Novel bioactive phospholipids: practical total syntheses of products from the oxidation of arachidonic and linoleic esters of 2-lysophosphatidylcholine(1)

Total syntheses of nine novel phospholipids were accomplished to facilitate the identification and biological testing of compounds that are generated upon oxidative cleavage of arachidonate and linoleate esters of 2-lysophosphatidylcholine, the two most abundant polyunsaturated phospholipids in low-density lipoprotein. An efficient general synthesis exploiting 2-lithiofuran as a 4-oxo-2-butenoyl carbanion equivalent provided phospholipids containing gamma-keto-alpha,beta-unsaturated carbonyl functional arrays. By exploiting facile cis-trans isomerizations, two commercially available cis alkenes, (2Z)-2-butene-1,4-diol and 2,5-dihydrofuran, could be employed as starting materials for preparing the Horner-Wadsworth-Emmons reagent 4-(diethoxyphosphoryl)-2E-butenal, a valuable building block for the synthesis of 2,4-dienals. The reagent was exploited in a total synthesis of 13-oxotridec-9E,11E-dienoic acid, confirming the identity of this product that is generated upon autoxidation of linoleic acid and by decomposition of 13-hydroperoxy-9,11-octadecadienoate (13-HPODE), especially in the presence of redox active transition metal ions, cytochrome p-450, or hydroperoxide lyase.     

A fullerene silirane derivative to improve the open circuit voltage in a polymer–fullerene solar cell: a theoretical study

In this letter quantum chemical calculations are performed on fullerene derivatives with varying reduction potentials, successfully used as electron acceptor in bulk heterojunction solar cells with the aim to investigate the energy levels of the frontier orbitals. We have successfully correlated the theoretical lowest unoccupied molecular orbital (LUMO) levels of different fullerenes with the open circuit voltage of the photovoltaic device based on the polymer–fullerene blend. We have also proposed a new fullerene silirane derivative with a raised LUMO level useful to increase the open circuit voltage of a polymer solar cell. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

LiI-doped N,N-dimethyl-pyrrolidinium iodide, an archetypal rotator-phase ionic conductor

N,N-Dimethyl-pyrrolidinium iodide, and the effect of doping with LiI, has been investigated using DSC, NMR, and impedance spectroscopy. It was found that the addition of a small amount of LiI enhances the ionic conductivity by up to 3 orders of magnitude for this ionic solid. Furthermore, a slight decrease in phase transition onset temperatures, as well as the appearance of a superimposed narrow line in the (1)H NMR spectra with dopant, suggest that the LiI facilitates the mobility of the matrix material, possibly by the introduction of vacancies within the lattice. (7)Li NMR line width measurements reveal a narrow Li line width, decreasing in width and increasing in intensity with temperature, indicating mobile Li ions.     

Electronic nose screening of limonene release from multicomponent essential oils encapsulated in pectin gels

Multicomponent essential oils Tagetes Minuta and Poleo as well as pure limonene were encapsulated in Tween doped-high methoxylated pectin gels. Optical microscopy reveals that the obtained gels containing limonene consisted in a highly heterogeneous oil-in-water emulsion stabilised by the gelled medium. The influence of limonene encapsulation in pectin gelation kinetics and the gel structural properties were followed by dynamic rheological measurements. An electronic nose device developed in our laboratory was used to follow the flavour release of the three systems in order to discriminate the samples according to the main components released to the headspace. PCA and Neural Network Analysis allowed us to discriminate Tagetes Minuta from Poleo due to the difference in their limonene content. It is remarkable that the fingerprints of encapsulated complex mixtures differ from those obtained for the non-encapsulated oils, showing a preferential release of some components. In the case of limonene, the effect of the encapsulated concentration on the detected odour was also studied.     

A new class of tethered-arene ruthenium(II) complexes with pendant P and C donor atoms: synthesis of eta6:eta1:eta1 phosphonio-azabutadienyl ruthenabicycles via allenylidene intermediates

The activation of 1,1-diphenyl-2-propyn-1-ol by complexes [RuCl(eta(6)-p-cymene)[eta(2)-P,N-Ph(2)PCH(2)P([=NR)Ph(2)]](+) results in the formation of the unusual tethered (eta(6)-arene)-ruthenium(ii) derivatives, via an unprecedented iminophosphorane-allenylidene coupling process.     

Synthesis of novel alkylamino zinc(II) phthalocyanines

The synthesis of tetramethyl‐tetraphthalimidomethyl‐phthalocyaninato zinc(II) ( 6 ) and tetramethyl‐tetraaminomethyl‐phthalocyaninato zinc(II) ( 7 ) is described.     

Asymmetric microbial reduction of ketones: absolute configuration of trans-4-ethyl-1-(1S-hydroxyethyl)cyclohexanol

A set of five fungal species, Botrytis cinerea, Trichoderma viride and Eutypa lata, and the endophytic fungi Colletotrichum crassipes and Xylaria sp., was used in screening for microbial biocatalysts to detect monooxygenase and alcohol dehydrogenase activities (for the stereoselective reduction of carbonyl compounds). 4-Ethylcyclohexanone and acetophenone were biotransformed by the fungal set. The main reaction pathways involved reduction and hydroxylations at several positions including tertiary carbons. B. cinerea was very effective in the bioreduction of both substrates leading to the chiral alcohol (S)-1-phenylethanol in up to 90% enantiomeric excess, and the cis–trans ratio for 4-ethylcyclohexanol was 0:100. trans-4-Ethyl-1-(1S-hydroxyethyl)cyclohexanol, obtained from biotransformation by means of an acyloin-type reaction, is reported here for the first time. The absolute configurations of the compounds trans-4-ethyl-1-(1S-hydroxyethyl)cyclohexanol and 4-(1S- and 4-(1R-hydroxyethyl)cyclohexanone were determined by NMR analysis of the corresponding Mosher’s esters.     

Bacterial Photosensory Proteins and Their Role in Plant–pathogen Interactions

Light is an important environmental signal for almost all living organisms. The light perception is achieved by photoreceptor proteins. As can be observed from the great number of bacterial genomes sequenced, plant pathogenic bacteria encode for a large number of photoreceptor proteins. The physiological implications of these photoreceptors are still poorly characterized. However, recent studies revealed the participation of these photosensory proteins in the pathogenic process. Here, we summarize what is known about these proteins and their role during the virulence process, concluding that the light environment modulates the plant–pathogen interaction.