Green Tea Information

Green Tea Research

Here are a few research articles for tea green and black. For more, please visit www.pubmed.com.

l-Theanine reduces psychological and physiological stress responses.

Nagoya University Department of Psychology, Chikusa-ku, Nagoya, 464-8601, Japan.

l-Theanine is an amino acid contained in green tea leaves which is known to block the binding of l-glutamic acid to glutamate receptors in the brain. Because the characteristics of l-Theanine suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took l-Theanine at the start of an experimental procedure, one in which they took l-Theanine midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that l-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of l-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.

[Effects of green tea polyphenol on the behaviour of Alzheimer' s disease like mice induced by D-galactose and Abeta25-35]

Department of Pharmacology, Jinan University Pharmacy College, Guangzhou 510632, China.

OBJECTIVE: To study the effects of green tea polyphenol (GTP) on the behaviour of Alzheimer' s Disease like mice induced by D-galactose and Abeta25-35. METHODS: D-galactose (120 mg/kg) was intraperitoneally injected into mice for 12 weeks and Abeta25-35 (4nmol) was injected by icv to establish Alzheimer' s Disease like mice. The protective and therapeutic effects of GTP were determined by using water maze test, step down test, step through test and open field test. RESULTS: GTP ameliorated the deleterious effects of D-galactose and Abeta25-35, and thereby improved the animal' s learning and memory, prolonged latency time, and the error numbers were significantly reduced. At the same time the autonomic activities were significantly increased. CONCLUSION: GTP can improve the behaviour of Alzheimer' s Disease like mice induced by D-galactose and Abeta25-35.

Green tea pain modulating effect in sciatic nerve chronic constriction injury rat model.

Department of Anatomy, Faculty of Medicine, Health Sciences Centre, University of Kuwait, Safat, Kuwait. wrenno@hsc.edu.kw

We investigated the effect of green tea (GT) in unilateral chronic constriction injury (CCI) to the rat scaitic nerve. Five groups (n = 6 rats/group) sham group: rats which underwent operation but with no ligation to the scaitic nerve, and received tap water for two weeks before and for five weeks after the surgery. Four experimental groups underwent CCI to the right sciatic nerve, divided randomly as follows: group E were given tap water throughout the study. Group B received GT before and after CCI. Group C was given GT following CCI. Group D received GT for two weeks prior to CCI. Groups which consumed GT showed significant improvement in the toe spread (P < 0.001) and foot positioning (P < 0.001) tests compared to the experimental control group. In addition, these groups showed a significant decrease in the behavioral mechanical hyperalgesia (P < 0.0001) and allodynia (P < 0.0002). Consumption of GT improves both reflexes and sensation which are often affected in the course of peripheral neuropathy.

Separation of catechin compounds from different teas.

Center for Advanced Bioseparation Technology, Department of Chemical Engineering, Inha University, 235 Yonghyun-dong, Nam-ku, Incheon 402-751, Korea.

Catechin compounds from Korean and Chinese green tea, and pu-erh, Indian black, Longjing, Tieguanyin, Bamboo, Jasmine, Oolong, Flower, Red teas, as potential anticancer and antioxidant components, were target material in this work. After extracting the green tea with water at 50 degrees C for 4 h, the extract was partitioned with water/chloroform, which was best suited to remove caffeine impurity from the extract. Further, the resulting extract was partitioned with water/ethyl acetate to deeply purify the five catechin compounds epigallocatechin, (+) catechin, epicatechin, epigallocatechin gallate and epicatechin gallate. The extracted samples were analyzed by reversed-phase high performance liquid chromatography. The mobile phase applied was the binary system of A (water/acetic acid, 100/0.1 vol%) and B (acetonitrile/acetic acid 100/0.1 vol%) from 90:10 to 70:30 (A:B vol%) in a linear gradient over 30 min time. The amount of catechin compounds extracted from Chinese green tea was 114.65% higher than from the Korean green tea. Comparing various tea sorts, the green teas contained more than 1.7 times of the five catechin compounds contained in other teas.

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