Chromosome aberrations induced by aflatoxin B1 in rat bone marrow cells in vivo and their suppression by green tea.

Abstract Aflatoxin B 1 (AFB 1 )-induced chromosome aberrations (CA) in rat bone marrow cells consisted mainly of gaps and breaks. Cells with exchanges and multiple CA were observed infrequently. The incidence of aberrant cells and the number of aberrations per cell were at their maximum levels 18 h after the AFB 1 injection. They were dependent on the administered dose of AFB 1 . Rats given the hot water extract from green tea (GTE) 24 h before they were injected with AFB 1 displayed considerably suppressed AFB 1 -induced CA in their bone marrow cells. Rats administered GTE 2 h before or after the AFB 1 injection showed no suppressive effect. The suppressive effect of GTE on AFB 1 -induced CA paralleled the dose of GTE when given in the range between 0.1 and 2 g/kg body weight; higher doses produced no additional suppression. On the other hand, rats given the hot water extract from black tea or coffee 24 or 2 h before the AFB 1 injection showed no suppressive effect. The administration of caffeine 24 h before the AFB 1 injection suppressed AFB 1 -induced CA as well as the administration of caffeine 2 h before the AFB 1 injection. However, the suppression rate with 2 h was larger than with 24 h. The suppression by ellagic acid was found only when it was given 2 h before the AFB 1 injection. The administration of ascorbic acid or tannic acid did not significantly suppress AFB 1 -induced CA. The tannin mixture extracted from green tea (GTTM) showed a similar tendency to GTE, that is, the administration of GTTM 24 h before the AFB 1 injection potently suppressed AFB 1 -induced CA, while the administration of GTTM 2 h before the AFB 1 injection did not suppress them significantly. The suppressive effect of GTTM on AFB 1 -induced CA paralleled the dose of GTTM when given in the range of 75–450 mg/kg body weight.