Article

L-Theanin, Unique Aminoacid of Tea, and Its Metabolism, Health Effects, Safety

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Tea has been a very popular beverage around the world for centuries. The reason that it is delicious, enabling hydration, showing warming and relaxing effect can be mentioned why it is consumed so much in addition to its prominent health effects. Although the catechins and caffeine are the primary bioactive components that are related with the health effects of the tea, the health effects of theanine amino acid, which is a non-proteinic amino acid special to tea, has become prominent in recent years. It has been known that the theanine amino acid in tea has positive effects especially on relaxing, cognitive performance, emotional status, sleep quality, cancer, cardiovascular diseases, obesity and common cold. The results of acute and chronic toxicity tests conducted on the safety of theanine express that L-theanine is reliable in general even if it is consumed too much with diet. However, it is not revealed a clear evidence based result yet regarding theanine metabolism, health effects and its safety. Within this frame, chemical structure of theanine, its bio-synthesis, dietary sources, metabolism, health effects, and safety are discussed in present study.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... In addition, many studies have indicated that tea and its bioactive components possess multiple health functions (as shown in Figure 1), including antioxidation, anti-inflammation, immuno-regulation, anticancer, cardiovascular-protection, anti-diabetes, anti-obesity, and hepatoprotection [14][15][16][17][18][19]. Moreover, several technologies, including recently developed nanotechnology, have been adopted to improve the bioavailability of tea polyphenols [20][21][22][23][24]. Furthermore, the adverse effects of tea were seldom observed [25][26][27][28][29]. Thus, the combination of health functions and safety of tea supports its consumption for people with the potential to prevent and manage certain chronic diseases, such as obesity and cancer. ...
... Tea brewing and its extract also contain a considerable amount of amino acids [52]. Aspartic acid, glutamic acid, arginine, alanine, tyrosine, and theanine have been reported as the major amino acids in tea, and the amino acid profile can be changed during fermentation [8,29,52]. Among them, theanine is a nonproteinic amino acid special to tea [8]. ...
... Among them, theanine is a nonproteinic amino acid special to tea [8]. It has been summarized that L-theanine has positive effects on relaxation, cognitive performance, emotional status, sleep quality, cancer, cardiovascular diseases, obesity, and the common cold [8,29]. ...
Article
Full-text available
Tea is widely consumed all over the world. Generally, tea is divided into six categories: White, green, yellow, oolong, black, and dark teas, based on the fermentation degree. Tea contains abundant phytochemicals, such as polyphenols, pigments, polysaccharides, alkaloids, free amino acids, and saponins. However, the bioavailability of tea phytochemicals is relatively low. Thus, some novel technologies like nanotechnology have been developed to improve the bioavailability of tea bioactive components and consequently enhance the bioactivity. So far, many studies have demonstrated that tea shows various health functions, such as antioxidant, anti-inflammatory, immuno-regulatory, anticancer, cardiovascular-protective, anti-diabetic, anti-obesity, and hepato-protective effects. Moreover, it is also considered that drinking tea is safe to humans, since reports about the severe adverse effects of tea consumption are rare. In order to provide a better understanding of tea and its health potential, this review summarizes and discusses recent literature on the bioactive components, bioavailability, health functions, and safety issues of tea, with special attention paid to the related molecular mechanisms of tea health functions.
... LT is the main nonprotein amino acid component responsible for the flavor and taste of green tea and thus determines the quality of green tea. LT is rapidly absorbed into the blood of the intestinal tract through cotransport with Na + and then further redistributed to other organs, including the brain (Türközü and Şanlier 2017). LT reportedly does not produce toxic effects in animals or humans. ...
... LT reportedly does not produce toxic effects in animals or humans. Moreover, because of its taste enhancement properties and promising health benefits, it has been approved as a generally considered safe ingredient by the US Food and Drug Administration and is widely used in food and pharmaceutical industries (Türközü and Şanlier 2017;Saeed et al. 2020). It exerts numerous pharmacological effects, such as sedative, hypotensive, anti-obesogenic, and anti-inflammatory effects (Türközü and Şanlier 2017;Wang et al. 2017;Soung et al. 2018;Unno et al. 2020;Yang et al. 2020), scavenging reactive radicals, alleviating peroxidative conditions, and it is expected to exhibit neuroprotective properties suitable for treating behavioral impairments induced by toxins, stress, and spinal cord injury (Jamwal et al. 2017;Chen et al. 2018;Soung et al. 2018;Unno et al. 2020;Yang et al. 2020). ...
... Moreover, because of its taste enhancement properties and promising health benefits, it has been approved as a generally considered safe ingredient by the US Food and Drug Administration and is widely used in food and pharmaceutical industries (Türközü and Şanlier 2017;Saeed et al. 2020). It exerts numerous pharmacological effects, such as sedative, hypotensive, anti-obesogenic, and anti-inflammatory effects (Türközü and Şanlier 2017;Wang et al. 2017;Soung et al. 2018;Unno et al. 2020;Yang et al. 2020), scavenging reactive radicals, alleviating peroxidative conditions, and it is expected to exhibit neuroprotective properties suitable for treating behavioral impairments induced by toxins, stress, and spinal cord injury (Jamwal et al. 2017;Chen et al. 2018;Soung et al. 2018;Unno et al. 2020;Yang et al. 2020). However, to the best of our knowledge, reports on the effects of LT on RO-induced motor impairment and the underlying mechanisms that may be involved in its ameliorating effects remain unclear. ...
Article
Full-text available
Rotenone (RO)-induced neurotoxicity exhibits pathophysiological features similar to those reported in patients with Parkinson’s disease (PD), such as nitrosative and oxidative stress, mitochondrial dysfunction, and neural cytoarchitecture alterations in the substantia nigra pars compacta (SNpc)/striatum (ST), which has been used for decades as an animal model of PD in humans. L-Theanine (LT), a major amino acid component of green tea, exhibits potent antioxidant and anti-inflammatory activities and protects against various neural injuries. We investigated the potential therapeutic effects of LT on RO-induced behavioral and neurochemical dysfunction in rats and the neuroprotective mechanisms underlying these effects. Unilateral stereotaxic intranigral infusion of RO into the SNpc to induce PD-like manifestations induced significant behavioral impairment as evaluated using an open field test, rotarod test, grip strength measurement, and beam-crossing task in rats. LT treatment (300 mg/kg i.p., 21 days) ameliorated most RO-induced behavioral impairments. In addition, LT treatment reduced nitric oxide level and lipid peroxidation production, increased mitochondrial function and integrity, as well as the activities of mitochondrial complexes I, II, IV, and V, and reduced the levels of neuroinflammatory and apoptotic markers in the SNpc and ameliorated the levels of catecholamines, GABA and glutamate in the ST induced by RO. These results demonstrate the possible therapeutic effects of LT against RO-induced behavioral impairments, including antioxidative effects, prevention of mitochondrial dysfunction, prevention of neurochemical deficiency, anti-neuroinflammatory effects, and anti-apoptotic effects. This is the first report on the neuroprotective effect of LT against RO-induced behavioral impairments, and the above evidence provides a potential clinically relevant role for LT in the management of human PD.
... Theanine is a nonprotein derivative amino acid found in tea leaves that recently has received much attention for its health benefits, including preventive or suppressive effects on cancer (Türközü & Şanlier, 2017). Tea is the most popular beverage after water worldwide. ...
... Theanine is a water-soluble molecule and is absorbed rapidly from the small intestine after oral ingestion. The blood concentration of theanine reaches its peak within 0.5-2 hr after oral administration and begins to drop within 24 hr (Adhikary & Mandal, 2017;Türközü & Şanlier, 2017). G. Zhang et al., 2016). ...
... This amino acid is additionally a precursor of glutathione in cancer cells (Cacace, Sboarina, Vazeille, & Sonveaux, 2017 (Sugiyama & Sadzuka, 1998;Türközü & Şanlier, 2017;Wu & Su, 2013). Moreover, according to the results of a randomized clinical trial, oral administration of theanine and cystine combination after gastrectomy reduced inflammation and enhanced recovery after surgery (Miyachi et al., 2013). ...
Article
A growing literature indicates several health benefits of theanine, a major nonprotein derivative amino acid special to tea, and a nonedible mushroom. This study aimed to systematically review the scientific evidence regarding the anticarcinogen and anticancer effects of natural theanine. A systematic search for the relevant articles published until January 2021 on MEDLINE, Scopus, and Web of Knowledge was conducted. Out of 377 initial records, 14 in vitro, ex vivo, and in vivo studies met our inclusion criteria. Most of the included in vitro and ex vivo studies reported beneficial effects of theanine on the proliferation, apoptosis, metastasis, migration, and invasion in various cancer cell lines. The in vivo studies also supported the potential impacts of theanine on cancer incidence or progression. Theanine exerted its anticancer function by inhibiting EGFR, VEGFR, Met, and Akt/mTOR, JAK2/STAT3, and ERK/NFκB pathways, as well as activating the intrinsic apoptosis pathway and caspase-independent programmed cell death. In conclusion, the results indicated moderate apoptotic, antimetastatic, antimigration, and anti-invasion effects, along with the mild antiproliferative influence of theanine on cancer. Further studies are necessary to ascertain the effectiveness of theanine on the prevention and suppression of cancer and shed light upon the attributable mechanisms in the in vivo condition.
... L-THE contains a glutamine backbone existing as an ethylamine derivative of glutamate also known as N-ethyl-L-glutamine [98]. Following consumption, L-THE is readily absorbed through the intestine into the bloodstream, reaching maximum concentration after approximately 30 minutes to two hours [100]. ...
... L-THE is generally well tolerated, with animal toxicity studies revealing no significant adverse events [98]. Additionally, the U.S. Food and Drug Administration regards the commercially available L-THE product, Suntheanine ® as safe, with an upper limit of 1284 mg/day [100]. ...
Article
Full-text available
Functional beverages can be a valuable component of the human diet with the ability to not only provide essential hydration but to deliver important bioactive compounds that can contribute to chronic disease treatment and prevention. One area of the functional beverage market that has seen an increase in demand in recent years are beverages that promote relaxation and sleep. Sleep is an essential biological process, with optimal sleep being defined as one of adequate duration, quality and timing. It is regulated by a number of neurotransmitters which are, in turn, regulated by dietary intake of essential bioactive compounds. This narrative review aimed to evaluate the latest evidence of the sleep promoting properties of a selection of bioactive compounds (such as L-theanine and L-tryptophan) for the development of a functional beverage to improve sleep quality; and the effectiveness of traditional sleep promoting beverages (such as milk and chamomile). Overall, the bioactive compounds identified in this review, play essential roles in the synthesis and regulation of important neurotransmitters involved in the sleep-wake cycle. There is also significant potential for their inclusion in a number of functional beverages as the main ingredient on their own or in combination. Future studies should consider dosage; interactions with the beverage matrix, medications and other nutraceuticals; bioavailability during storage and following ingestion; as well as the sensory profile of the developed beverages, among others, when determining their effectiveness in a functional beverage to improve sleep quality.
... Furthermore, the intake of theanine suppressed excessive tension in students (Unno et al., 2013b;Kimura et al., 2007). Since theanine has been reported to have various beneficial effects besides antistress effect (e.g., Türközü and Şanlier, 2017), industrially produced theanine has been marketed as tablets or powder supplements (Mu et al., 2015). However, in some individuals who consume prescription drugs daily, it may be difficult for them to take more tablets or powder. ...
... Theanine has shown a positive effect on stress reduction (Unno et al., 2013a,b, 2011, Yin et al., 2011Kimura et al., 2007), relaxation (Weeks, 2009), cognitive function (Lardner, 2014;Kakuda, 2011), emotional status (Garay et al., 2015;Arroll et al., 2014), and sleep quality (Rao et al., 2015;Barrett et al., 2013). The tests of acute and chronic toxicity on the safety of theanine have shown that theanine is reliable even if it is consumed in excess in a diet (Türközü and Şanlier, 2017). Orally consumed theanine is easily absorbed in the intestinal tract. ...
... It shows a lot of prominent health benefits, including the most significant effect i.e. relaxing. Tea powder is known for the most abundant source of catechins, caffeine, polyphenols, tannins, etc. which supports various health benefits (Türközü and Şanlier 2017). ...
... The regular consumption of tea plays a significant role in improving health benefits by delivering theanine. It proved that to consume a high amount of L-theanine with diet is to be safe (Türközü and Şanlier 2017). FDA suggests that the daily consumption amount of L-theanine should not exceed 1200 mg (Vuong et al., 2011;FDA, 2006). ...
Article
Tea is the second most consumed beverage around the world after water. Apart from other tea preparations, approximately 98% of peoples drink tea with milk. The essential bioactive component, i.e., L-theanine present in tea along with catechins, tannin, and polyphenols, which has prominent health benefits, including relaxation. L-theanine is proteionic amino acid present only in tea, and which is safe for daily intake. This review focused on L-theanine present in different types of tea, commercially available tea powders, extraction methods for L-theanine isolation, characterization, and health benefits of L-theanine.
... Brain waves can be divided into four types: α, β, θ and δ waves. It is generally believed that α waves can make people awake, sensitive, and relaxed, while LTA can promote the production of α waves in the brain (Chu et al. 1999;Kanari Kobayashi, Nagato, Aoi, Juneja, Kim, Yamamoto, and Sugimot 1998;Türközü and Şanlier 2017). In the animal model induced by sodium pentobarbital, compared with the control group, an increase in the θ and δ wave oscillations (the main brain waves during NREM sleep) was detected in the LTA group and the GABA/LTA mixture group (100/20 mg/kg) (Kim et al. 2019). ...
... LTA has a certain effect on improving sleep, and the safe use of LTA also needs to be paid attention to. LTA does not directly induce sleep, but can relax the body and mind to improve the sleep quality (Türközü and Şanlier 2017). Unlike sedatives that cause drowsiness or daytime sleepiness, LTA can reach the brain within 30-40 minutes without causing lethargy (Chu et al. 1999). ...
Article
Sleep disorders have received widespread attention nowadays, which have been promoted by the accelerated pace of life, unhealthy diets and lack of exercise in modern society. The chemical medications to improve sleep has shown serious side effects and risks with high costs. Therefore, it is urgent to develop efficient nutraceuticals from natural sources to ensure sleep quality as a sustainable strategy. As the second most consumed beverage worldwide, the health-promoting effects of tea have long been widely recognized. However, the modulatory effect of teas on sleep disorders has received much less attention. Tea contains various natural sleep-modulating active ingredients such as L-theanine (LTA), caffeine, tea polyphenols (TPP), tea pigments, tea polysaccharides (TPS) and γ-aminobutyric acid (GABA). This review focuses on the potential influence and main regulating mechanisms of different tea active ingredients on sleep, including being absorbed by the small intestine and then cross the blood-brain barrier to act on neurons in the brain as neurotransmitters, manipulating the immune system and further affect sleep-wake cycle by regulating the levels of cytokines, and controlling the gut microbes to maintain the homeostasis of circadian rhythm. Current research progress and limitations are summarized and several future development directions are also proposed. This review hopes to provide new insights into the future elucidation of the sleep-regulating mechanisms of different teas and their natural active ingredients and the development of tea-based functional foods for alleviating sleep disorders. Highlights• Natural sleep-modulating active ingredients in tea have been summarized.• Influences of drinking tea or tea active ingredients on sleep are reviewed.• Three main regulating mechanisms of tea active ingredients on sleep are explained.• The associations among nervous system, immune system and intestinal microbiota are investigated.• The potential of developing delivery carriers for tea active ingredients is proposed.
... 4,8 However, further research is warranted on the potential for synergy effects among the tea bioactive flavonoids, caffeine (CAF) and L-theanine (THEA), a non-protein amino acid "unique" to tea that accounting for up to 50% of all free amino acids. 3,9 Recent studies reports that THEA (5-N-ethyl glutamine) has many biological and physiological activities such as: calming effect on the mental state by lowering blood pressure; inhibits CAF's side effects; stimulates the release of dopamine, a brain's neurotransmitter responsible for confidence and sense of well-being; stimulates the production of alfa brain waves (an electromagnetic oscillation in the frequency range of 8-13 Hz) in the occipital and parietal regions of human brain, creating, consequently, a state of deep relaxation and mental alertness; enhances anti-tumor activity and promotes neuroprotection. [9][10][11] Besides catechins, the THEA and CAF are pharmacologically important tea constituents, especially due to their antagonist effects on the central nervous system. ...
... 3,9 Recent studies reports that THEA (5-N-ethyl glutamine) has many biological and physiological activities such as: calming effect on the mental state by lowering blood pressure; inhibits CAF's side effects; stimulates the release of dopamine, a brain's neurotransmitter responsible for confidence and sense of well-being; stimulates the production of alfa brain waves (an electromagnetic oscillation in the frequency range of 8-13 Hz) in the occipital and parietal regions of human brain, creating, consequently, a state of deep relaxation and mental alertness; enhances anti-tumor activity and promotes neuroprotection. [9][10][11] Besides catechins, the THEA and CAF are pharmacologically important tea constituents, especially due to their antagonist effects on the central nervous system. 12,13 So, the quantitative analysis of these compounds, and consequently their ratio, is essential to assess the degree of the stimulating effect of tea drinks, and it can be stated that tea samples with lower CAF/THEA ratio have less stimulating effect. ...
Article
Leaves from Camellia sinensis have been used to make teas for a long time, however, less attention has been paid to the flowers, which is a waste of an abundant resource that should be valorized. This study evaluates the representative tea metabolites content (dry weight basis) and antioxidant properties of Azorean C. sinensis flowers as compared to commercial Gorreana green tea (GorGT), the only one produced in Europe. We determined the variability of catechins, caffeine and L-theanine (THEA) by RP-HPLC/DAD and the confirmation of THEA by GC/MS. The antioxidants activities were determined by FRSA, FRAP and FIC methods. The total phenolics and total flavonoids were determined by the Folin-Ciocalteu and colorimetric methodologies. The results showed that flowers presented higher L-theanine (5.88 mg/g) but lower caffeine (4.10 mg/g) contents than GorGT (2.59 and 12.42 mg/g, respectively) and, therefore, a lower caffeine/theanine ratio (0.70 versus 4.80). The esterified catechins content (in percentage of total catechins) showed similar values for flowers (85.34%) and GorGT (86.45%), and the individual catechins decreased as follows: epigallocatechin-3-gallate > epicatechin-3-gallate ≫ gallocatecin-3-gallate. In antioxidant assays, GorGT presented better FRSA and FRAP but similar FIC as compared to flowers. Also, the total phenolics and flavonoids contents of dried extract presented higher values in GorGT: 321.56 mg gallic acid equivalents (GAE)/g and 47.17 mg rutin equivalents (RE)/g as compared to 141.94 mg GAE/g and 24.14 mg RE/g, respectively, for flowers. This study represents the first contribute to Azorean C. sinensis flowers valorization as a new-added material with nutraceutical benefits.
... Theanine is a special secondary metabolite of tea plants, and its metabolism is closely related to nitrogen metabolism [43]. The degradation of chloroplasts causes substantial protein degradation, and protein degradation increases nitrogen sources and activates nitrogen metabolism. ...
Preprint
Full-text available
Background Camellia sinensis ‘Yanlinghuayecha’ (YHC) is a variegated mutant developed recently in China. To dissect the physiological and molecular mechanisms of leaf variegation, we compared the leaf pigmentation, cellular ultrastructure, amino acid content, and transcriptome between the albino (A), mosaic (M), and green (G) sectors. Results The contents of photosynthetic pigments were significantly lower in sector A and higher in sector G than in sector M. Chloroplasts with well-organized thylakoids were found only in the mesophyll cells of the G sector but not in those of the A sector. The A sector had a significantly higher content of total and free amino acids. In particular, the levels of theanine, glutamate, and alanine in the A sector were higher than those in the G sector. Transcriptomics analysis showed that a total of 44,908 unique transcripts were identified. Comparing the differentially expressed genes (DEGs) in the three sectors, we conducted an in-depth study on chloroplast biogenesis, chlorophyll biosynthesis, and theanine synthesis pathways. The expression of CsPPOX in “porphyrin and chlorophyll metabolism” was significantly downregulated in the A sector. CsLHCB6 in “Photosynthesis - antenna proteins” and CsSCY1 in “Protein processing in endoplasmic reticulum”, both of which were associated with chloroplast biogenesis, were significantly downregulated in the A sector. The expression of CsTS1 was notably upregulated in the A sector. Conclusion Taken together, variegation alters the gene activities involved in chloroplast biogenesis, and our results suggest that leaf colour change in the A sector incorporates three aspects compared with that in the G sector: (1) Decreased CsPPOX expression slows the rate of chlorophyll synthesis, resulting in a decrease in chlorophyll content; (2) downregulated expression of CsLHCB6 and CsSCY1 inhibits chloroplast biogenesis, decreasing thylakoid morphogenesis and grana stacking; and (3) the metabolic flow of glutamate changes, possibly from chlorophyll biosynthesis to theanine biosynthesis. The accumulation of precursor synthetic substances and the high expression of CsTS1 generates a high theanine content. These analyses provide valuable insights into variegation in tea plants with regard to leaf colour change and L-theanine accumulation.
... Due to out-breeding and its long gestation period, the tea plant requires next-generation breeding strategies to improve its drought tolerance. This is possible through a deeper understanding of key regulators and their variants for precision introgressions to achieve better yield and quality under stress conditions [18]. Therefore, different approaches are necessary to deeply understand the tolerance mechanisms to certain stress factors. ...
Article
Full-text available
Osmotic stress is a major factor reducing the growth and yield of many horticultural crops worldwide. To reveal reliable markers of tolerant genotypes, we need a comprehensive understanding of the responsive mechanisms in crops. In vitro stress induction can be an efficient tool to study the mechanisms of responses in plants to help gain a better understanding of the physiological and genetic responses of plant tissues against each stress factor. In the present study, the osmotic stress was induced by addition of mannitol into the culture media to reveal biochemical and genetic responses of tea microplants. The contents of proline, threonine, epigallocatechin, and epigallocatechin gallate were increased in leaves during mannitol treatment. The expression level of several genes, namely DHN2, LOX1, LOX6, BAM, SUS1, TPS11, RS1, RS2, and SnRK1.3, was elevated by 2-10 times under mannitol-induced osmotic stress, while the expression of many other stress-related genes was not changed significantly. Surprisingly, down-regulation of the following genes, viz. bHLH12, bHLH7, bHLH21, bHLH43, CBF1, WRKY2, SWEET1, SWEET2, SWEET3, INV5, and LOX7, was observed. During this study, two major groups of highly correlated genes were observed. The first group included seven genes, namely CBF1, DHN3, HXK2, SnRK1.1, SPS, SWEET3, and SWEET1. The second group comprised eight genes, viz. DHN2, SnRK1.3, HXK3, RS1, RS2, LOX6, SUS4, and BAM5. A high level of correlation indicates the high strength connection of the genes which can be co-expressed or can be linked to the joint regulons. The present study demonstrates that tea plants develop several adaptations to cope under osmotic stress in vitro; however, some important stress-related genes were silent or downregulated in microplants.
... The tea plant [Camellia sinensis (L.) O. Kuntze] is an excellent model system to address these questions due to its high contents and diversity in all three classes of specialized metabolites [10][11][12][13][14] . Tea is the most popular non-alcoholic beverage and offers a plethora of health benefits such as anti-oxidant, anti-cancer, anticardiovascular disease and anti-allergic activities 15 . ...
Article
Full-text available
The tea plant (Camellia sinensis) presents an excellent system to study evolution and diversification of the numerous classes, types and variable contents of specialized metabolites. Here, we investigate the relationship among C. sinensis phylogenetic groups and specialized metabolites using transcriptomic and metabolomic data on the fresh leaves collected from 136 representative tea accessions in China. We obtain 925,854 high-quality single-nucleotide polymorphisms (SNPs) enabling the refined grouping of the sampled tea accessions into five major clades. Untargeted metabolomic analyses detect 129 and 199 annotated metabolites that are differentially accumulated in different tea groups in positive and negative ionization modes, respectively. Each phylogenetic group contains signature metabolites. In particular, CSA tea accessions are featured with high accumulation of diverse classes of flavonoid compounds, such as flavanols, flavonol mono-/di-glycosides, proanthocyanidin dimers, and phenolic acids. Our results provide insights into the genetic and metabolite diversity and are useful for accelerated tea plant breeding.
... Teh (Camelia sinensis) merupakan minuman yang memiliki banyak manfaat kesehatan (Da Silva Pinto, 2013; Türközü & Şanlier, 2017). ...
Article
Full-text available
Indonesia merupakan produsen teh terbesar ke tujuh dunia dengan total produk mencapai 125 ribu ton pada 2016 yang berkontribusi sebesar 3% dari total produksi teh dunia. Kualitas produk teh merupakan faktor utama untuk meningkatkan daya saing produk teh Indonesia. Penelitian ini bertujuan untuk mengevaluasi kesesuaian mutu produk teh dengan persyaratan SNI. Parameter mutu yang dievaluasi meliputi kadar air, kadar abu total, kadar abu larut dalam air, kadar abu larut asam, dan kadar alkalinitas abu. Sebanyak 18 produk teh yang terdiri atas teh hitam, teh putih, teh hijau, teh hijau melati, dan bubuk teh hijau digunakan dalam penelitian. Hasil penelitian menunjukkan bahwa Kadar air dari 18 sampel produk teh berkisar antara 1,6% hingga 14%. Sebanyak 9 (sembilan) sampel produk teh memiliki kadar air yang melebihi standar yang disyaratkan oleh SNI. Produk teh hijau dan teh hijau melati memiliki kadar abu larut dalam air sebesar 33,25% dan 41,15% lebih rendah jika dibandingkan dengan persyaratan yang ditetapkan oleh SNI sebesar minimal 45%. Secara keseluruhan, produk teh telah memenuhi persyaratan SNI teh pada parameter kadar abu total, kadar abu tidak larut asam, dan alkalinitas abu. Beberapa parameter seperti kadar abu larut dalam air, abu tidak larut dalam asam, dan alkalinitas abu belum ditetapkan standarnya pada SNI 7707-2011 tentang teh instan dan SNI 01-1898-2002 tentang teh wangi. Penelitian lebih lanjut diperlukan untuk mengevaluasi mutu produk teh dari aspek kimia, cemaran logam mineral, dan mikrobiologi yang ditetapkan di SNI.
... 5−8 Theanine also has many positive health benefits, including as a relaxant, improvement of sleep quality, a neuroprotectant, and enhancements in attention and cognitive abilities. 9,10 In addition, it has been proposed for use in therapy for schizophrenia and Parkinson's disease. 11,12 In tea plants, theanine is synthesized from glutamate and ethylamine, under the catalysis of theanine synthetase (TS) ( Figure 1A). ...
Article
Full-text available
Shading was thought as an effective approach to increase theanine in harvested tea shoots. Previous studies offered conflicting findings, perhaps since the integration of theanine metabolism and transport in different tissues was not considered. Theanine is synthesized primarily in the roots and is then transported, via the vascular system, to new vegetative tissues. Here, we found that theanine increased in the stem, was reduced in the leaf, and remained stable in the roots, under shading conditions. Notably, in tea roots, shading significantly increased ethylamine and activated the theanine biosynthesis pathway and theanine transporter genes. Furthermore, shading significantly increased the expression of theanine transporter genes, CsAAP2/4/5/8, in the stem, while decreasing the expression of CsAAP1/2/4/5/6 in the leaf, in accordance with shading effects on theanine levels in these tissues. These findings reveal that shading of tea plants promotes theanine biosynthesis and allocation in different tissues, processes which appear to involve the theanine biosynthesis pathway enzymes and AAP family of theanine transporters.
... In recent years, the health effects of theanine have begun to come forward (Turkozu & Sanlier, 2017). In this study, consuming LTh effectively ameliorated adiposity and metabolic dysfunction in HFD-fed mice, which is consistent with the results of previous study (Zheng et al., 2004). ...
Article
L-theanine (LTh), a unique nonproteinic amino acid of tea, is known to possess beneficial effects on diet-induced obesity. This study aimed to evaluate whether orally administrated LTh could improve the adaptive thermogenesis of high-fat diet (HFD)-induced obese mice through regulating the composition of gut microbiota. Mice were fed control diet or a HFD with or without LTh for 12 weeks. Oral LTh administration ameliorated adiposity and hepatic steatosis in HFD mice. LTh increased the metabolic activities of brown fat and subcutaneous white fat by enhancing the expression of a series of thermogenic genes. More importantly, LTh improved the intestinal dysbiosis by decreasing the ratio of Firmicutes/Bacteroidetes, along with increases in the fecal short chain fatty acids concentrations. In conclusion, LTh ameliorates metabolic features of obesity by promoting fat browning and improving gut microbiota composition in HFD mice, which may be a mechanism of LTh-induced beneficial metabolic health.
... A characteristic ingredient of green tea is theanine, a non-protein amino acid that only exists in tea and mushrooms [10]. Theanine has anti-stress effects. ...
Article
Full-text available
Matcha, a type of green tea, has a higher amino acid content than other types of tea. We previously examined the ability of matcha to improve cognitive function in older adults and determined that continuous matcha intake improves attention and executive function. This study aimed to compare the effects of matcha and caffeine and clarify the differences between these effects. The study was registered at the University Hospital Medical Information Network (UMIN000036578). The effect of single and continuous intake was compared, and the usefulness of continuous intake was evaluated under the stress condition. The Uchida–Kraepelin test (UKT) was used to induce mild acute stress, and the Cognitrax was used to evaluate cognitive function. A single dose of caffeine improved attentional function during or after stress loading. The reduced reaction time in the Cognitrax, observed following a single dose of matcha, was likely due to caffeine. The matcha group showed an increase in the amount of work after continuous intake, whereas the caffeine group only showed an increase in the amount of work for the UKT after a single dose. Ingesting matcha with caffeine improves both attention and work performance when suffering from psychological stress compared with caffeine alone.
... L-theanine was analyzed by HPLC with Agilent ZORBAX SB-C18 (5 μm, 4.6 × 250 mm). The essential amino acid composition was identified and quantified by an amino acid analyzer L-8900 (Hitachi, Tokyo, Japan) special kind of amino acids in green tea and is known to act in the brain following oral ingestion (Adhikary & Mandal, 2017;Türközü & Şanlier, 2015). Hu et al reported that there were no significant differences in amino acids of green tea powder with the decrease in particle size during superfine grinding (Hu et al., 2012). ...
Article
Full-text available
Green tea, superfine green tea powder (SGTP), and tea extract were prepared to determine their chemical components and antioxidant activity. The nutrition and aroma challenges of green tea during traditional extract technique and superfine grinding were profiled in this study. The traditional extract technique took advantage over superfine grinding in L‐theanine and glutamic acid (Glu) preservation, but not in other 16 essential amino acids. SGTP preserved a maximum of elements from green tea, whereas tea extract greatly changed the elements ratio. Tea extract contained higher VB2 and VC contents and doubled the tea polyphenol (TP) content in comparison with green tea and SGTP. Additionally, tea extract contained more favorable aroma compounds and maintained stronger antioxidant activity in comparison with green tea and SGTP. This study profiled an important basis for the comprehensive utilization of green tea resources by consumers and manufacturers. Demand and competition for utilization of tea resource have transferred the form of the art of drinking tea into the form of eating tea. Over last decades, products that contain tea extract and superfine grinding tea powder are preferred by consumers and become popular in food and cosmetics industry. However, characterization of nutrition and aroma compositions toward green tea, tea extract, and superfine grinding tea powder is scarce. In this study, the nutrients (polyphenols, amino acids, vitamins, and elements) and aroma composition among different forms of green tea products are investigated, paving the new way to deep processing and high‐value utilization of green tea resources.
... The tea plant (Camellia sinensis L.) is one of the most important economic crops in China, India, Sri Lanka, Kenya, and certain Caucasian countries (Turkey, Georgia, Russia, and Azerbaijan). This perennial woody evergreen crop is grown in more than 60 countries on five continents, from 49 • N in Ukraine to 33 • S in South Africa (Turkozu and Sanlier, 2017). Caucasus tea germplasm collection (44 • 36 ′ 40 ′′ N, 40 • 06 ′ 40 ′′ E) is located in the border region of the possible tea production and can be the source of the most tolerant cultivars; some genotypes here survive −15-17 • C (Tuov and Ryndin, 2011). ...
Article
Full-text available
Cold and drought are two of themost severe threats affecting the growth and productivity of the tea plant, limiting its global spread. Both stresses cause osmotic changes in the cells of the tea plant by decreasing their water potential. To develop cultivars that are tolerant to both stresses, it is essential to understand the genetic responses of tea plant to these two stresses, particularly in terms of the genes involved. In this study, we combined literature data with interspecific transcriptomic analyses (using Arabidopsis thaliana and Solanum lycopersicum) to choose genes related to cold tolerance. We identified 45 stress-inducible candidate genes associated with cold and drought responses in tea plants based on a comprehensive homologous detection method. Of these, nine were newly characterized by us, and 36 had previously been reported. The gene network analysis revealed upregulated expression in ICE1-related cluster of bHLH factors, HSP70/BAM5 connected genes (hexokinases, galactinol synthases, SnRK complex, etc.) indicating their possible co-expression. Using qRT-PCR we revealed that 10 genes were significantly upregulated in response to both cold and drought in tea plant: HSP70, GST, SUS1, DHN1, BMY5, bHLH102, GR-RBP3, ICE1, GOLS1, and GOLS3. SnRK1.2, HXK1/2, bHLH7/43/79/93 were specifically upregulated in cold, while RHL41, CAU1, Hydrolase22 were specifically upregulated in drought. Interestingly, the expression of CIP was higher in the recovery stage of both stresses, indicating its potentially important role in plant recovery after stress. In addition, some genes, such as DHN3, bHLH79, PEI54, SnRK1.2, SnRK1.3, and Hydrolase22, were significantly positively correlated between the cold and drought responses. CBF1, GOLS1, HXK2, and HXK3, by contrast, showed significantly negative correlations between the cold and drought responses. Our results provide valuable information and robust candidate genes for future functional analyses intended to improve the stress tolerance of the tea plant and other species.
... L-theanine also contributes to the formation of key volatiles during tea processing [9,10]. It has been found to have various health benefits, including neuroprotection, relaxation, improvement of memory and learning performance, and prevention of cancer and the common cold [11][12][13]. ...
Article
L-Theanine is a crucial secondary metabolite in tea and positively determines the potential quality and health benefits of tea products. Previous work found the content of L-theanine decreased during withering process, while the specific mechanism is still unknown. Here, weighted gene co-expression network analysis (WGCNA) was performed based on the transcriptome data obtained previously. The key hydrolysis gene CsPDX2.1 in L-theanine metabolism and seven candidate transcription factors were screened out. Among those transcription factors, CsWRKY40 presented the strongest activation on the CsPDX2.1 promoter (373.18-fold) by binding to W box element based on the dual luciferase assay and EMSA results. Meanwhile, CsWRKY40 protein was located in the nucleoplasm, while CsPDX2.1 was found in both the nucleoplasm and cytoplasm. Furthermore, it was confirmed that the water loss of tea leaves was the critical factor affecting the contents of ABA and L-theanine by activating the expression of CsPDX2.1 and CsPDX2.1 based on the analysis of the withering model, water-retention model and water-loss model. Our results provide a new insight into revealing the regulation mechanism of L-theanine hydrolysis metabolism.
... Different fermentation processing techniques not only endow tea with rich flavors, but also the different biochemical reactions in the tea-making process make the ratio and composition of the ingredients subtly change, which allows different types of tea to have different health benefits [6]. These health benefits are derived from the complex content of the tea, such as tea polyphenols, theanine, tea polysaccharides, and caffeine, which have been reported to be good for health [7,8]. Studies have confirmed that tea has the effects of reducing lipids and weight loss, blood sugar, blood pressure, etc., to relieve metabolic syndrome [9], and it has also gradually attracted attention in reducing uric acid [10]. ...
Article
Full-text available
Hyperuricemia (HUA) is a metabolic disease that threatens human health. Tea is a healthy beverage with an abundance of benefits. This study revealed the uric acid-lowering efficacy of six types of tea water extracts (TWEs) on HUA in mice. The results revealed that under the intervention of TWEs, the expression of XDH, a key enzyme that produces uric acid, was significantly downregulated in the liver. TWE treatment significantly upregulated the expression of uric acid secretion transporters ABCG2, OAT1, and OAT3, and downregulated the expression of uric acid reabsorption transporter URAT1 in the kidney. Furthermore, HUA-induced oxidative stress could be alleviated by upregulating the Nrf2/HO-1 pathway. The intervention of TWEs also significantly upregulated the expression of the intestinal ABCG2 protein. On the other hand, TWE intervention could significantly upregulate the expression of intestinal ABCG2 and alleviate HUA by modulating the gut microbiota. Taken together, tea can comprehensively regulate uric acid metabolism in HUA mice. Interestingly, we found that the degree of fermentation of tea was negatively correlated with the uric acid-lowering effect. The current study indicated that tea consumption may have a mitigating effect on the HUA population and provided a basis for further research on the efficacy of tea on the dosage and mechanism of uric acid-lowering effects in humans.
... The positive effect of L-TH on cognitive ability is one of its most important functions. The chemical structure of L-TH is similar to glutamate, and therefore it can act as a neurotransmitter related to memory (Türközü and Şanlier 2017). Firstly, it is pointed out that L-TH penetrates the BBB and shows brain protection, preventing neuronal cell death after transient cerebral ischemia. ...
Article
Full-text available
Alzheimer's disease (AD) has brought a heavy burden to society as a representative neurodegenerative disease. The etiology of AD combines multiple factors, concluding family, gender, head trauma, diseases and social psychology. There are multiple hypotheses explaining the pathogenesis of AD such as β-amyloid (Aβ) deposition and tau hyperphosphorylation, which lead to extracellular amyloid plaques and neurofibrillary tangles in neurons. The existing therapeutic drugs have several disadvantages including single target, poor curative effect, and obvious side effects. Tea contains many bioactive components, such as tea polyphenols (TPP), L-theanine (L-TH), tea pigment, tea polysaccharides and caffeine. The epidemiological investigations have shown that drinking tea can reduce the risk of AD. The mechanisms of tea active ingredients in the prevention and regulation of AD includes reducing the generation and aggregation of Aβ; inhibiting tau aggregation and hyperphosphorylation; inhibiting neuronal apoptosis and regulate neurotransmitters; relieving oxidative stress and neuroinflammation as well as the regulation of intestinal flora. This review summarizes the different signaling pathways that tea active ingredients regulate AD. Furthermore, we propose the main limitations of current research and future research directions, hoping to contribute to the development of natural functional foods based on tea active ingredients in the prevention and treatment of AD.
... It may also interact with kainate and NMDA receptors for glutamate. 53,56 The FDA has considered it to be generally regarded as safe (GRAS) but has recommended that its daily intake should not exceed 1200 mg. 54,56 In an open-label clinical trial, Hidese et al investigated the effect of L-theanine on 20 patients with MDD. ...
Article
Depression is a chronic and debilitating psychiatric disorder that affects 300 million people worldwide. Pharmacotherapy is one of the treatments. Due to delay in initiating treatment efficacy and the incomplete response to mono-drug therapy in one-third of patients, new approaches need to be considered. One of the ways to overcome this resistance to treatment and to enhance standard medical practice is to add complementary medicines. We aimed to document research progress from studies on integrative medicine for the treatment of depression. Review of PubMed and Scopus databases on the topic and a personal collection of the relevant publications are the sources for this study. Some of the nutraceuticals and complementary medicines in the treatment of depression will be reviewed. Supplements discussed in this review include S-adenosyl-methionine (SAMe), Crocus sativus (Saffron), carnosine, theanine, palmitoylethanolamide (PEA), tryptophan and 5-hydroxytryptophan (5-HTP), gemfibrozil, curcumin (the main active ingredient in turmeric), Hypericum perforatum (St John's wort), Lavandula angustifolia (Lavender), and Cinnamomum tamala. Despite evidence in favor of the antidepressant effect of several supplements, their efficacy and tolerability should be evaluated and validated by further high-quality studies.
... In recent years, agents derived from natural sources have been widely studied by researchers due to their low toxicity and various biological effects. L-theanine (γ-glutamylethylamide) is a non-protein amino acid found principally in the tea plant and mushrooms [5]. It shows beneficial effects on various nutritional and metabolic diseases in humans, and it has antioxidative [6], neuroprotective [7,8], hepatoprotective [9], anti-tumor [10] and anti-restenosis effects [11]. ...
Article
Full-text available
Background L-theanine, a non-protein amino acid was found principally in the green tea, has been previously shown to exhibit potent anti-obesity property and hepatoprotective effect. Herein, we investigated the effects of L-theanine on alleviating nonalcoholic hepatic steatosis in vitro and in vivo, and explored the underlying molecular mechanism. Methods In vitro, HepG2 and AML12 cells were treated with 500 μM oleic acid (OA) or treated with OA accompanied by L-theanine. In vivo, C57BL/6J mice were fed with normal control diet (NCD), high‐fat diet (HFD), or HFD along with L-theanine for 16 weeks. The levels of triglycerides (TG), accumulation of lipid droplets and the expression of genes related to hepatocyte lipid metabolic pathways were detected in vitro and in vivo. Results Our data indicated that, in vivo, L-theanine significantly reduced body weight, hepatic steatosis, serum levels of alanine transaminase (ALT), aspartate transaminase (AST), TG and LDL cholesterol (LDL-C) in HFD-induced nonalcoholic fatty liver disease (NAFLD) mice. In vitro, L-theanine also significantly alleviated OA induced hepatocytes steatosis. Mechanic studies showed that L-theanine significantly inhibited the nucleus translocation of sterol regulatory element binding protein 1c (SREBP-1c) through AMPK-mTOR signaling pathway, thereby contributing to the reduction of fatty acid synthesis. We also identified that L-theanine enhanced fatty acid β-oxidation by increasing the expression of peroxisome proliferator–activated receptor α (PPARα) and carnitine palmitoyltransferase-1 A (CPT1A) through AMP-activated protein kinase (AMPK). Furthermore, our study indicated that L-theanine can active AMPK through its upstream kinase Calmodulin-dependent protein kinase kinase-β (CaMKKβ). Conclusions Taken together, our findings suggested that L-theanine alleviates nonalcoholic hepatic steatosis by regulating hepatocyte lipid metabolic pathways via the CaMKKβ-AMPK signaling pathway.
... L-theanine (LTA), a non-protein amino acid in tea, has shown antidepressant, immunoregulation, learning and cognition improvement, and other beneficial activities [1][2][3][4][5]. ...
Article
Full-text available
Epigallocatechin gallate (EGCG) and L-theanine (LTA) are important bioactive components in tea that have shown promising effects on nutrient metabolism. However, whether EGCG alone or combined with LTA can regulate the glucose, lipid, and protein metabolism of healthy rats remains unclear. Therefore, we treated healthy rats with EGCG or the combination of EGCG and LTA (EGCG+LTA) to investigate the effects of EGCG on nutrient metabolism and the role of LTA in the metabolism-regulatory effects of EGCG. The results showed that compared with the control group, EGCG activated insulin and AMP-activated protein kinase (AMPK) signals, thus regulating glucose, lipid, and protein metabolism. Compared with EGCG, EGCG+LTA enhanced hepatic and muscle glycogen levels and suppressed phosphorylation of AMPK, glycogen synthase 2, mammalian target of rapamycin, and ribosomal protein S6 kinase. In addition, EGCG+LTA inhibited the expression of liver kinase B1, insulin receptor and insulin receptor substrate, and promoted the phosphorylation level of acetyl-CoA carboxylase. Furthermore, both EGCG and EGCG+LTA were harmless for young rats. In conclusion, EGCG activated AMPK and insulin pathways, thereby promoting glycolysis, glycogen, and protein synthesis and inhibiting fatty acid (FA) and cholesterol synthesis. However, LTA cooperated with EGCG to promote glycogen metabolism and suppressed the effect EGCG on FA and protein synthesis via AMPK signals.
... Though it is tempting to say that L-Tea, the primary amino acid component of green tea [19], is able to elevate extracellular D-Ser levels through direct inhibition of ASCT transporters and is thus responsible for the positive effects of green tea on memory and cognitive function, our results show only its weak inhibitory effect on D-Ser transport. The inhibition was only considerable when high concentrations (10-20 mM) of L-Tea were applied and its IC50 value was found markedly higher than that of the typical ASCT transporter substrates (such as L-alanine and L-threonine). ...
Article
Full-text available
Decreased extracellular level of d-Serine (D-Ser), a co-agonist of the N-methyl-d-aspartate (NMDA) receptors was connected to receptor hypofunction in the brain and the related deficit of cognitive functions. Extracellular D-Ser concentration is modulated by ASCT neutral amino acid transporters. L-Theanine (L-Tea), a neutral amino acid component of green tea was reported to improve cognitive functions. We thus intended to investigate the possible inhibitory effect of L-Tea on the D-Ser uptake of SH-SY5Y neuroblastoma cells, which was previously found as a good model of D-Ser transport into astrocytes. Cells were incubated with D-Ser and various concentrations of L-Tea or the reference compound S-ketamine (S-Ket). The effect on the uptake was assessed by measuring the intracellular D-Ser concentration using a capillary electrophoresis–laser induced fluorescence detection method. L-Tea competitively inhibited D-Ser uptake into SH-SY5Y cells with an IC50 value of 9.68 mM. Having previously described as an inhibitor of ASCT-2 transporter, S-Ket was intended to be used as a positive control. However, no acute inhibition of D-Ser transport by S-Ket was observed. Its long-term effect on the transport was also examined. No significant difference in D-Ser uptake in control and S-Ket-treated cells was found after 72 h treatment, although the intracellular D-Ser content of the 50 μM S-Ket pre-treated cells was significantly higher. L-Tea was found to be a weak competitive inhibitor of the ASCT transporters, while S-Ket did not directly affect D-Ser uptake or modify the uptake kinetics after a long-term incubation period.
... Theanine is a non-proteinogenic amino acid, contributing sweet, brothy and umami flavor in tea (Zhang et al., 2017). It has also been reported to have effects on relaxing, cancer, cardiovascular diseases, obesity and other diseases (Turkozu, & Sanlier, 2017). Theanine is more easily extracted in cold water than in hot water (Monobe, 2018). ...
Article
Full-text available
This study was designed to explore the anti-obesity effects of cold-water brewed green tea (CWB-GT) on high-fat diet (HFD)-fed mice. CWB-GT was prepared by brewing tea leaves with 30 ℃ cold water, which contained considerable active ingredients including catechins, gallic acid and theanine. Our data demonstrated that CWB-GT could significantly ameliorate obesity and modulate gut microbiota composition of HFD-fed mice by affecting some specific bacteria. Besides, the expression of lipogenesis-related genes including FAS, HMGR and SREBP-1c in liver was inhibited and the expression of fatty acid oxidation-related genes including PPARα and PGC-1α in adipose tissue was enhanced. These benefits might be attributed to the stimulation of serum peptide YY (PYY) secretion. In particular, specific bacteria modulated by CWB-GT including Lachnospiraceae bacterium DW67, Blautia coccoides, Parabacteroides merdae and Bacteroides_vulgatus might be key mediators in exerting anti-obesity effects. This study suggested that CWB-GT could represent a novel functional low-calorie beverage.
Article
Full-text available
During Camellia sinensis tea processing, manufacturers usually remove the internodes, which are classified as waste. This study presents the first determination of plant part contribution, particularly internodes, to green tea quality, in order to find the best blend to maximize impact on human health. Catechins, caffeine and free amino acid (FAA) profiles were determined by RP-HPLC/DAD, total phenolics (TPC) and total flavonoids (TFC) by Folin-Ciocalteu and colorimetric methodologies, respectively, and antioxidant activities by free radical-scavenging activity (FRSA), ferric-reducing antioxidant power (FRAP) and ferrous ion-chelating (FIC) methods. Individual esterified catechins content decreased as follows: epicatechin-3-gallate>epigallocatechin-3-gallate≫gallocatecin-3-gallate, and epicatechin derivatives content ranged from 63.91 to 91.22% of total catechins. Caffeine content was higher in internodes. L-theanine, histidine, asparagine, phenylalanine, glutamic acid and methionine were the major FAAs, and internodes contained the highest amounts of L-theanine and histidine (17 and 13.73 mg/g of sample, respectively). TPC ranged from 201.51 to 265.48 mg gallic acid equivalents/g dry extract (DE) and TFC ranged from 23.84 to 72.02 mg rutin equivalents/g DE. Internodes presented the lowest FRSA (EC50=6.10–13.50 μg/mL), FRAP (EC50=5.70–11.40 μg/mL) and FIC activity (36.96–79.21%). Bud presented the highest FRSA and FRAP, and bud+1st+2ndleaves+internodes the highest FIC activity. The results revealed the potential contribution of the internodes to green tea quality and, consequently, to human health.
Article
L-Theanine, found in green tea leaves has been shown to positively affect immunity and relaxation in humans. There have been many attempts to produce L-theanine through enzymatic synthesis to overcome the limitations of traditional methods. Among the many genes coding for enzymes in the L-theanine biosynthesis, glutamylmethylamide synthetase (GMAS) exhibits the greatest possibility of producing large amounts of production. Thus, GMAS from Methylovorus mays No. 9 was overexpressed in several strains including vectors with different copy numbers. BW25113(DE3) cells containing the pET24ma::gmas was selected for strains. The optimal temperature, pH, and metal ion concentration were 50°C, 7, and 5 mM MnCl₂, respectively. Additionally, ATP was found to be an important factor for producing high concentration of L-theanine so several strains were tested during the reaction for ATP regeneration. Baker's yeast was found to decrease the demand for ATP most effectively. Addition of potassium phosphate source was demonstrated by producing 4-fold higher L-theanine. To enhance the conversion yield, GMAS was additionally overexpressed in the system. A maximum of 198 mM L-theanine was produced with 16.5 mmol/L/h productivity. The whole-cell reaction involving GMAS has greatest potential for scale-up production of L-theanine.
Article
Full-text available
L-theanine (γ-Glutamylethylamide) is a non-protein water soluble amino acid (AA) mostly occurred in leaves of Camellia sinensis (green tea). This is a key component of green tea, and is considered as the most abundant form of total amino acids in green tea (i.e. about 50%). L-theanine is an exclusive taste ingredient of tea producing an attractive flavor and aroma in tea. It has worth notice biological effects like antioxidant, growth promoter, immune booster, anti-stresser, hepactoprotective, antitumor, anti-aging, antimicrobial, anti-inflammatory and anti-anxiety activities. It could reduce the oxidative impairment by reducing the synthesis of reactive oxygen species (ROS), oxidative parameters and lipid damage as well as increasing the activity of antioxidant enzymes. The oral ingestion of L-theanine enhanced γδ T-cell proliferation. Therefore, it is being considered an essential compound of green tea’ that has ability to improve immune function. The L-theanine can be used as a potential treatment for hepatic injury and immune-related liver diseases via the downregulation of the inflammatory response through the initiation of nitric oxide (NO) synthesis and glutathione (GSH) production are likely to be critical for the control of hepatic diseases as well as for the improvement of immune function. In addition it could be used as a best natural feed additive with potent anti-stressor via decreasing the levels of corticosterone (CORT), dopamine (DA) and noradrenaline (NA). After systematically reviewed the literature it is noticed that, mostly studies done on mice, pig, human and butterfly; while dietary supplementation studies of L-theanine in animal and poultry especially among broilers is very limited due to less awareness of this amino acid. So, the aim of this review is to encourage the veterinarian and poultry researchers to conduct more research at the molecular level about this amino acid to expose its’ more beneficial effects and its’ mechanism of absorption for potential use of this unique green tea amino acid in poultry nutrition.
Article
Full-text available
L-theanine is the most abundant free amino acid in tea that offers various favorable physiological and pharmacological effects. Bacterial enzyme of γ-glutamylmethylamide synthetase (GMAS) can catalyze the synthesis of theanine from glutamate, ethylamine and ATP, but the manufacturing cost is uncompetitive due to the expensive substrates and complex processes. In this study, we described pathway engineering of wild-type Escherichia coli for one-step fermentative production of theanine from sugars and ethylamine. First, the synthetic pathway of theanine was conducted by heterologous introduction of a novel GMAS from Paracoccus aminovorans. A xylose-induced T7 RNA polymerase-P T7 promoter system was used to enhance and control gmas gene expression. Next, the precursor glutamate pool was increased by overexpression of native citrate synthase and introduction of glutamate dehydrogenase from Corynebacterium glutamicum. Then, in order to push more carbon flux towards theanine synthesis, the tricarboxylic acid cycle was interrupted and pyruvate carboxylase from C. glutamicum was introduced as a bypath supplying oxaloacetate from pyruvate. Finally, an energy-conserving phosphoenolpyruvate carboxykinase from Mannheimia succiniciproducens was introduced to increase ATP yield for theanine synthesis. After optimizing the addition time and concentration of ethylamine hydrochloride in the fed-batch fermentation, the recombinant strain TH11 produced 70.6 g/L theanine in a 5-L bioreactor with a yield and productivity of 0.42 g/g glucose and 2.72 g/L/h, respectively. To our knowledge, this is the first report regarding the pathway engineering of E. coli for fermentative production of theanine. The high production capacity of recombinant strain, combined with the easy processes, will hold attractive industrial application potential for the future.
Article
Prostate cancer (PCa) is a very prevalent male-specific malignancy; most PCa patients eventually die as a result of metastasis. L-theanine (C7H14N2O3), a nonprotein amino acid derivative from green tea leaves, has been demonstrated to act as an anticarcinogen through proapoptotic and antiproliferative effects. However, the antimetastatic effect of L-theanine in tumor cells and its underlying mechanism are still unclear. Here, we found that L-theanine could suppress invasion, migration, and increase cell-cell adhesion of prostate cancer cells in vitro and in vivo. We also found that L-theanine could inhibit the epithelial-mesenchymal transition process in PCa. Our study revealed that L-theanine could downregulate MMP9, N-cadherin, Vimentin, Snail, and upregulate E-cadherin. Furthermore, L-theanine suppressed the transcription of MMP9 and Snail by significantly inhibiting the ERK/NF-κB signaling pathway and the binding activity of p65 to the promoter regions of MMP9 and Snail. All of these findings suggest that L-theanine has therapeutic potential for metastatic PCa and may be considered a promising candidate for antimetastatic therapy of prostate cancer.
Article
Aims: Theanine, as a naturally occurring component in tea, has been shown to deliver benefits against various diseases. However, the exact molecular mechanisms underlying theanine's protective actions against cerebral ischemia/reperfusion (IR) injury still remains largely unknown. Main methods: In this study, rat cerebral IR injury model was established and were randomly divided into the following five groups: Sham (SH), IR, IR + Theanine (TH), IR + TH+ heme oxygenase-1 (HO-1) inducer cobalt protoporphyrin (Copp), and IR + Copp groups. Key findings: We found that theanine significantly inhibited neuron damage and apoptosis in the hippocampus during the 48 h detection period, as detected by hematoxylin and eosin (HE) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Meanwhile, reduced levels of malondialdehyde (MDA) and elevated activities of superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-PX) were observed in the theanine-treated group. Enzyme-linked immunosorbent (ELISA) assay also revealed that theanine markedly decreased the levels of inflammatory cytokines, such as IL-6, IL-1β, and TNF-α, in IR rats. The anti-apoptotic effect of theanine on IR injury was further verified by flow cytometry assay. Besides, theanine dramatically inhibited HO-1 expression and activity but increased extracellular signal-regulated kinase 1/2 (ERK1/2) activity in hippocampal tissue from rats with cerebral IR injury. However, co-treatment with Copp remarkably abolished the protective effects of theanine on cerebral IR injury. Significance: These findings demonstrated that the neuroprotective role of theanine was associated with its anti-oxidative, anti-inflammatory, and anti-apoptotic properties, which might be through regulation of HO-1 activation in rats with cerebral IR injury.
Article
In this study, ‘Zhongcha108′ (ZC) and its offspring cultivar ‘Zhongming7′ (ZM) were used to investigate the variation in characteristic compounds at different leaf positions. The results showed that there were differences between the two cultivars beyond the leaf position. The concentrations of theanine and caffeine were significantly higher in ZM, whereas more catechins accumulated in ZC. The expression levels of genes related to the theanine, caffeine and catechin pathways were determined by quantitative real time PCR. Compared with ZC, ZM showed higher expression levels of genes involved in theanine biosynthesis and transport, including GOGAT, GS(TS), AlaAT, AspAT, AS and AAP, suggesting that effective biosynthesis and translocation facilitate theanine accumulation in ZM. The caffeine content in ZC was positively correlated with the gene expression of TCS. However, such a correlation was not observed in ZM, which might be related to highly expressed genes involved in caffeine degradation, including CYP1A2, ALN and XO. Furthermore, catechin biosynthesis was regulated by different structural genes in the two cultivars. Higher catechins contents in ZC were related to higher genes expression levels, particularly for PAL, 4CL, F3H, FLS and LAR. A correlation analysis among key genes involved in theanine, caffeine, and catechin biosynthesis also showed consistent results. In ZC, catechins biosynthesis was more active, which inhibited the biosynthesis of nitrogen-rich metabolites, particularly for theanine. The balance of secondary metabolisms in ZM was shifted toward increasing the synthesis of nitrogen-containing compounds, i.e., theanine and caffeine. Taken together, these data reveal different regulatory mechanisms of theanine, caffeine, and catechins within two genetically similar tea cultivars. This work provides an important basis for further research on the characteristic metabolites of tea plants.
Article
Ethnopharmacological relevance Matcha green tea (Camellia sinensis) based-supplements have been widely used since they present a greater content of phenolic compounds than traditional green tea, which is popularly used in the treatment of diabetes. However, there are few studies on the effectiveness and safety of matcha supplements. Aim of the study This work aimed to evaluate the efficacy and safety of this supplement in endothelial cells (EA.hy926) in the hyperglycemic model and in vivo Artemia salina. Materials and methods To assess the effect of Matcha herbal supplement (MHS), EA. hy926 endothelial cells were treated with 20 μg/mL of MHS for 24 h, in a hyperglycemic medium with 35 mM glucose. After treatment, cells were trypsinized and centrifuged at 4 °C and 47×g for 5 min. The pellet was used to determine the reaction products to thiobarbituric acid and the levels of nitric oxide. Electron transport chain activity and ATP levels were also evaluated. Intracellular pH, apoptosis, and mitochondrial membrane depolarization were evaluated by flow cytometry. MHS chemical characterization was performed by HPLC-UV and total phenolic content analysis. The evaluation of the antioxidant capacity of MHS was performed by 2,2-diphenyl-1-picrylhydrazyl radical scavenger assay. To determine the in vivo acute toxicity of MHS, an A. salina assay was conducted, using 0,2 mL of different concentrations of MHS (10, 50, 100, 250, 500, 750 and 1000 μg/mL). The LD50 values were obtained by interpolation of 50% (y = 50) of the dead individuals in the trend curves. Results Our data showed that MHS was able to avoid oxidative and nitrosative stress induced by hyperglycemia, demonstrating important antioxidant activity. However, it was observed that MHS reduced up to 90% the activity of the four-electron transport complexes, reducing the ATP production of the endothelial cells. In the toxicity assay performed in Artemia salina, MHS showed mild toxicity (LD50 = 0,4 mg/mL). The major compounds found in MHS were epigallocatechin gallate, epicatechin, rutin, kaempferol, and quercetin. Conclusions This data draws attention to the fact that supplements with high content of phenolic compounds, capable of avoiding oxidative and nitrosative stress can have a dual effect and, simultaneously to antioxidant activity, can induce toxicity in different cell types.
Article
Full-text available
Theanine and theobromine are abundantly present in tea and cocoa, respectively. This study was performed to assess the chemopreventive effects of these phytochemicals, alone or together, on dimethylhydrazine (DMH)-induced colon cancer. Thirty male Wistar rats were divided into five groups and subcutaneously injected with saline (negative control group) or 30 mg/kg DMH (the other groups) two times/week for 12 weeks. The negative and positive control animals were orally treated with drinking water, and the other groups were gavaged with theanine (400 mg/kg), theobromine (100 mg/kg), or their mixture for two weeks before and throughout the injection period. At the end of the study, the morphological and histopathological features, Ki-67 proliferation marker, and the expression of Akt/mTOR, JAK2/STAT3, MAPK/ERK, and TGF-β/Smad pathways were investigated. Theanine and theobromine, alone or together, reduced the number of cancerous and precancerous lesions, the volume of tumors, the Ki-67 immunostaining, and the expression of Akt/mTOR and JAK2/STAT3 oncogenic pathways. The simultaneous treatment was more effective in the down-regulation of Akt and mTOR compared to either theanine or theobromine alone. Theobromine administration also caused more inhibitory effects on the Ki-67 and Akt/mTOR expression than theanine. Besides, all dietary interventions increased the mRNA and protein expression of Smad2. In conclusion, theanine and theobromine, alone and in combination, inhibited tumori-genesis through down-regulation of the Akt/mTOR and JAK2/STAT3 pathways and an increment of the Smad2 tumor suppressor. The inhibition of the Akt/mTOR pathway was more pronounced by simultaneous treatment.
Article
Pu-erh tea is believed to be a beneficial beverage for health due to its many kinds of pharmacological effects. Nevertheless, detailed information related to differences in metabolites of Pu-erh raw tea from different geographical origins remains scarce. In this study, 43 elements were found in water-soluble components of Pu-erh raw tea by highly sensitive ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (U-HPLC/Q-TOF-MS). The characteristic groups of 29 metabolites from nondestructive proton nuclear magnetic resonance (1 H-NMR) spectroscopy were assigned. The variables contributed largely to the origin classification, mainly including valine, threonine, chlorogenic acid, quinic acid, epiafzelechin, and gallic acid ester, were screened out by sparse partial least squares discriminant analysis (sPLS-DA) method. This study provided a feasible and rapid technique for distinguishing Pu-erh tea from different areas by 1 H-NMR combined with sPLS-DA.
Article
The bio-production of theanine is currently of significant interest due to its wide applications in food and healthcare products. Gamma glutamyl transferase (GGT) has been widely applied in L-theanine synthesis, but L-theanine yields remain prohibitively low for commercial production. In this study, a robust high-throughput screening process for isolating GGT mutants was developed through a combination of error-prone PCR techniques and a colorimetric reaction. The co-expression of PrsA lipoprotein enhances the secretion of GGT, thus GGT could be obtained quickly and easily without crushing cells. Random mutations on ggt genes were introduced by using error-prone PCR kits to build a large mutant library. A colorless compound generated by the reaction between NH⁴⁺ (released from L-theanine synthesis) and OPA was measured quantitatively by UV/visible spectroscopy when mixed with TCA and DMSO. Approximately 30 positive clones with improved color formation on the 96-well plates were identified, and mutants T413 P and T463S with more than by 30% higher transpeptidation activity versus the original GGT were isolated. To improve the operational stability and economical use, mutant GGT was immobilized on a prepared oxidized cellulose nanofiber membrane. The remaining activity of immobilized GGT was 88% versus 72% of free enzyme over 15 h. A fed-batch conversion was performed with the immobilized GGT, and over 70 g/L L-theanine could be accumulated within 18 h after feeding twice. Versus other studies, this is one of the best L-theanine synthesis systems using immobilized GGT.
Article
Skin aging is characterized by the gradual loss of elasticity, the formation of wrinkles and various color spots, the degradation of extracellular matrix proteins, and the structural changes of the dermis. With the increasingly prominent problems of environmental pollution, social pressure, ozone layer thinning and food safety, skin problems have become more and more complex. The skin can reflect the overall health of the body. Skincare products for external use alone cannot fundamentally solve skin problems; it needs to improve the overall health of the body. Based on the literature review in recent 20 years, this paper systematically reviewed the potential delaying effect of tea and its active ingredients on skin aging by oral and external use. Tea is the second-largest health drink after water. It is rich in tea polyphenols, l-theanine, tea pigments, caffeine, tea saponins, tea polysaccharides and other secondary metabolites. Tea and its active substances have whitening, nourishing, anti-wrinkle, removing spots and other skincare effects. Its mechanism of action is ultraviolet absorption, antioxidant, anti-inflammatory, inhibition of extracellular matrix aging, inhibiting the accumulation of melanin and toxic oxidation products, balancing intestinal and skin microorganisms, and improving mood and sleep, among other effects. At present, tea elements skincare products are deeply loved by consumers. This paper provides a scientific theoretical basis for tea-assisted beauty and the high-end application of tea in skincare products.
Article
Pu-erh tea from thousands of years’ old trees (TPT) equip with both superior flavors and powerful antioxidative capabilities. With UHPLC-Q-TOF-MS approach, TPTs’ chemical profiles were characterized by comparing with Pu-erh teas from ecological trees (EPT). TPTs are discovered to possess higher contents of amino acids, fatty acids, phenolic acids, nucleosides and nucleobases but lower contents of flavonoids and caffeine congeners based on 117 discriminative constituents from 305 identified ones. Particularly, a series of caffeic acid congeners including ten new hydroxycinnamic acid depsides with higher contents in TPTs are discovered, and caffeic acid with a fold change of 638 is the foremost discriminative component. Furthermore, distinguishing constituent proportion including caffeic acid congeners in TPTs are found to take great responsibilities for their much powerful antioxidative abilities and superior flavors especially much aroma and pleasant bitterness. This research provides information for deciphering formation of TPTs’ superior qualities based on chemical profile.
Article
The aim of this study was to investigate the effect and mechanism of L-theanine (LT) on muscle fiber type transformation in C2C12 myotubes. Our data showed that LT exhibited significantly higher slow oxidative muscle fiber expression and lower glycolytic fibers expression. In addition, LT significantly increased the activities of malate dehydrogenase (MDH) and succinic dehydrogenase (SDH), and decreased lactate dehydrogenase (LDH) activity, the calcineurin (CaN) activity and the protein expressions of nuclear factor of activated T cell 1 (NFATc1), prospero-related homeobox1 (prox1), and calcineurin A (CnA) were significantly increased. However, inhibition of CaN activity by cyclosporine A (CsA) abolished LT-induced increase of slow oxidative muscle fiber expression and decrease of glycolytic fibers expression. Moreover, inhibition of prox1 expression by prox1-siRNA disrupted LT-induced activation of CaN signaling pathway and muscle fiber type transformation. Taken together, these results indicated that LT could promote skeletal muscle fiber type transformation from type II to type I via activation of prox1/CaN signaling pathway.
Chapter
In recent decades, preclinical research into natural products has focused on the identification of pharmacologically active secondary metabolites produced by plants, often traditionally used as medicinal remedies. Beyond vitamins and minerals, plants contain other secondary metabolites recently defined as “nutraceuticals,” which are at the center of important scientific studies. The term nutraceutical is a portmanteau word, a combination of “nutrition” and “pharmaceutical,” and refers to “naturally derived bioactive compounds that are found in foods, dietary supplements, and herbal products and have health-promoting, disease-preventing, and/or medicinal properties.” Several nutraceuticals exhibit antiaging features by acting on the inflammatory status and on the prevention of oxidative reaction. This results in a significant reduction of all risk factors for age-related diseases, enhancing the attainment of healthy aging. In this context, the chapter will summarize the available clinical evidence supporting the use of selected botanicals and phytochemicals with confirmed activity on the human central nervous system and demonstrated effects in modulating cognitive decline as an example of age-related disease. In particular, the chapter will focus on data supporting the potential usefulness of Ginkgo biloba, Vitis vinifera, Camellia sinensis, Theobroma cacao, Bacopa monnieri, Crocus sativus, and Curcuma longa.
Article
Atherosclerosis is one of the most common cardiovascular diseases with highly mortality worldwide. The formation of foam cell plays an important role in the early stage of atherosclerosis pathogenesis. L-theanine is the most abundant free amino acid in tea, which possesses anti-inflammatory, anti-tumor and anti-atherosclerosis effects. However, little is known about the effects of L-theanine on the foam cell formation. In our study, RAW264.7 cells and primary mouse peritoneal macrophages were exposed to oxidized low density lipoprotein (ox-LDL) for inducing foam cell formation. We found that L-theanine significantly impeded cholesterol accumulation in macrophages, while inhibiting the formation of foam cell. Our further experiments showed that L-theanine attenuated the cholesterol uptake of RAW264.7 cells and primary mouse peritoneal macrophages by reducing the protein level of macrophage scavenger receptor A (SR-A), but not the level of mRNA suggesting that L-theanine regulates scavenger receptor A at the translational rather than transcriptional level. The present results demonstrated that L-theanine obviously promoted the degradation of scavenger receptor A protein and scavenger receptor A was degraded by ubiquitination dependent manner. Collectively, our research indicates that L-theanine suppresses the formation of macrophage foam cell by promoting the ubiquitination dependent degradation of scavenger receptor A.
Article
Background l-theanine, the most represented non-proteinogenic amino acid in tea plants (Camellia sinensis), is extensively utilized as a food supplement and a pharmaceutical, nutraceutical, and cosmetic ingredient. Tea plants are major sources of l-theanine; however, successfully extracting l-theanine from plants is limited by environmental conditions. Furthermore, the chemical synthesis of l-theanine is inefficient owing to the coproduction of undesirable stereoisomers that affect downstream applications. To overcome these problems, microbial engineering processes based on enzymatic catalysis and fermentation have emerged as sustainable manufacturing approaches for l-theanine biosynthesis. Advantages of these processes include the availability of well-established microbial engineering tools and strategies and high production rates. Scope and approach In this review, we first introduced the natural biosynthetic pathway of l-theanine production and discussed the detailed microbial or enzymatic processes involved in l-theanine production. We then summarized the information from recently published studies on the production of l-theanine using microbial platforms, emphasizing the latest advances and most relevant process parameters in l-theanine biosynthesis. Key findings and conclusion As an alternative approach to the non-environmentally friendly and largely energy-consuming traditional methods, the microbial production of l-theanine is expected to be successfully utilized in various industrial applications.
Article
Acute alcoholic liver injury (AALI) refers to the inflammatory hepatic damage caused by alcohol. In severe cases, it can lead to steatohepatitis, alcoholic fibrosis and even cirrhosis. In this study, we analyzed the hepatoprotective activity of L-theanine on mice fed with a large amount of ethanol at one time, and the underlying molecular mechanism. The extensive liver injury caused by alcohol feeding was alleviated by L-theanine, which reduced tissue damage, decreased transaminase levels, and increased antioxidant activity. Mechanistically, L-theanine downregulated phosphorylated NF-κB, TNF-α and IKKα in the liver tissues and the LO2 normal hepatocyte cell line, which in turn lowered secretion of iNOS, IL-1β and IL-6. Taken together, L-theanine prevents alcohol-induced liver inflammation by blocking the intrahepatic TNF-α/NF-κB pathway, and is a promising treatment strategy against AALI.
Article
Background/purpose We investigated the protective efficacy of l-theanine (LT), the major amino acid components of green tea, on chronic constriction injury (CCI) of sciatic nerve-induced neuropathic pain (NP) development and neuronal functional changes in rats. Methods Rats with NP induced by CCI of the left sciatic nerve and sham-operated rats received LT or saline solution, with pain sensitive tests of thermal hyperalgesia and mechanical allodynia. Motor and sensory nerve conduction velocities were measured after surgery. Subsequently, the rats were sacrificed; the sciatic nerve was excised, homogenized, prepared and subjected for estimation of nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), myeloperoxidase (MPO), and caspase-3. Results CCI produced a significant increase in hyperalgesia and allodynia, an increase in SFI, a decrease in nerve conduction velocity, increases in NO, MDA, TNF-α, IL-1β, IL-6, MPO, and caspase-3 levels, as well as reduction of GSH, SOD, and CAT in the rat sciatic nerve. LT treatment significantly and dose-dependently alleviated CCI-induced nociceptive pain thresholds and ameliorated abnormal nerve conduction and functional loss in rats with CCI. Moreover, LT treatment reduced NO and MDA levels, increased antioxidative strength, and markedly suppressed the levels of neuroinflammatory and apoptotic markers in injured sciatic nerves. Conclusion This is the first report on the ameliorative effect of LT in CCI-induced NP in rats. This effect might be attributed to its anti-oxidative, anti-inflammatory, anti-apoptotic, and neuroprotective, thus making it potentially useful as an adjuvant to conventional treatment.
Article
Full-text available
Theanine, a tea plant-specific non-proteinogenic amino acid, is the most abundant free amino acid in tea leaves. It is also one of the most important quality components of tea because it endows the "umami" taste, relaxation-promoting, and many other health benefits of tea infusion. Its content in tea leaves is directly correlated with the quality and price of green tea. Theanine biosynthesis primarily occurs in roots and is transported to new shoots in tea plants. Recently, great advances have been made in theanine metabolism and transport in tea plants. Along with the deciphering of the genomic sequences of tea plants, new genes in theanine metabolic pathway were discovered and functionally characterized. Theanine transporters were identified and were characterized on the affinity for: theanine, substrate specificity, spatiotemporal expression, and the role in theanine root-to-shoot transport. The mechanisms underlying the regulation of theanine accumulation by: cultivars, seasons, nutrients, and environmental factors are also being rapidly uncovered. Transcription factors were identified to be critical regulators of theanine biosynthesis. In this review, we summarize the progresses in theanine: biosynthesis, catabolism, and transport processes. We also discuss the future studies on theanine in tea plants, and application of the knowledge to crops to synthesize theanine to improve the health-promoting quality of non-tea crops.
Article
L-Theanine Reduces Epileptiform Activity In Brain Slices ABSTRACT Objective: L-theanine is one of the main amino acid of tea plant which can cross the blood brain barrier. In the central nervous system, L-theanine has certain effects on a number of neurotransmitter systems. In this study we tested whether acute application of L-theanine could induce any seizure like or inhibitory activity in the brain slice. Materials and Methods: Effects of L-theanine on epileptiform activity were investigated in two different brain regions. Horizontal hippocampal-entorhinal cortex slices were obtained from 30-35 days old C57BL/6 mice. Extracellular field potentials were recorded from medial entorhinal cortex (EC) and CA3 region of hippocampus. Epileptiform activity was induced by application of 4 Aminopyridine (4AP, 100 µM) in the brain slices and 50 µM L-theanine was applied. From the recordings, the duration and frequencies of ictal like events as well as frequency and amplitude of inter-ictal like activities were calculated. Results: L-theanine alone did not initiate any synchronized activity. Although, bath application of L-theanine after 4AP induces epileptiform acitivities, did not significantly alter the duration and frequency of ictal discharges, L-theanine attenuated the interictal discharges. In EC the frequencies of interictal discharges were significantly decreased. In CA3, the amplitudes of interictal activities were significantly reduced. Conclusion: The present findings suggest that L-theanine do not induce any seizure like event but rather had a suppressive effect on ongoing epileptiform activity. Key Words: Theanine, 4 Aminopyridine, Brain Slice, Epileptiform activity, CA3, Entorhinal cortex
Article
Albino tea plants (Camellia sinensis, Atps) are among the most attractive germplasm resources because of their unique phenotype and flavor. Although previous studies have extensively investigated the transcriptional and metabolic mechanisms in Atps, the lack of research at the translational level hinders the understanding of translation control and multi-omics integration. Here, we integrated the transcriptome, translatome, and metabolome to study the global translation and its effect on the metabolic characteristics of Atps. Comparative analysis of RNA-seq and Ribo-seq datasets indicated that 4,295 genes were expressed as synergic responses in etiolated leaves and were mainly enriched in the carbon metabolism and phytohormone pathways. Further integration-omics analyses revealed that the HY5 gene was upregulated at both the transcription and translation levels and repressed chlorophyll biosynthesis and flavonoids metabolism due to low levels of indole acetic acid and auxin response factors. Moreover, sequence characterizations (guanine-cytosine (GC) content, length, and normalized minimal free energy (NMFE)) highly influenced the translational efficiencies (TE) of genes and upstream open reading frames (uORFs), and a higher quantity of uORFs and TE were observed in EL, inhibiting the expression of downstream genes. In summary, we demonstrated that translation regulation contributes to causing leaf color variation and provided a valuable method for exploring the potential regulatory mechanisms controlling phytohormones that affect crop quality using multi-omics technology.
Article
Our recent study showed that glutamate can inhibit dopamine oxidation via chelating copper. l-Theanine is an amino acid analogue of glutamate, whereas tea (-)-epigallocatechin-3-gallate (EGCG) is similar to dopamine in avidly undergoing oxidation. We thus hypothesized that l-theanine could also restrain EGCG oxidation via chelating copper. The current study scrutinized influences of l-theanine on EGCG oxidation in vitro and in vivo. The in vitro results showed that l-theanine and copper formed an l-theanine-copper complex with impaired redox activity of copper. Accordingly, l-theanine effectively suppressed copper-facilitated EGCG oxidation, hydroxyl radical production, and DNA damage; inhibited EGCG autoxidation which in essence involves catalysis of transition metals such as copper; and reduced EGCG oxidation-associated formation of a quinone adduct with proteins known as quinoproteins. Consistently, l-theanine significantly increased hepatic EGCG levels and reduced hepatic quinoprotein levels and liver injury in mice treated with EGCG. These lines of evidence together suggest that tea l-theanine can protect against tea catechin oxidation.
Chapter
Dementia is a chronic condition characterized by the decreased cognitive capacity, which is more severe than in case of normal aging. Cognitive impairment is a major social and economic problem of modern society, which affects about 47 million people worldwide. The first stage of dementia (mild cognitive impairment) is characterized by the decline of memory, executive function, attention, visuospatial skills and speech. Pathogenic links of cognitive impairment are represented by neuroinflammation, excessive amyloid-β protein deposition, oxidative stress, hyperphosphorylation etc. In the recent years, the interest in natural plant-derived compounds for the treatment of cognitive decline has increased. In this chapter, we summarize the available evidence supporting the benevolent action of some botanicals and phytochemicals on cognitive function. The most widely studied plants include Ginkgo biloba, Panax ginseng and Camellia sinensis (green tea), but there also some other promising ones like guarana, grape, soy etc. These nutraceuticals mostly influence memory, learning and attention. At the moment it is quite difficult to make a definite conclusion on the effects of nutraceuticals on cognitive decline, because human trials show significant discrepancies. This underpins the need of future trials and scientific analysis.
Article
Full-text available
Tea has been widely consumed around the world for thousands of years and drinking tea is a daily habit for people of all ages. Tea is a major source of flavanoids, which have become well known as antioxidants. Tea also contains caffeine and theanine, which have been found to associate with health benefits. Many animal and epidemiological studies have been conducted to investigate the link between tea consumption and human health. However, common questions that arise about tea consumption include: whether all teas are the same, why drinking tea is linked with health benefits, how do the different ways of tea preparation impact on availability of tea components, how much and how long a person should consume tea to obtain health benefits, and whether there is any negative health effect associated with drinking tea. To answer these questions, this paper outlines the tea components and their link to human health, discusses major factors affecting availability of tea components in a tea cup, and reviews the latest epidemiological evidence linking tea consumption to human health.
Article
Full-text available
Background L-theanine, an amino acid contained in green tea leaves, is known to block the binding of L-glutamic acid to glutamate receptors in the brain, and has been considered to cause anti-stress effects by inhibiting cortical neuron excitation. Both L-theanine and caffeine, which green tea contains, have been highlighted for their beneficial effects on cognition and mood. Methods In this study, we investigated the effects of orally administered L-theanine or caffeine on mental task performance and physiological activities under conditions of physical or psychological stress in humans. Fourteen participants each underwent three separate trials, in which they orally took either L-theanine + placebo, caffeine + placebo, or placebo only. Results The results after the mental tasks showed that L-theanine significantly inhibited the blood-pressure increases in a high-response group, which consisted of participants whose blood pressure increased more than average by a performance of a mental task after placebo intake. Caffeine tended to have a similar but smaller inhibition of the blood-pressure increases caused by the mental tasks. The result of the Profile of Mood States after the mental tasks also showed that L-theanine reduced the Tension-Anxiety scores as compared with placebo intake. Conclusions The findings above denote that L-theanine not only reduces anxiety but also attenuates the blood-pressure increase in high-stress-response adults.
Article
Full-text available
An overview is given on the manufacture of the different types of tea along with the most important phenolics present in tea and methods of analysis. Compositional data are presented for green, white and black teas. A differentiation of green and black tea by using the ratio between total phenolics and sum of the major catechins seems to be feasible. For white tea there is no general accepted definition. Possible approaches are geographic origin, the botanical variety and the manufacture or the appearance. The differentiation between green and white teas by the ratio mentioned above is not possible. Eswird eine Übersicht über die Teemanufaktur und die resultierenden Arten von Tee gegeben, begleitet von einer Übersicht über einige wichtige Inhaltsstoffe (Flavanole, Zusammenstellung analytischer Methoden zur Bestimmung von (Poly)-phenolen und Daten über grüne, schwarze undweiße Tees). Derzeit scheint eine Differenzierung von grünem und schwarzem Tee über das Flavanol:Gesamtphenolverhältnis möglich. Für weißen Tee gibt es derzeit keine allgemein akzeptierte Definition. Mögliche Ansätze für diese sind die geographische Herkunft, die botanische Varietät oder die Art der Herstellung. Eine Differenzierung durch das Flavanol:Gesamtphenolverhältnis von grünem und weißen Tee ist nicht realistisch.
Article
Full-text available
The common cold is one of the most frequent illnesses caused by viral infection. Recently, we have reported that oral administration of cystine and theanine (CT) to mice enhanced the humoral immune response associated with antibody production. Based on this mouse study, we investigated the effects of CT supplementation on the common cold in humans as a pilot study. A total of 176 healthy male volunteers were randomized to receive either placebo or CT (490 mg) tablets twice daily for 35 days. The incidence outcome was assessed using the definition in our laboratory based on questionnaires regarding cold symptoms. The incidence of subjects with colds during the trial was significantly lower in the CT group than in the placebo group, although the duration of the colds was not significantly different between the groups. These results suggest that CT supplementation may be useful for the prevention of the common cold.
Article
Full-text available
The purpose of this study was to investigate the efficacy and safety of L-theanine as an aid to the improvement of objectively measured sleep quality in a population of 98 male children formally diagnosed with attention-deficit/hyperactivity disorder (ADHD). A randomized, double-blind, placebo-controlled trial was conducted involving boys, ages 8-12 years, who had been previously diagnosed with ADHD. An experienced physician confirmed the diagnosis of ADHD in each subject. Randomization was stratified based upon current use of stimulant medication to ensure an equal distribution of stimulant/non-stimulant treated subjects into active and placebo treated groups. Participants consumed two chewable tablets twice daily (at breakfast and after school), with each tablet containing 100 mg of L-theanine (total 400 mg daily Suntheanine®, Taiyo Kagaku, Yokkaichi, Japan) or identical tasting chewable placebo for six weeks. Subjects were evaluated for five consecutive nights using wrist actigraphy at baseline, and again at the end of the six-week treatment period. The Pediatric Sleep Questionnaire (PSQ) was completed by parents at baseline and at the end of the treatment period. Actigraph watch data findings indicated that boys who consumed L-theanine obtained significantly higher sleep percentage and sleep efficiency scores, along with a non-significant trend for less activity during sleep (defined as less time awake after sleep onset) compared to those in the placebo group. Sleep latency and other sleep parameters were unchanged. The PSQ data did not correlate significantly to the objective data gathered from actigraphy, suggesting that parents were not particularly aware of their children's sleep quality. L-theanine at relatively high doses was well tolerated with no significant adverse events. This study demonstrates that 400 mg daily of L-theanine is safe and effective in improving some aspects of sleep quality in boys diagnosed with ADHD. Since sleep problems are a common co-morbidity associated with ADHD, and because disturbed sleep may be linked etiologically to this disorder, L-theanine may represent a safe and important adjunctive therapy in childhood ADHD. Larger, long-term studies looking at the wider therapeutic role of this agent in this population are warranted.
Article
Full-text available
Recent neuropharmacological research has suggested that certain constituents of tea may have modulatory effects on brain state. The bulk of this research has focused on either L-theanine or caffeine ingested alone (mostly the latter) and has been limited to behavioral testing, subjective rating, or neurophysiological assessments during resting. Here, we investigated the effects of both L-theanine and caffeine, ingested separately or together, on behavioral and electrophysiological indices of tonic (background) and phasic (event-related) visuospatial attentional deployment. Subjects underwent 4 d of testing, ingesting either placebo, 100 mg of L-theanine, 50 mg of caffeine, or these treatments combined. The task involved cued shifts of attention to the left or right visual hemifield in anticipation of an imperative stimulus requiring discrimination. In addition to behavioral measures, we examined overall, tonic attentional focus as well as phasic, cue-dependent anticipatory attentional biasing, as indexed by scalp-recorded alpha-band (8-14 Hz) activity. We found an increase in hit rate and target discriminability (d') for the combined treatment relative to placebo, and an increase in d' but not hit rate for caffeine alone, whereas no effects were detected for L-theanine alone. Electrophysiological results did not show increased differential biasing in phasic alpha across hemifields but showed lower overall tonic alpha power in the combined treatment, similar to previous findings at a larger dosage of L-theanine alone. This may signify a more generalized tonic deployment of attentional resources to the visual modality and may underlie the facilitated behavioral performance on the combined ingestion of these 2 major constituents of tea.
Article
Full-text available
Experimental studies have revealed that green tea catechins and theanine prevent influenza infection, while the clinical evidence has been inconclusive. This study was conducted to determine whether taking green tea catechins and theanine can clinically prevent influenza infection. A randomized, double-blind, placebo-controlled trial of 200 healthcare workers conducted for 5 months from November 9, 2009 to April 8, 2010 in three healthcare facilities for the elderly in Higashimurayama, Japan. The catechin/theanine group received capsules including green tea catechins (378 mg/day) and theanine (210 mg/day). The control group received placebo. The primary outcome was the incidence of clinically defined influenza infection. Secondary outcomes were (1) laboratory-confirmed influenza with viral antigen measured by immunochromatographic assay and (2) the time for which the patient was free from clinically defined influenza infection, i.e., the period between the start of intervention and the first diagnosis of influenza infection, based on clinically defined influenza infection. Eligible healthcare workers (n = 197) were enrolled and randomly assigned to an intervention; 98 were allocated to receive catechin/theanine capsules and 99 to placebo. The incidence of clinically defined influenza infection was significantly lower in the catechin/theanine group (4 participants; 4.1%) compared with the placebo group (13 participants; 13.1%) (adjusted OR, 0.25; 95% CI, 0.07 to 0.76, P = 0.022). The incidence of laboratory-confirmed influenza infection was also lower in the catechin/theanine group (1 participant; 1.0%) than in the placebo group (5 participants; 5.1%), but this difference was not significant (adjusted OR, 0.17; 95% CI, 0.01 to 1.10; P = 0.112). The time for which the patient was free from clinically defined influenza infection was significantly different between the two groups (adjusted HR, 0.27; 95% CI, 0.09 to 0.84; P = 0.023). Among healthcare workers for the elderly, taking green tea catechins and theanine may be effective prophylaxis for influenza infection. ClinicalTrials (NCT): NCT01008020.
Article
Full-text available
To find whether green tea has anti-obesity effects in mice, female ICR mice were fed on diets containing 1, 2 and 4% green tea powder for 16 weeks and the body weight and food intake were weighed. After the administration of green tea, the ovaries, kidneys, adrenals, liver, spleen, brain, pituitary and intraperitoneal adipose tissues in the mice were weighed and lipid levels in the serum and in the liver and serum leptin levels were measured. It was found that body weight increase and intraperitoneal adipose tissues were remarkably suppressed by the administration of diets containing 2 and 4% green tea powder. Food intake was suppressed by feeding the 4% green tea diet. Concentrations of total cholesterol in the liver, triglycerides in serum and liver and nonestrified fatty acids in serum from mice which were administered green tea diet were lower than those in the controls. Leptin levels in serum showed a decrease with green tea treatments. These results indicated that lipid metabolism in mice was suppressed by the administration of green tea powder and thereby the fatty accumulation and body weight increase was suppressed.
Article
Full-text available
L-Theanine (delta-glutamylethylamide) is one of the predominant amino acids ordinarily found in green tea, and historically has been used as a relaxing agent. The current study examined the acute effects of L-theanine in comparison with a standard benzodiazepine anxiolytic, alprazolam and placebo on behavioural measures of anxiety in healthy human subjects using the model of anticipatory anxiety (AA). Sixteen healthy volunteers received alprazolam (1 mg), L-theanine (200 mg) or placebo in a double-blind placebo-controlled repeated measures design. The acute effects of alprazolam and L-theanine were assessed under a relaxed and experimentally induced anxiety condition. Subjective self-reports of anxiety including BAI, VAMS, STAI state anxiety, were obtained during both task conditions at pre- and post-drug administrations. The results showed some evidence for relaxing effects of L-theanine during the baseline condition on the tranquil-troubled subscale of the VAMS. Alprazolam did not exert any anxiolytic effects in comparison with the placebo on any of the measures during the relaxed state. Neither L-theanine nor alprazalam had any significant anxiolytic effects during the experimentally induced anxiety state. The findings suggest that while L-theanine may have some relaxing effects under resting conditions, neither L-theanine not alprazolam demonstrate any acute anxiolytic effects under conditions of increased anxiety in the AA model.
Article
Full-text available
Theanine, first discovered in tea, is a chiral nonproteinic amino acid that has been reported to have cardiovascular, neurological, and oncological effects. It is being considered as a therapeutic/medicinal agent and additive in consumer products. The present study evaluated the pharmacokinetics of D-theanine, L-theanine, and D,L-theanine in plasma and urine using LC-ESI/MS in rats after oral (p.o.) and intraperitoneal (i.p.) administration. Oral administration data indicated that gut absorption of d-theanine was far less than that of L-theanine. However, after i.p. administration, plasma theanine concentrations of L- and D-theanine were similar. This indicated that D- and L-theanine may exhibit a competitive effect with respect to intestinal absorption. Regardless of the route of administration, p.o. or i.p., the presence of the other enantiomer always decreased theanine plasma concentrations, indicating D,L-theanine competition with respect to urinary reabsorption. Data on urinary concentrations of D-theanine suggested that the D-isomer may be eliminated with minimal metabolism. L-Theanine appeared to be preferentially reabsorbed and metabolized by the kidney while D-theanine was preferentially excreted. Clearly, the bioequivalencies of D,L-theanine and its enantiomers were found to be quite different from one another. Consequently, the efficacy of commercial theanine products containing D-theanine, L-theanine, or D,L-theanine may be quite different.
Article
Full-text available
This study was conducted to evaluate the safety of l-theanine (Suntheanine) when administered as a dietary admixture to male and female Crl:CD (SD)GS BR rats at concentrations providing doses of 0, 1500, 3000 or 4000 mg/kg bw/day for 13 weeks. The study design was consistent with OECD Guideline 408 and USFDA Redbook II (1993) and GLP. There were no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, hematology, or urinalysis. There were no consistent treatment-related adverse effects in gross pathology, organ weights or ratios or histopathology. The increased incidence of renal tubular cell adenomas in high-dose females only were not consistent with the characteristics of a renal carcinogen (due to early onset and low number of animals affected) but were more consistent with a genetic predisposition than with direct organ toxicity. The no-observed-adverse-effect-level (NOAEL) was 4000 mg/kg bw/day, the highest dose tested.
Article
Full-text available
: Ingestion of the nonproteinic amino acid theanine (5-N-ethylglutamine) has been shown to increase oscillatory brain activity in the so-called alpha band (8-14 Hz) during resting electroencephalographic recordings in humans. Independently, alpha band activity has been shown to be a key component in selective attentional processes. Here, we set out to assess whether theanine would cause modulation of anticipatory alpha activity during selective attentional deployments to stimuli in different sensory modalities, a paradigm in which robust alpha attention effects have previously been established. : Electrophysiological data from 168 scalp electrode channels were recorded while participants performed a standard intersensory attentional cuing task. : As in previous studies, significantly greater alpha band activity was measured over parieto-occipital scalp for attentional deployments to the auditory modality than to the visual modality. Theanine ingestion resulted in a substantial overall decrease in background alpha levels relative to placebo while subjects were actively performing this demanding attention task. Despite this decrease in background alpha activity, attention-related alpha effects were significantly greater for the theanine condition. : This increase of attention-related anticipatory alpha over the right parieto-occipital scalp suggests that theanine may have a specific effect on the brain's attention circuitry. We conclude that theanine has clear psychoactive properties, and that it represents a potentially interesting, naturally occurring compound for further study, as it relates to the brain's attentional system.
Article
Tea is a very popular beverage and mainly categorized as green, oolong, or black tea. The typical polyphenols in green and black teas are catechins and theaflavins. Observational studies have demonstrated that the consumption of green tea or green tea catechins decrease serum cholesterol concentration. The results of animal studies suggest that these polyphenols inhibit intestinal cholesterol absorption and thereby, reduce serum cholesterol concentrations. These polyphenols inhibit the micellar solubilization of cholesterol (Ikeda I, Imasato Y, Sasaki E, Nakayama M, Nagao H, Takeo T, et al. Tea catechins decrease micellar solubility and intestinal absorption of cholesterol in rats. Biochim Biophys Acta 1992;. 1127(2):141. -146; Ikeda I, Kobayashi M, Hamada T, Tsuda T, Goto H, Imaizumi K, et al. Heat-epimerized tea catechins rich in gallocatechin gallate and catechin gallate are more effective to inhibit cholesterol absorption than tea catechins rich in epigallocatechin gallate and epicatechin gallate. J Agric Food Chem 2003;. 51(25):7303. -7307; Ikeda I, Yamahira T, Kato M, Ishikawa A. Black-tea polyphenols decrease micellar solubility of cholesterol in vitro and intestinal absorption of cholesterol in rats. J Agric Food Chem 2010;. 58(15):8591. -8595). The limited solubility of cholesterol by these polyphenols may be a major cause of the inhibition of cholesterol absorption. However, there is no information on the effects of these polyphenols on cholesterol transporters in enterocytes. Detailed studies are necessary to clarify how these polyphenols inhibit cholesterol absorption in the intestinal lumen and enterocytes.
Article
Although among the five main types of teas (white, green, oolong, black and pu-erh), black tea is the most consumed worldwide, an impressive number of scientific publications have been focused on green tea and its major compounds, flavan-3-ols (“catechins”). However, besides flavan-3-ols, there are other compounds present in tea that could be accounted as potential bioactive compounds. Therefore, the objective of the present review is to provide a new perspective on the health benefits associated with tea consumption by critically analyzing the available literature on the potential tea bioactive compounds and the current level of scientific evidence for these health benefits. Until now the exact mechanisms of action or compounds responsible for the health benefits associated with tea consumption have only been poorly investigated. It is important to consider that tea compounds will be extensively metabolized to different metabolites that will, most likely, be the compounds circulating in blood and potentially reaching the different sites of action.
Article
L-Theanine is an amino acid found in green tea leaf and in its infusion, and is known to control excitement caused by caffeine. It is also known that the oral administration of L-theanine to rats results in a decrease of serotonin and increase of catecholamines in their brain. L-Theanine has been confirmed to be safe in animal experiments. We found recently that oral intake of L-theanine caused a feeling of relaxation among the human volunteers examined. These observations led us to do experiments on the effects of administration of L-theanine on the brain electric waves. Eight female university students were selected as volunteers. Four of them were ranked to be Grade I (the highest anxiety) and the remaining four, Grade V (the lowest anxiety) in an investigation done by the manifest anxiety scale method. A dose of oral administration of 200 mg of L-theanine dissolved in 100 ml of water resulted in the generation of α-electric waves in the occipital and parietal regions of the brains of the subjects. The emission intensity of α-brain waves (integrated as a function of investigation times and area) was significantly greater in the group of Grade I than that of Grade V. These results indicate the possibility for L-theanine to be applied to foods and beverages as a new type of functional food ingredient for its relaxation effect.
Article
The author discovered a new amide in the water extract of Japanese green tea, and named it “theanine”. This substance crystallizes in the form of colorless needle; molecular formula C7H14O3N2, melting point 217_??_218° (decompose), and [α]12 D=+7.1. It presents strong ninhydrin reaction. It is very soluble in water, and is dissolved in 2.6 times of water at 0° and 1.8 times of water at 100°, but insoluble in ethyl alcohol and ether. By hydrolysis of theanine, it gives L-glutamic acid and ethyl amine nearly quantitatively. From the fact that it shows no biuret reaction and that the natural glutamine is γ-amide, it seems very probable that theanine may be L-glutamic acid γ-ethyl amide. It is the first time that ethyl amine has been discovered, though not in a free state, in plant kingdom. The author has also studied the distribution of theanine in each stage of tea leaf developments. Gyokuro is rich (about 1%) in it, but Sencha is poor. It seems, therefore, that theanine assumes the analogous role of glutamine or asparagine in other plants though the destination of ethyl amine is yet unknown.
Article
A systematic review and meta-analysis was conducted on 11 randomized placebo-controlled human studies of acute effects of tea constituents L-theanine and epigallocatechin gallate, administered alone or in combination with caffeine, on cognitive function and mood. The outcome measures of mood were alertness, calmness, and contentedness, derived from the Bond-Lader scales, and state anxiety, from the State-Trait Anxiety Inventory. Cognitive measures assessed were attentional switch, intersensory attention, and rapid visual information processing. Standardized mean differences between placebo and treatment groups are presented for each study and outcome measure. Meta-analysis using a random-effects model was conducted when data were available for three or more studies. Evidence of moderate effect sizes in favor of combined caffeine and L-theanine in the first 2 hours postdose were found for outcome measures Bond-Lader alertness, attentional switching accuracy, and, to a lesser extent, some unisensory and multisensory attentional outcomes. Moderator analysis of caffeine and L-theanine doses revealed trends toward greater change in effect size for caffeine dose than for L-theanine dose, particularly during the first hour postdose.
Article
L-Theanine is a unique amino acid present in green tea. It elicits umami taste and has a considerable effect on tea taste and quality. We investigated L-theanine activity on the T1R1 + T1R3 umami taste receptor. L-Theanine activated T1R1 + T1R3-expressing cells and showed a synergistic response with inosine 5'-monophosphate. The site-directed mutagenesis analysis revealed that L-theanine binds to L-amino acid binding site in the Venus flytrap domain of T1R1. This study shows that L-theanine elicits an umami taste via T1R1 + T1R3.
Article
Doxorubicin (DOX) is a highly potent anti-neoplastic agent, which is widely used in clinical practice; however, its dosage and duration of administration are strictly limited due to dose-related cardiac damage. The present study investigated whether theanine, an amino acid found in green tea leaves, can reduce DOX-induced acute cardiotoxicity by examining changes in serum enzyme activities. The activities of creatine kinase (CK) and lactate dehydrogenase (LDH), biochemical markers of cardiac impairment, in serum were elevated by the administration of 20 mg/kg DOX to mice. Elevations in serum enzyme activities were attenuated by concurrent treatment with theanine, and significant suppression was observed at a dose of 10 mg/kg, which is comparable to daily intake in the form of supplement. Especially, CK activity was recovered by theanine almost to control levels. Body weight loss caused by DOX was significantly suppressed by theanine treatment. These results suggest that theanine can protect against DOX-induced acute cardiac injury.
Article
Recent interest into the possible benefits of l-theanine found in tea has raised the issue that there are few data available on amounts of l-theanine contained in cups of commercially-available teas, prepared by a standard method. HPLC along with a standard method of preparing tea was employed here to determine amounts of l-theanine in cups of tea and the effects that various preparation factors have on amounts of l-theanine extracted. Brewing time was found to be a major determinant of the amount of l-theanine extracted, while the addition of small amounts of milk and sugar made no significant difference. High levels of milk resulted in a marked lowering of the level of detectable l-theanine. Contrary to previous research, a standard (200ml) cup of black tea was found to contain the most l-theanine (24.2±5.7mg) while a cup of green tea contained the least (7.9±3.8mg).
Article
The metabolism of theanine, one of the major amino acid components in tea (Camellia sinensis), was studied in rats. High-performance liquid chromatography (HPLC) with fluorometric detection was used to evaluate the nature of theanine's metabolites in plasma, urine, and tissues. In the urine samples collected after administration of 100, 200, and 400 mg each of theanine, intact theanine, L-glutamic acid, and ethylamine, these compounds were detected in a dose-dependent manner. When 200 mg of theanine was orally administered to rats, the plasma concentrations of theanine and ethylamine reached their highest levels about 0.5 and 2 h after administration, respectively. It seems most likely that the enzymatic hydrolysis of theanine to glutamic acid and ethylamine was accomplished in the kidney. These results indicate that orally administered theanine is absorbed through the intestinal tract and hydrolyzed to glutamic acid and ethylamine in the rat kidney.
Article
Theanine, one of the main amino acid components in tea, is known as a precursor of the non‐peptide antigen ethylamine, which mediates a memory response leading to secretion of IFN‐γ. Tea which contains theanine is alleged to have various therapeutic benefits to man. Different types of tea contain various amounts of theanine. A method for reversed‐phase high performance liquid chromatographic separation of theanine with fluorescence detection and its application are described. The method was applied to determining theanine in different types and grades of tea samples, which were extracted in boiling water, followed by filtration through a 0.45 µm filter. Theanine was derivatized with o‐phthaldialdehyde (OPA) prior to analysis. Separation of theanine, using an isocratic elution with a mobile phase containing 15 mM sodium acetate, isobutanol, isopropanol, and acetonitrile (75∶3∶2.5∶8, pH 7.1) was achieved in less than ten minutes. The relative fluorescence of derivatized theanine remained steady during analysis. The limit of detection of theanine standard was 33.2 picograms, while the limit of quantitation of theanine in tea extract was about 0.33 ng/mL. The results show that there is a relative quantitative relationship between the degree of fermentation and the level of theanine. The findings indicate that non‐fermented green tea and partially fermented yellow tea contained more theanine than dark, black, and woo‐loong tea, which all undergo the fermentation.
Article
Theanine is the main amino acid component in tea. It usually constitutes between 1 and 2% of the dry weight of the tea leaves. It is as prevalent in tea as all other free amino acids combined. Both enantiomers of theanine were found to have a similar sweet taste, with little or no aftertaste. It was found that black and half-green teas (except for Formosa Oolong) contained as much, or more, theanine as green teas. No correlation was found between the absolute concentration of theanine in tea and its enantiomeric composition. An inverse correlation was found between certain grades of tea (e.g., pekoe, Flowery Orange Pekoe, etc.) and the percent of d-theanine present. This could provide the basis for a reproducible, scientific method to grade and/or evaluate teas. Theanine slowly racemizes in aqueous solution. It also undergoes hydrolysis, particularly at basic pH values. By monitoring these processes, information may be gleaned on the production, storage, handling, and shipping of tea and tea products. Keywords: Racemization; beverage; d-amino acid; tea grades; cyclodextrin column; column switching
Article
Theanine (γ-glutamylethylamide) is the most abundant free amino acid in tea seedlings, and is distributed in cotyledons, shoots and roots. Theanine was synthesised from 15N-labelled (NH4)2SO4, glutamic acid and alanine and from 14C-labelled ethylamine in all parts of seedlings. When (15NH4)2SO4 was supplied to intact seedlings in liquid culture, incorporation of 15N into theanine in roots was greater than in shoots. Incorporation into theanine was negligible in cotyledons, but theanine synthesis in roots and shoots was reduced in seedlings with cotyledons detached. Expression of theanine synthetase genes (TS1 and TS2) was found in all organs, but the transcript level was significantly lower in cotyledons. These results suggest that theanine can be synthesised from glutamic acid and ethylamine derived from alanine in all parts of tea seedlings. However, supplied NH3 exogenously to intact seedlings was converted to theanine mainly in roots. Amino acids stored in cotyledons may also be utilised for theanine synthesis in all parts of seedlings.Graphical abstractTheanine is a major amino acid in young tea seedlings. It is synthesised from [15N]glutamic acid, [15N]alanine and [14C]ethylamine in all parts of tea seedlings. Conversion of exogenously supplied (15NH4)2SO4 is utilised in theanine synthesis mainly in roots. Expression of theanine synthesis genes was observed in shoots and roots.
Article
After consumption of tea, L-theanine enters systemic circulation and is assumed to enter the brain. Several human studies indicate that L-theanine influences brain functioning. Knowledge about the pharmacokinetics of L-theanine facilitates further study of this health effect. Volunteers received 25–100 mg of L-theanine as tea, as L-theanine-enriched tea, and as biosynthetic L-theanine in aqueous solutions. Plasma was analysed for L-thea-nine content after which data were fitted with a 1-compartment model. For all interven-tions, the lag time was approximately 10 min and half-lives of absorption and elimination were approximately 15 and 65 min respectively. After approximately 50 min, maximum plasma concentrations of between 1.0 and 4.4 mg/L were achieved. Maximum plasma concentration and area under the plasma-concentration–time curve were dose-proportional. This knowledge allows prediction of plasma concentrations for various dose regimens supporting further study of a health benefit of L-theanine.
Article
Since ancient times, it has been said that drinking green tea brings relaxation. The substance that is responsible for a sense of relaxation, is theanine. Theanine is a unique amino acid found almost solely in tea plants and the main component responsible for the exotic taste of ‘green’ tea. It was found that L-theanine administered intraperitoneally to rats reached the brain within 30 min without any metabolic change. Theanine also acts as a neurotransmitter in the brain and decreased blood pressure significantly in hypertensive rats. In general, animals always generate very weak electric pulses on the surface of the brain, called brain waves. Brain waves are classified into four types, namely α,β,δ and θ-waves, based on mental conditions. Generation of α-waves is considered to be an index of relaxation. In human volunteers, α-waves were generated on the occipital and parietal regions of the brain surface within 40 min after the oral administration of theanine (50–200 mg), signifying relaxation without causing drowsiness. With the successful industrial production of L-theanine, we are now able to supply Suntheanine™ (trade name of L-theanine) which offers a tremendous opportunity for designing foods and medical foods targeting relaxation and the reduction of stress. Taiyo Kagaku Co., Ltd, Japan won the 1998 ‘Food Ingredient Research Award’ for development of Suntheanine™ at Food Ingredients in Europe (Frankfurt). The judges felt it was a particularly well-documented and fascinating piece of research.
Article
l-Theanine was orally administered at a concentration of 0–5% (maximum tolerated dose) of the diet to B6C3F1 mice for 13 weeks in a subacute test and 78 consecutive weeks, in a chronic toxicity test. There were no significant differences in intake of diet, weight gains or survival rates between treated and control groups. Unignorable differences in tumor incidence were observed at the end of 78 weeks; however, total number of tumors decreased significantly in the l-theanine administered groups. Thus, the long-term oral administration of l-theanine to mice did not show any chronic toxicological evidence or tumorigenic aberration.
Article
L-theanine has been reported to inhibit the excitatory effects of caffeine. The present study examined the effects of L-theanine on caffeine-induced sleep disturbances in rats. Rats received the following drug pairings: saline and saline (Control), 7.5 mg/kg caffeine and saline, or 7.5 mg/kg of caffeine followed by various doses of L-theanine (22.5, 37.5, 75, or 150 mg/kg). Vigilance states were divided into: wakefulness (W), transition to slow-wave sleep (tSWS), slow-wave sleep (SWS), and rapid-eye-movement sleep (REMS). Caffeine significantly increased the duration of W and decreased the duration of SWS and REMS compared to the Control. Although L-theanine failed to reverse the caffeine-induced W increase, at 22.5 and 37.5 mg/kg (but not at 75 and 150 mg/kg), it significantly reversed caffeine-induced decreases in SWS. In conclusion, low doses of L-theanine can partially reverse caffeine-induced reductions in SWS; however, effects of L-theanine on caffeine-induced insomnia do not appear to increase dose-dependently.
Article
Theanine is a non-protein amino acid that occurs naturally in the tea plant (Camellia sinensis) and contributes to the favourable taste of tea. It is also associated with effects such as the enhancement of relaxation and the improvement of concentration and learning ability. It is also linked with health benefits including the prevention of certain cancers and cardiovascular disease, the promotion of weight loss and enhanced performance of the immune system. Thus, there has been a significant rise in the demand for theanine. While theanine has been chemically and biologically synthesised, techniques to isolate theanine from natural sources remain an important area of research. In this review article, the properties and health benefits of theanine are summarised and the synthesis and isolation of theanine are reviewed and discussed. Future perspectives for the isolation of theanine from natural sources are also outlined.