Efficacies of tea components on doxorubicin induced antitumor activity andreversal of multidrug resistance

Considering of novel biochemical modulation by some foods and beverages, we have performed screening for green tea components that have enhancing effe cts on doxorubicin (DOX) induced antitumor activity. Components, such as ca ffeine, theanine, (-)-epigallocatechin gallate (EGCG) and flavonoids have i nhibitory effects on the DOX efflux from Ehrlich ascites carcinoma cells. T hus, it is suggested that EGCG and flavonoids may enhance DOX induced antit umor activity and increase the DOX concentrations in tumors through the inh ibition of DOX efflux. It is expected that these components in green tea ex hibit low toxicity and that there are few side effects of drinking green te a in combination with an antitumor agent. We think that the intake of a fav orite beverage favors a positive mental attitude of a patient and increases the efficacy of the chemotherapeutic index, and that this efficacy is usef ul for improving the quality of life on cancer chemotherapy. In DOX resista nt P388 leukemia cell bearing mice theanine increased the DOX induced effic acy through an increase in the DOX concentrations in the tumors. Theanine a ttacked the same transport process for DOX in both types of cells, elevated the DOX concentration and increased the DOX induced antitumor activity. (C ) 2000 Elsevier Science Ireland Ltd. All rights reserved.