Photocytotoxicity of a new Rh2(II,II) complex: increase in cytotoxicity upon irradiation similar to that of PDT agent hematoporphyrin

A new type of heteroleptic dirhodium complex cis-[Rh(2)(mu-O2CCH3)2-(bpy)(dppz)]2+ (3) was synthesized and its potential as a photodynamic therapy (PDT) agent was investigated. Although 27% hypochromicity of the absorption of 3 in the near-UV and visible regions is observed in the presence of duplex DNA, relative viscosity measurements reveal that the complex does not intercalate between the DNA bases. The DNA photocleavage with visible light by 3 proceeds via both oxygen dependent and independent mechanisms, and it is more efficient than that of related complexes. The increase in the cytotoxicity of 3 towards human skin cells is similar to that of hematoporphyrin, a key ingredient in a PDT drug currently in use. This feature makes this complex a useful candidate for further PDT studies.     

Distribution of amines in water/AOT/n-hexane reverse micelles: influence of the amine chemical structure

The distribution of different aliphatic and aromatic amines: n-butylamine (n-BA), isobutylamine (i-BA), tert-butylamine (t-BA), piperidine (PIP), N,N-dimethylaniline (DMA) and N-methylaniline (MA) in water/sodium 1,4-bis(2-ethylhexyl)sulfosuccinate(AOT)/n-hexane reverse micelles was investigated by steady-state fluorescence measurements. The partition constants were measured by an indirect method based on the effect that amine partitioning exert on the bimolecular rate of the reaction between a microphase incorporated fluorophore (Ru(bpy)2+(3)) and the quencher, (Fe(CN)3-(6)). For MA, that can act as a quencher of the fluorophore a direct method was used. The results show that primary amines have larger partition constants than the secondary ones. For tertiary amines the distribution constants were practically negligible. Laser flash photolysis experiments confirmed that tertiary amines, both aliphatic and aromatic, are not incorporated to the micellar pseudophase. The effect of the amine structure on the partition constant was analyzed through linear solvation free energy relationships (LSER) using solute parameters and compared with those obtained for alcohols. Hydrogen bond interactions with the AOT polar heads appear to be the main driving force for the distribution of amines between the organic and micellar pseudophases, whereas the size of the alkyl or aromatic group tends to hinder it.     

Identification of hPin1 inhibitors that induce apoptosis in a mammalian Ras transformed cell line

The authors have developed a class of potent inhibitors against the phosphate specific prolyl isomerase hPin1, which induced apoptosis in transformed cell lines.     

A -algorithm for convex minimization

For convex minimization we introduce an algorithm based on -space decomposition. The method uses a bundle subroutine to generate a sequence of approximate proximal points. When a primal-dual track leading to a solution and zero subgradient pair exists, these points approximate the primal track points and give the algorithm's , or corrector, steps. The subroutine also approximates dual track points that are -gradients needed for the method's -Newton predictor steps. With the inclusion of a simple line search the resulting algorithm is proved to be globally convergent. The convergence is superlinear if the primal-dual track points and the objective's -Hessian are approximated well enough. Dedicated to Terry Rockafellar who has had a great influence on our work via strong support for proximal points and for structural definitions that involve tangential convergence. On leave from INRIA Rocquencourt Research of the first author supported by the National Science Foundation under Grant No. DMS-0071459 and by CNPq (Brazil) under Grant No. 452966/2003-5. Research of the second author supported by FAPERJ (Brazil) under Grant No.E26/150.581/00 and by CNPq (Brazil) under Grant No. 383066/2004-2.     

Separation techniques in speciation analysis for organometallic species

A comprehensive review of the state-of-the-art of the separation of various organically-bound metals and metalloids for speciation analysis is presented. Recent developments in chromatographic (gas, liquid and supercritical fluid), electrophoretic (free-flow and gel) and fractionation techniques are discussed, followed by a survey of pertinent applications to speciation analysis for organometals and metalloids. The required sample characteristics for a given separation technique are specified and appropriate derivatization procedures are characterized. Methods applicable to the speciation of organic species of a particular element in various matrices are critically evaluated.List of abbreviations APS ammonium pentanesulfonate - CCC counter current chromatography - CZE capillary zone electrophoresis - DBT dibutyltin - DCyT dicyclohexyltin - DDTC diethyldithicarbamate - DEAE diethylaminoethyl gel (anion exchanger) - DEL diethyllead - DET diethyltin - DMA dimethylarsinic acid - DMGe dimethylgermanium - DMHg dimethylmercury - DML dimethyllead - DMSb dimethylstibinic acid - DMT dimethyltin - DPhT diphenyltin - DPrT dipropyltin - EDTA ethylenediaminetetraacetate - FFF field flow fractionation - GC gas chromatography - HEPES 4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid - HPLC high performance liquid chromatography - ICP inductively coupled plasma - IEC ion exchange chromatography - IIC ion interaction chromatography - LC liquid chromatography - MBT monobutyltin - MCyT monocyclohexyltin - MEA monoethylarsinic acid - MEHg monoethylmercury - MEL monoethyllead - MET monoethyltin - MIP microwave induced plasma - MMA monomethylarsonic acid - MMGe monomethylgermanium - MMHg monomethylmercury - MML monomethyllead - MMSb monomethylstibonic acid - MMT monomethyltin - MPhHg monophenylmercury - MPhT monophenyltin - MPrT monopropyltin - MS mass spectrometry - NAA neutron activation analysis - NaBS sodium 1-butanesulfonate - NaDS sodium dodecylsulfonate - NaPS sodium pentanesulfonate - PAGE polyacrylamide gel electrophoresis - PAR 4-(2-pyridylazo)resorcinol - PIXE proton induced X-ray emission - QF quartz furnace - RPC reversed phase partition chromatography - SDS sodium dodecyl sulfate - SEC size exclusion chromatography - SFC supercritical fluid chromatography - TBAP tetrabutylammonium phosphate - TAL tetraalkyllead - TBT tributyltin - TCyT tricyclohexyltin - TeEL tetraethyllead - TEL triethyllead - TeML tetramethyllead - TET triethyltin - TGME thioglycolic methyl ester - THF tetrahydrofuran - TMA trimethylarsinic acid - TMAH tetramethylammonium hydroxide - TMGe trimethylgermanium - TML trimethyllead - TMT trimethyltin - TPhT triphenyltin - TPrT tripropyltin - Tris tris(hydroxymethyl)aminomethane     

Phantom Ring‐Closing Condensation Polymerization: Towards Antibacterial Oligoguanidines

The first example of phantom ring‐closing condensation polymerization for the synthesis of oligoguanidines is presented. A new oligoguanidine with a ring structure was achieved in one step by the condensation reaction of a triamine, like diethylenetriamine, with guanidine hydrochloride. The condensation reaction proceeded by selective ring‐closure towards the formation of five‐membered rings in the oligomer backbone. The resulting polymer repeat unit structure was different from the starting monomers (phantom polymer) and was formed by elimination of three molecules of ammonia per repeat unit. The inter‐, intra‐, and inter‐molecular reaction sequences led to the new structure as proved by different spectroscopic techniques (atmospheric pressure chemical‐ionization mass spectrometry, and one‐dimensional and two‐dimensional homo‐ and heteronuclear correlation NMR experiments) as well as supported by quantum chemical investigations. Preliminary results regarding antibacterial use of the resulting oligoguanidine were also promising and showed its effect within 15–30 min as an antibacterial material.

     

Mouse brain expression patterns of <Emphasis Type="Italic">Spg7</Emphasis>, <Emphasis Type="Italic">Afg3l1</Emphasis>, and <Emphasis Type="Italic">Afg3l2</Emphasis> transcripts,encoding for the mitochondrial <Emphasis Type="Italic">m</Emphasis>-AAA protease

Background  

The m-AAA (ATPases Associated with a variety of cellular Activities) is an evolutionary conserved metalloprotease complex located in the internal mitochondrial membrane. In the mouse, it is a hetero-oligomer variably formed by the Spg7, Afg3l1, and Afg3l2 encoded proteins, or a homo-oligomer formed by either Afg3l1 or Afg3l2. In humans, AFG3L2 and SPG7 genes are conserved, whereas AFG3L1 became a pseudogene. Both AFG3L2 and SPG7 are involved in a neurodegenerative disease, namely the autosomal dominant spinocerebellar ataxia SCA28 and a recessive form of spastic paraplegia, respectively.