L-Theanine is a special amino acid contained in tea leaves. It was first isolated and named from Gyokuro tea by Japanese scholar Yajiro Saketo in 1950.
Its chemical name is N-ethyl-γ-L-gu. Amino amide (N-ethyl-γ-L-glutamine).
From the discovery so far, it has not been found in other plants except for a mushroom (Xeeocomus Badins) and Camellia. Sasangua.
L-Theanine accounts for 40%-60% of the total free amino acids in the tea tree, and 1%-2% of the dry matter of the tea tree.
It is considered to be the characteristic amino acid of tea, the main component of the fresh and refreshing tea soup, and the quality of green tea.
The positive correlation coefficient is 0.787～0.876.
Since its discovery, theanine has been widely studied as the main quality component of tea.
In recent years, with the deepening of research, the physiological health care effect of theanine has attracted widespread attention, which has led to the extraction and synthesis of theanine.
The development of craftsmanship. Nowadays, under the condition of mature theoretical technology and abundant raw materials, how to develop and utilize theanine has become a hot spot in the current research on functional components of tea.
Theanine is a water-soluble amino acid, and after oral intake, it shares a sodium-coupled co-transporter with glutamate and is transported into the blood circulation (Kitaoka Setal, 1996).
Absorbed theanine is transported to multiple organs of the body and can cross the blood-brain barrier into the brain via the leucine transport system (YokogoshiHetal, 1998).
The plasma concentration of theanine was the highest after 1 hour of oral intake of theanine in rats, and the highest concentration in the brain was reached after 5 hours, and then gradually decreased.
Theanine is decomposed into glutamate and ethylamine by glutaminase in the kidney and excreted, and completely disappears in the body after 24 hours (Terashima et al, 1999; Tayge Hetal, 2003).
1. Relaxation and relaxation
Tea contains more caffeine with refreshing and exciting effect, but after drinking tea, it will not produce the exciting effect of drinking the same amount of caffeine.
Studies have shown that theanine has an antagonistic effect on the excitation of caffeine. When the amount of theanine reaches 1,740 mg/kg, it can significantly inhibit the excitation of the nervous system caused by caffeine (Tsunoda Tetal, 1993).
Recently, some scholars have further determined that theanine and caffeine can antagonize the stimulating effect of caffeine at almost the same molar concentration by electroencephalography (Kakuda et al, 2000).
2. Protective effect on brain nerve cells
The neuroprotective effect of theanine was first discovered by Nozawa et al in 1998: 50% of the nerve cells died when the rat central nervous cells cultured in vitro were exposed to a certain concentration of glutamate, but if theanine was added The nerve cell death was significantly inhibited (NozawaAetal, 1998).
Subsequently, Kakuda et al. studied the protective effect of theanine on delayed neuronal death in the hippocampus of gerbils after ischemia-reperfusion injury.
The study found that microinjection of theanine 500μmol/L into the lateral ventricle 30 minutes before ischemia can significantly increase the number of intact CA1 neurons after injury in a dose-response relationship (Kakuda Tetal, 2000).
3. Lowering blood pressure
When injecting different doses of theanine (0, 500, 1000, 1500, 2000 mg/kg) into spontaneously hypertensive rats (SHR), blood pressure decreased, and the degree of decrease was dose-related, and it was observed in the high-dose group.
Blood pressure dropped significantly. But even the highest dose of theanine (2000mg/kg) did not change blood pressure in normal rats.
Moreover, glutamic acid, which is structurally similar to theanine, has not been found to have a blood pressure-lowering effect (YokogoshiHetal, 1995).
4. Anti-fatigue effect
Through research, Wang Xiaoxue et al. showed that oral administration of different doses (0, 4.2mg/kg, 8.3mg/kg, 16.6mg/kg) of theanine to mice for 30 days could significantly prolong the weight-bearing swimming time of mice and reduce liver glucose.
It can significantly inhibit the increase of blood lactate in mice after exercise, and can promote the elimination of blood lactate after exercise, indicating that theanine has anti-fatigue effect (Wang Xiaoxue et al., 2002).
Li Min et al. further proved through experiments that theanine has the effect of delaying exercise-induced fatigue, and its mechanism may be related to the effect of theanine increasing the content of dopamine (DA) in brain tissue and inhibiting the synthesis and release of serotonin (5-HTP). (Li Min et al., 2005).
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