Verónica Carrasco-Sánchez

The Morita-Baylis-Hillman reaction: insights into asymmetry and reaction mechanisms by electrospray ionization mass spectrometry.

This short review presents new insights on the mechanism and online monitoring using electrospray ionization tandem mass spectrometry (ESI–MS/MS) of Morita–Baylis–Hillman (MBH) reactions. MBH reactions are versatile carbon-carbon organocatalyzed bond forming reactions, making them environmentally friendly due to general organocatalysts employed. The organocatalyst behavior, which controls the transition state and thus the enantioselectivities in the obtained products, is very important in the performance of asymmetric MBH transformations. Some recent techniques and advances in asymmetric transformations are reviwed, as well as online reaction monitoring and analysis of the reaction intermediates. The mechanism accepted nowadays is also review through the insights gained from the use of ESI–MS/MS techniques.

In situ and in silico evaluation of amine- and folate-terminated dendrimers as nanocarriers of anesthetics

The search for new nano-systems for targeted biomedical applications and controlled drug release has attracted significant attention in polymer chemistry, pharmaceutics, and biomaterial science. Controlled drug delivery has many advantages over conventional drug administration, such as reduction of side effects, maintaining a stable plasma level concentration and improving the quality of life of patients. In this study, PAMAM G5 dendrimers and PAMAM G5-folic acid conjugates (PAMAM G5-FA) are synthesized and characterized by mass spectrometry (MALDI-MS). Controlled release studies at different pH values show that PAMAM G5-FA is a good candidate as a carrier for tramadol and morphine, while mathematical modeling is conducted, suggesting that the release process is governed by a diffusion mechanism. In addition, using molecular dynamics simulations, we investigate the structural and energetic properties that facilitate the encapsulation of tramadol and morphine by unmodified and functionalized PAMAM-G5 dendrimers at low, neutral and high pH. Our results correlate well with experimental data, confirming that tramadol and morphine may be encapsulated both by functionalized PAMAM dendrimers and unmodified PAMAM. Moreover, the simulations further reveal that hydrogen-bond and electrostatic interactions govern the affinity the dendrimers for both drugs. This information is envisioned to prove useful for the encapsulation of other drugs and for the design of novel functionalized dendrimers.

Synthesis and characterization of an insoluble polymer based on polyamidoamine: applications for the decontamination of metals in aqueous systems.

We present a novel, insoluble, low-generation polyamidoamine (PAMAM)-based polymer. The monomer and polymer were characterized by fourier transform infrared spectroscopy, electrospray ionization mass spectrometry and thermogravimetric measurement, revealing that G0 acryloyl-terminated PAMAM were synthesized and polymerized using ammonium persulfate as an initiator, producing a high-density PAMAM derivative (PAMAM-HD). PAMAM-HD was tested for its ability to remove Na(I), K(I), Ca(II), Mg(II), Cu(II), Mn(II), Cd(II), Pb(II) and Zn(II) ions from acidic, neutral and basic aqueous solutions. PAMAM-HD efficiently removed metals ions from all three solutions. The greatest absorption efficiency at neutral pH was observed against Cu(II), Cd(II) and Pb(II), and the experimental data were supported by the calculated Kd values. Our data could have a significant impact on water purification by providing an inexpensive and efficient polymer for the removal of metal ions.

The binding of 4-ethylguaiacol with polyaniline-based materials in wines

4-ethylguaiacol (4-EG) is one of the important compounds responsible for the Brett character (i.e. spicy and smoky aromas) found in wines contaminated with Brettanomyces yeast. In this trial, the ability of polyaniline-based materials (PANI-EB and PANI-ES) was tested as a potential fining agent for the removal of 4-EG in wine. First, a screening study was developed in order to determine the binding capacity of 4-EG by PANI materials in 12% ethanol solution. Then, the capturing ability of PANI against 4-EG was evaluated with a solution containing gallic acid (GA), 4-methyl-catechol (4-MC), in which the concentration of the phenolic compounds were maintained as in the real wine. The results obtained showed that the retention percentage varied between 0 to 100% (4-EG), 13.81% to 72.32% (GA), and 0 to 17.39% (4-MC), depending on the interaction time and amount of the PANI used. Finally, the capturing capacity of PANI-EB and PANI-ES against 4-EG was evaluated in a real wine sample containing originally 3.10±0.13 mg L(-1) of 4-EG and 2.55±0.10 g L(-1) of other total phenolic compounds. The analyses performed indicated that PANI-EB is more effective in removing 4-EG than PANI-ES, with retention percentages varying between 36 and 50%.

Removal of 4-Ethylphenol and 4-Ethylguaiacol with Polyaniline-Based Compounds in Wine-Like Model Solutions and Red Wine.

Volatile phenols, such as 4-ethyphenol (4-EP) and 4-ethylguaiacol (4-EG), are responsible for the “Brett character” found in wines contaminated with Brettanomyces yeast (i.e., barnyard, animal, spicy and smoky aromas). In these trials, we explore the effectiveness of polyaniline-based compounds (polyaniline emeraldin salt (PANI-ES) and polyanaline emeraldin base (PANI-EB)), for the removal of 4-EP and 4-EG from acidic model solutions and red wine. First, a screening study, performed in an acidified 12% ethanol solution, was used to optimize parameters such as contact time and the amount of polymers required to remove 4-EP and 4-EG. Then, the trapping ability of PANI agents towards 4-EP and 4-EG was evaluated in a model solution containing other wine phenolics that could potentially be trapped by PANI (i.e., gallic acid and 4-methylcatechol). The results of this trial showed that both PANI compounds were capable of removing 4-EP, 4-EG, regardless of the presence of other phenolic compounds present at a much higher concentration. Finally, the capturing ability of PANI was evaluated in a red wine sample containing 5 mg·L−1 of 4-EP, 5 mg·L−1 of 4-EG and 2.03 ± 0.02 g·L−1 of total phenolics. The results showed that PANI-EB removed significantly more 4-EP and 4-EG than PANI-ES. For instance, a treatment with 10 mg·mL−1 of PANI-EB produced a 67.8% reduction of 4-EP, 50% reduction of 4-EG and 41.38% decrease in total phenols.

Removal of fumonisin B1 and B2 from model solutions and red wine using polymeric substances

Fumonisins are a group of mycotoxins found in various foods whose consumption is known to be harmful for human health. In this study, we evaluated the ability of three polymers (Polyvinylpolypyrrolidone, PVPP; a resin of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate, PVP-DEGMA-TAIC; and poly(acrylamide-co-ethylene glycol-dimethacrylate), PA-EGDMA) to remove fumonisin B1 (FB1) and fumonisin B2 (FB2) from model solutions and red wine. Various polymer concentrations (1, 5 and 10mgmL-1) and contact times (2, 8 and 24h) were tested, with all polymers exhibiting fumonisin removal capacities (monitored by LC-MS). The impact of all polymers on polyphenol removal was also assessed. PA-EGDMA showed to be the most promising polymer, removing 71% and 95% of FB1, and FB2, respectively, with only a 22.2% reduction in total phenolics.

Chemotaxonomic Fingerprinting of Chilean Lichens Through Maldi and Electrospray Ionization Mass Spectrometry

The aim of this work was to study a fast, new, sensitive, and simple method for the chemotaxonomic classification of Chilean lichens (Teloschistes chrysophthalmus, Ramalina farinacea, Usnea pusilla, Ramalina chilensis and Stereocaulon ramulosum) using MALDI-TOF-MS and UPLC-ESI(-)-MS data. Lichens soluble proteins fingerprints were acquired by MALDI-TOF-MS and they were analyzed by chemometric (PCA). Lichens organic extracts fingerprints were obtained by UPLC-ESI(-)-MS. MALDI-TOF-MS associated with chemometric analysis was used to detect new m/z patterns of soluble proteins that were compared with Protein Data Bank of UnitPro. These data also permitted the satisfactory distinction among the families and species. UPLC-ESI(-)-MS fingerprints analyses of the organic extracts showed the presence of five major lichen compounds (atranorin, parietin, teloschistin, ramalinolic and usnic acids). In contrast to other techniques, MALDI-TOF-MS associated with chemometric analysis and UPLC-ESI(-)-MS provided a new, fast and sensitive method for chemotaxonomic characterization of lichens.

Rational Design, Synthesis and Evaluation of γ-CD-Containing Cross-Linked Polyvinyl Alcohol Hydrogel as a Prednisone Delivery Platform

This study describes the in-silico rational design, synthesis and evaluation of cross-linked polyvinyl alcohol hydrogels containing γ-cyclodextrin (γ-CDHSAs) as platforms for the sustained release of prednisone (PDN). Through in-silico studies using semi-empirical quantum mechanical calculations, the effectiveness of 20 dicarboxylic acids to generate a specific cross-linked hydrogel capable of supporting different amounts of γ-cyclodextrin (γ-CD) was evaluated. According to the interaction energies calculated with the in-silico studies, the hydrogel made from PVA cross-linked with succinic acids (SA) was shown to be the best candidate for containing γ-CD. Later, molecular dynamics simulation studies were performed in order to evaluate the intermolecular interactions between PDN and three cross-linked hydrogel formulations with different proportions of γ-CD (2.44%, 4.76% and 9.1%). These three cross-linked hydrogels were synthesized and characterized. The loading and the subsequent release of PDN from the hydrogels were investigated. The in-silico and experimental results showed that the interaction between PDN and γ-CDHSA was mainly produced with the γ-CDs linked to the hydrogels. Thus, the unique structures and properties of γ-CDHSA demonstrated an interesting multiphasic profile that could be utilized as a promising drug carrier for controlled, sustained and localized release of PDN.

Polymeric substances for the removal of ochratoxin A from red wine followed by computational modeling of the complexes formed

Ochratoxin A (OTA) is a mycotoxin produced by filamentous-type fungi that contaminates a wide variety of foods and beverages such as wines. In these trials, we evaluated the capacity of the following polymers for the removal of OTA from acidic model solutions and red wine: polyvinylpolypyrrolidone (PVPP), resin of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate (PVP-DEGMA-TAIC), and poly(acrylamide-co-ethylene glycol-dimethacrylate) (PA-EGDMA). In acidic model solution, PVP-DEGMA-TAIC and PA-EGDMA polymers removed up to 99.9% of OTA, but their trapping capacity was highly reduced by the presence of competing phenolic substances (i.e. gallic acid and 4-methylcathecol). In real red wine, PA-EGDMA polymer showed the most promising results, with more than 68.0% OTA removal and less than 14.0% reduction in total phenolic. Finally, computational chemistry analyses showed that the affinity between OTA and the polymers studied would be due to Van der Waals interactions.

Erratum: Carrasco-Sánchez, V.; et al. Removal of 4-Ethylphenol and 4-Ethylguaiacol with Polyaniline-Based Compounds in Wine-Like Model Solutions and Red Wine. Molecules 2015, 20(8), 14312–14325

The authors wish to make the following change to their paper [1]. The Acknowledgments sectionis incorrect in the published paper. The correct Acknowledgments should be as follows:Postdoctoral Fondecyt Project 3140295, Proyecto Anillo (Integracion de la BiologiaEstructural al desarrollo de la Bionanotecnologia, ACT 1107), Innova Chile CORFO(Grant FCR-CSB 09CEII-6991), Programa de insercion y atraccion CONICYT-79090038,and PIEI-QUIBIO (UTalca) are acknowledged. A.J acknowledges FONDECYT 11130087.We apologize for any inconvenience caused to the readers by this mistake.