Tautomerism and antioxidant activity of some 4-acylpyrazolone-based Schiff bases: a theoretical study

Orabi, Esam A.

doi:10.1039/c8ra05987j

Cited by 17 publications

(6 citation statements)

References 25 publications

(98 reference statements)

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“…34 NMR calculations at this level have been shown to yield results in good agreement with experiment. 34,35 To comprehend the observed trend in δ of the four H atoms, we calculated the atomic charges through natural bond orbital analysis.…”

Section: ■ Results and Discussionsupporting

confidence: 56%

“…The geometry of phyllagallin M2 was optimized starting from different initial conformers, and only the most stable structure is reported. To confirm the assignments of the 1 H NMR chemical shifts to H a –H d , we performed NMR calculations using the gauge invariant atomic orbitals method and use the calculated isotropic magnetic shielding to determine δ . NMR calculations at this level have been shown to yield results in good agreement with experiment. , To comprehend the observed trend in δ of the four H atoms, we calculated the atomic charges through natural bond orbital analysis.…”

Section: Experimental Sectionmentioning

confidence: 99%

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Structures, NMR Spectroscopic Features, and Cytotoxic Properties of Oligomeric Hellinoyl (m-GO-m-GOG)-Type Ellagitannins from the Galls of Tamarix aphylla

Orabi

Taniguchi

et al. 2019

J. Nat. Prod.

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Ellagitannin oligomers are large molecules habitually showing complex NMR spectra that are sometimes misinterpreted and lead to incorrect structures. Understanding the NMR spectroscopic features of a group of ellagitannins would overcome these inadequacies. In this study, investigation of the galls of Tamarix aphylla led to the isolation of three new ellagitannin oligomers, phyllagallins T1 (1), T2 (2), and Q1 (3), a known monomer nilotinin M4 (4), four known dimers, nilotinins D7 (5) and D8 (6), hirtellin B (7), and tamarixinin A (8), and a simple phenolic, dehydrotrigallic acid (9). 1D and 2D NMR, HRESI-TOFMS, and ECD experiments show that compounds 1−8 are hellinoyl-type ellagitannins. The NMR spectroscopic features of this type of ellagitannins and the reasons for the abnormal upfield shifts of glucose anomeric proton and hellinoyl moiety proton signals are established considering the experimental results as well as quantum chemical calculation on a simple hellinoyl-type monomer, phyllagallin M2. Based on these results, the NMR assignments reported previously by a different research group for bracteatinin T 1 and hirtellin T 3 are revised. A cytotoxicity study against human oral squamous cell carcinoma cell lines (Ca9-22, HSC-2, and HSC-4) and human mesenchymal normal oral cells (HGF, HPC, and HPLF) showed cytotoxic effects with tumorspecificity higher than 5.2, 3.0, 1.6, and 2.0 for compounds 5, 2, 9, and 3, respectively.

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Section: ■ Results and Discussionsupporting

confidence: 56%

Section: Experimental Sectionmentioning

confidence: 99%

Structures, NMR Spectroscopic Features, and Cytotoxic Properties of Oligomeric Hellinoyl (m-GO-m-GOG)-Type Ellagitannins from the Galls of Tamarix aphylla

Orabi

Taniguchi

et al. 2019

J. Nat. Prod.

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“…The latter functional was considered to better account for dispersion forces. 54 The ground-state geometries of compounds 2−6 were optimized in the gas phase, and the global minimum structures are reported. To get insight into their excitation spectra, the geometry of the first excited state of compounds 2 and 3 was also calculated.…”

Section: Methodsmentioning

confidence: 99%

“…Quantum mechanical calculations were achieved with Gaussian 09 using DFT with the 6-31+G(d,p) basis set and both B3LYP and M062X functionals. The latter functional was considered to better account for dispersion forces . The ground-state geometries of compounds 2 – 6 were optimized in the gas phase, and the global minimum structures are reported.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Novel Biocompatible Thienopyrimidine Chromophores with Aggregation-Induced Emission Sensitive to Molecular Aggregation

et al. 2020

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Biocompatible luminogens with aggregation-induced emission (AIE) have several applications in the biology field, such as in detecting biomacromolecules bioprobes and in bio-imaging. Due to their bioactivities and light-emitting properties, many heterocyclic compounds are good candidates for such applications. However, heterocyclic π-conjugated systems with AIE behavior remain rare as strong intermolecular π–π interactions usually quench their emission. In this work, new thienopyrimidine heterocyclic compounds were synthesized and their structures were verified by elemental analysis and Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), and 13C NMR spectra. The photophysical properties of some compounds were investigated in the solution and solid states. Density functional theory calculations were also performed to confirm the observed photophysical properties of the compounds. The studied dyes displayed AIE properties with spectral shapes related to the aggregate structure and a quantum yield up to 10.8%. The emission efficiency of the powder is attributed to the incorporation of multiply rotatable and twisted aryl groups to the fused heterocyclic moieties. The dyes also showed high thermal stability and potent antimicrobial activities against numerous bacterial and fungal strains. Additionally, the cytotoxicity of the new compounds was evaluated against the Caco-2 cell line, and molecular docking was used to investigate the binding conformation of the most effective compound with the MNK2 enzyme. Therefore, the presented structures may potentially be used for bioapplications.

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“…Finally, completely novel structures are proposed and investigated on the basis of recognized pharmacophores: phenolic units, − five-heterocyclic rings, − quinoline backbones, − and other moieties. − Importantly, despite their diversity, chain breakers share similar reactivity patterns and mechanisms, allowing common theoretical approaches to be used to study any of them.…”

Section: Introductionmentioning

confidence: 99%

Current Trends in Computational Quantum Chemistry Studies on Antioxidant Radical Scavenging Activity

Spiegel

2022

J. Chem. Inf. Model.

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The antioxidative nature of chemicals is now routinely studied using computational quantum chemistry. Scientists are constantly proposing new approaches to investigate those methods, and the subject is evolving at a rapid pace. The goal of this review is to collect, consolidate, and present current trends in a clear, methodical, and reference-rich manner. This paper is divided into several sections, each of which corresponds to a different stage of elaborations: preliminary concerns, electronic structure analysis, and general reactivity (thermochemistry and kinetics). The sections are further subdivided based on methodologies used. Concluding remarks and future perspectives are presented based on the remaining elements.

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Tautomerism and antioxidant activity of some 4-acylpyrazolone-based Schiff bases: a theoretical study

Abstract: Computational investigations reveal that 4-acylpyrazolone Schiff bases adopt the amine-one structure and that ionization potentials provide a measure for their antioxidant activity.

Cited by 17 publications

References 25 publications

Structures, NMR Spectroscopic Features, and Cytotoxic Properties of Oligomeric Hellinoyl (m-GO-m-GOG)-Type Ellagitannins from the Galls of Tamarix aphylla

Structures, NMR Spectroscopic Features, and Cytotoxic Properties of Oligomeric Hellinoyl (m-GO-m-GOG)-Type Ellagitannins from the Galls of Tamarix aphylla

Synthesis of Novel Biocompatible Thienopyrimidine Chromophores with Aggregation-Induced Emission Sensitive to Molecular Aggregation

Current Trends in Computational Quantum Chemistry Studies on Antioxidant Radical Scavenging Activity

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