“…A 1:1 Cu(II)–Lut complex has been characterized in our previous work as formed from Cu(II) addition to Lut with a yield of ∼90% by Cu(II) coordination to the 3′,4′-catechol group at a pH ∼ 7.4 aqueous solution with the structure as seen in Scheme 2 a, which agreed with the results of Malacaria et al 45 The 2:1 Cu(II)–Lut complex begins to transform into a 1:1 complex at pH 5.0, which is dominant with a percentage higher than 75% at pH higher than 5.5. The stoichiometry of Lut and Cu(II) complexes obtained by Říha et al 46 was between 1:1 and 1:2 by determination of ER 50 values (the concentration ratio of flavonoids to copper when 50% copper is chelated).…”
The interactions
of luteolin (Lut) with bovine serum albumin (BSA)
mediated by Cu(II) were investigated by spectroscopic, calorimetric,
and molecular dynamic (MD) methods. Fluorescence studies showed that
the binding of Lut to BSA was significantly enhanced by Cu(II) coordination
with the number of binding sites and binding constant increasing from
n
= 1 and
K
a
= 3.2 × 10
5
L·mol
–1
for Lut to
n
= 2 and
K
a
= 7.1 × 10
5
L·mol
–1
for a 1:1 Cu(II)–luteolin
complex, in agreement with the results from isothermal titration calorimetry
(ITC). Site-specific experiments with warfarin and ibuprofen and MD
confirmed that two binding sites of BSA were sequentially occupied
by two Cu(II)–luteolin complexes. Cu(II) coordination increased
the antioxidant activity of luteolin by 60% in the inhibition of carbonyl
formation from the oxidation of amino groups in the side chain of
BSA induced by the peroxyl radical ROO
•
; however,
it counteracted the antioxidant effects of luteolin and played pro-oxidative
roles in BSA aggregation induced by
•
OH.
“…A 1:1 Cu(II)–Lut complex has been characterized in our previous work as formed from Cu(II) addition to Lut with a yield of ∼90% by Cu(II) coordination to the 3′,4′-catechol group at a pH ∼ 7.4 aqueous solution with the structure as seen in Scheme 2 a, which agreed with the results of Malacaria et al 45 The 2:1 Cu(II)–Lut complex begins to transform into a 1:1 complex at pH 5.0, which is dominant with a percentage higher than 75% at pH higher than 5.5. The stoichiometry of Lut and Cu(II) complexes obtained by Říha et al 46 was between 1:1 and 1:2 by determination of ER 50 values (the concentration ratio of flavonoids to copper when 50% copper is chelated).…”
The interactions
of luteolin (Lut) with bovine serum albumin (BSA)
mediated by Cu(II) were investigated by spectroscopic, calorimetric,
and molecular dynamic (MD) methods. Fluorescence studies showed that
the binding of Lut to BSA was significantly enhanced by Cu(II) coordination
with the number of binding sites and binding constant increasing from
n
= 1 and
K
a
= 3.2 × 10
5
L·mol
–1
for Lut to
n
= 2 and
K
a
= 7.1 × 10
5
L·mol
–1
for a 1:1 Cu(II)–luteolin
complex, in agreement with the results from isothermal titration calorimetry
(ITC). Site-specific experiments with warfarin and ibuprofen and MD
confirmed that two binding sites of BSA were sequentially occupied
by two Cu(II)–luteolin complexes. Cu(II) coordination increased
the antioxidant activity of luteolin by 60% in the inhibition of carbonyl
formation from the oxidation of amino groups in the side chain of
BSA induced by the peroxyl radical ROO
•
; however,
it counteracted the antioxidant effects of luteolin and played pro-oxidative
roles in BSA aggregation induced by
•
OH.
The structural characterization of a new flavonoid from bergamot fruit (Citrus bergamia Risso) carrying the 3-hydroxy-3-methyl glutaryl (HMG) ester moiety has been accomplished, and its antioxidant ability was tested from a chemical point of view. The peculiarity of the new molecule, named peripolin, relies on the presence of the HMG chemical group linked to the sugar portion of neoeriocitrin; the structure was elucidated using both high-resolution mass spectrometry and nuclear magnetic resonance experiments performed on the purified molecule extracted from the fruit. The antioxidant ability of the new molecule was tested by classical chemical approaches, such as DPPH, ABTS and FRAP assays, and from a theoretical point of view. 1H and 13C NMR experiments and HR-ESI-MS/MS experiments show unequivocally that the HMG moiety is linked to the primary position of the glucose unit of neohesperidose, while the chemical tests and the computational results show that peripolin possesses strong antioxidant behavior, similar to that of neoeriocitrin and remarkably higher respect to the other flavonoids present in the fruit. Furthermore, the quantitative assays carried out by UPLC-MS/MS showed that its amount in the fruit is similar to that of the other main flavonoids. Furthermore, molecular dynamics simulations allowed us to investigate the possible conformations adopted by the antioxidants in the presence of water molecules. In particular, the switch of open-closed conformations of HMG-containing species was evidenced. As far as the reaction with DPPH, the calculation of ΔGrea supported the experimental outcomes regarding the peripolin and neoeriocitrin activity. In conclusion, bergamot fruit, already known for its potential to lower the level of blood cholesterol, has been proven to contain molecules such as neoeriocitrin and the newly characterized peripolin, which could have important in-vivo antioxidant characteristics.
“…Moreover, the coexistence of Fe 2+ and Fe 3+ ions on the dyed fiber leads to the overlapping of their spectra, resulting in a shift of λ max towards darker hues [ 61 ]. The enhanced color depth value of Cu-mordanted wool yarn may be attributed to the development of an insoluble Cu-flavonoid or Cu-tannate complex on the surface of the fiber [ 62 , 63 ]. Fig.…”
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
