An overview of biological production of L-theanine

Mu, Wanmeng; Tao, Zhang; Jiang, Bo

doi:10.1016/j.biotechadv.2015.04.004

Cited by 121 publications

(92 citation statements)

References 81 publications

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“…However, to our knowledge, no literature is available regarding the effect of BR on free AA and theanine concentration in tea leaves. It is to be noted that theanine is the major tea AA accounting for more than 50% of total free AA in tea (Mu et al, 2015). Two enzymes, such as glutamine synthetase (GS) and GOGAT, which are considered as key determinants of theanine biosynthesis, catalyze the initial steps of NH 3 assimilation into glutamic acid (Mu et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…It is to be noted that theanine is the major tea AA accounting for more than 50% of total free AA in tea (Mu et al, 2015). Two enzymes, such as glutamine synthetase (GS) and GOGAT, which are considered as key determinants of theanine biosynthesis, catalyze the initial steps of NH 3 assimilation into glutamic acid (Mu et al, 2015). To elucidate the mechanism underlying BR-induced AA accumulation, we analyzed transcript levels of key genes involved in theanine synthesis such as GLUTAMINE SYNTHETASE (CsGS) and GLUTAMINE: 2-OXOGLUTARATE AMINOTRANSFERASE (CsGOGAT) .…”

Section: Discussionmentioning

confidence: 99%

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Brassinosteroids Improve Quality of Summer Tea (Camellia sinensis L.) by Balancing Biosynthesis of Polyphenols and Amino Acids

Ahammed

et al. 2016

Front. Plant Sci.

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Summer grown green tea is less popular due to bitterness and high astringency, which are attributed to high levels of tea polyphenols (TP) and low levels of amino acids (AA) in tea leaves (Camellia sinensis L.). Brassinosteroids (BRs), a group of steroidal plant hormones can regulate primary and secondary metabolism in a range of plant species under both normal and stress conditions. However, specific effects of BRs on the photosynthesis of tea plants and the quality of summer green tea are largely unknown. Here we show that 24-epibrassinolide (EBR), a bioactive BR, promoted photosynthesis in tea plants in a concentration-dependent manner. Stimulation in photosynthesis by EBR resulted in an increased summer tea yield. Although all tested concentrations (0.01, 0.05, 0.1, 0.5, and 1.0 ppm) of EBR increased concentrations of TP and AA, a moderate concentration (0.5 ppm) caused the highest decrease in TP to AA ratio, an important feature of quality tea. Time-course analysis using 0.5 ppm EBR as foliar spray revealed that TP or AA concentration increased as early as 3 h after EBR application, reaching the highest peak at 24 h and that remained more or less stable. Importantly, such changes in TP and AA concentration by EBR resulted in a remarkably decreased but stable TP to AA ratio at 24 h and onward. Furthermore, concentrations of catechins and theanine increased, while that of caffeine remained unaltered following treatment with EBR. EBR improved activity of phenylalanine ammonia-lyase (PAL) and glutamine: 2-oxoglutarate aminotransferase (GOGAT) enzymes involved in catechins and theanine biosynthesis, respectively. Transcript analysis revealed that transcript levels of CsPAL and CsGS peaked as early as 6 h, while that of CsGOGAT peaked at 12 h following application of EBR, implying that EBR increased the concentration of TP and AA by inducing their biosynthesis. These results suggest a positive role of BR in enhancing green tea quality, which might have potential implication in improving quality of summer tea.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Brassinosteroids Improve Quality of Summer Tea (Camellia sinensis L.) by Balancing Biosynthesis of Polyphenols and Amino Acids

Ahammed

et al. 2016

Front. Plant Sci.

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“…In addition, NiR, which provides NH 4 + for GS/ GOGAT cycle and α-ketoglutarate reductive amination reaction, performs important functions in theanine synthesis. Interestingly, similar to GS in bacteria, γ-GGT can also catalyze theanine synthesis with glutamine and ethylamine as substrate (Mu et al, 2015). …”

Section: Introductionmentioning

confidence: 99%

L-Theanine Content and Related Gene Expression: Novel Insights into Theanine Biosynthesis and Hydrolysis among Different Tea Plant (Camellia sinensis L.) Tissues and Cultivars

Liu

et al. 2017

Front. Plant Sci.

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L-Theanine content has tissues and cultivars specificity in tea plant (Camellia sinensis L.), the correlations of theanine metabolic related genes expression profiles with theanine contents were explored in this study. L-theanine contents in the bud and 1st leaf, 2nd leaf, 3rd leaf, old leaf, stem, and lateral root were determined by HPLC from three C. sinensis cultivars, namely ‘Huangjinya’, ‘Anjibaicha’, and ‘Yingshuang’, respectively. The theanine contents in leaves and root of ‘Huangjinya’ were the highest, followed by ‘Anjibaicha’, and ‘Yingshuang’. The theanine contents in the leaves reduced as the leaf mature gradually, and in stem were the least. Seventeen genes encoding enzymes involved in theanine metabolism were identified from GenBank and our tea transcriptome database, including CsTS1, CsTS2, CsGS1, CsGS2, CsGOGAT-Fe, CsGOGAT-NAD(P)H, CsGDH1, CsGDH2, CsALT, CsSAMDC, CsADC, CsCuAO, CsPAO, CsNiR, CsNR, CsGGT1, and CsGGT3. The transcript profiles of those seventeen genes in the different tissues of three tea plant cultivars were analyzed comparatively. Among the different cultivars, the transcript levels of most selected genes in ‘Huangjinya’ were significantly higher than that in the ‘Anjibaicha’ and ‘Yingshuang’. Among the different tissues, the transcript levels of CsTS2, CsGS1, and CsGDH2 almost showed positive correlation with the theanine contents, while the other genes showed negative correlation with the theanine contents in most cases. The theanine contents showed correlations with related genes expression levels among cultivars and tissues of tea plant, and were determined by the integrated effect of the metabolic related genes.

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“…This amino acid has been demonstrated to have various therapeutic benefits including improving concentration and learning ability, enhancing antitumor activity, preventing the vascular diseases, reducing blood pressure, providing antiobesity effect, improving the immune system, and displaying neuroprotection [36]. This behaviourally and physiologically active compound is structurally similar to the excitatory neurotransmitter glutamate and, in accordance, binds to glutamate receptors, though with much lower affinity in comparison [37].…”

Section: Phytochemicals Against Depressionmentioning

confidence: 99%

Therapeutic Effects of Phytochemicals and Medicinal Herbs on Depression

Lee

Bae

2017

BioMed Research International

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Background. Depression is a recurrent, common, and potentially life-threatening psychiatric disease related to multiple assignable causes. Although conventional antidepressant therapy can help relieve symptoms of depression and prevent relapse of the illness, complementary therapies are required due to disadvantage of the current therapy such as adverse effects. Moreover, a number of studies have researched adjunctive therapeutic approaches to improve outcomes for depression patients. Purpose. One potential complementary method with conventional antidepressants involves the use of medicinal herbs and phytochemicals that provide therapeutic benefits. Studies have revealed beneficial effects of medical herbs and phytochemicals on depression and their central nervous system mechanism. Here, we summarize the current knowledge of the therapeutic benefits of phytochemicals and medicinal herbs against depression and describe their detailed mechanisms. Sections. There are two sections, phytochemicals against depression and medical herbs against depression, in this review. Conclusion. Use of phytomedicine may be an alternative option for the treatment of depression in case conventional drugs are not applicable due to their side effects, low effectiveness, or inaccessibility. However, the efficacy and safety of these phytomedicine treatments for depression have to be supported by clinical studies.

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An overview of biological production of L-theanine

Cited by 121 publications

References 81 publications

Brassinosteroids Improve Quality of Summer Tea (Camellia sinensis L.) by Balancing Biosynthesis of Polyphenols and Amino Acids

Brassinosteroids Improve Quality of Summer Tea (Camellia sinensis L.) by Balancing Biosynthesis of Polyphenols and Amino Acids

L-Theanine Content and Related Gene Expression: Novel Insights into Theanine Biosynthesis and Hydrolysis among Different Tea Plant (Camellia sinensis L.) Tissues and Cultivars

Therapeutic Effects of Phytochemicals and Medicinal Herbs on Depression

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