Publications

Abstract Monoamine oxidase (MAO) generates reactive oxygen species (ROS), which cause neuronal cell death, causing neurodegeneration. Agents that are able to concurrently inhibit MAO and scavenge free radicals represent promising multifunctional neuroprotective agents that could be used to delay or slow the progression of neurodegenerative diseases. In this work, variously substituted 3-amidocoumarins are described that exert neuroprotection in vitro against hydrogen peroxide in rat cortical neurons, as well as antioxidant activity in a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Selective and reversible inhibitors of the MAO-B isoform were identified. Interestingly, in the case of the 3-benzamidocoumarins, substitution at position4 with a hydroxy group abolishes MAO-B activity, but the compounds remain active in the neuroprotection model. Further evaluation of 3-heteroarylamide derivatives indicates that it is the nature of the heterocycle that determines the neuroprotective effects. Evaluation in a parallel artificial membrane permeability assay (PAMPA) highlighted the need to further improve the blood-brain barrier permeability of this compound class. However, the compounds described herein adhere to Lipinskis rule of five, suggesting that this novel scaffold has desirable properties for the development of potential drug candidates.

Abstract Introduction: Chromones are one of the major classes of naturally occurring compounds. Their chemistry has been widely explored and extensively reviewed. The following review intends to give a broad overview of the patented chromones. Particular attention has been given to their synthesis, uses and applications in last 10 years.Areas covered: The authors provide an overview of the recent scientific reports describing the obtaining and study of new chromones. The review emphasizes the rationale behind natural sources, synthesis, biological activities and structure-activity relationships of the new chromone derivatives. The article is based on the literature published from 2005 to 2015 related to the development of this family of compounds. The patents presented in this review have been collected from multiple electronic databases including SciFinder, Espacenet and Mendeley.Expert opinion: Although a great number of chromones have been published in bibliographic sources in the last years, there is little innovation in the synthetic methodologies. Some natural sources and isolation techniques were described. Different pharmacological applications have also been claimed. Two of the most studied applications have been the use of these compounds as therapeutic agents for cancer and skin diseases. Some safety requirements need to be developed in order to find new chemical entities as new drugs.

Abstract A computational study has been performed for protonated oxygen- or nitrogen-containing heterocyclic derivatives of cyclopropane and cyclopropanone. We have searched for the most stable conformations of the protonated species using density functional theory with the B3LYP functional and the 6-31G(2df,p) basis set. More accurate enthalpy values were obtained from G4 calculations. Proton affinities and gas-phase basicities were accordingly derived.

Abstract Fluorescent carbon dots (CDs) and its nitrogen doped (N-CDs) nanoparticles have been synthesized from lactose as precursor using a bottom-up hydrothermal methodology. The synthesized nanoparticles have been characterized by elemental analysis, FUR, Raman, TEM, DLS, XPS, and steady-state and life-time fluorescence. The synthesized carbon nanoparticles, CDs and N-CDs, have a size at about 7.7 +/- 2.4 and 50 +/- 15 nm, respectively, and quantum yields of 8% (CDs) and 11% (N-CDs). These techniques demonstrated the effectiveness of the synthesis procedure and the functionalization of the CDs surface with amine and amide groups in the presence of NH3 in aqueous media. The effect of excitation wavelength and pH on the luminescent properties was studied. Under the optimal conditions, the nitrogen doped nanoparticles can be used as pyridine sensor in aqueous media because they show an enhancement of its fluorescence with a good linear relationship. The analytical method is simple, reproducible and very sensitive for pyridine determination.

Abstract Highly luminescent nanoparticles based in Silicon quantum dots, coated by hydroxyl PAMAM dendrimer (PAMAM-OH) of 5th generation, were obtained by one step process by hydrothermal treatment of 3-Aminopropyl)triethoxysilane (APTES) in aqueous solution. Previous to the optimization of the synthesis procedure, different dendritic molecules of 5th generation were tested to obtain the most intense fluorescence signal. The influence of different parameters such ratio APTES/PAMAM-OH, pH and ionic strength on the fluorescence intensity was studied. The fluorescence spectra showed maximum excitation and emission wavelengths at 370 and 446 nm, respectively. The obtained silicon nanoparticles (SiQDs@PAMAM-OH) were characterized by TEM, DLS and XPS, and were found to detect selectively Cr (VI) in aqueous solutions at 2.7 mu M level of detection, sensitivity of 0.2 mu M with a RSD of 0.16% (n=10). To study the feasibility of the proposed system for Cr(VI) detection, it was tested in real electrochemical solution bath and a tanning effluent obtained from electrochemical industry and with two certified waters, demonstrating promising outcomes as nano-sensor.

Abstract This work presents the synthesis, volatility study and electrospray ionization mass spectrometry with energy-variable collision induced dissociation of the isolated [(cation)(2)(anion)](+) of a novel series of 2-alkyl-1-ethyl pyridinium based ionic liquids, [(CN-2C2Py)-C-2-C-1][NTf2]. Compared to the imidazolium based ionic liquids, the new ionic liquid series presents a higher thermal stability and lower volatility. The [(cation)(2)(anion)](+) collision induced dissociation energies of both [(CN-2C2Py)-C-2-C-1][NTf2] and [CNPy][NTf2] pyridinium series show an identical trend with a pronounced decrease of the relative cation-anion interaction energy towards an almost constant value for N = 6. It was found that the lower volatility of [(CN-2C2Py)-C-2-C-1][NTf2] with a shorter alkyl chain length is due to its higher enthalpy of vaporization. Starting from [(C3C2Py)-C-2-C-1][NTf2], the lower volatility is governed by the combination of slightly lower entropies and higher enthalpies of vaporization, an indication of a higher structural disorder of the pyridinium based ionic liquids than the imidazolium based ionic liquids. Dissociation energies and volatility trends support the cohesive energy interpretation model based on the overlapping of the electrostatic and van der Waals functional interaction potentials.

Abstract Six N-substituted-phenyl 4-oxo-4H-chromene-3-carboxamides, namely N-(2-nitrophenyl)-4-oxo-4H-chromene-3-carboxamide, C16H10N2O5 (2b), N-(3-methoxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (3a), N-(3-bromophenyl)-4-oxo-4H-chromene-3-carboxamide, C16H10BrNO3, (3b), N-(4-methoxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (4a), N-(4-methylphenyl)- 4-oxo-4H-chromene-3-carboxamide, C17H13NO3, (4d), and N-(4-hydroxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C16H11NO4, (4e), have been structurally characterized. All compounds exhibit an anti conformation with respect to the C-N rotamer of the amide and a trans-related conformation with the carbonyl groups of the chromone ring of the amide. These structures present an intramolecular hydrogen-bonded network comprising an N-H center dot center dot center dot O hydrogen bond between the amide N atom and the O atom of the carbonyl group of the pyrone ring, forming an S(6) ring, and a weak Car-H center dot center dot center dot O hydrogen bond in which the carbonyl group of the amide acts as acceptor for the H atom of an ortho-C atom of the exocyclic phenyl ring, which results in another S(6) ring. The N-H center dot center dot center dot O intramolecular hydrogen bond constrains the carboxamide moiety such that it is virtually coplanar with the chromone ring.

Abstract Globally it is estimated that between 7.9 and 15.1 % of agricultural harvests are destroyed by pests, being wheat, rice, maize, potato, soybean and cotton, the most affected crops. With the exponential growth of worldwide population, an optimization in the crops protection against pests is urgently required, and because of that a 15- to 20- fold increasing in the chemical pesticides use has been observed. However, no significant effects on pest control have been observed. Despite of pesticides harmful properties against pests, they can indirectly improve the nutritional value of food. Nevertheless, the increased knowledge on their benefits and risks posed additional safety issues, namely those related to their low water solubility (bioavailability) and easy photodegradation. Several pesticides are easily decomposed by light and in that way a large amount of pesticide is needed to be applied in the crops in order to be effective. Some estimates point to the fact that less than 1 % of applied pesticides effectively reach the target. Furthermore, in some cases the metabolites originated by photodegradation of pesticides display a higher toxicity level. These facts associated with their capacity to act as carcinogenic, mutagenic and teratogenic agents to mankind, have led to a growing concern among scientific community to find a solution aimed to reduce or minimize the mentioned drawbacks and increase pesticide efficiency against pests. To increase the solubility and photostability as well as to facilitate the handling of pesticides, microencapsulation in nanostructures, namely cyclodextrins (CDs), has been proposed as a putative solution. CDs are cyclic oligosaccharides composed by D-glucose units connected by α-1,4-glycosidic linkages. The CDs structural characteristics, hydrophobic interior cavity and hydrophilic shell, and its ability to alter the physical, chemical, and biological properties of guest molecules has been regarded as a solution to improve pesticide formulations and to attain environmental sustainability. In this chapter, we will give special attention to the main pesticide groups and their inherent health and environmental issues. General features of CDs and the progress done so far in the field of microencapsulation of pesticides in CDs, will also be reported.

Abstract As mitochondria have an important role as ATP supplier, cellular ROS producer and apoptosis regulator, these organelles are a promising target for pharmacological intervention in the treatment and management of several diseases. Consequently, research on mitochondria-targeted drugs, which exclude other intracellular structures or extracellular processes, is becoming a hot topic. One approach to address the specific targeting is to conjugate bioactive molecules to a lipophilic cation such as the triphenylphosphonium (TPP+). In this chapter, the development of a new antioxidant based on the dietary cinnamic acid-caffeic acid-is described as well as the demonstration of its mitochondriotropic activity. © Springer Science+Business Media New York 2015. All right reserved.

Abstract The in vivo NO sensing is of outstanding relevance for the comprehension of the diverse physiological and pathological process in which this species is involved. Nevertheless, in vivo NO sensing is a complex challenge due to its own physicochemical properties, antioxidant mechanisms and possible interferences. Some electrochemical and optical sensors have already been developed for in vivo NO sensing. Most of the electrochemical sensors are amperometric and most of the optical sensors are based on fluorescence. New materials are being developed for new NO electrochemical or optical sensors. Due to their intrinsic properties, the nanomaterials are one of the most promising emergent materials. This chapter review the most promising nanomaterials for the development of electrochemically or optical sensors for in vivo NO sensing. © 2015 Nova Science Publishers, Inc.