Theanine, a specific glutamate derivative in green tea, reduces the adverse reactions of doxorubicin by changing the glutathione level

We previously showed that theanine, a specific glutamate derivative in green tea, decreased doxorubicin (DOX)-induced adverse reactions such as the induction of the lipid peroxide level and the reduction of glutathione peroxidase activity in normal tissues. In order to clarify how theanine attenuates the adverse reactions of DOX, we have focused on the effects of theanine on glutamate and glutathione (GSH) levels in normal tissues. The administration of theanine to mice increased the glutamate concentration in the liver and heart, and not in tumors. In vitro examinations indicated that theanine was metabolized to glutamate mainly in the liver. Moreover, theanine inhibited GSH reduction induced by DOX in the liver and heart. Therefore, these results suggested that theanine attenuated the DOX-induced adverse reactions involved in oxidative damage, due to increase in glutamate and the recovery of GSH levels in normal tissues.