Publications

Abstract Persistent bacterial infections and increased resistance to multidrugs are mostly related with biofilm formation which constitute a global concern in nowadays society. Therefore, studies must be conducted in order to discover more efficient antibiofilm agents. Nine compounds with a catecholic moiety (catechol (CAT), veratrol (VER), guaiacol (GUA), 2-ethoxphenol (ETH), 4-methylcatechol (MEC), 4-tert-butylcatechol (TEB), pyrogallol (PYR), 3-methoxycatechol (MET), and o-phenylene-phosphochloridite (OPP)) were investigated for their potential to prevent and eradicate Escherichia coil biofilms. Their action was assessed on biomass and metabolic activity, sessile cells' membrane integrity and culturability, motility and cell surface hydrophobicity (CSH). ETH, MEC, TEB, PYR and OPP exhibited the best antibiofilm activities among the tested catechols, inducing biofilm removal and metabolic inactivation, sessile cells' membrane disruption and death. CAT, TEB and PYR significantly inhibited E. coil swimming motility. Likewise, ETH, MEC, TEB and PYR significantly reduced E. coil CSH. An additive interaction of combined catechols with ciprofloxacin was attained in both control and preventive strategies. From a structure activity relationship (SAR) study, an increase in the hydrocarbon side chain and lipophilicity using ETH and TEB as scaffolds is suggested for increased activity. Hydroxyl groups are also suggested to be particularly related to their antibiofilm activity. All the catechols fulfil the Lipinski's "rule of five" requisites and thus are promising scaffolds in the development of new formulations for therapeutic purposes.

Abstract The comprehension of molecular recognition phenomena demands the understanding of the energetic and kinetic processes involved. General equations valid for the thermodynamic analysis of any observable that is assessed as a function of the concentration of the involved compounds are described, together with their implementation in the AFFINImeter software. Here, a maximum of three different molecular species that can interact with each other to form an enormous variety of supramolecular complexes are considered. The corrections currently employed to take into account the effects of dilution, volume displacement, concentration errors and those due to external factors, especially in the case of ITC measurements, are included. The methods used to fit the model parameters to the experimental data, and to generate the uncertainties are described in detail. A simulation tool and the so called kinITC analysis to get kinetic information from calorimetric experiments are also presented. An example of how to take advantage of the AFFINImeter software for the global multi-temperature analysis of a system exhibiting cooperative 1:2 interactions is presented and the results are compared with data previously published. Some useful recommendations for the analysis of experiments aimed at studying molecular interactions are provided.

Abstract Bioseparation processes are a relevant part of modern biotechnology, particularly regarding the development of efficient and biocompatible methods for the separation and purification of added-value biologically active compounds. In this field, ionic liquids (ILs) have been proposed, either in liquid–liquid extractions, in which non-water miscible ILs or aqueous biphasic systems (ABS) formed by ILs can be used, or in solid–liquid extractions, in which they are covalently attached to create supported IL phases (SILPs). Aprotic ILs possess unique properties, such as non-volatility and designability, which are valuable in their use in bioseparation processes. In this chapter, we summarize and discuss bioseparation processes based on ILs, including both liquid–liquid and solid–liquid extractions, applied to amino acids and proteins. The most recent and remarkable advances in this area are emphasized, and improvements brought by the use of ILs properly discussed. New insights and envisaged directions with IL-based bioseparation processes are suggested. © Springer International Publishing AG, part of Springer Nature 2018.

Abstract The effects of essential oils (EOs) and their eight major components extracted from five aromatic and medicinal plant (AMP) species on the development of Fusarium oxysporum f. sp. albedinis, the phytopathogenic fungus responsible for fusarium wilt (referred to as Bayoud in Morocco) on date palm in Moroccan oases (Errachidia region), were studied. The EOs were extracted from the plants by hydrodistillation and chemically analyzed by gas chromatography-mass spectrometry. The major chemical components extracted from the EOs of each AMP were: Origanum compactum (carvacrol 29.26%, thymol 18.52%, O-cymene 11.89%, gamma-terpinene 10.77%); Thymus satureioides (borneol 22.73%, carvacrol 16.96%, alpha-terpineol: 12.20%); Rosmarinus officinalis (eucalyptol 26.45%, camphor 15.51%, alpha- and beta-pinene 21.31%); Lavandula dentata (linalool 30.22%, linalyl anthranilate 23.47%, eucalyptol 9.17%); Myrtus communis (myrtenyl acetate 50.28%, eucalyptol 15.01%). The antifungal activity of the isolated EOs and their major components in comparison to that of two synthetic fungicides was evaluated by calculating the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of each antifungal product. The results of this analysis showed that the EOs of O. compactum and T. satureioides were able to inhibit the growth of F. oxysporum at very low concentrations (MFC 5 and 13 mu l ml(-1), respectively); these values were relatively better than those of the mancozeb synthetic fungicide (MFC 6 mu l ml(-1)) and very much better than the EOs of R. officinalis, L. dentata and M. communis (MFC 40 mu l ml(-1)). Thymol and carvacrol were effective fungicides at a very low concentration (MFC 0.94 and 2.08 mu l ml(-1), respectively), followed in increasing concentration by alpha-terpineol (MFC 10 mu l ml(-1)), linalool (MFC 13.00 mu l ml(-1)) and borneol (MFC 26.67 mu l ml(-1)). alpha-Pinene, eucalyptol and myrtenyl acetate were shown to have comparable fungicide properties, but at high concentrations ranging from 20 to 80 mu l ml(-1). The effectiveness of the EO of Origanum and Thymus species would therefore appear to be linked to the abundant presence of carvracrol and thymol compounds. Given the damage caused by F. oxysporum on date palm trees and other plants in Morocco, as well as the environmental and health impacts of fungicides, the use of O. compactum and T. satureioides EOs or their major components (thymol and carvacrol) against this pathogen could be an alternative to commercially available synthetic fungicides.

Abstract Steady-state and time-resolved fluorescence techniques were used to study the excited-state proton transfer (ESPT) from an irreversible photoacid, 1-naphthol-3,6-disulfonate (1NP36DS), to methanol water mixtures. We found that at X-water = 0.3 the ESPT rate constant is higher by a factor of 10 that in neat methanol. TD-DFT calculations show that a mixed molecular bridge of two methanol molecules and one water molecule enables the ESPT from the 1-OH to the 3-sulfonate. The RO-(S-1) state is stable by -2.5 kcal/mol in comparison to the ROH(S-1) state. We compare the ESPT rate constants of a reversible photoacid, 8-hydroxy-1,3,6-pyrene-trisulfonate (HPTS), in the same methanol water mixtures. At X-water approximate to 0.3 the ESPT rate constant of HPTS increased by only 15%. We explain the large difference of the ESPT rate of 1NP36DS by the formation of a water bridge or a mixed methanol-water bridge from 1-OH to one of the sulfonates and the absence of such a bridge in HPTS. The water or mixed methanol-water bridge of 1NP36DS enhances the ESPT rate in methanol-water mixtures of low water mole ratio.

Abstract The volatility and cohesive energy of fluorinated ionic liquids, FILs, was evaluated and used to explored and understand the effect of fluorination of the ILs cations and anions on the cohesive interaction and structuration. For this, the vapour pressures at different temperatures using a Knudsen effusion apparatus coupled with a quartz crystal microbalance were measured for three fluorinated imidazolium-based ionic liquids. The enthalpies and entropies of vaporization were derived from the temperature dependence of the vapour pressures. The degree of fluorination of the ions leads to an increase of the IL volatility following the order: [C(8)mim][NTf2] < [C(8)mim] [BETI] <[C(8)H(4)F(13)mim][NTf2] < [C(8)H(4)F(13)mim][BETI]. The Gibbs energy of vaporization follows the opposite trend proving that the fluorination effect on the volatility of the studied ionic liquids is ruled by the increase of the entropy of vaporization that overlaps the increase of the cohesive energy of the liquids. The binding energies of gas-phase FILs ions were measured using electrospray tandem mass spectrometry (ESI-MS-MS). The energy required for extracting the fluorinated cation from the [(cation)(2)(anion)](+) aggregates in these fluorinated ionic liquids is significantly higher than in their non-fluorinated counterparts. The measured binding energies trends are in agreement with those found for the enthalpies of vaporization.

Abstract The order of the salting-in or salting-out inducing ability of ions on the aqueous solubility of macromolecules in aqueous solutions is known as the Hofmeister series. Taking into account that ionic liquids (ILs) are constituted by ions, they can exert similar effects on the solubility of other ILs in aqueous media. To expand the knowledge of the salting-in/-out ability of ILs, experimental studies on the solubility of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonylimide) in water and in the presence of other IL/salts, were conducted at 298.15K and atmospheric pressure. Both the impact of the anion and cation of the IL were evaluated with the following ILs/salts: 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium hydrogensulfate, cholinium bis(trifluoromethylsulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide, over a wide composition range. As happens with common salts, both salting-in and salting-out effects exerted by ILs were observed, with a higher impact exerted by the IL anion on the salting-out phenomenon. These data allow better understanding of the ILs impact when designing liquid-liquid separation processes. [GRAPHICS] .

Abstract Recent studies have shown that besides the well-known T-3 (triiodothyronine) and T-4 (thyroxine) there might be other important thyroid hormones, in particular T(0)AM (thyronamine) and T(1)AM (3-iodothyronamine). The absence of a large number of studies showing their precise importance might be explained by the limited number of analytical methodologies available. This work aims to show an electroanalytical alternative making use of electropolymerized molecularly imprinted polymer (MIPs). The MIPs' polymerization is performed on the surface of screen-printed carbon electrodes (SPCEs), using 4-aminobenzoic acid (4-ABA) as the building and functional monomer and the analyte T(0)AM as the template. The step-by-step construction of the SPCE-MIP sensor was studied by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS). After optimization, by means of square-wave voltammetry, the SPCE-MIP showed suitable selectivity (in comparison with other thyroid hormones and catechol amines), repeatability (intra-day of 3.9%), a linear range up to 10 mu mol L-1 (0.23 x 10(3) mu g dL(-1)) with an r(2) of 0.998 and a limit of detection (LOD) and quantification (LOQ) of 0.081 and 0.27 mu mol L-1 (L9 and 6.2 mu g dL(-1)), respectively.

Abstract The chain-length dependence of the thermodynamic properties associated with the solid-to-liquid, liquid-to-gas, and solid-to-gas phase equilibria is analyzed and discussed for homologous families of linear alpha,omega-disubstituted alkanes, R-(CH2)(n)-R series. A remarkable alternation on the melting properties exhibited by even and odd-numbered alkanes is clearly emphasized in their a,w-disubstituted derivatives since the even members display increased properties due to their higher crystal packing density. The odd-even effect is also perceived in the values of Delta H-sub degrees and Delta S-sub degrees. Strong hydrogen bonding contributes to high boiling points and Delta H-vap degrees values evidenced by alkane-alpha,omega-diols. Moreover, the anomalously low values of Delta H-sub degrees and Delta H-vap degrees reported for larger dicarboxylic acids suggest the formation, in the vapor phase, of hydrogen-bonded cyclic structures. Furthermore, the analysis of the Delta H-fus degrees/Delta H-sub degrees and Delta S-sub degrees/Delta S-sub degrees ratios is used to highlight the contribution of functional groups to the cohesive interaction preserved in the liquid phase after a fusion transition. The thermodynamic interpretation indicates a higher structuration in the liquid alkane-alpha,omega-diols and alkane-alpha,omega-dioic acids, which have lower ratios of Delta H-fus degrees/A(sub)H degrees than corresponding n-alkanes. In addition, the thermodynamic analysis supports that hydrogen bonding in the liquid phase of alkanamines or alkane-alpha,omega-diamines has a significant low contribution to the overall intermolecular interactions.