Suppressive effect of (-)-epigallocatechin gallate on aflatoxin B1-induced chromosome aberrations in rat bone marrow cells

The suppressive effect of (-)-epigallocatechin gallate (EGCG), the major polyphenolic constituent present in green tea, on aflatoxin B-1 (AFB(1))-induced chromosome aberrations (CA) in rat bone marrow cells was studied. The administration of EGCG 24 hr before the AFB(1) injection significantly suppressed AFB(1)-induced CA. The suppression was observed 18 hr, 24 hr and 48 hr after the AFB(1) treatment but no suppressive effect was observed at the early period (6 hr acid 12 hr) after the AFB(1) treatment. Furthermore. the suppression was observed in all doses of AFB(1) ( 1, 5. 10 and 20 mg/kg) investigated. Rats given EGCG 2 hr before the AFB(1) injection displayed no suppressive effect. The suppressive effect of EGCG paralleled the dose of EGCG when given in a dose range of 10-60 mg/kg body weight. The administration of (-)-epicatechin gallate 24 hr before the AFB(1) injection significantly suppressed AFB(1)-induced CA as well as EGCG. On the other hand, in rats given green tea polyphenols (GTP) 2 hr before the AFB(1) injection, (-)-epigallocatechin and gallic acid significantly suppressed AFB(1)-induced CA. The pretreatment with EGCG or gallic acid did not induce the drug-metabolizing enzymes in rat liver, such as cytochrome P450 and glutathione S-transeferase. Rats given 2% green tea infusion as the sole source of drinking water for four days before sacrifice displayed significantly suppressed AFB(1)-induced CA. However, rats given various kinds of canned tea for four days showed no suppressive effect. The amount of GTP in canned tea determined by high performance liquid chromatography (HPLC) analysis was much less than that in 2% green tea infusion.