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Papers by Karla Espinoza

Research paper thumbnail of Synthesis of Triazoles by Electro-Assisted Click Reaction Using a Copper Foil Electrode

Journal of the Brazilian Chemical Society

This paper presents an innovative pathway for the synthesis of triazoles using the well-known “cl... more This paper presents an innovative pathway for the synthesis of triazoles using the well-known “click chemistry” assisted by the electrochemical oxidation of metallic Cu0. The click reaction is used to couple a wide range of biological interest compounds. In this case, faster and less polluting methods for a biological environment was achived by in situ Cu0 electrooxidation, providing the suitable quantity of catalyst required by click reaction. The electrochemical cell was composed of a copper foil as the working electrode, a platinum wire serving as a counter electrode, and an Ag/AgCl wire as the reference electrode. Linear anodic sweep voltammetry in a tert-butanol-water medium (1:1), an electrolyte of tetrabutylammonium tetrafluoroborate (TBATFB), showed the onset potential of Cu0 electrooxidation. Using the same electrode configuration three different triazoles were prepared under constant electrode potential, in a short time (60 min), and splendid yields (78-90%). These results...

Research paper thumbnail of Virtual Screening of Putative Anticonvulsant Hydantoin Derived Drugs and Biological Evaluation

It has been found that derivatives of benzyl N-piperidin-4-one have similar effect than phenytoin... more It has been found that derivatives of benzyl N-piperidin-4-one have similar effect than phenytoin drug as an anticonvulsant for the treatment of epilepsy according to docking simulation studies. This is due to the similar binding mode in these chemicals. In this study, a series of six N-piperidinespirohydantoins derivatives were prepared by Bucherer-Bergs reaction, from corresponding N-piperidin-4-ones derivatives benzyl and phenethyl groups, substituted in the aromatic ring with metoxy and nitro groups. The hydantoins were evaluated for anticonvulsant activity with maximal electroshock (MES) induced method in vivo in male Wistar rats in the treatment of epilepsy.

Research paper thumbnail of Synthesis of Triazoles by Electro-Assisted Click Reaction Using a Copper Foil Electrode

This paper presents an innovative pathway for the synthesis of triazoles using the well-known “cl... more This paper presents an innovative pathway for the synthesis of triazoles using the well-known “click chemistry” assisted by the electrochemical oxidation of metallic Cu. The click reaction is used to couple a wide range of biological interest compounds. In this case, faster and less polluting methods for a biological environment was achived by in situ Cu electrooxidation, providing the suitable quantity of catalyst required by click reaction. The electrochemical cell was composed of a copper foil as the working electrode, a platinum wire serving as a counter electrode, and an Ag/AgCl wire as the reference electrode. Linear anodic sweep voltammetry in a tert-butanol-water medium (1:1), an electrolyte of tetrabutylammonium tetrafluoroborate (TBATFB), showed the onset potential of Cu electrooxidation. Using the same electrode configuration three different triazoles were prepared under constant electrode potential, in a short time (60 min), and splendid yields (78-90%). These results in...

Research paper thumbnail of Eco-Friendly Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones Catalyzed by FeCl3/Al2O3 and Analysis of Large 1 H NMR Diastereotopic Effect

Journal of the Brazilian Chemical Society

In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydr... more In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones from 2-amino-N-benzylbenzamide and different aromatic aldehydes using FeCl 3 catalyst supported on Al 2 O 3. It was demonstrated that this material can be used successfully for the nucleation of quinazolinones with good to excellent yield; furthermore, the FeCl 3 /Al 2 O 3 catalyst can be recovered and reused. This catalyst was used before in the synthesis of imidazole with very good yields. The synthesized quinazolinones showed a large range diastereotopic effect over the methylene group and, this anomalous difference was studied through nuclear magnetic resonance (NMR) and computational calculations.

Research paper thumbnail of Eco-Friendly Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones Catalyzed by FeCl3/Al2O3 and Analysis of Large 1 H NMR Diastereotopic Effect

Journal of the Brazilian Chemical Society, 2018

In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydr... more In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones from 2-amino-N-benzylbenzamide and different aromatic aldehydes using FeCl 3 catalyst supported on Al 2 O 3. It was demonstrated that this material can be used successfully for the nucleation of quinazolinones with good to excellent yield; furthermore, the FeCl 3 /Al 2 O 3 catalyst can be recovered and reused. This catalyst was used before in the synthesis of imidazole with very good yields. The synthesized quinazolinones showed a large range diastereotopic effect over the methylene group and, this anomalous difference was studied through nuclear magnetic resonance (NMR) and computational calculations.

Research paper thumbnail of Synthesis and Electrochemistry Evaluation of Multivalent o- Aminobenzamides and Quinazoline-2,4-diones

International Journal of Electrochemical Science, 2018

The o-aminobenzamides (OAB) and quinazoline-2,4-diones (QZD) are alkaloids with important biologi... more The o-aminobenzamides (OAB) and quinazoline-2,4-diones (QZD) are alkaloids with important biological properties such as sedatives, antipsychotics and anticonvulsants, these last properties can be evaluated by electrochemistry methods, using its electron transfer capacity. In this study six compounds (OAB, QZD) were synthesized and characterized, using spacers groups to link the functional moieties (presents on the mono, di and tri substituted systems of each alkaloid kind), when the spacers groups are present, an increase of pharmacological properties has been shown. We carried on electrochemistry evaluations to the synthetized compounds to predict the electron transfer. The results show a single oxidation potential (OP) for the mono and di-substituted compounds (OAB, QZD), and two different OP when the system is trimeric (OAB, QZD). The intensity of the OP signals in the open systems (OAB) is considerable higher in comparison with the closed systems (QZD), these oxidation potentials are assignation at amine groups, and the tertiary amines of trimeric compound present the highest intensity oxidation signals in comparison with secondary amines. The most favorable compound to realize the electron transfer are the open trimeric system.

Research paper thumbnail of Effect of Heteroatom Bridge in the Transfer Electron Process of O-Aminebenzamides and Quinazolinendiones Evaluated By Electrochemistry

Research paper thumbnail of Preparation of Polymeric Films of PVDMA–PEI Functionalized with Fatty Acids for Studying the Adherence and Proliferation of Langerhans β-Cells

ACS Omega

This study reports the synthesis of thin polymeric films by the layer-by-layer deposition and cov... more This study reports the synthesis of thin polymeric films by the layer-by-layer deposition and covalent cross-linking of polyvinyl dimethylazlactone and polyethylene imine, which were functionalized with lauric (12-C), myristic (14-C), and palmitic (16-C) saturated fatty acids, whose high levels in the bloodstream are correlated with insulin resistance and the potential development of type 2 diabetes mellitus. Aiming to assess the effect of the fatty acids on the adhesion and proliferation of Langerhans β-cells, all prepared films (35 and 35.5 bilayers with and without functionalization with the fatty acids) were characterized in terms of their physical, chemical, and biological properties by a battery of experimental techniques including 1 H and 13 C NMR, mass spectrometry, attenuated total reflectance−Fourier transform infrared spectroscopy, field emission scanning electron microscopy, atomic force microscopy, cell staining, and confocal laser scanning microscopy among others. In general, the developed films were found to be nanometric, transparent, resistant against manipulation, chemically reactive, and highly cytocompatible. On the other hand, in what the effect of the fatty acids is concerned, palmitic acid was found to impair the proliferation of the cultured βcells, contrary to its homologues which did not alter this biological process. In our opinion, the multidisciplinary study presented here might be of interest for the research community working on the development of cytocompatible 2D model substrates for the safe and reproducible characterization of cell responses.

Research paper thumbnail of Study of the green synthesis of silver nanoparticles using a natural extract of dark or white Salvia hispanica L. seeds and their antibacterial application

Applied Surface Science

Abstract In this research work, we report for the first time the green synthesis of silver nanopa... more Abstract In this research work, we report for the first time the green synthesis of silver nanoparticles (AgNPs), using two varieties of a natural extract of dark (D) or white (Wh) Salvia hispanica L. seeds, commonly named chia (Ch), as a reducing-stabilizing agent. Similarly, it was carried out a study on the effect of the variation of different physicochemical parameters, like aging time and storage temperature of the natural extract of dark Ch seeds, in the morphology, size and polydispersity of the prepared AgNPs. We found that the ideal conditions to do the green synthesis of AgNPs, are to use the Ch extract one day after it have been prepared and stored at 5 °C (1D C). The AgNPs were characterized by UV–Vis, FT-IR, FE-SEM-EDS and TEM. The TEM images of the synthesized AgNPs showed spherical morphology with an average nanoparticle size of 7 nm, at optimum conditions (AgNPs/D Ch (1D C)). Additionally, we studied the antimicrobial activity of the green synthesized AgNPs with both types of Ch seeds, against bacteria gram-positive and gram-negative, using as the bacterial model E. coli and S. aureus, respectively. We determined that the synthesized AgNPs/D Ch have more antimicrobial activity against both bacteria, in comparation with AgNPs/W Ch (ZOI against E. coli, 18.5 mm; S. aureus, 14.9 mm).

Research paper thumbnail of Microstrain analyses of Fe3O4NPs greenly synthesized using Gardenia jasminoides flower extract, during the photocatalytic removal of a commercial dye

Applied Nanoscience

The Gardenia jasminoides flower extract (Gjfe) was employed to prevent agglomeration during the m... more The Gardenia jasminoides flower extract (Gjfe) was employed to prevent agglomeration during the magnetite nanoparticles (Fe3O4NPs) synthesis. Different analytical techniques such as FTIR-ATR, Raman, SEM–EDS, XPS, XRD, and TEM, were used to characterize the synthesized nanoparticles. Also, microstrain analyses of Fe3O4NPs were carried out. The results of the characterization techniques indicated spherical and well dispersed Fe3O4NPs/Gjfe, with a nanoparticle size (TEM) of about 4.5 nm. The XRD analysis resulted in good agreement with respect to JCPDS no. 89-4319. Fe3O4NPs/Gjfe were employed in the photocatalytic degradation of a commercial fabric dye, without the addition of any extra reagents, or control of pH or temperature. The photocatalytic reaction, studied by UV–Vis spectroscopy, showed excellent results, achieving a dye removal of 100% in 60 min (0.20 mg/mL of commercial dye) using 50 mg of Fe3O4NPs/Gjfe. The stability of the recycled Fe3O4NPs/Gjfe was determined by the number of times that the synthesized nanoparticles can be re-used in the dye removal process, obtaining that after five cycles of use, they do not lose their photocatalytic activity.

Research paper thumbnail of In Situ Controlled Release of Dopamine for Treatment of Parkinson’s Disease

Research paper thumbnail of In-situ Release of Antiepileptic Drugs from Nanostructured Reservoirs

Underlying Mechanisms of Epilepsy, 2011

Research paper thumbnail of Study of the stabilization of zinc phthalocyanine in sol-gel TiO2 for photodynamic therapy applications

Nanomedicine: Nanotechnology, Biology and Medicine, 2010

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for ... more Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer. It is a two-step procedure that uses a combination of molecular oxygen, visible light, and photosensitizer (PS) agents; phthalocyanine (Pc) was supported over titanium oxide but has not yet been used for cell inactivation. Zinc phthalocyanine (ZnPc) molecules were incorporated into the porous network of titanium dioxide (TiO 2) using the sol-gel method. It was prepared from stock solutions of ZnPc and TiO 2. ZnPc-TiO 2 was tested with four cancer cell lines. The characterization of supported ZnPc showed that phthalocyanine is linked by the N-pyrrole to the support and is stable up to 250°C, leading to testing for PDT. The preferential localization in target organelles such as mitochondria or lysosomes could determine the cell death mechanism after PDT. The results suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent candidate as sensitizer in PDT against cancer and infectious diseases. From the Clinical Editor: Photodynamic therapy is a two-step procedure that uses a combination of molecular oxygen, visible light and photosensitizer agents as an alternative and promising non-invasive treatment for cancer. The results of this study suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent photosensitizer candidate against cancer and infectious diseases.

Research paper thumbnail of Alkylation of 2,4-(1H,3H)-Quinazolinediones with Dialkyl Carbonates Under Microwave Irradiations

Molecules, 2009

Alkylation is a very important chemical reaction which modifies the biological properties of drug... more Alkylation is a very important chemical reaction which modifies the biological properties of drugs. Quinazolinedione derivatives are of considerable interest due to their wide array of pharmacological properties. We now report application of a practical alkylation procedure to several quinazolinediones, including pelanserine (5f), which shows antihypertensive properties, 1-methyl-3-(2'-phenylethyl)-1H,3H-quinazoline-2,4-dione (1ab) and 1-methyl-3-[2'-(4'-methoxyphenyl)ethyl]-lH,3H-quinazoline-2,4-dione (1ae), which had been isolated from natural sources. The alkylation was optimized using dimethyl and diethyl carbonates under microwave irradiations.

Research paper thumbnail of Effect of Thermal Treatment of Sol-Gel Titania Reservoirs on Release Kinetics of Phenytoin

Journal of the American Ceramic Society, 2012

ABSTRACT The thermal stability of antiepileptic drug phenytoin was investigated on its encapsulat... more ABSTRACT The thermal stability of antiepileptic drug phenytoin was investigated on its encapsulation in titania matrix. It was shown that the drug is stable up to 150°C, even though phenytoin melting point was previously reported to be much higher. The mechanism of phenytoin decomposition is suggested and confirmed by the experiment on heating to higher temperatures. The influence of thermal treatment on physicochemical parameters of the matrix was studied. Quite different drug release kinetics were obtained in vitro and discussed in terms of temperature treatment influence and interplay of parameters of the matrix.

Research paper thumbnail of Alkylation of 2, 4-(1H, 3H)-Quinazolinediones with Dialkyl Carbonates Under Microwave Irradiations

Molecules, 2009

Alkylation is a very important chemical reaction which modifies the biological properties of drug... more Alkylation is a very important chemical reaction which modifies the biological properties of drugs. Quinazolinedione derivatives are of considerable interest due to their wide array of pharmacological properties. We now report application of a practical alkylation procedure to several quinazolinediones, including pelanserine (5f), which shows antihypertensive properties, 1-methyl-3-(2'-phenylethyl)-1H,3H-quinazoline-2,4-dione (1ab) and 1-methyl-3-[2'-(4'-methoxyphenyl)ethyl]-lH,3H-quinazoline-2,4-dione (1ae), which had been isolated from natural sources. The alkylation was optimized using dimethyl and diethyl carbonates under microwave irradiations.

Research paper thumbnail of Study of the stabilization of zinc phthalocyanine in sol-gel TiO 2 for photodynamic therapy applications

Nanomedicine-nanotechnology Biology and Medicine, 2010

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for ... more Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer. It is a two-step procedure that uses a combination of molecular oxygen, visible light, and photosensitizer (PS) agents; phthalocyanine (Pc) was supported over titanium oxide but has not yet been used for cell inactivation. Zinc phthalocyanine (ZnPc) molecules were incorporated into the porous network of titanium dioxide (TiO 2) using the sol-gel method. It was prepared from stock solutions of ZnPc and TiO 2. ZnPc-TiO 2 was tested with four cancer cell lines. The characterization of supported ZnPc showed that phthalocyanine is linked by the N-pyrrole to the support and is stable up to 250°C, leading to testing for PDT. The preferential localization in target organelles such as mitochondria or lysosomes could determine the cell death mechanism after PDT. The results suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent candidate as sensitizer in PDT against cancer and infectious diseases. From the Clinical Editor: Photodynamic therapy is a two-step procedure that uses a combination of molecular oxygen, visible light and photosensitizer agents as an alternative and promising non-invasive treatment for cancer. The results of this study suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent photosensitizer candidate against cancer and infectious diseases.

Research paper thumbnail of The Use of Solid-Phase Supported 1- N -Piperazine-4- N -carboxaldehyde in Vilsmeier Reactions

Journal of Combinatorial Chemistry, 2004

A Vilsmeier salt supported on solid phase was prepared using piperazine bound to Merrifield resin... more A Vilsmeier salt supported on solid phase was prepared using piperazine bound to Merrifield resin. Piperazine was selected because it contains two secondary amines: one of the amines is protected upon binding to the resin, and the second was formylated to give resin-1-N-piperazine-4-N-carboxaldehyde (9). Activation of the formamide with either bis(trichloromethyl)carbonate (BTC) or POCl 3 afforded the Vilsmeier salt 10. Several olefins were used to test the supported Vilsmeier reagent. The in-solution activation with BTC and POCl 3 of various secondary amides was also evaluated: dimethylformamide (1), N-methyformanilide (4), 4-formylmorpholine (5), and 1,4-dicarboxylpiperazine (6), which showed that amides with one additional heteroatom increase the yields in the Vilsmeier salt formation.

Research paper thumbnail of Method for Analysis of Polymer-Supported Organic Compounds Using Mass Spectrometry Direct Insertion

Journal of Combinatorial Chemistry, 2003

A new approach on the use of mass spectrometry direct-insertion and a quadrupole detector for ana... more A new approach on the use of mass spectrometry direct-insertion and a quadrupole detector for analysis of organic compounds supported in solid phase has been developed. This is a simple and efficient method based on cleavage due to the thermal-instability of the benzylic group of most commercial resins. The cleavage of supported compounds takes place in the spectrometer as a consequence of the high temperature in the instrument's chamber. These compounds are detected using a similar fragmentation pattern and a molecular ion corresponding to the same compound obtained by traditional synthesis. Polymer degradation fragments do not interfere with the spectrum interpretation, because only a few peaks and low intensities are detected. We report here the identification of different types of compounds supported in Merrifield resin, such as bis-o-aminobenzamides and simple aromatic and aliphatic compounds, using this new approach.

Research paper thumbnail of Role of Hydrolysis Degree in the Drug-Matrix Interactions of Nanosized Sol-Gel Titania Reservoirs for Epilepsy Treatment

... T. L pez* † ‡ § , K. Espinoza † , A. Kozina † , A. Galano , and R. Alexander-Katz. Laboratori... more ... T. L pez* † ‡ § , K. Espinoza † , A. Kozina † , A. Galano , and R. Alexander-Katz. Laboratorio de Nanotecnolog a ... Autonomous Metropolitan University (UAM). We gratefully acknowledge the support of Atilano Guti rrez in the NMR studies. ...

Research paper thumbnail of Synthesis of Triazoles by Electro-Assisted Click Reaction Using a Copper Foil Electrode

Journal of the Brazilian Chemical Society

This paper presents an innovative pathway for the synthesis of triazoles using the well-known “cl... more This paper presents an innovative pathway for the synthesis of triazoles using the well-known “click chemistry” assisted by the electrochemical oxidation of metallic Cu0. The click reaction is used to couple a wide range of biological interest compounds. In this case, faster and less polluting methods for a biological environment was achived by in situ Cu0 electrooxidation, providing the suitable quantity of catalyst required by click reaction. The electrochemical cell was composed of a copper foil as the working electrode, a platinum wire serving as a counter electrode, and an Ag/AgCl wire as the reference electrode. Linear anodic sweep voltammetry in a tert-butanol-water medium (1:1), an electrolyte of tetrabutylammonium tetrafluoroborate (TBATFB), showed the onset potential of Cu0 electrooxidation. Using the same electrode configuration three different triazoles were prepared under constant electrode potential, in a short time (60 min), and splendid yields (78-90%). These results...

Research paper thumbnail of Virtual Screening of Putative Anticonvulsant Hydantoin Derived Drugs and Biological Evaluation

It has been found that derivatives of benzyl N-piperidin-4-one have similar effect than phenytoin... more It has been found that derivatives of benzyl N-piperidin-4-one have similar effect than phenytoin drug as an anticonvulsant for the treatment of epilepsy according to docking simulation studies. This is due to the similar binding mode in these chemicals. In this study, a series of six N-piperidinespirohydantoins derivatives were prepared by Bucherer-Bergs reaction, from corresponding N-piperidin-4-ones derivatives benzyl and phenethyl groups, substituted in the aromatic ring with metoxy and nitro groups. The hydantoins were evaluated for anticonvulsant activity with maximal electroshock (MES) induced method in vivo in male Wistar rats in the treatment of epilepsy.

Research paper thumbnail of Synthesis of Triazoles by Electro-Assisted Click Reaction Using a Copper Foil Electrode

This paper presents an innovative pathway for the synthesis of triazoles using the well-known “cl... more This paper presents an innovative pathway for the synthesis of triazoles using the well-known “click chemistry” assisted by the electrochemical oxidation of metallic Cu. The click reaction is used to couple a wide range of biological interest compounds. In this case, faster and less polluting methods for a biological environment was achived by in situ Cu electrooxidation, providing the suitable quantity of catalyst required by click reaction. The electrochemical cell was composed of a copper foil as the working electrode, a platinum wire serving as a counter electrode, and an Ag/AgCl wire as the reference electrode. Linear anodic sweep voltammetry in a tert-butanol-water medium (1:1), an electrolyte of tetrabutylammonium tetrafluoroborate (TBATFB), showed the onset potential of Cu electrooxidation. Using the same electrode configuration three different triazoles were prepared under constant electrode potential, in a short time (60 min), and splendid yields (78-90%). These results in...

Research paper thumbnail of Eco-Friendly Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones Catalyzed by FeCl3/Al2O3 and Analysis of Large 1 H NMR Diastereotopic Effect

Journal of the Brazilian Chemical Society

In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydr... more In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones from 2-amino-N-benzylbenzamide and different aromatic aldehydes using FeCl 3 catalyst supported on Al 2 O 3. It was demonstrated that this material can be used successfully for the nucleation of quinazolinones with good to excellent yield; furthermore, the FeCl 3 /Al 2 O 3 catalyst can be recovered and reused. This catalyst was used before in the synthesis of imidazole with very good yields. The synthesized quinazolinones showed a large range diastereotopic effect over the methylene group and, this anomalous difference was studied through nuclear magnetic resonance (NMR) and computational calculations.

Research paper thumbnail of Eco-Friendly Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones Catalyzed by FeCl3/Al2O3 and Analysis of Large 1 H NMR Diastereotopic Effect

Journal of the Brazilian Chemical Society, 2018

In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydr... more In the present study, we have carried out a condensation reaction for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones from 2-amino-N-benzylbenzamide and different aromatic aldehydes using FeCl 3 catalyst supported on Al 2 O 3. It was demonstrated that this material can be used successfully for the nucleation of quinazolinones with good to excellent yield; furthermore, the FeCl 3 /Al 2 O 3 catalyst can be recovered and reused. This catalyst was used before in the synthesis of imidazole with very good yields. The synthesized quinazolinones showed a large range diastereotopic effect over the methylene group and, this anomalous difference was studied through nuclear magnetic resonance (NMR) and computational calculations.

Research paper thumbnail of Synthesis and Electrochemistry Evaluation of Multivalent o- Aminobenzamides and Quinazoline-2,4-diones

International Journal of Electrochemical Science, 2018

The o-aminobenzamides (OAB) and quinazoline-2,4-diones (QZD) are alkaloids with important biologi... more The o-aminobenzamides (OAB) and quinazoline-2,4-diones (QZD) are alkaloids with important biological properties such as sedatives, antipsychotics and anticonvulsants, these last properties can be evaluated by electrochemistry methods, using its electron transfer capacity. In this study six compounds (OAB, QZD) were synthesized and characterized, using spacers groups to link the functional moieties (presents on the mono, di and tri substituted systems of each alkaloid kind), when the spacers groups are present, an increase of pharmacological properties has been shown. We carried on electrochemistry evaluations to the synthetized compounds to predict the electron transfer. The results show a single oxidation potential (OP) for the mono and di-substituted compounds (OAB, QZD), and two different OP when the system is trimeric (OAB, QZD). The intensity of the OP signals in the open systems (OAB) is considerable higher in comparison with the closed systems (QZD), these oxidation potentials are assignation at amine groups, and the tertiary amines of trimeric compound present the highest intensity oxidation signals in comparison with secondary amines. The most favorable compound to realize the electron transfer are the open trimeric system.

Research paper thumbnail of Effect of Heteroatom Bridge in the Transfer Electron Process of O-Aminebenzamides and Quinazolinendiones Evaluated By Electrochemistry

Research paper thumbnail of Preparation of Polymeric Films of PVDMA–PEI Functionalized with Fatty Acids for Studying the Adherence and Proliferation of Langerhans β-Cells

ACS Omega

This study reports the synthesis of thin polymeric films by the layer-by-layer deposition and cov... more This study reports the synthesis of thin polymeric films by the layer-by-layer deposition and covalent cross-linking of polyvinyl dimethylazlactone and polyethylene imine, which were functionalized with lauric (12-C), myristic (14-C), and palmitic (16-C) saturated fatty acids, whose high levels in the bloodstream are correlated with insulin resistance and the potential development of type 2 diabetes mellitus. Aiming to assess the effect of the fatty acids on the adhesion and proliferation of Langerhans β-cells, all prepared films (35 and 35.5 bilayers with and without functionalization with the fatty acids) were characterized in terms of their physical, chemical, and biological properties by a battery of experimental techniques including 1 H and 13 C NMR, mass spectrometry, attenuated total reflectance−Fourier transform infrared spectroscopy, field emission scanning electron microscopy, atomic force microscopy, cell staining, and confocal laser scanning microscopy among others. In general, the developed films were found to be nanometric, transparent, resistant against manipulation, chemically reactive, and highly cytocompatible. On the other hand, in what the effect of the fatty acids is concerned, palmitic acid was found to impair the proliferation of the cultured βcells, contrary to its homologues which did not alter this biological process. In our opinion, the multidisciplinary study presented here might be of interest for the research community working on the development of cytocompatible 2D model substrates for the safe and reproducible characterization of cell responses.

Research paper thumbnail of Study of the green synthesis of silver nanoparticles using a natural extract of dark or white Salvia hispanica L. seeds and their antibacterial application

Applied Surface Science

Abstract In this research work, we report for the first time the green synthesis of silver nanopa... more Abstract In this research work, we report for the first time the green synthesis of silver nanoparticles (AgNPs), using two varieties of a natural extract of dark (D) or white (Wh) Salvia hispanica L. seeds, commonly named chia (Ch), as a reducing-stabilizing agent. Similarly, it was carried out a study on the effect of the variation of different physicochemical parameters, like aging time and storage temperature of the natural extract of dark Ch seeds, in the morphology, size and polydispersity of the prepared AgNPs. We found that the ideal conditions to do the green synthesis of AgNPs, are to use the Ch extract one day after it have been prepared and stored at 5 °C (1D C). The AgNPs were characterized by UV–Vis, FT-IR, FE-SEM-EDS and TEM. The TEM images of the synthesized AgNPs showed spherical morphology with an average nanoparticle size of 7 nm, at optimum conditions (AgNPs/D Ch (1D C)). Additionally, we studied the antimicrobial activity of the green synthesized AgNPs with both types of Ch seeds, against bacteria gram-positive and gram-negative, using as the bacterial model E. coli and S. aureus, respectively. We determined that the synthesized AgNPs/D Ch have more antimicrobial activity against both bacteria, in comparation with AgNPs/W Ch (ZOI against E. coli, 18.5 mm; S. aureus, 14.9 mm).

Research paper thumbnail of Microstrain analyses of Fe3O4NPs greenly synthesized using Gardenia jasminoides flower extract, during the photocatalytic removal of a commercial dye

Applied Nanoscience

The Gardenia jasminoides flower extract (Gjfe) was employed to prevent agglomeration during the m... more The Gardenia jasminoides flower extract (Gjfe) was employed to prevent agglomeration during the magnetite nanoparticles (Fe3O4NPs) synthesis. Different analytical techniques such as FTIR-ATR, Raman, SEM–EDS, XPS, XRD, and TEM, were used to characterize the synthesized nanoparticles. Also, microstrain analyses of Fe3O4NPs were carried out. The results of the characterization techniques indicated spherical and well dispersed Fe3O4NPs/Gjfe, with a nanoparticle size (TEM) of about 4.5 nm. The XRD analysis resulted in good agreement with respect to JCPDS no. 89-4319. Fe3O4NPs/Gjfe were employed in the photocatalytic degradation of a commercial fabric dye, without the addition of any extra reagents, or control of pH or temperature. The photocatalytic reaction, studied by UV–Vis spectroscopy, showed excellent results, achieving a dye removal of 100% in 60 min (0.20 mg/mL of commercial dye) using 50 mg of Fe3O4NPs/Gjfe. The stability of the recycled Fe3O4NPs/Gjfe was determined by the number of times that the synthesized nanoparticles can be re-used in the dye removal process, obtaining that after five cycles of use, they do not lose their photocatalytic activity.

Research paper thumbnail of In Situ Controlled Release of Dopamine for Treatment of Parkinson’s Disease

Research paper thumbnail of In-situ Release of Antiepileptic Drugs from Nanostructured Reservoirs

Underlying Mechanisms of Epilepsy, 2011

Research paper thumbnail of Study of the stabilization of zinc phthalocyanine in sol-gel TiO2 for photodynamic therapy applications

Nanomedicine: Nanotechnology, Biology and Medicine, 2010

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for ... more Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer. It is a two-step procedure that uses a combination of molecular oxygen, visible light, and photosensitizer (PS) agents; phthalocyanine (Pc) was supported over titanium oxide but has not yet been used for cell inactivation. Zinc phthalocyanine (ZnPc) molecules were incorporated into the porous network of titanium dioxide (TiO 2) using the sol-gel method. It was prepared from stock solutions of ZnPc and TiO 2. ZnPc-TiO 2 was tested with four cancer cell lines. The characterization of supported ZnPc showed that phthalocyanine is linked by the N-pyrrole to the support and is stable up to 250°C, leading to testing for PDT. The preferential localization in target organelles such as mitochondria or lysosomes could determine the cell death mechanism after PDT. The results suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent candidate as sensitizer in PDT against cancer and infectious diseases. From the Clinical Editor: Photodynamic therapy is a two-step procedure that uses a combination of molecular oxygen, visible light and photosensitizer agents as an alternative and promising non-invasive treatment for cancer. The results of this study suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent photosensitizer candidate against cancer and infectious diseases.

Research paper thumbnail of Alkylation of 2,4-(1H,3H)-Quinazolinediones with Dialkyl Carbonates Under Microwave Irradiations

Molecules, 2009

Alkylation is a very important chemical reaction which modifies the biological properties of drug... more Alkylation is a very important chemical reaction which modifies the biological properties of drugs. Quinazolinedione derivatives are of considerable interest due to their wide array of pharmacological properties. We now report application of a practical alkylation procedure to several quinazolinediones, including pelanserine (5f), which shows antihypertensive properties, 1-methyl-3-(2'-phenylethyl)-1H,3H-quinazoline-2,4-dione (1ab) and 1-methyl-3-[2'-(4'-methoxyphenyl)ethyl]-lH,3H-quinazoline-2,4-dione (1ae), which had been isolated from natural sources. The alkylation was optimized using dimethyl and diethyl carbonates under microwave irradiations.

Research paper thumbnail of Effect of Thermal Treatment of Sol-Gel Titania Reservoirs on Release Kinetics of Phenytoin

Journal of the American Ceramic Society, 2012

ABSTRACT The thermal stability of antiepileptic drug phenytoin was investigated on its encapsulat... more ABSTRACT The thermal stability of antiepileptic drug phenytoin was investigated on its encapsulation in titania matrix. It was shown that the drug is stable up to 150°C, even though phenytoin melting point was previously reported to be much higher. The mechanism of phenytoin decomposition is suggested and confirmed by the experiment on heating to higher temperatures. The influence of thermal treatment on physicochemical parameters of the matrix was studied. Quite different drug release kinetics were obtained in vitro and discussed in terms of temperature treatment influence and interplay of parameters of the matrix.

Research paper thumbnail of Alkylation of 2, 4-(1H, 3H)-Quinazolinediones with Dialkyl Carbonates Under Microwave Irradiations

Molecules, 2009

Alkylation is a very important chemical reaction which modifies the biological properties of drug... more Alkylation is a very important chemical reaction which modifies the biological properties of drugs. Quinazolinedione derivatives are of considerable interest due to their wide array of pharmacological properties. We now report application of a practical alkylation procedure to several quinazolinediones, including pelanserine (5f), which shows antihypertensive properties, 1-methyl-3-(2'-phenylethyl)-1H,3H-quinazoline-2,4-dione (1ab) and 1-methyl-3-[2'-(4'-methoxyphenyl)ethyl]-lH,3H-quinazoline-2,4-dione (1ae), which had been isolated from natural sources. The alkylation was optimized using dimethyl and diethyl carbonates under microwave irradiations.

Research paper thumbnail of Study of the stabilization of zinc phthalocyanine in sol-gel TiO 2 for photodynamic therapy applications

Nanomedicine-nanotechnology Biology and Medicine, 2010

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for ... more Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer. It is a two-step procedure that uses a combination of molecular oxygen, visible light, and photosensitizer (PS) agents; phthalocyanine (Pc) was supported over titanium oxide but has not yet been used for cell inactivation. Zinc phthalocyanine (ZnPc) molecules were incorporated into the porous network of titanium dioxide (TiO 2) using the sol-gel method. It was prepared from stock solutions of ZnPc and TiO 2. ZnPc-TiO 2 was tested with four cancer cell lines. The characterization of supported ZnPc showed that phthalocyanine is linked by the N-pyrrole to the support and is stable up to 250°C, leading to testing for PDT. The preferential localization in target organelles such as mitochondria or lysosomes could determine the cell death mechanism after PDT. The results suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent candidate as sensitizer in PDT against cancer and infectious diseases. From the Clinical Editor: Photodynamic therapy is a two-step procedure that uses a combination of molecular oxygen, visible light and photosensitizer agents as an alternative and promising non-invasive treatment for cancer. The results of this study suggest that nanoparticulated TiO 2 sensitized with ZnPc is an excellent photosensitizer candidate against cancer and infectious diseases.

Research paper thumbnail of The Use of Solid-Phase Supported 1- N -Piperazine-4- N -carboxaldehyde in Vilsmeier Reactions

Journal of Combinatorial Chemistry, 2004

A Vilsmeier salt supported on solid phase was prepared using piperazine bound to Merrifield resin... more A Vilsmeier salt supported on solid phase was prepared using piperazine bound to Merrifield resin. Piperazine was selected because it contains two secondary amines: one of the amines is protected upon binding to the resin, and the second was formylated to give resin-1-N-piperazine-4-N-carboxaldehyde (9). Activation of the formamide with either bis(trichloromethyl)carbonate (BTC) or POCl 3 afforded the Vilsmeier salt 10. Several olefins were used to test the supported Vilsmeier reagent. The in-solution activation with BTC and POCl 3 of various secondary amides was also evaluated: dimethylformamide (1), N-methyformanilide (4), 4-formylmorpholine (5), and 1,4-dicarboxylpiperazine (6), which showed that amides with one additional heteroatom increase the yields in the Vilsmeier salt formation.

Research paper thumbnail of Method for Analysis of Polymer-Supported Organic Compounds Using Mass Spectrometry Direct Insertion

Journal of Combinatorial Chemistry, 2003

A new approach on the use of mass spectrometry direct-insertion and a quadrupole detector for ana... more A new approach on the use of mass spectrometry direct-insertion and a quadrupole detector for analysis of organic compounds supported in solid phase has been developed. This is a simple and efficient method based on cleavage due to the thermal-instability of the benzylic group of most commercial resins. The cleavage of supported compounds takes place in the spectrometer as a consequence of the high temperature in the instrument's chamber. These compounds are detected using a similar fragmentation pattern and a molecular ion corresponding to the same compound obtained by traditional synthesis. Polymer degradation fragments do not interfere with the spectrum interpretation, because only a few peaks and low intensities are detected. We report here the identification of different types of compounds supported in Merrifield resin, such as bis-o-aminobenzamides and simple aromatic and aliphatic compounds, using this new approach.

Research paper thumbnail of Role of Hydrolysis Degree in the Drug-Matrix Interactions of Nanosized Sol-Gel Titania Reservoirs for Epilepsy Treatment

... T. L pez* † ‡ § , K. Espinoza † , A. Kozina † , A. Galano , and R. Alexander-Katz. Laboratori... more ... T. L pez* † ‡ § , K. Espinoza † , A. Kozina † , A. Galano , and R. Alexander-Katz. Laboratorio de Nanotecnolog a ... Autonomous Metropolitan University (UAM). We gratefully acknowledge the support of Atilano Guti rrez in the NMR studies. ...