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3. A DFT Study on the Kinetics of HOO • , CH 3 OO • , and O 2 •− Scavenging by Quercetin and Flavonoid Catecholic Metabolites.

Author

Amić, Ana and Mastiľák Cagardová, Denisa

Subjects
FLAVONOIDS, QUERCETIN, CHARGE exchange, METABOLITES, PHENOXIDES, RADICALS (Chemistry)
Abstract

Reaction kinetics have been theoretically examined to ascertain the potency of quercetin (Q) and flavonoid catecholic metabolites 1–5 in the inactivation of HOO•, CH3OO•, and O2•− under physiological conditions. In lipidic media, the k overall TST / Eck rate constants for the proton-coupled electron transfer (PCET) mechanism indicate the catecholic moiety of Q and 1–5 as the most important in HOO• and CH3OO• scavenging. 5-(3,4-Dihydroxyphenyl)-γ-valerolactone (1) and alphitonin (5) are the most potent scavengers of HOO• and CH3OO•, respectively. The k overall Mf rate constants, representing actual behavior in aqueous media, reveal Q as more potent in the inactivation of HOO• and CH3OO• via single electron transfer (SET). SET from 3-O− phenoxide anion of Q, a structural motif absent in 1–5, represents the most contributing reaction path to overall activity. All studied polyphenolics have a potency of O2•− inactivation via a concerted two-proton–coupled electron transfer (2PCET) mechanism. The obtained results indicate that metabolites with notable radical scavenging potency, and more bioavailability than ingested flavonoids, may contribute to human health-promoting effects ascribed to parent molecules. [ABSTRACT FROM AUTHOR]

Published
2023
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5. LOX INHIBITION AND IRON CHELATION BY FERULIC ACID – A THEORETICAL APPROACH

Author

Amić, Ana, Dimitrić Marković, Jasmina M., Marković, Zoran, Milenković, Dejan, Milanović, Žiko, Antonijević, Marko, Mastiľák Cagardová, Denisa, and Rodríguez-Guerra Pedregal, Jaime

Subjects
ferulic acid, hydroxyl radical, LOX, iron chelation
Abstract

The main goal of this study was to examine some of the underlying mechanisms of protection by ferulic acid (FA) from damage caused by free radicals, mainly mechanisms involving enzymes to suppress formation of free radicals and the sequestration of transition metal ions that catalyse free radical production. Hence, potential of FA to act as antioxidant via suppressing •OH radical formation by sequestering the catalytic Fe2+ ion, and by inhibiting prooxidative lipoxygenase (LOX) enzyme, i.e., by suppressing formation of free radical precursors, was studied. The M06-2X functional and 6-311++G(d, p) basis set implemented in the Gaussian 09 program package [1] was used for geometry optimisations and frequency calculations. All calculations were performed in gas-phase at 298.15 K. The AutoDock 4.0 software package [2] was used to predict the binding mode between LOX and investigated compounds, FA and 5- hydroxyferulic acid (5-OHFA). The crystal structure of LOX was taken from Protein Data Bank. Discovery Studio 4.0 [3] was used to prepare protein structures and for analysis of the obtained results. Polar hydrogen atoms were added using the hydrogen module in AutoDockTools (ADT) graphical interface. Grid maps were determined using the AutoGrid module with grid box of dimension 60×60×60 with point separated by 0.375 Å. The Lamarckian Genetic Algorithm (LGA) was implemented for rigid-flexible docking simulation. Results of molecular docking calculations indicate favourable binding interactions of FA and 5OHFA with LOX active site. Exergonicity of chelation reactions of catalytic Fe2+ ion with FA and 5OHFA indicate potency of these chelators to prevent the formation of •OH radicals via Fenton-like reactions. Based on obtained results, inhibition of LOX could be more relevant mechanisms of protection against oxidative stress than iron chelation.

Published
2021

6. A DFT Study on the Kinetics of HOO • , CH 3 OO • , and O 2 •- Scavenging by Quercetin and Flavonoid Catecholic Metabolites.

Author

Amić A and Mastiľák Cagardová D

Abstract

Reaction kinetics have been theoretically examined to ascertain the potency of quercetin ( Q ) and flavonoid catecholic metabolites 1 - 5 in the inactivation of HOO • , CH 3 OO • , and O 2 •- under physiological conditions. In lipidic media, the koverallTST/Eck rate constants for the proton-coupled electron transfer (PCET) mechanism indicate the catecholic moiety of Q and 1 - 5 as the most important in HOO • and CH 3 OO • scavenging. 5-(3,4-Dihydroxyphenyl)-γ-valerolactone ( 1 ) and alphitonin ( 5 ) are the most potent scavengers of HOO • and CH 3 OO • , respectively. The koverallMf rate constants, representing actual behavior in aqueous media, reveal Q as more potent in the inactivation of HOO • and CH 3 OO • via single electron transfer (SET). SET from 3-O - phenoxide anion of Q , a structural motif absent in 1 - 5 , represents the most contributing reaction path to overall activity. All studied polyphenolics have a potency of O 2 •- inactivation via a concerted two-proton-coupled electron transfer (2PCET) mechanism. The obtained results indicate that metabolites with notable radical scavenging potency, and more bioavailability than ingested flavonoids, may contribute to human health-promoting effects ascribed to parent molecules.

Published
2023
Full Text
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