Improvement of idarubicin induced antitumor activity and bone marrow suppression by theanine, a component of tea

We have examined the effect of theanine. a specific amino acid in green tea , on idarubicin (IDA)-induced antitumor activity and toxicity. In combinati on with theanine. IDA (0.25 mg/kg per day X 4 days, a dose that does not sh ow antitumor activity) had significant antitumor activity in P388-bearing m ice. The IDA concentration in the tumors in the theanine plus IDA group inc reased to twice the level in the IDA alone group. Furthermore, the decrease in tumor weight caused by IDA at 1.0 mg/kg per day x 4 days (at this dose IDA exhibits antitumor activity) was significantly amplified by theanine. T he numbers of leukocyte and bone marrow cells decreased significantly on ID A injection. Theanine significantly reversed these changes. These results s uggest that theanine selectively moderates the IDA-induced toxicities, Unti l recently. the antitumor activity and related toxicities of this chemother apeutic agent in leukemia could not be distinguished. Theanine increases th e IDA-induced antitumor activity and ameliorates the toxicities. (C) 2000 E lsevier Science Ireland Ltd. All rights reserved.