ABSTRACT
Theanine, γ-glutamylethylamide (5-N-ethylglutamine) (gure 16.1), was rst found in tea leaves (Camellia sinensis and others of the Camellia genus) in the early 1950s.1 The only other reported natural source of theanine is in the mushroom Xerocomus basius,2 but it is otherwise rare in nature. Theanine is a nonprotein amino acid. It
16.1 Introduction ................................................................................................. 255 16.2 Biosynthesis of Theanine in Tea Plant ........................................................ 257 16.3 Production of Theanine ............................................................................... 258
16.3.1 Biosynthesis of Theanine.............................................................. 258 16.3.2 Chemical Synthesis of Theanine .................................................. 259
16.4 Biological Properties of Theanine .............................................................. 261 16.4.1 Fate of Theanine after Oral Ingestion .......................................... 262 16.4.2 Theanine Inuences the Release and Concentration
of Several Neurotransmitters ........................................................ 262 16.4.3 Relaxation Effect .......................................................................... 262 16.4.4 Improvement of Learning Ability ................................................ 263 16.4.5 Regulation of Blood Pressure .......................................................264 16.4.6 Neuroprotection ............................................................................264 16.4.7 Theanine Reduces the Adverse Reactions of Doxorubicin by
Changing the Glutathione Level ................................................... 267 16.4.7.1 Tumor Development Inhibitor ...................................... 267 16.4.7.2 Chemotherapeutic Drug Enhancement ........................ 267
16.5 Additional Benets of Theanine .................................................................269 16.5.1 Inhibition of the Stimulating Effects of Caffeine .........................269 16.5.2 Promotion of Weight Loss ............................................................269 16.5.3 Enhancement of Immune System .................................................269
