Free amino acid theanine in tea

Twenty-five amino acids are reportedly found in made; among those theanine is the highest in quantity. Theanine is a unique free amino acid found only in tea leaves. It is the analogue of glutamine. Theanine is found in every part of the tea except for the fruit and contributes the major part of amino acids in tea.

Theanine is present in highest concentration in the roots of tea plants, but is absent from tea seeds in which the principal amino acid is pipecolic acid. Theanine naturally occurs in tea nearly exclusively as L-theanine. The other one is D-theanine but present in lower concentration in tea leaves.

The relative amounts of D-theanine display inverse correlation to tea quality. The ratio of D-theanine to L-theanine increases under high temperature of storage. Theanine showed a lowering effect on blood pressure in hypertensive rat.

Theanine may also act as biochemical modulator to enhance the antitumor effect of doxorubicin. It has been a common view that drinking green tea imparts a sense of well being and relaxation. This may be related to the fact that after administration of L-theanine, the intracerebral gamma-amino butyric acid level, which has antioxidant activity, significantly increases in as little as 30 min.
Free amino acid theanine in tea