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Search Results: 1 - 10 of 203424 matches for " Norma Flores-Holguín "
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Chemical Reactivity Theory (CRT) Study of the Melanoidin M8: Local Conceptual Density Functional Theory Descriptors  [PDF]
Juan Frau, Norma Flores-Holguín, Daniel Glossman-Mitnik
Computational Molecular Bioscience (CMB) , 2018, DOI: 10.4236/cmb.2018.82004
Abstract: This study evaluated a fixed long-range corrected range-separated hybrid (RSH) density functional associated with the Def2TZVP basis set alongside the Solvation Model based on Density (SMD) for the computation of the structure, molecular properties and chemical reactivity of the M8 intermediate melanoidin pigment. The preference of the active sites pertinent to radical, nucleophilic and electrophilic attacks is made through linking them with the electrophilic and nucleophilic Parr functions, Fukui function indices, and condensed Dual Descriptor. This study showed that the MN12SX density functional is the most suitable one for predicting the chemical reactivity of this system.
Conceptual Density Functional Theory Study of the Chemical Reactivity Properties and Bioactivity Scores of the Leu-Enkephalin Opioid Peptide Neurotransmitter  [PDF]
Juan Frau, Norma Flores-Holguín, Daniel Glossman-Mitnik
Computational Molecular Bioscience (CMB) , 2019, DOI: 10.4236/cmb.2019.91002
Abstract: The SMD solvation model (Solvation Model based on the Density) and eight density functionals, CAM-B3LYP, LC-ωPBE, M11, MN12SX, N12SX, ωB97, ωB97X, and ωB97XD, were assessed in link with the Def2TZVP basis set for the calculation of the structure of the Leu-Enkephalin Opioid Peptide Neurotransmitter as well as their molecular properties. Through the Conceptual Density Functional Theory (CDFT), the entire chemical descriptors for the system were calculated. The active regions of the molecules necessary for electrophilic, nucleophilic and radical attacks were chosen through linking them with the corresponding Fukui functions. Furthermore, the prediction of the pKa value for the peptide is done with great accuracy as well as the ability of the studied molecule in acting as an efficient inhibitor of the formation of Advanced Glycation Endproducts (AGEs), which comprises of a useful knowledge for the development of drugs for preventing Alzheimer, Diabetes and Parkinson diseases. Lastly, the bioactivity scores for the studied peptides are predicted via various methodologies.
Natural Carotenoids as Nanomaterial Precursors for Molecular Photovoltaics: A Computational DFT Study
Teresita Ruiz-Anchondo,Norma Flores-Holguín,Daniel Glossman-Mitnik
Molecules , 2010, DOI: 10.3390/molecules15074490
Abstract: In this work several natural carotenoids were studied as potential nanomaterial precursors for molecular photovoltaics. M05-2X/6-31+G(d,p) level of theory calculations were used to obtain their molecular structures, as well as to predict the infrared (IR) and ultraviolet (UV-Vis) spectra, the dipole moment and polarizability, the pKa, and the chemical reactivity parameters (electronegativity, hardness, electrophilicity and Fukui functions) that arise from Conceptual DFT. The calculated values were compared with the available experimental data for these molecules and discussed in terms of their usefulness in describing photovoltaic properties.
Chemical Reactivity Properties, Drug-Likeness Features and Bioactivity Scores of the Cholecystokinin Peptide Hormone  [PDF]
Norma Flores-Holguín, Juan Frau, Daniel Glossman-Mitnik
Computational Molecular Bioscience (CMB) , 2019, DOI: 10.4236/cmb.2019.92004
Abstract: Five density functionals, CAM-B3LYP, LC-ωPBE, MN12SX, N12SX and ωB97XD, in connection with the Def2TZVP basis set were assessed together with the SMD solvation model for the calculation of the molecular and chemical reactivity properties of the Cholecystokinin peptide hormone (CCK-8) in the presence of water. All the chemical reactivity descriptors for the systems were calculated via Conceptual Density Functional Theory (CDFT). The potential bioavailability and druggability as well as the bioactivity scoresfor CCK-8 were predicted through different methodologies already reported in the literature which have been previously validated during the study of different peptidic systems. The conclusion was that the CCK-8 peptide will be moderately bioactive regarding all the interactions.
Computational Study of the Chemical Reactivity and Bioactivity Rates of Marine Peptides Hemiasterlin and Its A and B Derivatives Used in the Cancer Treatment through Conceptual Density Functional Theory  [PDF]
Norma Flores-Holguín, Juan Frau, Daniel Glossman-Mitnik
Computational Molecular Bioscience (CMB) , 2019, DOI: 10.4236/cmb.2019.94008
Abstract: This study involved the assessment of the MNI2SX/Def2TZVP/H2O model chemistry to enhance the understanding of the structural composition of the marine peptide Hemiasterlin and its derivatives A and B used in cancer treatment. The Conceptual Density Functional theory was used in the calculation of molecular properties of the system chemical descriptors during the study. Integration of the active molecular regions into their respective Fukui functions was used in the selection of electrophilic and nucleophilic attacks. Additionally, the proposed correlation between global hardness and the pKa was used as the basis of deriving accurate predictions for the pKa values while a homology technique was used in the prediction of bioactivity and bioavailability scores of the peptides under investigation.
Computational molecular characterization of the flavonoid rutin
Sergio A Payán-Gómez, Norma Flores-Holguín, Antonino Pérez-Hernández, Manuel Pi?ón-Miramontes, Daniel Glossman-Mitnik
Chemistry Central Journal , 2010, DOI: 10.1186/1752-153x-4-12
Abstract: Flavonoids are phenolic substances characterized for a low molecular weight and they are abundant in plant tissues, apple being one of the most important (particularly its skin) [1,2]. In the human body they show a lot of biological properties as antioxidants, antiallergenic, antibacterial, antifungal, antiviral and anticarcinogenic agents. These characteristics confer to them pharmacological properties useful for the treatment of diseases that go from allergies, bacterial and viral infectious processes, to those of greater risk like the coronary diseases, cancer and HIV [3-5]. The mechanism by which flavonoids carry out their properties, mainly their antioxidant power, is either by inhibiting the formation or activity of reactive oxygen species, or by direct interaction with DNA, enzymes and membrane receptors.Theoretical investigations of the physical and chemical properties of flavonoids are very important in order to disclose the relationship between the structure, properties and performance, and to help in the design and synthesis of new derivatives with improved properties. We have experimentally found that some natural flavonoids have a strong ability for complexing metal ions, in particular, those related to heavy metals [6-8]. Thus, natural flavonoids could be useful in water treatment, cleaning and purification. The objective of this letter is to report the results of the calculation of the molecular structure and properties of the flavonoid Rutin using a recently developed density functional [9]. The IR and UV-Vis spectra, the dipole moment and polarizability, the free energy of solvation in different solvents as an indication of solubility, the HOMO and LUMO orbitals, and the chemical reactivity parameters that arise from Conceptual DFT [10,11] are reported. The calculated values are compared with the available experimental data for this molecule as a means of validation of the used model chemistry. The spectra and the calculated values are important in
Density Functional Theory (DFT) Study of Triphenylamine-Based Dyes for Their Use as Sensitizers in Molecular Photovoltaics
Jesús Baldenebro-López,José Castorena-González,Norma Flores-Holguín,Jorge Almaral-Sánchez,Daniel Glossman-Mitnik
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044418
Abstract: In this work we studied three dyes which are proposed for potential photovoltaic applications and named Dye7, Dye7-2t and Dye7-3t. The Density Functional Theory (DFT) was utilized, using the M05-2X hybrid meta-GGA functional and the 6–31+G(d,p) basis set. This level of calculation was used to find the optimized molecular structure and to predict the main molecular vibrations, the absorption and emission spectra, the molecular orbitals energies, dipole moment, isotropic polarizability and the chemical reactivity parameters that arise from Conceptual DFT. Also, the p K a values were calculated with the semi-empirical PM6 method.
Computational Molecular Nanoscience Study of the Properties of Copper Complexes for Dye-Sensitized Solar Cells
Jesús Baldenebro-López,José Castorena-González,Norma Flores-Holguín,Jorge Almaral-Sánchez,Daniel Glossman-Mitnik
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms131216005
Abstract: In this work, we studied a copper complex-based dye, which is proposed for potential photovoltaic applications and is named Cu (I) biquinoline dye. Results of electron affinities and ionization potentials have been used for the correlation between different levels of calculation used in this study, which are based on The Density Functional Theory (DFT) and time-dependent (TD) DFT. Further, the maximum absorption wavelengths of our theoretical calculations were compared with the experimental data. It was found that the M06/LANL2DZ + DZVP level of calculation provides the best approximation. This level of calculation was used to find the optimized molecular structure and to predict the main molecular vibrations, the molecular orbitals energies, dipole moment, isotropic polarizability and the chemical reactivity parameters that arise from Conceptual DFT.
Computational Nanochemistry Study of the Molecular Structure and Properties of Chlorophyll a
Mónica Alvarado-González,Norma Flores-Holguín,Daniel Glossman-Mitnik
International Journal of Photoenergy , 2013, DOI: 10.1155/2013/424620
Abstract:
Experimental and quantum chemical studies of a novel synthetic prenylated chalcone
José C Espinoza-Hicks, Alejandro A Camacho-Dávila, Norma R Flores-Holguín, Guadalupe V Nevárez-Moorillón, Daniel Glossman-Mitnik, Luz M Rodríguez-Valdez
Chemistry Central Journal , 2013, DOI: 10.1186/1752-153x-7-17
Abstract: A novel substituted chalcone has been synthetized. In order to identify the functional groups present in the new synthesized compound and confirm its chemical structure, experimental and theoretical 1H-NMR and 13C-NMR spectra were analyzed. The theoretical molecular structure and NMR spectra were calculated at both the Hartree-Fock and Density Functional (meta: TPSS; hybrid: B3LYP and PBE1PBE; hybrid meta GGA: M05-2X and M06-2X) levels of theory in combination with a 6-311++G(d,p) basis set. The structural parameters showed that the best method for geometry optimization was DFT:M06-2X/6-311++G(d,p), whereas the calculated bond angles and bond distances match experimental values of similar chalcone derivatives. The NMR calculations were carried out using the Gauge-Independent Atomic Orbital (GIAO) formalism in a DFT:M06-2X/6-311++G(d,p) optimized geometry.Considering all HF and DFT methods with GIAO calculations, TPSS and PBE1PBE were the most accurate methods used for calculation of 1H-NMR and 13C-NMR chemical shifts, which was almost similar to the B3LYP functional, followed in order by HF, M05-2X and M06-2X methods. All calculations were done using the Gaussian 09 software package. Theoretical calculations can be used to predict and confirm the structure of substituted chalcones with good correlation with the experimental data.Chalcones are ubiquitous substances found in a diversity of plants. They are precursors to other natural products, such as flavonoids, which have reported a wide range of biological activities such as antioxidant, antibacterial, antitumoral among others [1]. Due to the importance of these compounds, diverse studies on synthesis and biological activities of molecules containing the chalcone ring system, have been reported recently [2]. The prenyloxychalcones are important derivatives of chalcones, which contain a prenyl-type side chain with different length, including 2,2-dimethylallyl, geranyl or farnesyl chains; these compounds have shown i
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