Complexation of epigallocatechin gallate (a green tea extract, egcg) with Mn2+: nuclear spin relaxation by the paramagnetic ion

Navarro, Rosa Elena; Santacruz‐Ortega, Hisila; Inoue, Motomichi

doi:10.1016/j.jinorgbio.2004.11.013

Cited by 35 publications

(27 citation statements)

References 15 publications

(21 reference statements)

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“…Hence, it is likely that the generation of reactive oxygen species induced by catechins and zinc ions peroxidized membrane unsaturated fatty acids, which could lead to a decrease in membrane fluidity (Teresa et al, 2002 and structural characters of EGCG. The D-ring hydroxyl groups of EGCG occupy the first coordination sphere around metal ion to form a diolate combination ring, while B-ring hydroxyl groups have weak interactions with metal ions (Navarro et al, 2005). As suggested by previous reports (Hashimoto et al, 1999;Kajiya et al, 2001), the number of hydroxyl groups on the B-ring in EGCG structure, the presence of a galloyl moiety, and the steric characters on the D-ring could affect its affinity for the lipid bilayers.…”

Section: +mentioning

confidence: 82%

“…Recent studies showed that EGCG-metal ion complex has a role in the initiation and development of cancer (Furukawa et al, 2003;Azam et al, 2004). It is likely that the D-ring hydroxyl groups could occupy the first coordination sphere around metal ion, whereas the B-ring hydroxyl group may have a secondary effect on such a complex formation (Navarro et al, 2005). Thermo-gravimetric and atomic absorption spectrophotometric studies indicate that the 3-OH-4-oxo and 3-OH-4-OH moieties are the most likely binding sites of flavonoids for metals.…”

Section: +mentioning

confidence: 99%

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Epigallocatechin-3-gallate affects the growth of LNCaP cells via membrane fluidity and distribution of cellular zinc

Yang

Sun

et al. 2009

J. Zhejiang Univ. Sci. B

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Abstract:Objective: To evaluate effects of epigallocatechin-3-gallate (EGCG) on the viability, membrane properties, and zinc distribution, with and without the presence of Zn . The proportion of EGCG incorporated into liposomes treated with the mixture of EGCG and Zn 2+ at the ratio of 1:1 was 90.57%, which was significantly higher than that treated with EGCG alone (30.33%). Electron spin resonance (ESR) studies and determination of fatty acids showed that the effects of EGCG on the membrane fluidity of LNCaP were decreased by Zn 2+. EGCG accelerated the accumulation of zinc in the mitochondria and cytosol as observed by atomic absorption spectrometer. Conclusion: These results show that EGCG interacted with cell membrane, decreased the membrane fluidity of LNCaP cells, and accelerated zinc accumulation in the mitochondria and cytosol, which could be the mechanism by which EGCG inhibits proliferation of LNCaP cells. In addition, high concentrations of Zn 2+ could attenuate the actions elicited by EGCG.

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Section: +mentioning

confidence: 82%

Section: +mentioning

confidence: 99%

Epigallocatechin-3-gallate affects the growth of LNCaP cells via membrane fluidity and distribution of cellular zinc

Yang

Sun

et al. 2009

J. Zhejiang Univ. Sci. B

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“…Since fluid properties of biological membranes were essential for numerous cell functions including solute transport and membraneassociated enzymatic activities [27], it is possible that even mild alterations produced by the lipophilic structures of flavonoids on membrane fluidity could cause aberrant function and changes in membrane permeability [28]. The D-ring hydroxyl groups of the flavonoid structure occupy the first coordination sphere around metal ion to form a diolate combination ring, while B-ring hydroxyl groups have weak interactions with metal ions [29]. As suggested by previous reports [30,31], the number of hydroxyl groups on the B-ring in many flavonoids structures, the presence of a galloyl moiety, and the steric characters on the D-ring could affect its affinity for the lipid bilayers.…”

Section: Discussionmentioning

confidence: 99%

Effects of Long-Term Use of Flavonoids on the Absorption and Tissue Distribution of Orally Administered Doses of Trace Elements in Rats

Jaccob¹,

Hussain²

2012

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The risk of pharmacokinetic polyphenols-trace elements interaction may undesirable therapeutic outcomes. We evaluate the long-term use of silibinin, epigallocatechin (ECGC), quercetin and rutin on the absorption and tissue distribution of zinc, copper and iron after single oral doses in rats. Five groups of rats received either with olive oil as control or one of the polyphenols silibinin, EPGC, quercetin or rutin, administered orally as oily solutions for 30 days. At day 30, a solution contains sulphate salt of zinc, copper and iron was administered orally; 3 hrs later blood samples, tissues of brain, kidney and liver were obtained for evaluation of the elements levels. The results showed that the polyphenols increased both serum and tissue levels of these elements compared with controls. This effect was relatively varied according to the structural differences among flavonoids. In conclusion, long-term use of supraphysiological doses of flavonoids increase absorption of Zn, Cu and Fe and their tissue availability in brain, kidney and liver; this effect seems to be different with variations in structural features.

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“…XPS results also revealed that the composition of the outmost surface layer included EGCG-Cr (III) ion complex. The complexing behaviour of EGCG with metal ions such as Al 3+ and Mn 2+ has been previously reported [40][41][42] . Signifi cant differences exist between the complex formation properties of EGCG and other polyphenols lacking the gallate ring (D-ring).…”

Section: Discussionmentioning

confidence: 81%

“…Signifi cant differences exist between the complex formation properties of EGCG and other polyphenols lacking the gallate ring (D-ring). Major coordinate bonds in EGCG metal complexes are formed by the gallate ring, while the gallocatechin ring (B-ring) has a secondary coordination effect [40][41][42] . In the present study, it seemed probable that the central -OH group of B-ring was deprotonated and coordinated to Cr 3+ ion.…”

Section: Discussionmentioning

confidence: 99%

Effect of (−)-epigallocatechin gallate on electrochemical behavior and surface film composition of Co-Cr alloy used in dental restorations

Qiao

2012

Dent. Mater. J.

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The aim of this study was to investigate the electrochemical behavior of Co-Cr alloy in artifi cial saliva containing (−)-epigallocatechin gallate (EGCG) and to characterize the composition and structure of the passive fi lm formed by potentiodynamic polarization. Electrochemical measurements ranked the corrosion resistance of Co-Cr dental cast alloy as follows when exposed to artifi cial saliva containing different concentrations of EGCG: 4.0 g/L<2.0 g/L<0 g/L<0.5 g/L<1.0 g/L. This showed that the concentration of EGCG in artifi cial saliva affected the corrosion behavior of Co-Cr alloy. X-ray photoelectron spectroscopy (XPS) results revealed that the outermost surface layer on Co-Cr alloy was mainly composed of Cr 2 O 3 and EGCG-Cr (III) ion complex, which were formed by redox and complex formation reactions respectively. When the redox reaction was dominant, Co-Cr alloy exhibited high corrosion resistance in EGCG-containing artifi cial saliva. On the contrary, when the complex formation reaction was dominant, Co-Cr alloy exhibited low corrosion resistance.

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Complexation of epigallocatechin gallate (a green tea extract, egcg) with Mn2+: nuclear spin relaxation by the paramagnetic ion

Cited by 35 publications

References 15 publications

Epigallocatechin-3-gallate affects the growth of LNCaP cells via membrane fluidity and distribution of cellular zinc

Epigallocatechin-3-gallate affects the growth of LNCaP cells via membrane fluidity and distribution of cellular zinc

Effects of Long-Term Use of Flavonoids on the Absorption and Tissue Distribution of Orally Administered Doses of Trace Elements in Rats

Effect of (−)-epigallocatechin gallate on electrochemical behavior and surface film composition of Co-Cr alloy used in dental restorations

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