Modification of gamma-radiation response in mice by green tea polyphenols.
In this study we evaluated the effect of water extracts of green tea (GT) and mixtures of green tea polyphenols (GTPs), epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC) on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of mice irradiated with gamma-ray. The radioprotective effect of green tea was compared with the effect of diethyldithiocarbamate (DDC). Jejunal crypts were protected by pretreatment of GT and ECG. Administration of GT, GTPs and EC prior to irradiation resulted in an increase in the formation of endogenous spleen colonies. The frequency of apoptosis in crypt cells was also reduced by pretreatment of GT, GTPs, EGCG, ECG and EGC. In the experiment on the effect of catechins, the effects were partly contradicted in irradiated mice. The rank order of activity was ECG > EGC > EGCG > EC on intestinal crypt survival assay, EC > EGC > ECG > EGCG on the spleen colony formation assay, EGCG > EGC > EC > ECG on inhibiting the death of cells caused by apoptosis. The results indicate that GT and GTPs may have a major radioprotective effect. Each one of the catechins was a much less effective radioprotector, suggesting that total extract or a mixture of GTPs may be more effective than individual catechins.
Lee
Hae June
HJ
Korea Institute of Radiological & Medical Science, Seoul 139-240, South Korea.
Kim
Joong Sun
JS
Moon
Changjong
C
Kim
Jong Choon
JC
Lee
Yun Sil
YS
Jang
Jong Sik
JS
Jo
Sung Kee
SK
Kim
Sung Ho
SH
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D005260:Female; D005419:Flavonoids / Q000494:pharmacology*; D005720:Gamma Rays; D007583:Jejunum / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects*; D051379:Mice; D008813:Mice, Inbred ICR; D010636:Phenols / Q000494:pharmacology*; D059808:Polyphenols; D013662:Tea / Q000737:chemistry*
D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea