Density functional computations of the energetic and spectroscopic parameters of quercetin and its radicals in the gas phase and in solvent

Leopoldini, Monica; Marino, Tiziana; Russo, Nino; Toscano, Marirosa

doi:10.1007/s00214-003-0544-1

Cited by 167 publications

(127 citation statements)

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“…[6][7][8][9][10][11][12][13][14][15] It is well recognized that the OH group at C-3 position on the C ring and the OQH 2 moiety (B-ring) play an important role in the free radical scavenging activities of Que derivatives (flavonols). It has been reported that reaction of Que with O 2 ·− is triggered by proton transfer from Que to yield dismutated products of O 2 ·− and deprotonated Que at the OH group at C-3 position on the C ring, which allows quercetinase-like dioxygenation to give the corresponding depside in high yield through an SFO reaction.…”

Section: Cyclic Voltammetry Of O 2 In the Presence Of Flavonoidsmentioning

confidence: 99%

“…1,2) Therefore, free radical scavenging by natural polyphenols has been widely studied experimentally and theoretically from thermodynamic perspectives, such as redox potentials and energy calculations. [3][4][5][6][7][8][9][10][11][12][13][14][15] Currently, phenolic antioxidants are well known to play a protective role by interrupting chain reactions, such as lipid peroxidation, ascribed to H-atom transfer (HAT) involving concerted proton-coupled electron transfer (PCET), sequential PCET, and sequential proton loss electron transfer (SPLET) to intermediate radicals. [16][17][18][19] In a solvent that supports dissociation of phenols the SPLET mechanism is considered to be significant compared with the HAT mechanism.…”

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confidence: 99%

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Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging

Nakayama

Uno

2015

CHEMICAL & PHARMACEUTICAL BULLETIN

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Section: Cyclic Voltammetry Of O 2 In the Presence Of Flavonoidsmentioning

confidence: 99%

mentioning

confidence: 99%

Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging

Nakayama

Uno

2015

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…7,8 Furthermore, QCT exhibits various anomalous spectroscopic properties. [9][10][11][12][13][14] Flavonols such as QCT that contain an -OH group at position 5 (C-5) have been considered to comprise a special class of nonfluorescent molecules, and it is believed that these molecules can act as photoprotectors in that they allow the excess sunlight striking on a plant leaf to be harmlessly converted to heat.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Properties of Flavonoids in Various Aqueous-Organic Solvent Mixtures

Park¹,

Yu²,

Park³

et al. 2013

Bulletin of the Korean Chemical Society

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The characteristic fluorescence properties of quercetin (QCT) and apigenin (API) were studied in various CH3OH-H2O and CH3CN-H2O mixed solvents. The structure of QCT is completely planar. API is not planar at the ground state but becomes nearly planar at the excited state. If the molecules are excited to the S1 state in organic solvents, QCT exhibits no fluorescence due to excited state intramolecular proton transfer (ESIPT) between the -OH and the carbonyl oxygen, but API shows significant fluorescence because ESIPT occurs slowly. If the molecules are excited to the S2 state, both QCT and API exhibit strong S2 → So emission without any dual fluorescence. As the H2O composition of both solvents increases, the fluorescence intensity decreases rapidly due to the intermolecular hydrogen bonding interaction. The theoretical calculation further supports these results. The change in fluorescence properties as a function of the solvatochromic parameters was also studied.

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“…In the unrestricted scheme, the spin density is often considered to be a more realistic parameter and provides a better representation of the reactivity [33]. Spin density of flavonoid has been an important factor in the description of antioxidant behaviour [34].…”

Section: Spin Density and Their Reactivitymentioning

confidence: 99%

Electronic Description of Few Selected Flavonoids by Theoretical Study

Rajendran¹,

Ravichandran²,

Devapiriam³

2013

IJCA

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The electronic properties responsible for free radical scavenging and metal chelation of a set of 7 flavonoids compounds were studied. Electronic parameters were calculated using semi empirical PM3 method. The structure activity relationship of OH substitution, C2-C3 double bond, chelation site of flavonoid and related property of antioxidant efficiency, BDE, mulliken atomic charge, electron current movement among A, B and C-rings were investigated. The relative change in energy (H f ) associated with the formation of phenoxyl radicals and spin density distribution of phenoxyl radicals were determined. The complexation mechanism of seven flavonoids quercetin, morin, apigenin, naringenin, chrysin, taxifolin and fisetin with metal ions, by molecular mechanics (UFF) method was investigated. Flavonoids metal chelation site order on toxic metals Pb, Bi and Cd was investigated. The most likely chelation site for metal ion was 5-OH & 4=O group, followed by 4=O & 3-OH group and the 3'& 4' hydroxyl for all the flavonoid molecules studied. In the absence of C2-C3 double bond (taxifolin) the order of metal chelation site with metal was 3-OH & 4=O, followed by 5-OH & 4=O group and 3' & 4' hydroxyl.

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Density functional computations of the energetic and spectroscopic parameters of quercetin and its radicals in the gas phase and in solvent

Cited by 167 publications

References 0 publications

Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging

Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging

Spectroscopic Properties of Flavonoids in Various Aqueous-Organic Solvent Mixtures

Electronic Description of Few Selected Flavonoids by Theoretical Study

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