GABA Tea Research Articles

GABA tea ameliorates cerebral cortex apoptosis and autophagy in streptozotocin-induced diabetic rats

The γ-aminobutyric acid (GABA) tea is popular by consumers in Asia in recent years. This study investigated the effects of GABA tea on apoptosis and autophagy in the cerebral cortex of streptozotocin (STZ)-induced diabetic rats. Thirty-four male Wistar rats at 8weeks of age were randomly divided into control group, STZ-induced (60mg/kg, i.p.) diabetes (DM), and DM rats with water GABA tea extracts of containing GABA either 3.01 or 30.1μg/rat per day for 6weeks. Treatment with GABA tea dose-dependently lowered blood glucose level in the diabetic rats compared with vehicle. GABA tea reduced the diabetic-induced Fas-dependent and mitochondrial-dependent apoptotic pathway in the diabetic cerebral cortex compared with vehicle, the evidence for which is based on decreases in Fas, activated caspase-8, pro-apoptotic t-Bid, Bax, cytosolic cytochrome c, activated caspase-9 and activated caspase-3. GABA tea also reduced the diabetic-induced autophagy. The results suggest that GABA tea obviously inhibits diabetic-induced apoptosis in the cerebral cortex through the suppression of Fas and mitochondrial pathways. These findings provide the possible diabetes-related apoptotic and autophagy pathways in the cerebral cortex and suggest that GABA tea treatment has the potential to prevent diabetic brain abnormality.

Optimization of Extrusion Conditions for GABA Tea Powder/Corn Grit Blend Extrudates

γ-aminobutyric acid (GABA) tea powder blended with corn grits to develop a puffed snack foods by the extrusion technology was studied. Response surface methodology (RSM) was used to analyze the effects of screw speed (179, 200, 250, 300, 321 rpm) and GABA tea powder levels (6, 8, 13, 18 and 20%) on the objective attributes of a corn-based GABA tea powder extrudates. Areas of optimum performance were located by superimposing contour graphs for longitudinal expansion, maximum shear force, hardness and water solubility index for compositions and screw speed levels, which established limits of acceptable quality for each factor. Individual contour plots of the different responses were overlaid, and regions meeting the optimum longitudinal expansion of 18.3883 cm/g, hardness of 39.9659 (N), maximum shear force of 5.1670 (N) and water solubility index of 9.1190 (%) were identified at the GABA tea powder level of 12.9577% and the screw speed of 240.6332 rpm, respectively. Practical Applications According to the optimum conditions given for the variables, the process can be referred for industrial production and the extrudates are suitable for extruded snack food with GABA tea powder. In this study, the parameters of optimum operation condition for extruded corn-GABA tea powder snack products were suggested based on the product characteristics by RSM. Hence, the effects of extruder operation conditions on the physiochemical properties of corn extrudate blended with GABA tea powder are worthy of further exploration in the future.

Study on flavour volatiles of γ-aminobutyric acid (GABA) green tea

The volatile components of γ-aminobutyric acid (GABA) tea produced by two different kinds of technological process separately namely: vacuum and water immersion were studied. It was shown by the sensory evaluation that the color of the soup and the extracted leaves of GABA tea were similar to that of the oolong tea, and the smell was similar to the aroma of cooked sweet red dates mixed with some of sour. In GABA tea, the contents of 2,6-bis(1,1-dimethylethyl)-4-methyl phenol, methyl myristate, methyl laurate and methyl palmitate were higher than that of the normal green tea. The characteristic aroma constituents of the GABA tea made by vacuum treatment concluded methyl myristate, hexadecane, methyl laurate and methyl palmitate, while to the GABA tea made by water immersion, they were 2,6-bis (1,1-dimethylethyl) -4-methylphenol and 1-octanol. Keywords: γ-Aminobutyric acid (GABA), GABA tea, volatile flavour compounds

Zinc Ion Enhances GABA Tea-Mediated Oxidative DNA Damage

GABA tea is a tea product that contains a high level of γ-aminobutyric acid (GABA). Previous study has demonstrated a synergistic effect of GABA tea and copper ions on DNA breakage. This study further explored whether zinc (Zn), a nonredox metal, modulated DNA cleavage induced by GABA tea extract. In a cell-free system, Zn(2+) significantly enhanced GABA tea extract and (-)-epigallocatechin-3-gallate (EGCG)- or H(2)O(2)-induced DNA damage at 24 h of incubation. Additionally, low dosages of GABA tea extract (1-10 μg/mL) possessed pro-oxidant activity to increase H(2)O(2)/Zn(2+)-induced DNA cleavage in a dose-dependent profile. By use of various reactive oxygen scavengers, it was observed that glutathione, catalase, and potassium iodide effectively inhibited DNA degradation caused by the GABA tea extract/H(2)O(2)/Zn(2+) system. Moreover, the data showed that the GABA tea extract itself (0.5-5 mg/mL) could induce DNA cleavage in a long-term exposure (48 h). EGCG, but not the GABA tea extract, enhanced H(2)O(2)-induced DNA cleavage. In contrast, GABA decreased H(2)O(2)- and EGCG-induced DNA cleavage, suggesting that GABA might contribute the major effect on the antioxidant activity of GABA tea extract. Furthermore, a comet assay revealed that GABA tea extract (0.25 mg/mL) and GABA had antioxidant activity on H(2)O(2)-induced DNA breakage in human peripheral lymphocytes. Taken together, these findings indicate that GABA tea has the potential of both pro-oxidant and antioxidant. It is proposed that a balance between EGCG-induced pro-oxidation and GABA-mediated antioxidation may occur in a complex mixture of GABA tea extract.

A synergistic effect of GABA tea and copper(II) on DNA breakage in human peripheral lymphocytes

GABA tea is a tea product that contains a high level of γ-aminobutyric acid (GABA). The oxidant and antioxidant roles of GABA tea in DNA damage were investigated in this study. DNA cleavage was observed by GABA-tea extract in the presence of copper ions. Comet assay revealed that combination of GABA-tea extract, but not pure GABA, and Cu 2+ is capable of oxidatively degrading cellular DNA in human peripheral lymphocytes. Using various reactive oxygen scavengers, we found that catalase and sodium azide effectively inhibited GABA-tea extract/Cu(II)-induced DNA degradation, suggesting the essential role of singlet oxygen and H 2O 2 in the reaction. In addition, neocuproine inhibited the DNA degradation, confirming that Cu(I) is an intermediate in the DNA cleavage reaction. Therefore, we speculate that GABA-tea extract/Cu(II)-induced DNA damage is probably mediated through the formation of H 2O 2 and the reduction of copper. Furthermore, our data showed that GABA-tea extract was more genotoxic and pro-oxidant than its major catechin constituent, (−)-epigallocatechin-3-gallate (EGCG), leading to DNA cleavage in the presence of Cu 2+. These findings will provide implications for the potential of GABA-tea extract in anticancer property, which may involve copper ions and the consequent pro-oxidant action.

The study on the optimum fermentation conditions of the TTES-12 GABA tea production

The study on the optimum fermentation conditions of the TTES-12 GABA tea production

Effects of fermentation time and seasons on the γ-aminobutyric acid and glutamic acid contents of TTES-12 GABA tea producing

effects of fermentation time and seasons on the γ-aminobutyric acid and glutamic acid contents of TTES-12 GABA tea producing

Determination of Theanine, GABA, and Other Amino Acids in Green, Oolong, Black, and Pu-erh Teas with Dabsylation and High-Performance Liquid Chromatography

Dabsyl chloride (dimethylaminoazobenzene sulfonyl chloride), a useful chromophoric labeling reagent for amino acids and amines, was developed in this laboratory in 1975. Although several methods have been developed to determine various types of amino acids, a quick and easy method of determining theanine, GABA, and other amino acids has not been developed in one HPLC system. In this paper are analyzed the free amino acid contents of theanine and GABA in different teas (green tea, black tea, oolong tea, Pu-erh tea, and GABA tea) with a dabsylation and reverse phase high-performance liquid chromatography (HPLC) system coupled with a detector at 425 nm absorbance. Two reverse phase columns, Hypersil GOLD and Zorbax ODS, were used and gave different resolutions of dabsyl amino acids in the gradient elution program. The data suggest that the tea source or the steps of tea-making may contribute to the theanine contents variations. High theanine contents of high-mountain tea were observed in both green tea and oolong tea. Furthermore, the raw (natural fermented) Pu-erh tea contained more theanine than ripe (wet fermented) Pu-erh tea, and the GABA contents in normal teas were generally lower than that in GABA tea.

Evaluation of antioxidant activity of aqueous extract of some selected nutraceutical herbs

The objectives of this study were to examine the antioxidant activities and free radical scavenging effects of extracts of aqueous leaves of Psidium guajava L. (PE), Camellia sinensis (GABA tea; CE), Toona sinensis Roem. (TE) and Rosemarinus officinalis L. (RE). Among the four extracts, PE exhibited the strongest efficiency and showed over 50% scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals at the concentration of 100 μg/mL. The reducing power of four nutraceutical herbs was in the order of PE > RE > CE > TE. The antioxidant activities of nutraceutical herbs were evaluated in a liposomes oxidation system promoted by Fe 3+/ascorbic acid/H 2O 2. PE still showed the strongest antioxidant activity and exhibited over 95% inhibition at concentration of 50 μg/mL. The antioxidant activity of TE was still lower than that of other herbal plants; however, it also displayed 89% inhibition at concentration of 250 μg/mL. RE exhibited well inhibitory effects on the UVB-induced oxidation of erythrocyte ghosts at lower concentration (100 μg/mL). However, the protection of PE on the UVB-induced oxidation was significantly raised with increasing the concentrations and reached 95.4% inhibitory effects at concentration of 500 μg/mL. These results show that the tested herbal tea, especially PE could be considered as a natural antioxidant source.

Comparison of bioactive components in GABA tea and green tea produced in Taiwan

The aim of this study is to investigate the bioactive components of GABA (γ-aminobutyric acid) tea as compared with green tea produced in Taiwan. Using in total 56 tea samples (28 green tea and 28 GABA tea), moisture content, Hunter L, a and b values, phenolic compounds, amino acids including GABA, fatty acids and ascorbic acid were determined. The results showed that moisture, total free amino acids, crude fat, Hunter L value, total nitrogen, free fatty acids and reducing sugar did not differ significantly between GABA tea and green tea. However, GABA tea had higher Hunter a and b values, while green tea had higher total catechin and ascorbic acid contents ( p < 0.05). Of major catechins, epicatechin and epigallocatechin gallate were found to be lower in GABA tea than in green tea. For free amino acids, GABA, alanine, ammonia, lysine, leucine and isoleucine were found to be significantly higher in GABA tea, while the glutamic acid, aspartic acid, and phenylalanine were higher in green tea ( p < 0.05). Theanine, tryptophan, valine, threonine and methionine were not found to be different between the two kinds of tea.