Scavenging mechanisms of (-)-epigallocatechin gallate and (-)-epicatechin gallate on peroxyl radicals and formation of superoxide during the inhibitory action

Kondo, Kazunari; Kurihara, Masaaki; Miyata, Naoki; Suzuki, Takashi; Toyoda, Masatake

doi:10.1016/s0891-5849(99)00133-1

Cited by 164 publications

(111 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Although the scavenging mechanisms for EGCG are still poorly understood, there is recent evidence pointing to the production of superoxide (O 2Ϫ ) by EGCG in the process of scavenging peroxyl radicals. 40 It is of interest that DCFH is readily oxidized by superoxide formation whereas DHR shows little reactivity to this species. 39 EGCG had an antiproliferative effect on unirradiated HaCaT cells as expressed by a fall in cell survival upon subsequent plating.…”

Section: Discussionmentioning

confidence: 99%

The green tea polyphenol, epigallocatechin‐3‐gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation

Tobi

Gilbert

Paul

et al. 2002

Intl Journal of Cancer

101

View full text Add to dashboard Cite

A number of biological activities have been ascribed to the major green tea polyphenol epigallocatechin-3-gallate (EGCG) to explain its chemopreventive properties. Its antioxidant properties emerge as a potentially important mode of action. We have examined the effect of EGCG treatment on the damaging oxidative effects of UVA radiation in a human keratinocyte line (HaCaT). Using the ROS-sensitive probes dihydrorhodamine 123 (DHR) and 2 ,7 -dichlorodihydrofluorescein diacetate (DCFH-DA), we detected a reduction in fluorescence in UVA-irradiated (100 kJ/m 2 ) cells in the case of the former but not the latter probe after a 24-hr treatment with EGCG (e.g., 14%, [p < 0.05] after 10 M EGCG). In the absence of UVA, however, both DHR and DCFH detected a pro-oxidant effect of EGCG at the highest concentration used of 50 M. Measurements of DNA damage in UVA-exposed cells using the single cell gel electrophoresis assay (comet assay) also showed the protective effects of EGCG. A concentration of 10 M EGCG decreased the level of DNA single strand breaks and alkali-labile sites to 62% of the level observed in non-EGCG, irradiated cells (p < 0.001) with a 5-fold higher concentration producing little further effect. Correspondingly, EGCG ablated the mutagenic effects of UVA (500 kJ/m 2 ) reducing an induced hypoxanthine-guanine phosphoribosyl transferase (HPRT) mutant frequency of (3.39 ؎ 0.73) ؋ 10 ؊6 to spontaneous levels (1.09 ؎ 0.19) ؋ 10 ؊6 . Despite having an antiproliferative effect in the absence of UVA, EGCG also served to protect against the cytotoxic effects of UVA radiation. Our data demonstrate the ability of EGCG to modify endpoints directly relevant to the carcinogenic process in skin. © 2002 Wiley-Liss, Inc. Key words: epigallocatechin-3-gallate; antioxidant; ultraviolet AThere has been considerable recent interest in the chemopreventive properties of the polyphenols or catechins of green tea that have been shown to inhibit tumorigenesis in a variety of organs in rodent models. 1-3 The major polyphenol component by mass, (Ϫ)-epigallocatechin-3-gallate (EGCG) is an effective protectant against the mutagenicity of a number of chemical carcinogens including benzo[a]pyrene (B[a]P), aflatoxin B1 and 3-hydroxyamino-1-methyl-5H-pyrido [4,3-b]indole. 4 -6 EGCG, together with other green tea polyphenols also exhibits growth inhibitory properties in a variety of tumour cell lines. 7-9 Several mechanisms have been proposed by which these compounds exert their anti-tumorigenic action: these include the blockade of growth factors binding to their receptors, 10 phosphorylation (activation) of mitogen-activated protein kinases (MAPKs) 11,12 possibly resulting in the observed induction of Phase II drug-metabolizing enzymes, 13,14 and the generation of oxidative stress leading to apoptosis. 7,9 In the face of an oxidative challenge, however, it is now well documented that green tea catechins act as antioxidants. For example, EGCG abrogates oxidation by hydrogen peroxide both in a cell free system 15 and in terms of DNA single-s...

show abstract

Section: Discussionmentioning

confidence: 99%

The green tea polyphenol, epigallocatechin‐3‐gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation

Tobi

Gilbert

Paul

et al. 2002

Intl Journal of Cancer

101

View full text Add to dashboard Cite

show abstract

“…[81] Between ECG and EGCG, the former one has 7 hydroxyl groups and the latter has 8, but the antioxidant property of ECG is somewhat higher than EGCG at physiological pH. [32] Cao et al, [81] reported that at physiological pH (pH 7.4), AOH deprotonation occurs mainly at C4 0 AOH and C4 00 AOH for both ECG and EGCG owing to the very low dissociation energy (DE) of OH at these sites. The subsequent anion formed, plays a crucial role since the ease of electron donation becomes the underlying mechanism for antioxidant property and not hydrogen atom donation, as suggested from ionization potential (IP) data.…”

Section: Docking Studiesmentioning

confidence: 99%

“…Although EGCG is the most abundant catechin [31] the maximum antioxidant property is shown by ECG. [32,33] Interaction of RNase A with several green tea polyphenols (GTP) has been previously investigated in our laboratory. [34] This study highlighted that the gallate moiety promotes better interaction between protein and polyphenol.…”

Section: Introductionmentioning

confidence: 99%

β‐cyclodextrin encapsulated polyphenols as effective antioxidants

et al. 2017

View full text Add to dashboard Cite

Formation of dityrosine (DT) cross-linkages in proteins is one of the most widely used markers of oxidative stress. Ribonuclease A (RNase A) has 6 Tyr residues and shows a characteristic DT fluorescence peak upon oxidation in addition to major changes in its secondary structure. DT formation can be prevented by using polyphenols (GA, ECG, and EGCG) which are known to have strong antioxidant activity. However, it has been observed that ECG and EGCG initiate protein oligomerization due to protein-polyphenol cross-linkages. To prevent the formation of such crosslinkages we have used b-cyclodextrin (b-CD) to encapsulate the polyphenols and studied its antioxidant properties along with that of free polyphenols. The polyphenol/b-cyclodextrin (b-CD) inclusion complexes not only prevent DT formation but also reduce protein oligomerization. This may be attributed to the fact that the quinone forming rings of ECG and EGCG become encapsulated in the cavity of b-CD and are no longer available for protein cross-linking.b-cyclodextrin encapsulation, dityrosine, oxidative stress, polyphenols, protein oligomerization | I N TR ODU C TI ONBiological aging in mammalian cells is a direct indication of oxidative stress in proteins. [1] These oxidatively modified forms of proteins are generated due to the presence of reactive oxygen species (ROS) such as hydroxyl and superoxide free radicals. [2,3] Persulfates, a key ingredient in flour, are a source of sulfate (SO 2 4 ) free radicals under neutral pH. [4,5] Due to the higher oxidizing power of the sulfate radical (E 0 5 12.60 V) and longer half-life period over the OH radical, it has drawn attention in recent times as a powerful oxidizing agent. [6][7][8] Many chemical and cosmetic industries require persulfates as their key components [9] and workers often suffer from skin and respiratory diseases due to hypersensitive reactions. [10] Generally, the lower thermal energy at room temperature (25-508C) is not sufficient enough to activate persulfate, but generation of SO 2 4 radical is facilitated in presence of metal cations. Since proteins tend to lose their structure and function at high temperatures, [11] we have carried out the oxidation of ribonuclease A (RNase A) in presence of persulfate using cobalt (II) ion at 378C. [12] Cobalt is an integral component of vitamin B12 and thus physiologically found in most tissues mainly in liver and kidney. [13,14] Gill et al., reported the formation of oligomeric species (dimer, trimer, tetramer) when RNase A was exposed to KHSO 5 in presence of metal ions such as Ni 21 and Cu 21 and the high molecular weight species were identified using SDS-PAGE. [12] An important biomarker of oxidative stress is the dityrosine moiety generated due to the covalent linkage of two Tyr residues. [15] Dityrosine bond formation is an indication of aging, and disease related problems since it generally occurs during amyloid fibril formation, [16] Parkinson disease, [17] cerebrospinal fluid damage, [18] and also in the cataract of the eye lens. [19,20] D...

show abstract

“…The advantage of this disinfection technique is that polyphenols are supposed to be safe for humans because they are edible compounds naturally occurring in fruits, vegetables, nuts, seeds, and flowers. In addition, since those polyphenolic compounds are noteworthy for its antioxidative activity [74,75], they might alleviate the oxidative damage in the tissue after the disinfection treatment. Therefore, it is expected that this disinfection technique is applicable to the fields of medical and food sanitation.…”

Section: Other Hydroxyl Radical Generation Systemsmentioning

confidence: 99%

Microbicidal Activity of Artificially Generated Hydroxyl Radicals

Sheng

Nakamura

Kanno

et al. 2015

Interface Oral Health Science 2014

View full text Add to dashboard Cite

The hydroxyl radical, one of the reactive oxygen species, has one unpaired electron in the structure, so that it tends to deprive other substances of an electron which is so-called oxidation. It is known that hydroxyl radicals produced by immunological response kill invading microorganisms by the oxidation. Besides the immune system, it has been demonstrated that hydroxyl radicals play an important role in the bactericidal action of antibiotics. In this context, we have conducted a research to develop disinfection techniques utilizing artificially generated hydroxyl radicals. We adopted photolysis of H 2 O 2 , sonolysis of water and the other photo-chemical reaction as generators of hydroxyl radicals. A series of studies demonstrated that the microbicidal activity of hydroxyl radicals was sufficient to kill bacteria in an experimental biofilm as well as planktonic bacteria and fungi within a short-treatment time. In addition, the safety aspect is confirmed by an in vivo study and a literature review. Thus, it is suggested that disinfection treatment utilizing artificially generated hydroxyl radicals can be applicable to medical/dental therapy as novel disinfection treatments.

show abstract

Scavenging mechanisms of (-)-epigallocatechin gallate and (-)-epicatechin gallate on peroxyl radicals and formation of superoxide during the inhibitory action

Cited by 164 publications

References 36 publications

The green tea polyphenol, epigallocatechin‐3‐gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation

The green tea polyphenol, epigallocatechin‐3‐gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation

β‐cyclodextrin encapsulated polyphenols as effective antioxidants

Microbicidal Activity of Artificially Generated Hydroxyl Radicals

Contact Info

Product

Resources

About