Influence of Steric Hindrance on The Antioxidant Activity of Some Schiff Base Ligands And Their Copper(II) Complexes

Salga, Muhammad Saleh; Sada, Ibrahim; Mustapha, Adamu

doi:10.13005/ojc/300410

Cited by 6 publications

(6 citation statements)

References 5 publications

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“…Their activity was markedly lower compared to the standard antioxidant, and differences in their activity were observable only at the highe concentrations tested (Figure 4). Several other Cu(II) complexes with various N-heterocy clic ligands displayed similar properties, which have been described in the literature [39][40][41]. The results showed that the Cu-L1 complex displayed a concentration-dependent, low-to-moderate radical scavenging activity (5-34%) when compared to ascorbic acid (AA, 24-86%).…”

Section: Determination Of Antioxidant Activitysupporting

confidence: 71%

Enhancement of the Cytotoxicity of Quinazolinone Schiff Base Derivatives with Copper Coordination

Gurgul,

Hricovíniová,

Mazuryk

et al. 2023

Inorganics

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Two copper(II) complexes (Cu-L1, Cu-L2) derived from 2,3-substituted quinazolinone Schiff base ligands (L1, L2) were prepared to examine their anticancer activity. Compounds were characterized using various spectroscopic methods (FTIR, NMR, UV-vis) and quantum-chemical calculations. The biological effects of Cu(II) complexes bearing quinazolinone scaffolds were evaluated on two cancers’ cell lines (breast—MCF-7 and lung—A549), as well as on untransformed cells (keratinocytes—HaCaT). Copper complexes were highly cytotoxic, with IC50 in the low micromolar range, while the quinazoline ligands L1 and L2 remained inactive in inhibiting cell proliferation. Antioxidant activity was investigated in the model systems using DPPH and FRAP assays. The Cu-L1 and Cu-L2 complexes exhibited enhanced DPPH free radical scavenging efficiency compared to the L1 and L2 ligands, but their reducing ability was comparable to that of the free ligands. Evaluation of oxidative stress in vitro carried out by staining cells with various ROS-specific indicators showed reduced production of superoxide anion radical and hydrogen peroxide after treatment of cells with copper complexes. Such a negative impact on ROS formation in cells can lead to cellular redox imbalance and consequent cell death, among others, by inducing apoptosis and/or necrosis, depending on the copper complex used. We hypothesize that the high cytotoxic activity of the investigated copper complexes is apparently the result of multiple mechanisms of action, and the imbalance in the cellular antioxidant system partly contributes to the overall cytotoxic effect.

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Section: Determination Of Antioxidant Activitysupporting

confidence: 71%

Enhancement of the Cytotoxicity of Quinazolinone Schiff Base Derivatives with Copper Coordination

Gurgul,

Hricovíniová,

Mazuryk

et al. 2023

Inorganics

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“…is finding has already been underlined through the assessment of the radical scavenging activity of juglone and its derivatives done by Jin [27]. e 0.299 eV drop in IP obtained after a replacement of the hydrogen atom attached to C 5 carbon atom of F 0 by a great aliphatic substituent (D 0 ) exhibits the influence of the steric hindrance on the antioxidant activity observed during the study of Schiff base ligands and their copper (II) complexes [28]. A 0.363 eV similar decrease in IP (E 0 ) has been yielded by substituting the hydrogen atom of hydroxide group bound to C 4 carbon atom of (F 0 ) by this same aliphatic substituent.…”

Section: Antioxidant Propertiesmentioning

confidence: 79%

A DFT Analysis on Antioxidant and Antiradical Activities from Anthraquinones Isolated from the Cameroonian Flora

Nyobe

Andiga

Mama

et al. 2019

Journal of Chemistry

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The present work is devoted to the exploration antioxidant and antiradical activity of twenty anthraquinones isolated from the Cameroonian flora at B3LYP/6-311++G(d,p) level of theory using the B3LYP/6-31 + G(d,p) geometrical data as geometry optimization starting points. The single electron transfer mechanism has been adopted to examine both biological activities. The classification of the antiradical profile to integrate the electrodonating power (ω−), electroaccepting power (ω+), donor index (Rd) and acceptor index (Ra) has been performed using the donor-acceptor map (DAM). The antioxidant and radical powers of compounds analyzed have been compared to that of two classical vitamins (vitamin C and gallic acid). The stability of each anthraquinone derivative of the molecular library has been developed according to thermodynamic and kinetic concepts. The global reactivity descriptors (GRDs; electrophilicity index (ω), electronegativity (χ), global softness (S), and global hardness (η)) have been used to analyze the reactivity. The topological analysis of optimized structures indicates that the strength of the hydrogen bonds formed is situated between 44.205 and 52.001 kJ/mol. Our B3LYP results reveal that 3-methoxy-1-vismiaquinone (in a configuration without hydrogen bond) exhibits the best antioxidant capacity in gas phase. A comparison between antioxidant performance of molecules examined and that of classical vitamins (gallic acid, caffeic acid, ferulic acid, and ascorbic acid (vitamin C)) displayed the fact that the single electron transfer (SET) mechanism is more prominent for compounds of the molecular library analyzed. In the same vein, the antiradical behaviors of anthraquinone derivatives have shown to be higher than that of gallic acid and vitamin C in gas phase and water. The 5,8-dihydroxy-2-methylantraquinone structure in a configuration bearing one hydrogen bond has been found to be the best antiradical of the series in aqueous solution.

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“…e difference in IP for La 2 and La 6 equal to 4.776 kJ/mol exhibits the effect of steric hindrance on antioxidant activity. e alteration of the antioxidant activity of some Schiff base ligands and their copper (II) complexes by this steric hindrance has been reviewed by Salga et al [44]. Similarly, Sun et al have experimentally demonstrated that the antioxidant activity of flavonoids isolated from Hebei balmy chrysanthemum is sensitive to the steric hindrance of glucoside [45].…”

Section: Electron Transfer Mechanismmentioning

confidence: 99%

Antioxidant Properties of Lapachol and Its Derivatives and Their Ability to Chelate Iron (II) Cation: DFT and QTAIM Studies

Pajoudoro

Lissouck

Amana

et al. 2020

Bioinorganic Chemistry and Applications

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The elucidation of the complexation of lapachol and its derivatives to Fe2+ cation has been done using the density functional theory (DFT). This complexation has been limited to bidentate and tridentate to Fe2+ cation. Geometry optimizations have been implemented in gas and solution phase (water, acetonitrile, chlorobenzene, benzene, and toluene) for ligands at B3LYP/6-311++G (d,p) level of theory using B3LYP/6-31+G(d,p) optimized data as starting point. But, the geometrical optimizations in solution phase of the 22 complexes analyzed of lapachol and its derivatives to Fe2+ cation were restricted to acetonitrile and benzene. The complexation energy and the metal ion affinity (MIA) have also been calculated using the B3LYP method. The results obtained indicated a proportionality between the MIA values and the retained charge on Fe2+ cation for k2-(O1,O2) modes. But, an inverse proportionality has been yielded between these two parameters for k3-(O2, C=C) tridentate modes. For k3-(O3,C=C) tridentate mode coordination, the higher stability has been obtained. In this latter tridentate coordination in gas phase, the topological analysis of complexes exhibits the fact that the electron density is concentrated between the O3 oxygen atom of the ligand attached to Fe2+ and this metal cation. Moreover, the hydrogen bond strength calculated for isolated ligands (situated between 23.92 and 30.15 kJ/mol) is in the range of normal HBs. Collectively, all the complexation processes have shown to be highly exothermic. Our results have also shown that the electron extraction from Fe2+...Lai complexes is more difficult compared to that from free ligands.

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Influence of Steric Hindrance on The Antioxidant Activity of Some Schiff Base Ligands And Their Copper(II) Complexes

Cited by 6 publications

References 5 publications

Enhancement of the Cytotoxicity of Quinazolinone Schiff Base Derivatives with Copper Coordination

Enhancement of the Cytotoxicity of Quinazolinone Schiff Base Derivatives with Copper Coordination

A DFT Analysis on Antioxidant and Antiradical Activities from Anthraquinones Isolated from the Cameroonian Flora

Antioxidant Properties of Lapachol and Its Derivatives and Their Ability to Chelate Iron (II) Cation: DFT and QTAIM Studies

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