L-Theanine: properties, synthesis and isolation from tea

Vuong, Quan V.; Bowyer, Michael C.; Roach, Paul D.

doi:10.1002/jsfa.4373

Cited by 182 publications

(165 citation statements)

References 65 publications

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“…The roots are also considered as an important part of the plant, and in case of tea (C. sinensis), the roots are primary site of theanine biosynthesis which is a novel non-proteogenic amino acid (Vuong et al 2011). From roots theanine gets translocated to aerial parts.…”

Section: Resultsmentioning

confidence: 99%

Screening and purification of catechins from underutilized tea plant parts and their bioactivity studies

et al. 2016

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Comparative investigation of major phytoconstituents was performed from various parts of tea plant viz. apical bud, subtending 1st-5th leaf, stem, coarse leaves, flowers, fruits and roots. From the results of comparative RP-HPLC-DAD analysis it was found that underutilized tea parts especially coarse leaves, flowers and fruits contains abundant amount of phenolics (17.5%) and catechins (4-5%). From these underutilized tea plant parts the catechins were extracted and purified and then screened for their anticancer, immunomodulatory effect and antimicrobial activity against food borne pathogens. The results showed that tea fruit extract exhibited higher toxicity against oral cancer cells and also promotes proliferation of mice splenocytes. The results of antimicrobial studies revealed the inhibitory effect of these extracts against both gram positive and gram negative bacteria. These investigations clearly demonstrated that the underutilized tea plant parts could act as economical and sustainable bioresource of functionally active constituents which further lead to the development of new cost-effective nutraceuticals and other formulations.

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Section: Resultsmentioning

confidence: 99%

Screening and purification of catechins from underutilized tea plant parts and their bioactivity studies

et al. 2016

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“…The "zdrugs", such as eszopiclone and zolpidem are specifically indicated for sleep problems in adults; [41][42][43] however, their safety and efficacy in patients below the age of 18 have not been established. L-theanine (5-N-ethyl-L-glutamine) is a herbal remedy that is a constituent of teas, including both green and black tea; it is promoted as inducing relaxation, although the evidence for this appears to be limited 44,45 .…”

Section: Systematic Searchmentioning

confidence: 99%

Safety, Tolerability and Efficacy of Drugs for Treating Behavioural Insomnia in Children with Attention-Deficit/Hyperactivity Disorder: A Systematic Review with Methodological Quality Assessment

et al. 2017

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ObjectiveA large proportion of paediatric patients with attention-deficit/hyperactivity disorder (ADHD) have associated sleep problems which not only affect the child's well-being but also impact family functioning. Management of sleep problems is consequently an important aspect of overall ADHD management in paediatric patients. Although some drugs are being used off-label for the management of paediatric insomnia, there is scant clinical evidence supporting their use. Our aim was to identify and assess the quality of published studies reporting the safety, tolerability and efficacy of drugs used for treating behavioural insomnia in children with ADHD. MethodAfter an initial screen to determine which drugs were most commonly used, we conducted a systematic review of English-language publications from searches of PubMed, EMBASE, PsychInfo and two trial register databases to February 2017, using keywords clonidine, melatonin, zolpidem, eszopiclone, L-theanine, guanfacine, ADHD, sleep disorder and children. For quality assessment of included studies, we used the CONSORT checklist for randomized control trials (RCTs) and the Downs and Black checklist for non-RCTs. ResultsTwelve studies were included. Two case series for clonidine, two RCTs and four observational studies for melatonin and one RCT each for zolpidem, eszopiclone, L-theanine and guanfacine. Of the 12 included studies, only one on eszopiclone scored excellent. The quality of the rest of the studies varied from moderate to low. For clonidine, melatonin and L-theanine, improvement in sleep-onset latency and total sleep duration, were reported; however, zolpidem, eszopiclone and guanfacine failed to show any improvement when compared with placebo. Clonidine, melatonin, L-theanine, eszopiclone and guanfacine were well tolerated with mild to moderate adverse events except for zolpidem which was associated with neuropsychiatric adverse effects. ConclusionThere is generally poor evidence for prescribing drugs for behavioural insomnia in children with ADHD. Further controlled studies are warranted.

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“…In fact, it contains the same concentration of bioactive compounds, L-theanine and polyphenols, as the corresponding commercial tea [Chander et al, 2005]. L-theanine is the dominant amino acid in tea which exerts health benefits such as improved learning and relaxing, cancer and cardiovascular diseases prevention and strengthening of the immune system [Juneja et al, 1999;Vuong et al, 2011]. Polyphenols are powerful antioxidants and prevent various diseases such as obesity, diabetes and neurodegenerative disorders as well as cancer and cardiovascular diseases [Chacko et al, 2010;Khan & Mukhtar, 2007].…”

Section: Introductionmentioning

confidence: 99%

Fermentation of Plant Material – Effect on Sugar Content and Stability of Bioactive Compounds

Reis¹,

Kosińska-Cagnazzo²,

Schmitt³

et al. 2014

Pol. J. Food Nutr. Sci.

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Extraction is a method often used to obtain products rich in bioactive compounds from plant material. Most of the solvents used for the polyphenols extraction simultaneously extract also sugars, undesirable as a component of health-promoting food. Fermentation might be a simple, cheap and efficient way of sugar elimination. In our study, black tea and goji berries, both known for their health benefits, were used and alcoholic fermentation by Saccharomyces cerevisiae was carried out to eliminate sugars. In the course of fermentation the concentration of polyphenols, L-theanine and carotenoids was evaluated in order to verify the preservation of selected bioactive compounds. Decreases in sugar content, formation of ethanol and yeasts growth were monitored during fermentation. The fermentation of black tea decreased the sugar concentration by 84% within 6 h without decreasing total polyphenols and L-theanine contents. Goji berry fermentation yielded a sugars decrease of 87% within 24 h, without decrease in polyphenol content. However, carotenoid content was reduced by 17%. The study showed that fermentation was an effective way to decrease sugar content in plant extracts, and therefore it might be a pertinent step to concentrate bioactives.

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L-Theanine: properties, synthesis and isolation from tea

Cited by 182 publications

References 65 publications

Screening and purification of catechins from underutilized tea plant parts and their bioactivity studies

Screening and purification of catechins from underutilized tea plant parts and their bioactivity studies

Safety, Tolerability and Efficacy of Drugs for Treating Behavioural Insomnia in Children with Attention-Deficit/Hyperactivity Disorder: A Systematic Review with Methodological Quality Assessment

Fermentation of Plant Material – Effect on Sugar Content and Stability of Bioactive Compounds

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