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Facile modification of silica substrates provides a platform for direct-writing surface click chemistry

Oberhansl, S., Hirtz, M., Lagunas, A., Eritja, R., Martínez, E., Fuchs, H., Samitier, J.

Small, 8(4), 541-545, 2012

A facile two-step functionalization strategy for silicon oxide-based substrates generates a stable platform for surface click chemistry via direct writing. The suitability of the obtained substrates is proven by patterning with two different direct-writing techniques and three different molecules. 

 

Determination of sphingosine-1-phosphate lyase activity by gas chromatography coupled to electron impact mass spectrometry.

Reina E, Camacho L, Casas J, Van Veldhoven PP, Fabrias G.

Chem Phys Lipids. 165(2), 225-231, 2012

Sphingosine-1-phosphate lyase (SGPL1) is the last enzyme in the catabolism of sphingolipids. It catalyzes the retroaldolic cleavage of long chain base phosphates into phosphoethanolamine and a fatty aldehyde. In this article we report on an easy and sensitive procedure to determine SPL activity. The assays uses C17-sphinganine-1-phosphate as substrate and the aldehyde product, pentadecanal, is quantified as its pentafluorobenzyloxime derivative by GC/MS. Derivatization of pentadecanal is performed as a one-step reaction, and the oxime product is directly injected for GC/MS analysis without any further purification. Acquisition in selected ion monitoring mode allows very high sensitivity, with a limit of detection of 281fmol. The assay is linear with both protein concentration and incubation time up to 20 g and 40min, respectively. The K(m) value obtained (6 M) is similar to that for the natural substrate sphingosine-1-phosphate. Using this method, FTY720 and deoxypyridoxine phosphate inhibited SPL with similar potencies to those reported.

 

Sensitive and label-free biosensing of RNA with predicted secondary structures by a triplex affinity capture method

Carrascosa, L.G., Gómez-Montes, S., Aviñó, A., Nadal, A., Pla, M., Eritja, R., Lechuga, L.M.

Nucleic Acids Res., 1-11, 2012

A novel biosensing approach for the label-free detection of nucleic acid sequences of short and large lengths has been implemented, with special emphasis on targeting RNA sequences with secondary structures. The approach is based on selecting 8-aminoadenine-modified parallel-stranded DNA tail-clamps as affinity bioreceptors. These receptors have the ability of creating a stable triplex-stranded helix at neutral pH upon hybridization with the nucleic acid target. A surface plasmon resonance biosensor has been used for the detection. With this strategy, we have detected short DNA sequences (32-mer) and purified RNA (103-mer) at the femtomol level in a few minutes in an easy and level-free way. This approach is particularly suitable for the detection of RNA molecules with predicted secondary structures, reaching a limit of detection of 50 fmol without any label or amplification steps. Our methodology has shown a marked enhancement for the detection (18% for short DNA and 54% for RNA), when compared with the conventional duplex approach, highlighting the large difficulty of the duplex approach to detect nucleic acid sequences, especially those exhibiting stable secondary structures. We believe that our strategy could be of great interest to the RNA field.

 

Two-photon confocal imaging study: Cell uptake of two photon dyes-labeled PAMAM dendrons in HeLa cells

Hsieh-Chih Tsai, Toyoko Imae, Gabriela Calderó, Conxita Solans

J Biomed Mater Res Part A, 100A, 746–756, 2012

A two-photon excitation difluoroboron dye activated in the near infrared region for biological image analysis was synthesized in this study. Cell affinity, membrane interaction, and the endocytosis pathway of PAMAM dendrons were investigated using only covalent two-photon dyes (TPD) at the periphery of the PAMAM dendrons. Generation 3 TPD-labeled PAMAM dendrons (BG3) exhibited multivalency binding on the HeLa cell membranes from the cell affinity study in the fixation of HeLa cells. Photo-stimulation on the membrane of the living HeLa cell was observed by confocal optical imaging in situ, using the two-photon model, when incubated with BG3. Analyses of cell membrane integrity via lactate dehydrogenase (LDH) assay confirmed membrane damage at two photon excitation model. However, no variation in the cell was observed using the one-photon excitation model. These results indicated a high degree of dendrons uptake by cells through binding to the cell membrane following the endocytotic pathway. Furthermore, the wide excitation fluorescence spectrum of difluoroboron dye provides dual imaging with which to study the endocytosis of TPD-labeled PAMAM dendrons using a single near infrared laser.

 

Structure−Activity Relationship Study of Opiorphin, a Human Dual Ectopeptidase Inhibitor with Antinociceptive Properties

Mónica Rosa, Gemma Arsequell, Catherine Rougeot, Luis P. Calle, Filipa Marcelo, Marta Pinto, Nuria B. Centeno, Jesús Jiménez-Barbero, and Gregorio Valencia

J. Med. Chem., 55, 1181−1188, 2012

Toward developing new potential analgesics, this first structure−activity relationship study of opiorphin (HGln-Arg-Phe-Ser-Arg-OH), a human peptide inhibiting enkephalin degradation, was performed. A systematic Ala scanning proved that Phe3 is a key residue for neprilysin and aminopeptidase N (AP-N) ectoenkephalinase inhibition. A series of Phe3-halogenated analogues revealed that halogen bonding based optimization strategies are not applicable to this residue. Additional substituted Phe3 derivatives showed that replacing L-Phe3 for D-Phe3 increased the AP-N inhibition potency by 1 order of magnitude. NMR studies and molecular mechanics calculations indicated that the improved potency may be due to CH−π stacking interactions between the aromatic ring of D-Phe3 and the Hγ protons of Arg2. This structural motif is not possible for the native opiorphin and may be useful for the design of further potent and metabolically stable analogues.

 

Moths Behaving like Butterflies. Evolutionary Loss of Long Range Attractant Pheromones in Castniid Moths: A Paysandisia archon Model

Víctor Sarto i Monteys, Patricia Acín, Glòria Rosell, Carmen Quero, Miquel A. Jiménez, Angel Guerrero

PLoS ONE, 7 (1), 29282, 2012

This study provides evidence for the first time in Lepidoptera that females of a moth do not produce any pheromone to attract males, and that mate location is achieved only visually by patrolling males, which may release a pheromone at short distance, putatively a mixture of Z,E-farnesal, E,E-farnesal, and (E,Z)-2,13-octadecadienol. The outlined behavior, long thought to be unique to butterflies, is likely to be widespread in Castniidae implying a novel, unparalleled butterfly-like reproductive behavior in moths. This will also have practical implications in applied entomology since it signifies that the monitoring/control of castniid pests should not be based on the use of female-produced pheromones, as it is usually done in many moths.

 

Hamamelitannin from Witch Hazel (Hamamelis virginiana) Displays Specific Cytotoxic Activity against Colon Cancer Cells.

Sánchez-Tena S, Fernández-Cachón ML, Carreras A, Mateos-Martín ML, Costoya N, Moyer MP, Nuñez MJ, Torres JL, Cascante M.

J. Nat. Prod. 76, 26-33, 2012 (A)

Hamamelis virginiana (witch hazel) bark is a rich source of condensed and hydrolyzable tannins reported to exert a protective action against colon cancer. The present study characterizes different witch hazel tannins as selective cytotoxic agents against colon cancer. To cover the structural diversity of the tannins that occur in H. virginiana bark, the hydrolyzable tannins, hamamelitannin and pentagalloylglucose, together with a proanthocyanidin-rich fraction (F800H4) were selected for the study. Treatment with these compounds reduced tumor viability and induced apoptosis, necrosis, and S-phase arrest in the cell cycle of HT29 cells, with hamamelitannin being the most efficient. Owing to polyphenol-mediated H(2)O(2) formation in the incubation media, the antiproliferative effect was determined in the presence and absence of catalase to rule out any such interference. The presence of catalase significantly changed the IC(50) only for F800H4. Furthermore, at concentrations that inhibit the growth of HT29 cells by 50%, hamamelitannin had no harmful effects on NCM460 normal colonocytes, whereas pentagalloylglucose inhibited both cancerous and normal cell growth. Using the TNPTM assay, we identified a highly reactive phenolic position in hamamelitannin, which may explain its efficacy at inhibiting colon cancer growth.

 

Tailor-made biopolymers from leather waste valorisation

Mercedes Catalina, Jaume Cot, Alina Mariana Balu, Juan Carlos Serrano-Ruiz and Rafael Luque

Green Chem., 14, 308, 2012

Tanning waste from leather processing can be valorised to tailor-made collagen biopolymers with diverse shapes (fibers, gels, films and sponges). The obtained biopolymers have been conveniently modified using various methodologies including crosslinking with various compounds with the aim of generating waste-derived renewable biopolymers with enhanced properties which can have important and promising applications in the fields of cosmetics, medicine or veterinary. 

 

Unsaturated Fatty Alcohol Derivatives of Olive Oil Phenolic Compounds with Potential Low-Density Lipoprotein (LDL) Antioxidant and Antiobesity Properties

Bruno Almeida Cotrim, Jesús Joglar, M. Jesús L. Rojas, Juan Manuel Decara del Olmo, Manuel Macias-González, Miguel Romero Cuevas, Montserrat Fito, Daniel Muñoz-Aguayo, María Isabel Covas Planells, Magí Farre, Fernando Rodríguez de Fonseca, and Rafael de la Torre

J. Agric.Food Chem. 60, 1067−1074, 2012

A new route for the synthesis of fatty alcohol derivatives of hydroxytyrosol and other olive oil phenolic compounds was developed to allow the preparation of unsaturated derivatives. The biological activity of synthesized compounds was evaluated. Most of the compounds presented a significant antioxidant activity on low-density lipoprotein (LDL) particles. The activity of the tested products was significantly influenced by the number and position of unsaturations as well as modifications on the polar head of the synthesized compounds. Some of them presented modulation of food intake in rats and, due to their molecular similarity with CB1 endogenous ligands, the endocannabinoid system and PPAR-α were also evaluated as potential targets. The pharmacodynamics could not be totally explained by CB1 and PPAR-α receptor interactions because only two of the four compounds with biological activity showed a CB1 activity and all of them presented low PPAR-α affinity, not justifying its whole in vivo activity. The hydroxytyrosol linoleylether (7) increased LDL resistance to oxidation with a capacity similar to that of hydroxytyrosol and was the most active in vivo compound with a hypophagic effect comparable to that of oleoylethanolamine. We consider that this compound could be a good lead compound for future drug development in obesity treatments.

 

Nanobiosensors for In Vitro and In Vivo Analysis of Biomolecules

J.-Pablo Salvador , Mark P. Kreuzer , Romain Quidant , Gonçal Badenes , and M.-Pilar Marco

Methods in Molecular Biology 811, 207-221, 2012. Springer Science+Business Media, LLC

This chapter presents as a proof of concept the development of a nanosensor based on the localized surface plasmon resonance for the analysis of biomolecules. The method presented take advantage of the plasmon generated in the surrounding of gold nanoparticles (i.e., 100 nm) for the specifi c interaction between antigen and antibody. The procedure for the optimization of an assay for the determination of biomolecules consisted mainly of four steps. First, the immobilization of gold nanoparticles over the glass surface using the appropriate ratio, concentration and time-contact of amino-sylilating agent, and nonreactive sylilating agent. Next, the suitable concentration of coating antigen in order to obtain the maximum signal LSPR. Following this step, the interaction between antigen and antibody (specifi c antibody) is evaluated by measuring the signal LSPR. Finally, a calibration curve was obtained for the detection of a small organic molecule such as stanozolol using this nanobiosensor. As a proof of concept, the use of a model is performed that in this case is for the detection of an anabolic androgenic steroid, such as stanozolol which is banned for the European Commission (EC) as a growth promoter and for the World Anti-Doping Agency (WADA) as a doping agent. The nanosensor developed demonstrates its feasibility for screening purposes due to the limit of detection achieved (0.7 μ g/L) is under the MRPL required for both organizations (10 μ g/L). A protocol such as that presented here may be generally applied for the analysis of other pollutant such as pesticides or antibiotics, or for biomedical applications for the analysis of biomarkers using the LSPR principle using gold nanoparticles (i.e., 30–120 nm).

 


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