Studies On Theanine For Seperation Mechanism, Measurement And Anti-senescence Effects

Theanine is an unique nonproteinous amino acid comprising 50%of total free amino acids in tea(Camellia sinensis). Owing to its delicate taste and the ability to alleviate the astringency, theanine plays an important role in determining the quality and characteristics of green tea. Furthermore, various favorable physiological functions of theanine such as neuroprotective effects have been reported. The demand for theanine has increased greatly in the industry of natural health care products and functional drinks, not only as a taste-enhancing additive, but also as a supplement for improving and maintaining human health. In order to provide effective scientific theory support for the development and utilization of theanine, the studies focus on four aspects in this paper as follows:(1) Measurement of theanine in tea; (2) The adsorption behaviors of theanine on ion exchange resin; (3) The anti-senescence effect of theanine; (4) The protective effect of theanine on Alzheimer's disease.(1) An ion-pair reversed-phase liquid chromatographic method for the analysis of theanine has been developed. The sample can be analyzed directly after sonication for 10 min. 2 mmol/L pentadecafluorooctanoic acid aqueous solution (ion pair reagent) and acetonitrile (82:18, v/v) were used as the mobile phase.The wavelength was kept at 200 nm. The LOD and LOQ were 5.1ng and 15.6ng respectively. The purity identification showed other ingredients in tea do not interfere with the analysis of theanine. This method is accurate with high recovery and can be applied for the analysis of theanine in commercial tea and theanine products.(2) In order to provide the theory basis for adsorption and separation of theanine ion exchange resin, the adsorption behaviors of theanine on ion exchange resin were studied. Effect of pH on adsorption of theanine was not obvious; The adsorption data of theanine on HD-8 macroporous anion resin fit well into the Freundlich isotherm equation within temperature range of 303-323K and investigative concentration range; The rate of adsorption was under control of some factors simultaneously such as film diffusion and chemical reaction.(3) Senescence and related disease has become increasingly serious medical even social problems. The anti-senescence effect of theanine in vivo biological model of C.elegans(Caenorhabditis elegans) had been investigated. The results showed that theanine can extend C.elegans lifespan under heat stress. But it is difficult to find this effect in normal animal without stress. Using methods including GFP expression detection in transgenic worm line CL2006 and west-blotting in wide-type C. elegans N2, It was found that theanine can up-regulate the expression of heat shock protein HSP-16.2.(4) Base on the beta-amyloid transgenic model of C.elegans worm CL2006, The neuroprotective effect of theanine on Alzheimer's disease had been investigated. The studies suggested that theanine can decrease paralysis behavior of the CL2006. This behavior was caused by the down-regulation of Aβ1-42 mRNA and the level of reactive oxygen specises.