(S)-3-Amino-1-ethylglutarimide from green tea (Camellia sinensis)

Abstract

The sub-critical water extraction of green tea (Camellia sinensis), composing of free amino acid, was investigated to produce a glutarimide derivative, (S)-3-amino-1-ethylglutarimide (1) along with a known compound, pyroglutamic acid. The structure of 1 was decided on the basis of spectroscopic evidence, including NMR (1H, 13C, DEPT, HSQC and HMBC) and FAB-MS studies. The taste assessment of 1 showed higher umami (good-tasting), bitterness, and astringency than those of the theanine standard. A large quantity preparation of 1 was achieved by sub-critical water extraction of aq. theanine at 180 C and 3 min reaction time. The first isolation of 1 from the plant sourse is described.