Prooxidative activities of tea catechins in the presence of Cu2+.
The ability of various tea catechins to generate H2O2 and the hydroxyl radical in the presence of the Cu2+ ion was investigated and compared with the effect of iron ions. The presence of Cu2+ accelerated the generation of H2O2 by EGC, while EGCg with Cu2+ generated a little H2O2. The presence of iron ions inhibited the generation of H2O2 by EGC. EGC and EC with Cu2+ generated the hydroxyl radical, while EGCg and ECg with Cu2+ did not. The fact that EGCg showed less prooxidative activity than EGC can be explained by the chelating ability of catechin gallates to metal ions under the experimental conditions.
Hayakawa
Fumiko
F
School of Human Cultures, The University of Shiga Prefecture, Hassaka-cho, Hikone, Japan.
Ishizu
Yoko
Y
Hoshino
Nobuo
N
Yamaji
Akira
A
Ando
Takashi
T
Kimura
Takahide
T
D000975:Antioxidants / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry*; D003300:Copper / Q000737:chemistry / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry / Q000494:pharmacology; D010084:Oxidation-Reduction; D013662:Tea / Q000737:chemistry*
D000975:Antioxidants; D013662:Tea; D003300:Copper; D002392:Catechin; C062669:epicatechin gallate; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D007501:Iron; C057580:gallocatechol