The decreases in the glutathione (GSH) level in the mouse spleen and liver after immune stimulation are suppressed by the oral administration of cystine and theanine (CT). GSH is considered to be important for the control of immune responses. Antibody production in mice after infection is enhanced by the oral administration of CT. In humans, also, the oral administration of CT has been confirme...

Summer grown green tea is less popular due to bitterness and high astringency, which are attributed to high levels of tea polyphenols (TP) and low levels of amino acids (AA) in tea leaves (Camellia sinensis L.). Brassinosteroids (BRs), a group of steroidal plant hormones can regulate primary and secondary metabolism in a range of plant species under both normal and stress conditions. However, s...

In 1949, Sakato2) isolated an amino acid, theanine (L-GluNHEt), from Japanese tea leaves and identified it as N-ethylglutamine amide. The presence of L-GluNHEt in other varieties of tea was confirmed by Cartwright, et al.3) And L-GluNHEt has been thought to be a flavourous constituent of tea leaves. On the other hand, caffeine, a central stimulant, has been known to be a pharmacological active ...