Changes in electronic structures of flavonoids upon electrochemical oxidation and a theoretical model for the estimation of the first oxidation potential

Miličević, Ante; Jovanović, Ivana; Miletić, Goran

doi:10.1016/j.electacta.2018.07.202

Cited by 14 publications

(41 citation statements)

References 43 publications

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“…Furthermore, I correlated the determined generally accepted (26,27) active sites (A site, Table 1) using our earlier method (15). When s(C)…”

Section: Resultsmentioning

confidence: 99%

“…This stability depends on the number and spatial relations between phenolic hydroxyl groups in the molecule, i.e. their electronic structure (9)(10)(11)(12)(13)(14)(15)(16)(17)(18).…”

mentioning

confidence: 99%

“…AOSP Rad showed excellent correlation with E p1 (15). For that purpose I performed PM6 calculations in water to optimise the geometries of the 14 flavonoids and their cations and radicals.…”

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confidence: 99%

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The relationship between antioxidant activity, first electrochemical oxidation potential, and spin population of flavonoid radicals

Miličević

2019

Archives of Industrial Hygiene and Toxicology

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I have shown that by averaging antioxidant activity (AA) values measured by different methods it is possible to obtain an excellent correlation (R2=0.960) between the first electrochemical oxidation potential, Ep1, and AA. Separate correlations using the AA values obtained with each of the four methods [R2 were 0.561 for diphenyl-1-picrylhydrazyl (DPPH), 0.849 for Folin Ciocalteu reagent (FCR), 0.848 for the ferric-reducing ability of plasma (FRAP), and 0.668 for the Trolox equivalent antioxidant capacity (TEAC)] were all worse, and in some cases not useful at all, such as the one for DPPH. Also, the sum of atomic orbital spin populations on the carbon atoms in the skeleton of radicals ( s(C) Σ AOSPRad), calculated with the semi-empirical parameterisation method 6 (PM6) in water, was used to correlate both Ep1 and AA, yielding R2=0.926 and 0.950, respectively. This showed to be a much better variable for the estimation of Ep1 and AA than the bond dissociation energy (BDE), R2=0.854 and 0.901 for Ep1 and AA, respectively, and especially the ionisation potential (IP), R2=0.445 and 0.435 for Ep1 and AA, respectively.

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“…Furthermore, I correlated the determined generally accepted (26,27) active sites (A site, Table 1) using our earlier method (15). When s(C)…”

Section: Resultsmentioning

confidence: 99%

“…This stability depends on the number and spatial relations between phenolic hydroxyl groups in the molecule, i.e. their electronic structure (9)(10)(11)(12)(13)(14)(15)(16)(17)(18).…”

mentioning

confidence: 99%

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The relationship between antioxidant activity, first electrochemical oxidation potential, and spin population of flavonoid radicals

Miličević

2019

Archives of Industrial Hygiene and Toxicology

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“…In the range of 7.0 ≤ pH ≤ 12.0, a new anodic peak (Peak X 1‐PFF‐A ) in lower potential value as compared to P a 1‐PFF‐A was observed, and another new anodic peak (Peak X 2‐PFF‐A ) was appeared in media with pH ranging from 8.0 to 10.0. It should be addressed that these anodic peaks with relatively low potential values indicated high abilities in radical scavenging (Milicevic, Jovanovic, & Miletic, ; Zhang et al, ). The appearance of these peaks suggested that ionization of ETPs at neutral or alkaline solution would generate new antioxidants in solutions.…”

Section: Resultsmentioning

confidence: 99%

“…This suggests that the acid-base dissociation constant (pK a ) ≈ 6.0 was determined for anodic peaks of PFF-A. In the range of 7.0 ≤ pH ≤ 12.0, a new anodic peak (Peak X 1-PFF-A ) in lower potential value as compared to P a1-PFF-A was observed, and another ities in radical scavenging (Milicevic, Jovanovic, & Miletic, 2018;Zhang et al, 2011). The appearance of these peaks suggested that ionization of ETPs at neutral or alkaline solution would generate new antioxidants in solutions.…”

Section: Based On the Equationsmentioning

confidence: 94%

Voltammetric, spectroscopic, and cellular characterization of redox functionality of eckol and phlorofucofuroeckol‐A: A comparative study

et al. 2019

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Interest in phlorotannins has increased in recent years largely due to antioxidant capacity, however, the redox mechanism of phlorotannins is still obscure. In the present study, the electrochemical oxidation mechanisms of eckol (EL) and phlorofucofuroeckol‐A (PFF‐A), two representative phlorotannin compounds, were comparatively analyzed in a wide pH range using cyclic and differential pulse voltammetry as well as spectroscopic assay. The voltammetric study revealed that EL and PFF‐A were successively oxidized in three pH‐dependent steps. Moreover, it was found that the PFF‐A presented a stronger proton and electron transferring activity as compared to EL since PFF‐A exhibited lower acid–base dissociation constant (pKa) value and higher heterogeneous rate constant (kbh) value in the first oxidation step. These property were further evidenced by comparison of direct antioxidant activity (i.e., superoxide anion and peroxide radicals) as well as indirect antioxidant activity (i.e., mRNA expression of two phase II enzymes) between EL and PFF‐A. Practical applications Phlorotannins from edible algae have been regarded as novel antioxidants those presented high application potential in food industry. Even though antioxidant activity of phlorotannin compounds have been widely investigated in both in vitro and in vivo studies, very few reports focused on electron transferring functionality which is chemical basis for antioxidant process. Herein, the oxidative mechanisms of two representative phlorotannins were comparatively analyzed using multiple electrochemical methods. This is hopefully to give information on the chemical meaning behind the antioxidant activity of dietary phlorotannins.

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An electrochemical study on the redox chemistry of cyclic benzimidazole derivatives with potent anticancer activity

Jovanović

Jadreško

Miličević

et al. 2019

Electrochimica Acta

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Changes in electronic structures of flavonoids upon electrochemical oxidation and a theoretical model for the estimation of the first oxidation potential

Cited by 14 publications

References 43 publications

The relationship between antioxidant activity, first electrochemical oxidation potential, and spin population of flavonoid radicals

The relationship between antioxidant activity, first electrochemical oxidation potential, and spin population of flavonoid radicals

Voltammetric, spectroscopic, and cellular characterization of redox functionality of eckol and phlorofucofuroeckol‐A: A comparative study

An electrochemical study on the redox chemistry of cyclic benzimidazole derivatives with potent anticancer activity

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