• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.228-234
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• 2022

Various types of tea have been cultivated to obtain different flavors and enhance their functional properties. The objective of this study was to investigate the physicochemical properties of γ-aminobutyric acid (GABA) teas produced from commercial Korean green, white, and black teas. The concentration of total minerals was reduced in GABA green tea and GABA white tea but was improved in GABA black tea. The essential, non-essential, and total free amino acid contents were remarkably increased in the GABA teas. The amino acid GABA content was increased by 561.00 and 294.20 times in GABA white tea and GABA black tea, respectively. The antioxidant potential was not reduced, although the total polyphenol and total flavonoid contents decreased in GABA green tea and GABA black tea. The results indicated that the overall nutritional value of commercial green, white, and black teas could be improved by processing them into GABA teas.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.5
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• pp.461-469
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• 1999

Glutamate and ${\gamma}-aminobutyric$ acid (GABA) are major excitatory and inhibitory neurotransmitters in the vertebrate retina, respectively. Using the whole-cell patch clamp technique and a rapid solution changer, glutamate and GABA receptors have been extensively investigated in carp retina. Glutamate receptors on both horizontal and amacrine cells may be an AMPA preferring subtype, which predominantly consists of flop splice variants. $GABA_A$ and $GABA_C$ receptors coexist in bipolar cells and they both show significant desensitization. Kinetics analysis demonstrated that activation, deactivation and desensitization of the $GABA_C$ receptor-mediated response of these cells are overall slower than those of the $GABA_A$ response. Endogenous modulator $Zn^{2+}$ in the retina was found to differentially modulate the kinetic characteristics of the $GABA_C$ and $GABA_A$ responses.

• BMB Reports
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• v.36 no.3
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• pp.319-325
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• 2003

Changes in the concentrations of $\gamma$-aminobutyric acid (GABA), soluble calcium ions, glutamic acid, and the activity of glutamate decarboxylase (GAD) were investigated in non-germinated vs. germinated brown rice. Brown rice was germinated for 72 h by applying each of the following solutions: (1) distilled water, (2) 5 mM lactic acid, (3) 50 ppm chitosan in 5 mM lactic acid, (4) 5 mM glutamic acid, and (5) 50 ppm chitosan in 5 mM glutamic acid. GABA concentrations were enhanced in all of the germinated brown rice when compared to the non-germinated brown rice. The GABA concentration was highest in the chitosan/glutamic acid that germinated brown rice at 2,011 nmol/g fresh weight, which was 13 times higher than the GABA concentration in the non-germinated brown rice at 154 nmol/g fresh weight. The concentrations of glutamic acid were significantly decreased in all of the germinated rice, regardless of the germination solution. Soluble calcium and GAD were higher in the germinated brown rice with the chitosan/glutamic acid solution when compared to the rice that was germinated in the other solutions. GAD that was partially purified from germinated brown rice was stimulated about 3.6-fold by the addition of calmodulin in the presence of calcium. These data show that the germination of brown rice in a chitosan/glutamic acid solution can significantly increase GABA synthesis activity and the concentration of GABA.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.940-946
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• 2008

In the development of a nutrient enhanced functional food, kimchi was produced by using high $\gamma$-aminobutyric acid (GABA) producing lactic acid bacterium as a starter strain. The strain isolated from kimchi was identified by using an API kit and named Lactobacillus sp. OPK 2-59. Kimchi was produced by 3 methods 1) monosodium glutamate (MSG) added (M group); 2) starter added (S group); 3) MSG+starter added (M&S group). The produced kimchi was fermented for 24 hr in an incubator at a temperature of $15^{\circ}C$ and stored at $0-1^{\circ}C$ to examine its characteristics. The M&S group exhibited a sharper increase in acidity and a steeper fall in pH as well as a higher number of lactobacilli. The M&S group kimchi had 18 mg/100 g (fresh weight, f.w.) of GABA, whereas the M and S group each had 6 mg/100 g (f.w.) GABA. According to functional evaluation, the M&S group kimchi, which has higher GABA, was not significantly different in taste, color, texture, or smell, but the M&S group was generally superior. In summary, using Lactobacillus sp. OPK 2-59 and MSG, a high quality kimchi with increased GABA content can be produced as a functional food.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.559-565
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• 2021

This study aimed to optimize gamma-aminobutyric acid (GABA) production by employing five strains of lactic acid bacteria (LAB) that were capable of high cell growth and GABA production using a modified synthetic medium. GABA production in the strains was qualitatively confirmed via detection of colored spots using thin layer chromatography. Lactobacillus plantarum SGL058 and Lactococcus lactis SGL027 were selected as the suitable strains for GABA production. The conditions of the carbon and nitrogen sources were determined as 5 g/l glucose (L. plantarum SGL058), 5 g/l lactose (L. lactis SGL027), 10 g/l yeast extract (L. plantarum SGL058), and 20 g/l yeast extract (L. lactis SGL027) for GABA production. The cell growth, monitored by optical density at 600 nm, was 5.93 for L. plantarum SGL058. This value was higher than the 3.04 produced by L. lactis SGL027 at 36 h using a 5-L fermenter. The highest concentration of GABA produced was 546.7 ㎍/ml by L. plantarum SGL058 and 404.6 ㎍/ml by L. lactis SGL027, representing a GABA conversion efficiency of (%, w/w) of 4.0% and 3.4%, respectively. The fermentation profiles of L. plantarum SGL058 and L. lactis SGL027 provide a basis for the utilization of LAB in GABA production using a basal synthetic medium.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.1952-1960
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• 2017

Recently, soybean isoflavone aglycones (i.e., daidzein and genistein) and ${\gamma}-aminobutyric$ acid (GABA) have begun to receive considerable consumer attention owing to their potential as nutraceuticals. To produce these ingredients, multiple microorganisms and their enzymes are commonly used for catalysis in the nutraceutical industry. In this work, we introduce a novel fermentation process that uses whole-cell biocatalysis to accelerate GABA and isoflavone aglycone production in doenjang (a traditional Korean soybean paste). Microbial enzymes transform soybean isoflavone glycosides (i.e., daidzin and genistin) and monosodium glutamate into soybean isoflavone aglycones and GABA. Lactobacillus brevis GABA 100 and Aspergillus oryzae KACC 40250 significantly reduced the production time with the aid of a protease. The resulting levels of GABA and daidzein were higher, and genistein production resembled the levels in traditional doenjang fermented for over a year. Concentrations of GABA, daidzein, and genistein were measured as 7,162, 60, and $59{\mu}g/g$, respectively on the seventh day of fermentation. Our results demonstrate that the administration of whole-cell L. brevis GABA 100 and A. oryzae KACC 40250 paired with a protease treatment is an effective method to accelerate GABA, daidzein, and genistein production in doenjang.

• Biomolecules & Therapeutics
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• v.23 no.3
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• pp.268-274
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• 2015

${\gamma}$-Aminobutyric acid (GABA), a major inhibitory neurotransmitter in the mammalian central nervous system, is involved in sleep physiology. Caffeine is widely used psychoactive substance known to induce wakefulness and insomnia to its consumers. This study was performed to examine whether GABA extracts from fermented rice germ ameliorates caffeine-induced sleep disturbance in mice, without affecting spontaneous locomotor activity and motor coordination. Indeed, caffeine (10 mg/kg, i.p.) delayed sleep onset and reduced sleep duration of mice. Conversely, rice germ ferment extracts-GABA treatment (10, 30, or 100 mg/kg, p.o.), especially at 100 mg/kg, normalized the sleep disturbance induced by caffeine. In locomotor tests, rice germ ferment extracts-GABA slightly but not significantly reduced the caffeine-induced increase in locomotor activity without affecting motor coordination. Additionally, rice germ ferment extracts-GABA per se did not affect the spontaneous locomotor activity and motor coordination of mice. In conclusion, rice germ ferment extracts-GABA supplementation can counter the sleep disturbance induced by caffeine, without affecting the general locomotor activities of mice.

• Korean Journal of Food Science and Technology
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• v.42 no.6
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• pp.688-692
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• 2010

The aim of this study was to investigate the effects of molecular weight and concentrations of chitosan on the germination of brown rice. Brown rice was germinated at $30^{\circ}C$ for three days in various chitosan solutions. The germination rate of the brown rice increased with increasing concentrations of chitosan solution, and was higher in the chitosan solution than in water. GABA content increased with increasing germination time and chitosan solution concentration. As the molecular weight of the chitosan decreased, germination rate and GABA content increased in the brown rice. The GABA content of germinated brown rice using low molecular weight chitosan A in a 100 ppm solution was 5145.5 nmole/g. This is approximately a five times higher value than that of the water-germinated brown rice. Texture properties were enhanced in all the germinated brown rice samples in chitosan solution compared to the brown rice germinated in water. These results indicate that chitosan solution treatment can increase germination rate and GABA synthesis activity in brown rice during germination, and can also improve the texture properties of brown rice.

• Journal of Mushroom
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• v.15 no.1
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• pp.38-44
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• 2017

Sparassis latifolia (formerly S. crispa) is used in food and nutraceuticals or dietary supplements, as rich in flavor compounds and ${\beta}-glucan$. Some previous studies have reported the effects of mushroom on brain function, including its neuroprotective effect. Thus, for this mushroom to be used as an effective nutraceutical for brain function, it would be desirable for it to contain other compounds such as ${\gamma}-aminobutyric$ acid (GABA) in addition to ${\beta}-glucan$. In this study, the enhancement of growth and GABA production in the mycelium of medicinal and edible mushroom S. latifolia was investigated. Amino acids were added externally as the main source of nutrition, and the effects of amino acids were investigated using liquid medium, specifically amino acid-free potato dextrose broth (PDB). The amino acids added were L-glutamic acid (named PDBG medium) and L-ornithine (named PDBO medium). The growth of mycelia was determined to be $0.9{\pm}0.00g/L$, $2.2{\pm}0.16g/L$, and $1.93{\pm}0.34g/L$ PDBG respectively. The GABA content was $21.3{\pm}0.9mg/100g$ in PDB medium, and it in PDBG 1.4% medium, at $115.4{\pm}30.2mg/100g$. However, the PDBO medium was not effective in increasing the GABA content of mycelia. Amino acids had little effect on the ${\beta}-glucan$ content of mycelia. The ${\beta}-glucan$ content was $39.7{\pm}1.4mg/100mg$, $34.4{\pm}0.2mg/100mg$, and $35.2{\pm}9.2mg/100mg$ in PDB, PDBG 1.8% and PDBO 1.4% media, respectively. Addition of glutamic acid and ornithine positively affected the growth of S. latifolia mycelia, and glutamic acid positively affected GABA production; no degradation of GABA was observed with addition of glutamic acid.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.579-584
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• 2013

In this study, we synthesized functional dendrimer derivatives as nonviral gene delivery vectors. Poly(amidoamine) dendrimer (PAMAM, generation 4) was modified to possess functional amino acids to enhance gene transfection efficiency. PAMAM G4 derivatives conjugated with L-arginine (Arg) and ${\gamma}$-aminobutyric acid (GABA) showed higher transfection efficiency and lower cytotoxicity compared to the native PAMAM G4 dendrimer. The polyplex of the PAMAM G4 derivative/pDNA was evaluated using an agarose gel retardation assay and Picogreen reagent assay. Additionally, the MTT assay was performed to examine the cytotoxicity of synthesized polymers. All PAMAM G4 derivatives showed lower cytotoxicity than PEI25kD. Particularly, PAMAM G4-GABA-Arg displayed enhanced transfection efficiency compared to the native PAMAM G4 dendrimer.