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4 results on '"Joyce K. L. Vale"'

1. ESTUDO TEÓRICO E EXPERIMENTAL DE ESTRUTURA E REATIVIDADE RELACIONADO AO METABOLISMO E TOXICIDADE DO PARACETAMOL

Author

Rosivaldo S. Borges, Wanda S. Costa, Ellen P. C. Gurrão, Luiz H. C. Holanda, Alanna C. L. F. Sousa, Joyce K. L. Vale, Cláudio N. Alves, and Albérico B. F. da Silva

Subjects
Chemistry, QD1-999
Abstract

An experimental and theoretical approach on oxidative metabolism of paracetamol was applied for the pharmaceutical chemistry learning. Classical reactions, functional group identification, structural parameter, and chemical reactivity using frontier orbitals and Fukui index were used explaining the main products between N-acetyl-p-benzosemiquinone (NAPQI) and thiolic compounds. The chemoprotection mechanisms by N-acetyl-cysteine on high dosage of paracetamol are consistent with theoretical and experimental results. The methods also described the relationship between the chemical reactivity of quinone-imine system and the induced-toxicity of paracetamol by Michael reaction. These results can be applied in experimental pharmaceutical chemistry teaching.

Published
2022
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2. Alkylated Sesamol Derivatives as Potent Antioxidants

Author

Ivanete C. Palheta, Lanalice R. Ferreira, Joyce K. L. Vale, Osmarina P. P. Silva, Anderson M. Herculano, Karen R. H. M. Oliveira, Antonio M. J. Chaves Neto, Joaquín M. Campos, Cleydson B. R. Santos, and Rosivaldo S. Borges

Subjects
antioxidant capacity, sesamol, DFT, electron transfer, hydrogen transfer, Organic chemistry, QD241-441
Abstract

Sesamol is a phenolic derivative. Its antioxidant activity is low than that of Trolox and depends on benzodioxole moiety. Thus, a molecular modification strategy through alkylation, inspired by natural and synthetic antioxidants, was studied by molecular modeling at the DFT/B3LYP level of theory by comparing the 6-31+G(d,p) and 6-311++G(2d,2p) basis sets. All proposed derivatives were compared to classical related antioxidants such as Trolox, t-butylated hydroxytoluene (BHT) and t-butylated hydroxyanisole (BHA). According to our results, molecular orbitals, single electron or hydrogen-atom transfers, spin density distributions, and alkyl substitutions at the ortho positions related to phenol moiety were found to be more effective than any other positions. The trimethylated derivative was more potent than Trolox. t-Butylated derivatives were stronger than all other alkylated derivatives and may be new alternative forms of modified antioxidants from natural products with applications in the chemical, pharmaceutical, and food industries.

Published
2020
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3. Design and Evaluation of 4-Aminophenol and Salicylate Derivatives as Free-Radical Scavenger

Author

Luiz C. S. França, Marta Chagas Monteiro, Albérico B. F. da Silva, Joyce K. L. Vale, Glaécia A. N. Pereira, Rosivaldo S. Borges, and Cláudio Nahum Alves

Subjects
Pharmacology, Antioxidant, Thiobarbituric acid, 4-Aminophenol, medicine.medical_treatment, Organic Chemistry, Ascorbic acid, Free radical scavenger, Biochemistry, Medicinal chemistry, Lipid peroxidation, chemistry.chemical_compound, chemistry, Drug Discovery, medicine, Molecular Medicine, Structure–activity relationship, Organic chemistry, Salicylic acid
Abstract

This theoretical and experimental study describes the design and evaluation of the free-radical scavenging effect for the molecular association of 4-aminophenol and salicylate derivatives. For this purpose, we employed theoretical methods for the selection of antioxidant drugs and the rapid methods of evaluation: the 1,1-diphenyl-2-picrylhydrazyl radical and the thiobarbituric acid reactive substances in the lipid peroxidation initiated by Fe 2+ and ascorbic acid in human erythrocytes. The associate derivatives exhibited a more potent inhibition than the salicylic acid, while the benzoyl compound exhibited a more potent inhibition than paracetamol. The molecular parameters related to the electron distribution and structure (ionization potential and energy of the highest occupied molecular orbital) correlated very well with the antioxidant action of the compounds studied here in different tests.

Published
2013
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4. Design and evaluation of 4-aminophenol and salicylate derivatives as free-radical scavenger

Author

Rosivaldo S, Borges, Glaécia A N, Pereira, Joyce K L, Vale, Luiz C S, França, Marta C, Monteiro, Cláudio N, Alves, and Albérico B F, da Silva

Subjects
Structure-Activity Relationship, Erythrocytes, Drug Design, Drug Evaluation, Preclinical, Computer-Aided Design, Humans, Quantum Theory, Free Radical Scavengers, Lipid Peroxidation, Aminophenols, Salicylates
Abstract

This theoretical and experimental study describes the design and evaluation of the free-radical scavenging effect for the molecular association of 4-aminophenol and salicylate derivatives. For this purpose, we employed theoretical methods for the selection of antioxidant drugs and the rapid methods of evaluation: the 1,1-diphenyl-2-picrylhydrazyl radical and the thiobarbituric acid reactive substances in the lipid peroxidation initiated by Fe(2+) and ascorbic acid in human erythrocytes. The associate derivatives exhibited a more potent inhibition than the salicylic acid, while the benzoyl compound exhibited a more potent inhibition than paracetamol. The molecular parameters related to the electron distribution and structure (ionization potential and energy of the highest occupied molecular orbital) correlated very well with the antioxidant action of the compounds studied here in different tests.

Published
2013

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