(-)-Epigallocatechin gallate protects against NO stress-induced neuronal damage after ischemia by acting as an anti-oxidant.
The present study investigated the effects of (-)-epigallocatechin gallate (EGCG), which is the major component of polyphenol in green tea, on nitric oxide (NO) stress-induced neuronal damage, by monitoring NO mobilizations in the intact rat hippocampus and assaying the viability of cultured rat hippocampal neurons. A 10-min ischemia increased NO (NO(3)(-)/NO(2)(-)) concentrations in the intact rat hippocampus, while EGCG (50 mg/kg i.p.) inhibited the increase by 77% without affecting hippocampal blood flow. The NO donor, sodium nitroprusside (SNP; 50 microM), produced NO (NO(3)(-)/NO(2)(-)), while EGCG inhibited it in a dose-dependent manner at concentrations ranging from 50 to 200 microM. Treatment with SNP (100 microM) reduced the viability of cultured rat hippocampal neurons to 22% of control levels, while EGCG caused it to recover to 51% for 10 microM, 73% for 20 microM, and 70% for 50 microM. Taken together, it appears that EGCG could protect against ischemic neuronal damage by deoxidizing peroxynitrate/peroxynitrite, which is converted to NO radical or hydroxy radical.
Nagai
Kaoru
K
Department of Physiology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan.
Jiang
Min Hai
MH
Hada
Junichi
J
Nagata
Tetsu
T
Yajima
Yukio
Y
Yamamoto
Satoshi
S
Nishizaki
Tomoyuki
T
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002545:Brain Ischemia / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009569:Nitric Oxide / Q000009:adverse effects*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D000975:Antioxidants; D018696:Neuroprotective Agents; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D009569:Nitric Oxide; D002392:Catechin; C045651:epigallocatechin gallate