Investigation of the presence and significance of theanine in the tea plant

Abstract

Theanine was determined in black teas and tea plants by a combination method of thin-layer chromatography (t.1.c.) and densitometry. It was shown that in 20 samples of black tea from different qualities and sources the amount varied from 0.33 to 1.59 g 100 8-l dry wt. The highest quality black teas possessed the lowest amount of theanine, but it is subject to chemical degradation during black tea manufacture. The investigation of physiological function of theanine in the tea plant showed that during germination the theanine level reached a maximum after 45 days. This indicates that at this period of the growth of the tea plant theanine acted as a source of nitrogen and as a starting point for the synthesis of the carbon skeletal compounds of the tea plant. Theanine was found to exist in all parts of the tea plant but it accumulated more in young and active tissues and also in younger plants, which emphasises its metabolic role in tHe tea plant. The distribution of theanine in the shoots indicated that the first leaf was the principal site for the synthesis of polyphenolic compounds from theanine.

Absorption of foliar-applied urea-15N and the impact of low nitrogen, potassium, magnesium and sulfur nutritional status in tea (Camellia sinensisL.) plants

“…Total N concentrations in young shoots, roots and stem decreased from the beginning to the end of sampling (Fig. 1c), which is in line with earlier findings that the total N content of young shoots decreased gradually with flush growth, and those in leaves, stem and roots tended to decrease when the tea plants became older (Feldheim et al 1986). On the other hand, it was also likely that the decreasing N concentrations in stem and roots were caused by N remobilization from these organs to support the rapid growth of the young shoots.…”

Optimum conditions for the water extraction of L‐theanine from green tea

“…The tea had stems as well as leaf material in it. As reported in a previous study 25, it is well known that theanine is often found at a higher concentration in stems than in leaves. The stems are harder to grind into small pieces than the leaves and therefore the particle sizes of the ground stem material may have been bigger than the particle sizes from the ground leaf material.…”

Occurrence, Biosynthesis and Metabolism of Theanine (γ-Glutamyl-L-ethylamide) in Plants: A Comprehensive Review

“…These results suggest that theanine can be synthesised from glutamic acid and ethylamine derived from alanine in all parts of tea seedlings. However, 15 supplied exogenously to intact seedlings was converted to theanine mainly in roots [24]. Amino acids stored in cotyledons may also be utilised for theanine synthesis in all parts of seedlings.…”