L-theanine

L-theanine is a natural non-protein amino acid with wide applications. Thus, a high yield of L-theanine production is required on an industrial scale. Herein, an efficient L-theanine-producing strain of Corynebacterium glutamicum was constructed by combining protein and metabolic engineering. Firstly, a γ-glutamylmethylamide synthetase from Paracoccus aminovorans (PaGMAS) was isolated and engineered by computer-aided design, the resulting mutant E179K/N105R improved L-theanine yield by 36.61 %. Subsequently, to increase carbon flux towards L-theanine production, the gene ggt which degrades L-theanine, the gene alaT which participated in L-alanine synthesis, and the gene NCgl1221 which encodes glutamate-exporting protein were deleted...

Lactic acid bacteria (LAB) that metabolize sugars to obtain energy and produce a large amount of lactate through the process are well known for their benefits. However, they can be used on a large scale only when good storage stability is guaranteed. The vitality and stability of several LAB strains were effectively protected in this investigation by L-theanine at 1% of the appropriate concentration (Lactiplantibacillus plantarum MG5023, Enterococcus faecium MG5232, Lactococcus lactis MG4668, Streptococcus thermophilus MG5140, and Bifidobacterium animalis subsp...

The processing of tea leaves plays a crucial role in the formation of the taste of the resulting tea. In order to study the compositions of and changes in taste-related substances during the processing of Rizhao green tea, non-targeted metabolomics was used, based on UHPLC-Q Exactive MS. Totals of 529, 349, and 206 non-volatile metabolites were identified using three different detection modes, of which 112 secondary metabolites were significantly changed. Significant variations in secondary metabolites were observed during processing, especially during the drying stage, and the conversion intensity levels of non-volatile metabolites were consistent with the law of "Drying > Fixation > Rolling"...

BACKGROUND: Intestinal senescence is associated with several aging-related diseases. l-Theanine (LTA) has demonstrated great potential as an antioxidant and anti-senescence agent. In this study, we investigated the regulatory effect of LTA on cellular senescence using an in vitro model of d-galactose (d-Gal)-induced senescence in the rat epithelial cell line IEC-6. RESULTS: We confirmed that treatment of IEC-6 cells with 40 mg/mL d-Gal for 48 h resulted in the successful development of the senescent cell model...

BACKGROUND: Heat stress (HS) damages the intestines, disrupting gut microbiota and immune balance. L-theanine (LTA), found in tea, alleviates oxidative stress and cell apoptosis under HS; however, its effects on gut microbiota and immunity under HS remain unclear. To investigate this, we administered LTA doses of 100, 200, and 400 mg·kg-1 ·d-1 to C57BL/6J mice. On day 44, the model group and LTA intervention group were subjected to continuous 7-day HS treatment for 2 h per day...

[This retracts the article DOI: 10.1155/2021/5679665.].

This study discusses the genetic mutations that have a significant association with economically important traits that would benefit tea breeders. The purpose of this study was to analyze the leaf quality and SNPs in quality-related genes in the tea plant collection of 20 mutant genotypes growing without nitrogen fertilizers. Leaf N-content, catechins, L-theanine, and caffeine contents were analyzed in dry leaves via HPLC. Additionally, the photochemical yield, electron transport efficiency, and non-photochemical quenching were analyzed using PAM-fluorimetry...

The protein levels in a diet are correlated with immunity but the long-term intake of excessive protein can compromise various aspects of health. L-theanine regulates immunity and protein metabolism; however, how its regulatory immunity effects under a high-protein diet are unclear. We used proteomics, metabonomics, and western blotting to analyze the effects of diets with different protein levels on immune function in rats to determine the role of L-theanine in immunity under a high-protein diet. The long-term intake of high-protein diets (≥40% protein) promoted oxidative imbalance and inflammation...

PURPOSE: Previous studies have investigated the effect of single or combined caffeine (CAF) and L-theanine (THE) intake on attention performance. However, its effect on shooting performance and cognitive performance in a sport is unknown. The aim of this study was to investigate the hypothesis "Does single or combined CAF and THE supplementation have an effect on shooting and cognitive performance in elite curling athletes?." It is predicted that over the next decade, studies based on nutritional ergogenic supplements in the developing sport of curling will continue to increase, leading to a significant increase in studies examining the effects of CAF and THE supplementation, alone or in combination, on throwing and cognitive performance in elite curling athletes...

Adaptogens are a group of substances capable to increase the nonspecific resistance of the organism to a wide range of harmful effects and stress. However, only limited data exist on their use in the composition of foods for special dietary uses. The aim of the study was to evaluate the effect of a diet that included vegetable-fat spread enriched with 5-hydroxytryptophan, L-theanine and γ-aminobutyric acid on memory, general well-being and emotional status of healthy volunteers. Material and methods ...

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RATIONALE: Inadequate responses to current schizophrenia treatments have accelerated research into novel therapeutic approaches. OBJECTIVES: This study investigated the efficacy and tolerability of adjunctive L-theanine, an ingredient with neuroimmunomodulatory and neuroprotective properties, for chronic schizophrenia. METHODS: Eighty chronic schizophrenia inpatients were equally assigned to receive risperidone (6 mg/day) plus either L-theanine (400 mg/day) or matched placebo in this 8-week, randomized, parallel-group, double-blind, placebo-controlled trial...

Huangjin green tea (HJC) is one of the most famous regional green teas in China, and has gained attention for its unique flavor. Research on HJC has focused mainly on the synthesis of L-theanine, with fewer studies concentrating on sensory characteristics. In this study, molecular sensory science techniques, including color analysis, gas chromatography-ion mobility spectrometry, and E-tongue, were used to characterize the sensory properties of HJC, with Fuding Dabai and Anji Baicha teas used as conventional and high amino acid controls, respectively...

INTRODUCTION: This randomized, controlled, single-blinded trial assessed the effect of magnesium (Mg)-Teadiola (Mg, vitamins B6, B9, B12, Rhodiola, and green tea/L-theanine) versus placebo on the brain response to stressful thermal stimulus in chronically stressed, but otherwise healthy subjects. Impacts on stress-related quality-of-life parameters (depression, anxiety, sleep, and perception of pain) were also explored. METHODS: The study recruited a total of 40 adults (20 per group), suffering from stress for more than 1 month and scaling ≥14 points on the Depression Anxiety Stress Scale (DASS)-42 questionnaire at the time of inclusion...

Excessive protein intake causes liver and brain damage and neurotransmitter disorders, thereby inducing cognitive dysfunction. L-theanine can regulate the neurotransmitter content and show great potential in liver and brain protection. However, it remains unclear whether l-theanine effectively regulates neurotransmitter content under high-protein diet. A 40-day feeding experiment was performed in Sprague Dawley rats to investigate the regulatory effects and mechanisms of l-theanine on neurotransmitters via liver-brain axis in high-protein diets...

Theanine is a unique secondary metabolite in tea plants and contributes to the umami taste and health benefits of tea. However, theanine biosynthesis in tea plants is not fully understood, and its mechanism of transcriptional regulation remains poorly reported. Theanine content was significantly correlated with the expression of theanine biosynthesis-related gene CsGS1c and transcription factor CsMYB42 in different leaf positions and picking times, but there was no significant correlation in different tissues of albino tea plant 'Anjibaicha'...

This study aimed to elucidate how the Maillard reaction (MR) affects the flavor and bioactivities of Lentinula edodes hydrolysates (LEHs). Changes in flavor were investigated using non-targeted metabolomics techniques (GC-MS and LC-MS/MS) and sensory evaluation. Simultaneously, UV absorption, fluorescence, and FT-IR spectra were used to characterize the process of MR. We also evaluated the effects of MR on the antioxidant activity, hypoglycemic activity and antimicrobial activity of LEHs in vitro. The results revealed that MR produced many volatile aldehydes and ketones and decreased the content of most amino acids, sugars and flavonoids in the LEHs while increasing the content of l-theanine and succinic acid...

In 2021, the Global Brain Health Supplement Industry Market size was valued at US$7.6 billion. It is predicted to increase to US$15.59 billion by 2030. Memory and its enhancement are a segment of the market that comprised the highest global revenue share in 2021. In the USA alone, dietary supplement sales reached US$18 billion in 2018. The US Food and Drug Administration (FDA) does not have the authority to approve dietary supplements' safety, effectiveness, or labeling before products go on the market...

Maillard reaction products (MRPs) produced during thermal processing of tea are intimately related to its flavor. Our recent work revealed that both levels of l-theanine and d-galacturonic acid in tea leaves decreased dramatically during drying, whereas the specific MRPs from l-theanine and d-galacturonic acid remain elusive. Here, the MRPs formed from l-theanine and d-galacturonic acid were investigated and their taste characteristics and the involved mechanisms were explored. Two novel MRPs from l-theanine and d-galacturonic acid were identified as 1-(1-carboxy-4-(ethylamino)-4-oxobutyl)-3-hydroxypyridin-1-ium (MRP 1) and 2-(2-formyl-1H-pyrrole-1-yl) theanine (MRP 2)...

ATP, an important cofactor, is involved in many biocatalytic reactions that require energy. Polyphosphate kinases (PPK) can provide energy for ATP-consuming reactions due to their cheap and readily available substrate polyphosphate. We determined the catalytic properties of PPK from different sources and found that PPK from Cytophaga hutchinsonii (ChPPK) had the best catalytic activity for the substrates ADP and polyP6 . An extracellular-intracellular dual system was constructed to high-throughput screen for better catalytic activity of ChPPK mutants...