and formaldehyde or glyoxal, have been studied. It has been shown that template synthesis of macrocyclic co-ordination compounds, (2,8-dithio-3,7-diaza-5-oxanonandithioamide-1,9)nickel(II) and (2,7-dithio-3,6-diazaoctadien-3,5-dithioamide-1,8)nickel(II), occurs. Dithiooxamide, formaldehyde and glyoxal act as ligand synthons in this process.     

Unusual complexation of 1-phenylthiocarbamoyl-3-(pyridin-2-yl)pyrazoline with copper(ii) chloride

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