Spin-trapping study on the hydroxyl radical formed from a tea catechin-Cu(II) system.
Biosci Biotechnol Biochem
; 65(8): 1697-706, 2001 Aug.
Article
en En
| MEDLINE
| ID: mdl-11577706
ABSTRACT
A spin-trapping method was applied to examine the formation of the hydroxyl (OH) radical from a tea catechin-Cu(II) system to elucidate a previous result that some tea catechin-Cu(II) systems induced DNA scission. Three tea catechins, (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCg) and (-)-epicatechin (EC), were used. The spin-trapping agent, 5,5'-dimethyl-pyrroline-1-oxide (DMPO), was dissolved in a pH 9 phosphate buffer solution, then a catechin and Cu(II) were added in that order, and the ESR spectral change was monitored for one hour. The order of adding the catechin and Cu(II) was then reversed, and the ESR spectral change was again monitored to examine the coordinating activity of each catechin toward the Cu(II) ion and the effect on OH radical generation. The intensity changes of the spin adducts, DMPO-OH, DMPO-CH3 and DMPO-H, were analyzed, the results suggesting that the OH radical generated in the system decomposed DMPO, resulting in the formation of DMPO-CH3 and DMPO-H. The results show that EGC formed a stable complex with Cu(II) and generated the OH radical. EGCg seemed to have this activity, but the OH radical that was generated was scavenged by the gallate group existing in the complex. EC did not show strong coordinating and OH-generating activities. These characteristics of the three catechins are consistent with the results shown for DNA scission.
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Bases de datos:
MEDLINE
Asunto principal:
Té
/
Catequina
/
Radical Hidroxilo
/
Cobre
Idioma:
En
Revista:
Biosci Biotechnol Biochem
Año:
2001
Tipo del documento:
Article
País de afiliación:
Japón