Empirically predicted <sup>13</sup>C NMR chemical shifts for 8‐hydroxyflavone starting from 7,8,4′‐trihydroxyflavone and from 7,8‐dihydroxyflavone

March, Raymond E.; Burns, Darcy C.; Ellis, David

doi:10.1002/mrc.2232

Cited by 6 publications

(2 citation statements)

References 5 publications

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“…Using the proposed strategy proposed, 13 C NMR data for the remaining 17 flavonoids can be predicted. The 13 C chemical shifts for 8‐hydroxyflavone, which does not occur in nature, have been predicted using this model 133. The 13 C chemical shifts can also be predicted for polyhydroxylated flavonoids for which NMR spectra have not been observed, for rapid assessment of unassigned flavonoids NMR spectra and for verifying previously reported 13 C chemical shifts of flavonoids.…”

Section: Nuclear Magnetic Resonance Spectroscopysupporting

confidence: 53%

Analysis of flavonoids: Tandem mass spectrometry, computational methods, and NMR

March

Brodbelt

2008

J. Mass Spectrom.

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Due to the increasing understanding of the health benefits and chemopreventive properties of flavonoids, there continues to be significant effort dedicated to improved analytical methods for characterizing the structures of flavonoids and monitoring their levels in fruits and vegetables, as well as developing new approaches for mapping the interactions of flavonoids with biological molecules. Tandem mass spectrometry (MS/MS), particularly in conjunction with liquid chromatography (LC), is the dominant technique that has been pursued for elucidation of flavonoids. Metal complexation strategies have proven to be especially promising for enhancing the ionization of flavonoids and yielding key diagnostic product ions for differentiation of isomers. Of particular value is the addition of a chromophoric ligand to allow the application of infrared (IR) multiphoton dissociation as an alternative to collision-induced dissociation (CID) for the differentiation of isomers. CID, including energy-resolved methods, and nuclear magnetic resonance (NMR) have also been utilized widely for structural characterization of numerous classes of flavonoids and development of structure/activity relationships.The gas-phase ion chemistry of flavonoids is an active area of research particularly when combined with accurate mass measurement for distinguishing between isobaric ions. Applications of a variety of ab initio and chemical computation methods to the study of flavonoids have been reported, and the results of computations of ion and molecular structures have been shown together with computations of atomic charges and ion fragmentation. Unambiguous ion structures are obtained rarely using MS alone. Thus, it is necessary to combine MS with spectroscopic techniques such as ultraviolet (UV) and NMR to achieve this objective. The application of NMR data to the mass spectrometric examination of flavonoids is discussed.

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Section: Nuclear Magnetic Resonance Spectroscopysupporting

confidence: 53%

Analysis of flavonoids: Tandem mass spectrometry, computational methods, and NMR

March

Brodbelt

2008

J. Mass Spectrom.

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“…7,8,4´‐Trihydroxyflavone (structure shown in Scheme ), a member of the flavanol family, exists abundantly in the petals and foliage of plants, and its pharmacological activities have attracted widespread attention. It has been reported that 7,8,4´‐trihydroxyflavone exerts anti‐allergy pharmacological activity .…”

Section: Introductionmentioning

confidence: 99%

The effect of 7,8,4´‐trihydroxyflavone on tyrosinase activity and conformation: Spectroscopy and docking studies

et al. 2018

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Tyrosinase is a ubiquitous enzyme that plays an essential role in the production of melanin. Effective inhibitors of tyrosinase have extensive applications in the medical, cosmetic and food industries. In this study, a combination of enzyme kinetics, ultraviolet (UV)-visible absorption, fluorescence spectroscopic techniques and a computational simulation method was used to characterize the inhibitory mechanism of 7,8,4´-trihydroxyflavone on tyrosinase. 7,8,4´-Trihydroxyflavone was found to strongly inhibit the oxidation of l-DOPA by tyrosinase with an IC value of 10.31 ± 0.41 μM. The inhibitory mechanism was determined to be reversible and non-competitive with a K of 9.50 ± 0.40 μM. The UV absorption spectra showed that 7,8,4´-trihydroxyflavone could chelate with copper ions and form a complex with tyrosinase. The intrinsic fluorescence of tyrosinase was quenched by 7,8,4´-trihydroxyflavone through a static quenching mechanism. 7,8,4´-Trihydroxyflavone was found to occupy a single binding site with a binding constant of 7.50 ± 1.20 × 10 M at 298 K. The conformation of tyrosinase changed, and the microenvironment became more hydrophilic after 7,8,4´-trihydroxyflavone binding. Thermodynamics parameters indicated that the binding was a spontaneous process and involved hydrogen bonds and van der Waals forces. The binding distance was evaluated to be 4.54 ± 0.05 nm. Docking simulation analysis further authenticated that 7,8,4´-trihydroxyflavone could form hydrogen bonds with the residues His244 and Met280 within the tyrosinase active site. Our results will contribute to further understanding of the inhibitory mechanisms of 7,8,4´-trihydroxyflavone against tyrosinase and will facilitate future screening for tyrosinase inhibitors.

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Raymond E. March

March¹

2015

The Encyclopedia of Mass Spectrometry

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Empirically predicted ¹³C NMR chemical shifts for 8‐hydroxyflavone starting from 7,8,4′‐trihydroxyflavone and from 7,8‐dihydroxyflavone

Cited by 6 publications

References 5 publications

Analysis of flavonoids: Tandem mass spectrometry, computational methods, and NMR

Analysis of flavonoids: Tandem mass spectrometry, computational methods, and NMR

The effect of 7,8,4´‐trihydroxyflavone on tyrosinase activity and conformation: Spectroscopy and docking studies

Raymond E. March

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Empirically predicted 13C NMR chemical shifts for 8‐hydroxyflavone starting from 7,8,4′‐trihydroxyflavone and from 7,8‐dihydroxyflavone

Cited by 6 publications

References 5 publications

Analysis of flavonoids: Tandem mass spectrometry, computational methods, and NMR

Analysis of flavonoids: Tandem mass spectrometry, computational methods, and NMR

The effect of 7,8,4´‐trihydroxyflavone on tyrosinase activity and conformation: Spectroscopy and docking studies

Raymond E. March

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Empirically predicted ¹³C NMR chemical shifts for 8‐hydroxyflavone starting from 7,8,4′‐trihydroxyflavone and from 7,8‐dihydroxyflavone