Publications

Abstract Background: Skin fungal infections are regular injuries suffered by people living in tropical areas. Most common pathogens are Trichophyton, Microsporum and Epidermophyton which can cause skin lesions in many parts of body. Topical antifungal phytochemicals are commonly used to avoid systemic adverse events and are more convenient for patient application than those administered by other routes. However, the effectiveness of topical treatments in eradicating fungal infection is more limited since the stratum corneum acts as the skin barrier, resulting in long treatment duration and low patient's compliance. Methods: The goal of this work is to identify optimized drug delivery systems to improve topic clinical efficacy. Microemulsions i.e. liquid dispersions of oil and water stabilized with an interfacial film of surfactant are well known drug delivery systems. Results: A thickening agent may be included to form microemulsion-based gels to increase skin adhesion. Microemulsions and microemulsion-based gels can be loaded with several hydrophilic and lipophilic drugs because they are composed of both water and oil phases. Conclusion: Microemulsions and microemulsion-based gels can also be used for the delivery of many drugs including antifungal drugs through stratum corneum due to their capacity to act as skin penetration enhancement. In addition to a comprehensive review of microemulsion and microemulsion-based gels as suitable carriers for skin delivery of various antifungal drugs, this review also aims to discuss the delivery of antifungal phytochemicals.

Abstract In this paper, we investigate the nature of the carbonyl and the intraring C-C, C-N, C-O, N-N, O-O and N-O bonds of cyclopropanone and the following cyclopropanone derivatives: aziridine-2-one (1); oxirane-2-one (2); 1,2-diaziridine-3-one (3); 1,2-dioxirane-3-one (4); 1,2-oxaziridine-3-one (5); cyclopropane-1,2-dione (6); aziridine-2,3-dione (7); and oxirane-2,3-dione (8). The intramolecular distribution of the electronic charge density and the L(r) = -A1/4a double dagger(2) rho(r) function have been investigated within the framework of the quantum theory of atoms in molecule theory. This methodology allowed us to characterize the bonds of cyclopropanone and the cyclopropanone derivatives studied here.

Abstract Carbon dots (CDs) were prepared from citric acid and urea, and their fluorescence was found to be quenched by hypochlorite and peroxynitrite. Microwave based synthesis gives CDs with excitation/emission wavelength-dependent quantum yields (8 % at 400/520 nm; 10 % at 360/451 nm; 12 % at 350/420 nm). Quenching of fluorescence depends on pH values, and response is most selective and sensitive to hypochlorite at pH 4, and to peroxynitrite at pH 9. The lower detection limits are 0.5 and 1.5 mu M, respectively. The method was successfully applied to quantify hypochlorite and peroxynitrite in standard solutions and in spiked dilute serum samples.

Abstract We present herein the synthesis, and the structural and spectroscopic analysis of a non-planar tripod-shaped p-(N,N'-dimethylamino) benzyliden-1,3-indandione (DMABI) chromophore. This novel molecule is composed of a Si core with three incorporated arms, each of them contains a 1,3-indandione derivative with an electron donating (-NMe2) group, thus providing fluorescence capabilities. We prepared a DMABI arm by coupling a p-(N,N'-dimethylamino) benzaldehyde (DMAB) tripod substituted molecule with 1,3-indandione via aldol condensation. The structures of DMAB-tripods were confirmed by spectroscopic data and studied by quantum chemical calculations. Fluorescence spectroscopy was used for optical characterization. Quantum yields and the corresponding lifetimes reveal typical characteristics of conjugated derivatives. Finally, we monitored the enhancement in fluorescence intensity of compound 1 in the presence of 4-chloro-2,6-dinitroaniline (4CDNA) in the range between 0 and 20 mg L-1. We justify this enhancement by calculated energies and the distribution of the HOMO and the LUMO for DMABI-tripod and 4CDNA.

Abstract The thermodynamics and phase behavior of mixtures of cationic gemini surfactant decanediyl-alpha, omega-bis(dodecyldimethylammonium bromide) (12-10-12) and sodium dodecylsulfate (SDS) were studied in the dilute SDS-rich region. The enthalpy of interaction between both surfactant monomers before the critical micelle concentration for the mixture (cmc(mix)) was determined by isothermal titration calorimetry (ITC). After the cmc(mix), ITC results exhibited a first process associated with a large endothermic enthalpy change followed by a second one with a very small exothermic enthalpy change. In the same regions, the conductivity curves show an increase in slope after the break, followed by a plateau region, respectively for the two processes. The combined results from the various methodologies used lead us to propose that the first process reflects the formation of non-spherical micelles and the second one the vesicle formation. The area per catanionic complex was obtained through surface pressure measurements, leading to an apparent packing parameter >= 1. The observed behavior may be rationalized on the basis of the hypothesis that both surfactants distribute asymmetrically in the vesicle bilayers and unevenly in the non-spherical micelle. In order to get structural information Cryo-TEM experiments were performed, which provided images that support this interpretation. From all the information gathered a phase diagram was mapped, including three one-phase regions of spherical micelles, non-spherical micelles and vesicles.

Abstract Biofilms are encountered on nearly all wet surfaces, with their development being often unwanted due to the serious problems they can cause in different fields, including in the food sector. They are recognized as the preferential microbial lifestyle due to the numerous advantages for the embedded cells. Biofilm cells are highly resistant to stress conditions, particularly to antimicrobials, as their complex and compact structure hampers the penetration of antimicrobials and the access to the deep positioned cells. The increased resistance to the currently employed control strategies emphasizes the urgent need of new alternative and/or complementary eradication approaches. To this direction, the use of enzymes is an interesting alternative anti-biofilm approach due to their capability to degrade crucial components of the biofilm matrix, cause cell lysis, promote biofilm disruption and interrupt the cell-to-cell signaling events governing biofilm formation and maintenance. This review provides an overview of the enzymes used for biofilm control, their targets and examples of effective applications.

Abstract Background: Virtual Screening methodologies have emerged as efficient alternatives for the discovery of new drug candidates. At the same time, ensemble methods are nowadays frequently used to overcome the limitations of employing a single model in ligand-based drug design. However, many applications of ensemble methods to this area do not consider important aspects related to both virtual screening and the modeling process. During the application of ensemble methods to virtual screening the proper validation of the models in virtual screening conditions is often neglected. No analysis of the diversity of the ensemble members is performed frequently or no considerations regarding the applicability domain of the base models are being made. Methods: In this research, we review basic concepts and definitions related to virtual screening. We comment recent applications of ensemble methods to ligand-based virtual screening and highlight their advantages and limitations. Results: Next, we propose a method based on genetic algorithms optimization for the generation of virtual screening tailored ensembles which address the previously identified problems in the current applications of ensemble methods to virtual screening. Conclusion: Finally, the proposed methodology is successfully applied to the generation of ensemble models for the ligand-based virtual screening of dual target A2A adenosine receptor antagonists and MAO-B inhibitors as potential Parkinson's disease therapeutics.

Abstract Steady-state and time-resolved fluorescence techniques, in addition to quantum mechanical calculations, were employed to study the excited-state proton transfer (ESPT) to solvent of three 7-hydroxycoumarin dyes. We found that for 7-hydroxycoumarins in water, the ESPT rate is high, about 2 X 10(10) s(-1), whereas in methanol the ESPT rate is much lower than that over the nonradiative lifetime of the excited singlet state; thus, the ESPT efficiency is very low.

Abstract The heat capacities in the temperature range (5 to 370) K and the parameters of solid-phase transitions and fusion were determined for three [C(n)mim][NTf2] (n = 10, 14, 16) ILs. The temperature-dependent vapour pressures of [C(14)mim][NTf2] and [C(16)mim][NTf2] were measured with a Knudsen effusion apparatus combined with a quartz crystal microbalance. Thermodynamic properties of these compounds in the crystal, liquid, and gas states were derived from the obtained data. The results obtained in this work were combined to those available in the literature for the short-chain homologues to discuss regularities in thermodynamic properties of the series. While some properties demonstrate simple linear dependence on the alkyl chain length, a more complicated behaviour with strong non-linearity or a break at n = 6 is observed for others. Published by Elsevier Ltd.