Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together

Phased secondary small interfering RNAs in Camellia sinensis var. assamica

Phased secondary small interfering RNAs (phasiRNAs) in plants play important roles in regulating genome stability, plant development and stress adaption. Camellia sinensis var. assamica has immense economic, medicinal and cultural significance. However, there are still no studies of phasiRNAs and their putative functions in this valuable plant. We identified 476 and 43 PHAS loci which generated 4290 twenty one nucleotide (nt) and 264 twenty four nt phasiRNAs, respectively. Moreover, the analysis of degradome revealed more than 35000 potential targets for these phasiRNAs. We identified several conserved 21 nt phasiRNA generation pathways in tea plant, including miR390 → TAS3, miR482/miR2118 → NB-LRR, miR393 → F-box, miR828 → MYB/TAS4, and miR7122 → PPR in this study. Furthermore, we found that some transposase and plant mobile domain genes could generate phasiRNAs. Our results show that phasiRNAs target genes in the same family in cis- or trans-manners, and different members of the same gene family may generate the same phasiRNAs. The phasiRNAs, generated by transposase and plant mobile domain genes, and their targets, suggest that phasiRNAs may be involved in the inhibition of transposable elements in tea plant. To summarize, these results provide a comprehensive view of phasiRNAs in Camellia sinensis var. assamica.

Effect of single or combined caffeine and L-Theanine supplementation on shooting and cognitive performance in elite curling athletes: a double-blind, placebo-controlled study

PURPOSE

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

METHODS

In this double-blind, randomized controlled crossover study, twenty-two elite national curling athletes (age 20.20 ± 1.61 and sports age 6.20 ± 0.51 years, height 174.10 ± 7.21 cm, BMI 21.80 ± 3.47 kg/m2) were randomly assigned to CAF (6 mg/kg single dose CAF), THE (6 mg/kg single dose THE), CAF*THE (6 mg/kg CAF and 6 mg/kg THE combined) and PLA (400 mg maltodextrin) groups at each of four sessions. 60 minutes after taking the supplement, the athletes were first given the Stroop test and then asked to shoot.

RESULTS

Our main findings have shown that the performance of athletes in guard (F=3.452, P < .001, ηp2 = .842), draw (F=1.647, P < .001, ηp2 = .485), and take-out (F=3.121, P < .001, ηp2 = .743) shot styles significantly improved when comparing the combined intake of CAF and THE to the PLA. Regarding cognitive performance evaluation through the Stroop test, during the NR task (F=4.743, P = .001, ηp2 = .653), the combined intake of CAF and THE significantly improved reaction times compared to the intake of single CAF, THE, or PLA. The best reaction times during the CR and ICR (respectively; F=2.742, P = .004, ηp2 = .328; F = 1.632, P < .001, ηp2 = .625) tasks were achieved with the combined CAF and THE intake, showing a significant improvement compared to PLA. During the NER (F=2.961, P < .001, ηp2 = .741), task, the combined intake of CAF and THE significantly improved error rates compared to the intake of CAF, THE, or PLA single. The best accuracy rates during the CER and ICER (respectively; F=4.127, P < .001, ηp2 = .396; F=3.899, P < .001, ηp2 = .710) tasks were achieved with the combined CAF and THE intake, leading to a significant reduction in error rates compared to PLA. Based on these findings, it has been demonstrated in this study that the best shooting scores and cognitive performance were achieved, particularly with the combined intake of CAF and THE.

CONCLUSIONS

Based on these findings, it has been demonstrated in this study that the best shooting scores and cognitive performance were achieved, particularly with the combined intake of CAF and THE. The combined use of these supplements has been found to be more effective on shooting and cognitive performance than their single use.

Molecular and biological investigating of tea plant necrotic ring blotch virus as a worldwide threat

Tea plant necrotic ring blotch virus (TPNRBV) has emerged as a significant threat to tea plantations, primarily in China. Since 2020, similar symptoms have been observed in tea plants in northern Iran, raising concerns about the spread of this viral infection. In this study, we conducted an extensive investigation involving approximately 70 samples collected from both symptomatic and asymptomatic tea plants. Using reverse transcription-polymerase chain reaction with specially designed primers, we successfully amplified DNA fragments from 26 samples, confirming the presence of TPNRBV. Subsequent sequencing of these fragments revealed various segments of the TPNRBV genome. Our phylogenetic analysis revealed that the Iranian TPNRBV isolates formed a distinct sub-cluster alongside Chinese isolates, distinguishing them from Japanese isolates. These finding sheds light on the genetic diversity and relationships of TPNRBV across different regions. Additionally, we explored the potential modes of TPNRBV transmission. Mechanical transmission experiments confirmed the ability of the virus to infect Nicotiana rustica and Chenopodium quinoa seedlings, highlighting the risk of mechanical spread within tea plantations. Moreover, we investigated seed transmission and found evidence of TPNRBV in various parts of tea seeds, suggesting the possibility of seed-borne transmission. Overall, this comprehensive study enhances our understanding of the biological and molecular characteristics of TPNRBV, an emerging threat to global tea production. Our findings provide valuable insights into the virus's transmission dynamics and genetic diversity, which are essential for developing effective management strategies to mitigate its impact on tea cultivation worldwide.

Matcha Tea Powder's Antidepressant-like Effect through the Activation of the Dopaminergic System in Mice Is Dependent on Social Isolation Stress

Matcha tea powder is believed to have various physiological benefits; however, its detailed mechanism of action has been poorly understood. Here, we investigated whether the mental state of mice, due to social isolation stress, affects the antidepressant-like effect of Matcha tea powder by using the tail suspension test. Oral administration of Matcha tea powder reduced the duration of immobility in the stress-susceptible C57BL/6J strain, but not in BALB/c strain. In C57BL/6J mice, SCH23390, a dopamine D1 receptor blocker, prevented Matcha tea powder from exerting its antidepressant-like effect. Matcha tea powder also increased the number of c-Fos-positive cells in the prefrontal cortex (PFC) region and the nucleus accumbens (NAc) region in C57BL/6J mice, but not in BALB/c mice. In contrast, Matcha tea powder did not change the number of c-Fos-positive cells in the ventral tegmental area (VTA) region. Notably, C57BL/6J mice with a shorter immobility time had a higher number of c-Fos-positive cells in the PFC, NAc, and VTA regions. However, no such correlation was observed in the stress-tolerant BALB/c mice. These results suggest that Matcha tea powder exerts an antidepressant-like effect through the activation of the dopaminergic system including the PFC-NAc-VTA circuit and that mental states are important factors affecting the physiological benefits of Matcha tea powder.

United States tea: A synopsis of ongoing tea research and solutions to United States tea production issues

Tea is a steeped beverage made from the leaves of Camellia sinensis. Globally, this healthy, caffeine-containing drink is one of the most widely consumed beverages. At least 50 countries produce tea and most of the production information and tea research is derived from international sources. Here, we discuss information related to tea production, genetics, and chemistry as well as production issues that affect or are likely to affect emerging tea production and research in the United States. With this review, we relay current knowledge on tea production, threats to tea production, and solutions to production problems to inform this emerging market in the United States.

Study on the effects of combined tea drinking and mental activity after dinner on smokers in China

INTRODUCTION

Cigarette and tobacco use is a leading cause of chronic obstructive pulmonary disease, lung cancer, and other malignant tumors. In China, people prefer to engage in mental activities (gambling, overtime work, playing video games, or other mental activities) on the weekends or during spare time, especially in the evening before they prepare for bed. In China, smokers frequently consume tea while smoking. The relationship between smokers who consume tea, engage in mental activities after dinner, or both (drinking tea and engaging in cognitive activities after dinner together), and daily cigarette smoking or nicotine addiction must be clarified.

METHODS

A total of 438 smokers were included in the study. Age, gender, body mass index (BMI), smoking habits, Fagerström test for nicotine dependence scores, and behaviors, were recorded. The study excluded smokers with a Fagerström score <1 or with a mental disorder diagnosis. The smokers were divided into four groups based on their behaviors: those who did not drink tea, did not engage in mental activities after dinner, those who drank tea only, those who engaged in mental activities only, and those who engaged in both.

RESULTS

Only drinking tea or doing mental activities after dinner cannot increase cigarettes per day (22.20 ± 10.143 vs 23.49 ± 11.966, p=0.362; 22.20 ± 10.143 vs 22.66 ± 1.192, p=0.750) or FTND scores [6.0 (4.0; 7.0) vs 6.0 (4.0; 7.75), p=0.941; 6.0 (4.0; 7.0) vs 6.0 (4.25; 7.75), p=0.980]. People who drink tea and engage in mental activities after dinner smoke more (22.20 ± 10.143 vs 30.75 ± 17.264, p<0.0001) and have higher nicotine dependence levels [6.0 (4.0; 7.0) vs 7.0 (5.0; 8.0), p=0.015].

CONCLUSIONS

The consumption of tea or a mental activity after dinner is not associated with daily smoking or nicotine dependence. There is an association between the combined behaviors (tea drinking and mental activity after dinner) and the daily consumption of cigarettes, and the degree of nicotine dependence.

Evaluating the productivity of ancient Pu'er tea trees (Camellia sinensis var. assamica): a multivariate modeling approach

BACKGROUND

The demand for productive economic plant resources is increasing with the continued growth of the human population. Ancient Pu'er tea trees [Camellia sinensis var. assamica (J. W. Mast.) Kitam.] are an important ecological resource with high economic value and large interests. The study intends to explore and evaluate critical drivers affecting the species' productivity, then builds formulas and indexes to make predicting the productivity of such valuable plant resources possible and applicable.

RESULTS

Our analysis identified the ideal values of the seven most important environmental variables and their relative contribution (shown in parentheses) to the distribution of ancient Pu'er tea trees: annual precipitation, ca. 1245 mm (28.73%); min temperature of coldest month, ca. 4.2 °C (18.25%); precipitation of driest quarter, ca. 47.5 mm (14.45%); isothermality, 49.9% to 50.4% (14.11%); precipitation seasonality, ca. 89.2 (6.77%); temperature seasonality, ca. 391 (4.46%); and solar radiation, 12,250 to 13,250 kJ m^-2 day^-1 (3.28%). Productivity was indicated by the total value (viz. fresh leaf harvested multiplied by unit price) of each tree. Environmental suitability, tree growth, and management positively affected productivity; regression weights were 0.325, 0.982, and 0.075, respectively. The degree of productivity was classified as follows: > 0.8, "highly productive"; 0.5-0.8, "productive"; 0.3-0.5, "poorly productive"; and < 0.3, "unproductive". Overall, 53% of the samples were categorized as "poorly productive" or "unproductive"; thus, the management of these regions require attention.

CONCLUSIONS

This model improves the accuracy of the predictions of ancient Pu'er tea tree productivity and will aid future analyses of distribution shifts under climate change, as well as the identification of areas suitable for Pu'er tea tree plantations. Our modeling framework provides insights that facilitate the interpretation of abstract concepts and could be applied to other economically valuable plant resources.

Theanine metabolism and transport in tea plants (Camellia sinensis L.): advances and perspectives

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.

Optimizing the Quality and Commercial Value of Gyokuro-Styled Green Tea Grown in Australia

Gyokuro is a style of Japanese green tea produced by employing agricultural shading in the weeks before harvest. This method results in a tea product with different organoleptic and chemical properties than common Japanese green tea. In an effort to yield the highest quality and commercially valuable green tea product, the present study explores the influence of shading treatments and the duration of shading on the natural biochemistry of the green tea plant. This study applied shading treatments at light intensity conditions of 40%, 16%, 10% and 1% of available ambient light and the application of a red-colored shade cloth of 60% opacity. The Quality Index Tool was used to measure the quality and commercial value of the green tea, using individual target constituents (theanine, caffeine and the catechins) quantified from HPLC analysis. This study shows that very high levels of total visible spectrum light shading (~99%) is required to achieve improvements in quality and commercial value. Specifically, this improvement is a direct result of changes in the mood- modifying bioactive metabolites theanine and caffeine. This study concludes that in green tea growing regions with more hours of sunlight per year, such as on the Central Coast of Australia, more intense shading will achieve products with improved quality and commercial value, which has more potential to be marketed as a functional ingredient.

Glutamine Synthetases Play a Vital Role in High Accumulation of Theanine in Tender Shoots of Albino Tea Germplasm "Huabai 1"

Theanine (N-ethyl-γ-l-glutamine) is a special nonprotein amino acid that contributes to the umami taste and health function of tea. Although recent studies on tea breeding have focused on albino tea because of its umami taste, a factor of higher theanine concentration, the mechanism of biosynthesis of l-theanine is still unclear. In this study, four glutamine synthetase genes (CsGSs) were obtained and functionally characterized by overexpressing them in Arabidopsis. The enzyme activities of the purified CsGS proteins from Escherichia coli were detected. The results showed that CsGSs have a dual function in the synthesis of glutamine and theanine in vivo and in vitro. Interestingly, l-theanine was abundantly synthesized in the tender shoots of "Huabai 1". In the white tender shoots, the cytosol CsGS1.2 might exhibit increased expression to compensate for decreasing levels of chloroplast CsGS2, which plays a vital role in high accumulation of theanine in "Huabai 1". In addition, CsGS2 was most likely the key l-theanine synthases in green tissues of tea. The present findings will provide basis for and considerably broaden the scope of understanding the function of CsGSs and the mechanism of l-theanine accumulation in the tender shoots of "Huabai 1", and will be useful for breeding and screening tea with high l-theanine content.

Genome-level diversification of eight ancient tea populations in the Guizhou and Yunnan regions identifies candidate genes for core agronomic traits

The ancient tea plant, as a precious natural resource and source of tea plant genetic diversity, is of great value for studying the evolutionary mechanism, diversification, and domestication of plants. The overall genetic diversity among ancient tea plants and the genetic changes that occurred during natural selection remain poorly understood. Here, we report the genome resequencing of eight different groups consisting of 120 ancient tea plants: six groups from Guizhou Province and two groups from Yunnan Province. Based on the 8,082,370 identified high-quality SNPs, we constructed phylogenetic relationships, assessed population structure, and performed genome-wide association studies (GWAS). Our phylogenetic analysis showed that the 120 ancient tea plants were mainly clustered into three groups and five single branches, which is consistent with the results of principal component analysis (PCA). Ancient tea plants were further divided into seven subpopulations based on genetic structure analysis. Moreover, it was found that the variation in ancient tea plants was not reduced by pressure from the external natural environment or artificial breeding (nonsynonymous/synonymous = 1.05). By integrating GWAS, selection signals, and gene function prediction, four candidate genes were significantly associated with three leaf traits, and two candidate genes were significantly associated with plant type. These candidate genes can be used for further functional characterization and genetic improvement of tea plants.

An imaging approach for determining the mechanism of enhancement of intestinal absorption of an L-theanine supplement

BACKGROUND & OBJECTIVE

Theanine (L-glutamylethylamide) contained in green tea is a functional food component that has been attracting attention due to its relaxation effect. It was shown that the ingredients added to the theanine formulations increased the absorption of theanine. If this mechanism can be elucidated, it would be possible to contribute to development of evidence-based formulations. In this study, we investigated the effect of ingredients in the formulations on the absorption of theanine in detail.

MAIN METHODS

After oral administration of a mixture of theanine and additional components to Wistar rats the plasma concentration was determined by an HPLC and the pharmacokinetic parameters were calculated. In addition, a new system for evaluating intestinal blood flow was developed since the involvement of intestinal blood flow was considered as a factor that increased absorption of theanine.

KEY FINDINGS

Plasma concentration of theanine increased significantly in the combined use group with eight ingredients containing piperine as compared with theanine only group. Piperine would increase theanine absorption by increased blood flow, not an inhibition of metabolism. We succeeded to develop a visual and quantitative system to evaluate the effect of these ingredients directly including piperine on the intestinal blood flow using indocyanine green while maintaining physiological conditions.

SIGNIFICANCE

Increased intestinal blood flow by these ingredients including piperine enhanced the absorption of theanine. Other mechanisms may also be considered as the mechanism by which theanine absorption is increased in addition to increased blood flow.

Nutraceuticals as Potential Targets for the Development of a Functional Beverage for Improving Sleep Quality

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.

Preoperative Management of Surgical Patients Using Dietary Supplements: Society for Perioperative Assessment and Quality Improvement (SPAQI) Consensus Statement

The widespread use of complementary products poses a challenge to clinicians in the perioperative period and may increase perioperative risk. Because dietary supplements are regulated differently from traditional pharmaceuticals and guidance is often lacking, the Society for Perioperative Assessment and Quality Improvement convened a group of experts to review available literature and create a set of consensus recommendations for the perioperative management of these supplements. Using a modified Delphi method, the authors developed recommendations for perioperative management of 83 dietary supplements. We have made our recommendations to discontinue or continue a dietary supplement based on the principle that without a demonstrated benefit, or with a demonstrated lack of harm, there is little downside in temporarily discontinuing an herbal supplement before surgery. Discussion with patients in the preoperative visit is a crucial time to educate patients as well as gather vital information. Patients should be specifically asked about use of dietary supplements and cannabinoids, as many will not volunteer this information. The preoperative clinic visit provides the best opportunity to educate patients about the perioperative management of various supplements as this visit is typically scheduled at least 2 weeks before the planned procedure.

Characterizing microRNAs and their targets in different organs of Camellia sinensis var. assamica

To comprehensively annotate miRNAs and their targets in tea plant, Camellia sinensis, we sequenced small and messenger RNAs of 9 samples of Camellia sinensis var. assamica (YK-10), a diploid elite cultivar widely grown in southwest China. In order to identify targets of miRNAs, we sequenced two degradome sequencing profiles from leaves and roots of YK-10, respectively. By analyzing the small RNA-Seq profiles, we newly identified 137 conserved miRNAs and 23 species specific miRNAs in the genome of YK-10, which significantly improved the annotation of miRNAs in tea plant. Approximately 2000 differently expressed genes were identified when comparing RNA-Seq profiles of any two of the three organs selected in the study. Totally, more than 5000 targets of conserved miRNAs were identified in the two degradome profiles. Furthermore, our results suggest that a few miRNAs play roles in the biosynthesis pathways of theanine, caffeine and flavonoid. These results enhance our understanding of small RNA guided gene regulations in different organs of tea plant.

Transcriptomic analysis of tea plant (Camellia sinensis) revealed the co-expression network of 4111 paralogous genes and biosynthesis of quality-related key metabolites under multiple stresses

The tea plant is an essential economic plant in many countries. However, its growing season renders them vulnerable to stresses. To understand the transcriptomic influences of these stresses on tea plants, we sequenced and analyzed the transcriptomes under drought, high-temperature, and pest. Paralogs were identified by comparing 14 evolutionarily close genomes. The differentially expressed paralog (DEPs) genes were analyzed regarding single or multiple stresses, and 1075 of the 4111 DEPs were commonly found in all the stresses. The co-expression network of the DEPs and TFs indicated that genes of catechin biosynthesis were associated with most transcription factors specific to each stress. The genes playing a significant role in the late response to drought and pest stress mainly functioned in the early response to high-temperature. This study revealed the relationship between stress and regulation of QRM synthesis and the role of QRMs in response to these (a)biotic stresses.

Time-series transcriptomic analysis reveals novel gene modules that control theanine biosynthesis in tea plant (Camellia sinensis)

Theanine (thea) is a unique non-protein amino acid in tea plant (Camellia sinensis) and one of the most important small molecular compounds for tea quality and health effects. The molecular mechanism that maintains thea biosynthesis is not clear but may be reflected in complicated biological networks as other secondary metabolites in plants. We performed an integrative transcriptomic analysis of tea seedlings bud and leave over the time-course of ethylamine (EA) treatment that activated thea pathway. We identified 54 consistent differentially expressed genes (cDEGs, 25 upregulated and 29 downregulated) during thea activation. Gene Ontology (GO) functional enrichment analysis of upregulated genes and downregulated genes showed that they may function as a cascade of biological events during their cooperative contribution to thea biosynthesis. Among the total cDEGs, a diversity of functional genes (e.g., enzymes, transcription factors, transport and binding proteins) were identified, indicating a hierarchy of gene control network underlying thea biosynthesis. A gene network associated with thea biosynthesis was modeled and three interconnected gene functional modules were identified. Among the gene modules, several topologically important genes (e.g., CsBCS-1, CsRP, CsABC2) were experimentally validated using a combined thea content and gene expression analysis. Collectively, we presented here for the first time a comprehensive landscape of the biosynthetic mechanism of thea controlled by a underling gene network, which might provide a theoretical basis for the identification of key genes that contribute to thea biosynthesis.

γ-Glutamyltranspeptidase from Bacillus amyloliquefaciens: transpeptidation activity enhancement and L-theanine production

L-theanine, a unique amino acid in green tea with health benefits, can be enzymatically synthesized by γ-glutamyltranspeptidase (γ-GT; EC 2.3.2.2). Here, a salt-tolerant γ-glutamyltranspeptidase from a marine bacterium Bacillus amyloliquefaciens was expressed in Escherichia. coli BL21 (DE3) and was shown to be optimally active at 55 °C, pH 8.5 and alkali stable. A mutant, with higher transpeptidation activity, was obtained following two rounds of directed evolution using error-prone PCR and site-saturation mutagenesis. The mutation increased the ratio of transpeptidation to hydrolysis from 1.6 to 35.6. Additionally, Kinetic analysis exhibited 17.5% decrease of K_m, 13.0-fold increase of K_cat, and 16.3-fold increase of K_cat/K_m in mutant V319A/S437 G versus the wild-type. The 3-D modelling analysis revealed a tighter binding pocket in mutant V319A/S437 G. The frequency of hydrogen bond between donor substrate and two residues in the catalytic pocket (Gly437 and Thr375) was enhanced, which stabilized the ligand binding and thus improved the catalytic efficiency. The optimal conditions for the biocatalytic synthesis were determined as pH 10.0, 20 μg mL^-1BaGT, 200 mM L-glutamine, 2 M ethylamine, and a reaction time of 5 h. The V319A/S437 G mutant was shown to increase the percentage yield of L-theanine from 58% to 83%. These results indicate the great potential of V319A/S437 G in L-theanine production after further study.

L-theanine: an astounding sui generis amino acid in poultry nutrition

L-theanine (γ-Glutamylethylamide) is a nonprotein water soluble amino acid (AA) mostly found 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 AAs 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 biological effects such as antioxidant, growth promoter, immune booster, anti-stresser, hepatoprotective, antitumor, antiaging, antimicrobial, anti-inflammatory, and antianxiety activities that are worth noticing. It could reduce the oxidative impairment by reducing the synthesis of reactive oxygen species, 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 the 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 synthesis and glutathione production which 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 a potent antistressor by decreasing the levels of corticosterone, dopamine, and noradrenaline. After systematically reviewing the literature, it is noticed that most studies were carried out on mice, pig, human, and butterfly; while dietary supplementation studies of L-theanine in animal and poultry especially among broilers are very limited because of less awareness of this AA. So, the aim of this review is to encourage the veterinarian and poultry researchers to conduct more research at the molecular level about this AA to expose its more beneficial effects and its mechanism of absorption for potential use of this unique green tea AA in poultry nutrition.

Transcriptional regulation of amino acid metabolism in response to nitrogen deficiency and nitrogen forms in tea plant root (Camellia sinensis L.)

Free amino acids, including theanine, glutamine and glutamate, contribute greatly to the pleasant taste and multiple health benefits of tea. Amino acids in tea plants are mainly synthesized in roots and transported to new shoots, which are significantly affected by nitrogen (N) level and forms. However, the regulatory amino acid metabolism genes have not been systemically identified in tea plants. Here, we investigated the dynamic changes of free amino acid contents in response to N deficiency and forms in tea plant roots, and systemically identified the genes associated amino acid contents in individual metabolism pathways. Our results showed that glutamate-derived amino acids are the most dynamic in response to various forms of N and N deficiency. We then performed transcriptomic analyses of roots treated with N deficiency and various forms of N, and differentially expressed amino acid metabolic genes in each pathway were identified. The analyses on expression patterns and transcriptional responses of metabolic genes to N treatments provided novel insights for the molecular basis of high accumulation of theanine in tea plant root. These analyses also identified potential regulatory genes in dynamic amino acid metabolism in tea plant root. Furthermore, our findings indicated that the dynamic expression levels of CsGDH, CsAlaDC, CsAspAT, CsSDH, CsPAL, CsSHMT were highly correlated with changes of amino acid contents in their corresponding pathways. Herein, this study provides comprehensive insights into transcriptional regulation of amino acid metabolism in response to nitrogen deficiency and nitrogen forms in tea plant root.

The Effect of L-Theanine Incorporated in a Functional Food Product (Mango Sorbet) on Physiological Responses in Healthy Males: A Pilot Randomised Controlled Trial

Consumption of L-Theanine (L-THE) has been associated with a sensation of relaxation, as well as a reduction of stress. However, these physiological responses have yet to be elucidated in humans where L-THE is compared alongside food or as a functional ingredient within the food matrix. The aim of this study was to determine the physiological responses of a single intake of a potential functional food product (mango sorbet) containing L-THE (ms-L-THE; 200 mgw/w) in comparison to a flavour and colour-matched placebo (ms). Eighteen healthy male participants were recruited in this randomised, double-blind, placebo-controlled trial. The participants were required to consume ms-L-THE or placebo and their blood pressure (BP) (systolic and diastolic), heart rate (HR), and heart rate variability (HRV) were monitored continuously over 90 minutes. Eleven males (age 27.7 ± 10.8 years) completed the study. Changes in area under the curve for systolic and diastolic blood pressure and HRV over the 90 minute observation period indicated no differences between the three conditions (all p > 0.05) or within individual groups (all p > 0.05). The values for heart rate were also not different in the placebo group (p = 0.996) and treatment group (p = 0.066), while there was a difference seen at the baseline (p = 0.003). Based on the findings of this study, L-THE incorporated in a food matrix (mango sorbet) demonstrated no reduction in BP or HR and showed no significant parasympathetic interaction as determined by HRV high-frequency band and low-frequency/high-frequency ratio. Further studies should be focussed towards the comparison of pure L-THE and incorporation within the food matrix to warrant recommendations of L-THE alongside food consumption.

The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review

The green tea amino acid, L-theanine (L-THE) is associated with several health benefits, including improvements in mood, cognition and a reduction of stress and anxiety-like symptoms. This systematic review evaluated the effect of pure L-THE intake, in the form of orally administered nutritional supplements, on stress responses and anxiety levels in human randomised controlled trials. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, 9 peer-reviewed journal articles were identified where L-THE as a supplement was compared to a control. Our findings suggest that supplementation of 200-400 mg/day of L-THE may assist in the reduction of stress and anxiety in people exposed to stressful conditions. Despite this finding, longer-term and larger cohort clinical studies, including those where L-THE is incorporated into the diet regularly, are needed to clinically justify the use of L-THE as a therapeutic agent to reduce stress and anxiety in people exposed to stressful conditions.

Identification of MYB Transcription Factors Regulating Theanine Biosynthesis in Tea Plant Using Omics-Based Gene Coexpression Analysis

Theanine (thea) is the most abundant free amino acid in tea plant (Camellia sinensis) and one of the most important secondary metabolites conferring tea quality and health benefits. Great effort has recently been made to functionally dissect enzyme genes (e.g., GS, GDH, GOGAT) responsible for in vivo thea accumulation. However, the transcriptional regulation of its biosynthesis remains to be explored. Starting from publicly available (condition-independent) tea transcriptome data, we performed an exhaustive coexpression analysis between transcription factor (TF) genes and thea enzyme genes in tea plant. Our results showed that two typical plant-specialized (secondary) metabolites related TF families, such as MYB, bHLH, together with WD40 domain proteins, were prominently involved, suggesting a potential MYB-bHLH-WD40 (MBW) complex-mediated regulatory pattern in thea pathway. Aiming at the most involved MYB family, we screened seven MYB genes as thea candidate regulators through a stringent multistep selection (e.g., filtering with condition-specific nitrogen-treated transcriptome data). The control of MYB regulators in thea biosynthesis was further demonstrated using an integrated analysis of thea accumulation and MYB expression in several major tea tissues, including leave, bud, root, and stem. Our investigation aided tea researchers in having a comprehensive view of transcriptional regulatory landscape in thea biosynthesis, serving as the first platform for studying molecular regulation in thea pathway and a paradigm for understanding the characteristic components biosynthesis in nonmodel plants.

Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes

BACKGROUND

A limited amount of research has demonstrated beneficial effects of caffeine and theanine supplementation for enhancement of mental performance. The purpose of this investigation was to determine whether the acute ingestion of a supplement containing caffeine, theanine and tyrosine improves mental and physical performance in athletes.

METHODS

Twenty current or former male collegiate athletes (age: 20.5 ± 1.4 y; height: 1.82 ± 0.08 m; weight: 83.9 ± 12.6 kg; body fat: 13.8 ± 5.6%) completed this randomized, double-blind, placebo-controlled crossover trial. After familiarization, each participant completed two identical testing sessions with provision of a proprietary dietary supplement (SUP) containing caffeine theanine and tyrosine or a placebo (PL). Within each testing session, participants completed assessments of mental and physical performance before and after provision of SUP or PL, as well as after two rounds of exercise. Assessments were performed using a performance testing device (Makoto Arena) that evaluated multiple aspects of mental and physical performance in response to auditory and visual stimuli. Testing was performed both with the body in a static position and during dynamic movement. General linear models were used to evaluate the effects of SUP and PL on performance.

RESULTS

Changes in movement accuracy during performance assessment were greater following SUP ingestion as compared to PL for both static and dynamic testing (SUP: + 0.4 to 7.5%; PL: - 1.4 to 1.4% on average; p < 0.05). For dynamic testing, the change in number of targets hit was higher and the change in average hit time was lower with SUP as compared to PL (p < 0.05). However, there were no differences between conditions for the changes in number of targets hit or average hit time during static testing. There were no differences in changes of subjective variables during either condition, and performance measures during the two rounds of exercise did not differ between conditions (p > 0.05).

DISCUSSION

The present results indicate that a combination of a low-dose of caffeine with theanine and tyrosine may improve athletes' movement accuracy surrounding bouts of exhaustive exercise without altering subjective variables. Based on this finding, supplementation with caffeine, theanine and tyrosine could potentially hold ergogenic value for athletes in sports requiring rapid and accurate movements.

TRIAL REGISTRATION

NCT03019523. Registered 24 January 2017.

Psychotropic effects of L-theanine and its clinical properties: From the management of anxiety and stress to a potential use in schizophrenia

Anxiety disorders are highly prevalent in modern societies, and are ranked the sixth most important contributor of non-fatal negative health outcomes. _L-theanine is an amino acid naturally found in green tea (Camellia sinensis) and some other plant extracts, and recent clinical studies have proposed promising adjuvant effects of _L-theanine for the negative impact of anxiety and psychological stress on health. In this integrative narrative review, we aimed to appraise and further discuss the effects of _L-theanine administration on anxiety disorders and psychological stress. Published data suggests that _L-theanine administered at daily doses ranging from 200 to 400 mg for up to 8 weeks are safe and induce anxiolytic and anti-stress effects in acute and chronic conditions. _L-theanine at doses lower and higher than these may also show promising therapeutic potential; however, a more thorough investigation through randomized double-blind placebo-controlled crossover clinical trials are necessary to elucidate its effects for longer periods, providing further insights for meta-analyses and the development of recommendation guidelines. Additionally, animal studies investigating a higher dosage, its combination with other pharmacological compounds and associated metabolic comorbidities are recommended, as cases of hepatotoxicity associated with the consumption of green tea extract have been reported.

Advances in research on functional genes of tea plant

Tea plant (Camellia sinensis) is an important leaf-type woody crop used to produce non-alcoholic beverages all over the world. Tea is one of the oldest and most popular non-alcoholic beverages in the world, and long-term tea drinking has numerous healthful for humans due to many of the important secondary metabolites, such as polyphenols and theanine. Theanine and polyphenols are also closely related to tea flavor and tea aroma, which is usually as the standard for judging tea quality. The growth of tea plants and quality of teas are susceptible to adversity abiotic and biotic stresses, such as low temperatures and pests. Consequently, this review focus on the research progress of key genes related to the stress resistance and material metabolism of tea plants in recent years. We aim at comprehensively understanding the growth and metabolism of tea plants and their relationship with the external environment, so as to provide an in-depth and broad theoretical support for the breeding of excellent tea plant varieties.

More than just caffeine: psychopharmacology of methylxanthine interactions with plant-derived phytochemicals

In general, preparations of coffee, teas, and cocoa containing high levels of polyphenols, L-theanine and other bioactive compounds selectively enhance mood and cognition effects of caffeine. This review summarizes the bioactive components of commonly consumed natural caffeine sources (e.g. guayusa, mate and camellia teas, coffee and cocoa) and analyzes the psychopharmacology of constituent phytochemicals: methylxanthines, polyphenols, and L-theanine. Acute and chronic synergistic effects of these compounds on mood and cognition are compared and discussed. Specific sets of constituent compounds such as polyphenols, theobromine and L-theanine appear to enhance mood and cognition effects of caffeine and alleviate negative psychophysiological effects of caffeine. However, more research is needed to identify optimal combinations and ratios of caffeine and phytochemicals for enhancement of cognitive performance.

Identification of a Novel Gene Encoding the Specialized Alanine Decarboxylase in Tea (Camellia sinensis) Plants

Theanine, a unique amino acid in Camellia sinensis, accounts for more than 50% of total free amino acids in tea and has a significant contribution to the quality of green tea. Previous research indicated that theanine is synthesized from glutamic acid (Glu) and ethylamine mainly in roots, and that theanine accumulation depends on the availability of ethylamine which is derived from alanine (Ala) decarboxylation catalyzed by alanine decarboxylase (AlaDC). However, the specific gene encoding AlaDC protein remains to be discovered in tea plants or in other species. To explore the gene of AlaDC in tea plants, the differences in theanine contents and gene expressions between pretreatment and posttreatment of long-time nitrogen starvation were analyzed in young roots of two tea cultivars. A novel gene annotated as serine decarboxylase (SDC) was noted for its expression levels, which showed high consistency with theanine content, and the expression was remarkably high in young roots under sufficient nitrogen condition. To verify its function, full-length complementary DNA (cDNA) of this candidate gene was cloned from young roots of tea seedlings, and the target protein was expressed and purified from Escherichia coli (E. coli). The enzymatic activity of the protein for Ala and Ser was measured in vitro using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). The results illustrated that the target protein could catalyze the decarboxylation of Ala despite of its high similarity with SDC from other species. Therefore, this novel gene was identified as AlaDC and named CsAlaDC. Furthermore, the gene expression levels of CsAlaDC in different tissues of tea plants were also quantified with quantitative real-time PCR (qRT-PCR). The results suggest that transcription levels of CsAlaDC in root tissues are significantly higher than those in leaf tissues. That may explain why theanine biosynthesis preferentially occurs in the roots of tea plants. The expression of the gene was upregulated when nitrogen was present, suggesting that theanine biosynthesis is regulated by nitrogen supply and closely related to nitrogen metabolism for C. sinensis. The results of this study are significant supplements to the theanine biosynthetic pathway and provide evidence for the differential accumulation of theanine between C. sinensis and other species.

Metabolite profiling and transcriptomic analyses reveal an essential role of UVR8-mediated signal transduction pathway in regulating flavonoid biosynthesis in tea plants (Camellia sinensis) in response to shading

BACKGROUND

Tea is the most popular nonalcoholic beverage worldwide for its pleasant characteristics and healthful properties. Catechins, theanine and caffeine are the major natural products in tea buds and leaves that determine tea qualities such as infusion colors, tastes and fragrances, as well as their health benefits. Shading is a traditional and effective practice to modify natural product accumulation and to enhance the tea quality in tea plantation. However, the mechanism underlying the shading effects is not fully understood. This study aims to explore the regulation of flavonoid biosynthesis in Camellia sinensis under shading by using both metabolomic and transcriptional analyses.

RESULTS

While shading enhanced chlorophyll accumulation, major catechins, including C, EC, GC and EGC, decreased significantly in tea buds throughout the whole shading period. The reduction of catechins and flavonols were consistent with the simultaneous down-regulation of biosynthetic genes and TFs associated with flavonoid biosynthesis. Of 16 genes involved in the flavonoid biosynthetic pathway, F3'H and FLS significantly decreased throughout shading while the others (PAL, CHSs, DFR, ANS, ANR and LAR, etc.) temporally decreased in early or late shading stages. Gene co-expression cluster analysis suggested that a number of photoreceptors and potential genes involved in UV-B signal transductions (UVR8_L, HY5, COP1 and RUP1/2) showed decreasing expression patterns consistent with structural genes (F3'H, FLS, ANS, ANR, LAR, DFR and CHSs) and potential TFs (MYB4, MYB12, MYB14 and MYB111) involved in flavonoid biosynthesis, when compared with genes in the UV-A/blue and red/far-red light signal transductions. The KEGG enrichment and matrix correlation analyses also attributed the regulation of catechin biosynthesis to the UVR8-mediated signal transduction pathway. Further UV-B treatment in the controlled environment confirmed UV-B induction on flavonols and EGCG accumulation in tea leaves.

CONCLUSIONS

We proposed that catechin biosynthesis in C. sinensis leaves is predominantly regulated by UV through the UVR8-mediated signal transduction pathway to MYB12/MYB4 downstream effectors, to modulate flavonoid accumulation. Our study provides new insights into our understanding of regulatory mechanisms for shading-enhanced tea quality.

Effect of Green Tea Phytochemicals on Mood and Cognition

BACKGROUND

Green tea is traditionally known to induce mental clarity, cognitive function, physical activation and relaxation. Recently, a special green tea, matcha tea, is rapidly gaining popularity throughout the world and is frequently referred to as a mood- and brain food. Matcha tea consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on tea constituents caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on mood and cognitive performance. These effects were observed when these phytochemicals were consumed separately and in combination.

METHODS

A review was conducted on 49 human intervention studies to summarize the research on acute psychoactive effects of caffeine, L-theanine, and EGCG on different dimensions of mood and cognitive performance.

CONCLUSION

Caffeine was found to mainly improve performance on demanding long-duration cognitive tasks and self-reported alertness, arousal, and vigor. Significant effects already occurred at low doses of 40 mg. L-theanine alone improved self-reported relaxation, tension, and calmness starting at 200 mg. L-theanine and caffeine combined were found to particularly improve performance in attention-switching tasks and alertness, but to a lesser extent than caffeine alone. No conclusive evidence relating to effects induced by EGCG could be given since the amount of intervention studies was limited. These studies provided reliable evidence showing that L-theanine and caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction. Moreover, L-theanine was found to lead to relaxation by reducing caffeine induced arousal.

Prevention of Doxorubicin-Induced Renal Toxicity by Theanine in Rats

Doxorubicin (DOX) is a highly potent anti-neoplastic agent widely used in clinical practice, but its dosage and duration of administration are strictly limited due to dose-related organ damage. In the present study, we examined whether theanine, an amino acid derivative found in green tea leaves, can protect against DOX-induced acute nephrotoxicity in rats. Decreases in the creatinine clearance by DOX administration were attenuated by concurrent treatment with theanine, which was consistent with the change in histological renal images assessed by microscopic examination. Theanine had no effect on the distribution of DOX to the kidney. The production of lipid peroxide in the kidney after DOX administration was suppressed by concurrent treatment with theanine. Reduced glutathione content, but not superoxide dismutase activity, was decreased following DOX administration, whereas this change was suppressed when theanine was given in combination with DOX. These results suggest that theanine prevents DOX-induced acute nephrotoxicity through its antioxidant properties.

Effects of L-theanine on anxiety-like behavior, cerebrospinal fluid amino acid profile, and hippocampal activity in Wistar Kyoto rats

RATIONALE AND OBJECTIVES

The amino acid L-theanine (N-ethyl-L-glutamine) has historically been considered a relaxing agent. In the present study, we examined the effects of repeated L-theanine administration on behavior, levels of amino acids in the cerebrospinal fluid (CSF), and hippocampal activity in Wistar Kyoto (WKY) rats, an animal model of anxiety and depressive disorders.

METHODS

Behavioral tests were performed after 7-10 days of L-theanine (0.4 mg kg^-1 day^-1) or saline administration, followed by CSF sampling for high-performance liquid chromatography (HPLC) analysis. An independent set of animals was subjected to [¹⁸F]fluorodeoxyglucose positron emission tomography (PET) scanning after the same dose of L-theanine or saline administration for 7 days.

RESULTS

In the elevated plus maze test, the time spent in the open arms was significantly longer in the L-theanine group than in the saline group (P = 0.035). In addition, significantly lower CSF glutamate (P = 0.039) and higher methionine (P = 0.024) concentrations were observed in the L-theanine group than in the saline group. A significant increase in the standard uptake value ratio was observed in the hippocampus/cerebellum of the L-theanine group (P < 0.001).

CONCLUSIONS

These results suggest that L-theanine enhances hippocampal activity and exerts anxiolytic effects, which may be mediated by changes in glutamate and methionine levels in the brain. Further study is required to more fully elucidate the mechanisms underlying the effects of L-theanine.

Cognitive and Mood Effects of a Nutrient Enriched Breakfast Bar in Healthy Adults: A Randomised, Double-Blind, Placebo-Controlled, Parallel Groups Study

Objectives: Few previous studies have assessed the effects of concomitant administration of multiple potentially psychoactive nutrients. Methods: 95 healthy adult participants consumed either a nutrient enriched breakfast bar (containing α-Linolenic acid, l-tyrosine, l-theanine, vitamins, minerals and 21.5 mg of caffeine) or an isocaloric, macronutrient matched control bar for 56 days. Cognitive function and mood were assessed pre-dose and at 40- and 160-min post-dose on the 1st and 56th day of the intervention period. Results: The results demonstrated acute effects of treatment across post-dose assessments on both assessment days in terms of alertness, and on tasks assessing attention, working and episodic memory and executive function, including cognitively demanding Serial subtraction and Rapid Visual Information Processing tasks. There were no evident chronic effects independent of the breakfast bars’ acute effects. Discussion: These results demonstrate that a nutrient enriched breakfast bar with low caffeine content can exert striking beneficial effects on acute cognitive function and alertness.

l-Theanine: An astounding sui generis integrant in tea

l-theanine (l-Th), a non-protein amino acid present in tea, is a valuable nutraceutical product with unique health benefits and used as an additive in food industry. l-Th enhances the umami taste but its use is limited due to its inadequate production. Different extraction approaches from tea shoots, chemical synthesis to microbial transformation have been tried to meet its demand. In vitro, in vivo as well as clinical studies have shown its positive effect in regulating CNS disorders. l-Th has become choice ingredient in CNS active products due to its anti-stress and neuroprotective role in dementias particularly in retrogression of Alzheimer's. l-Th biochemically modulates various anti-neoplastic agents by increasing their bioavailability in tumour cells. The review, is an effort to condense the recent research on l-Th highlighting its biological resource, plausible role in tea plant, production approaches, its physiological role on human health and future prospects.

Studies on the Biochemical Formation Pathway of the Amino Acid l-Theanine in Tea (Camellia sinensis) and Other Plants

Tea (Camellia sinensis) is the most widely consumed beverage aside from water. The flavor of tea is conferred by certain metabolites, especially l-theanine, in C. sinensis. To determine why more l-theanine accumulates in C. sinensis than in other plants, we compare l-theanine contents between C. sinensis and other plant species (Camellia nitidissima, Camellia japonica, Zea mays, Arabidopsis thaliana, and Solanum lycopersicum) and use a stable isotope labeling approach to elucidate its biosynthetic route. We quantify relevant intermediates and metabolites by mass spectrometry. l-Glutamic acid, a precursor of l-theanine, is present in most plants, while ethylamine, another precursor of l-theanine, specifically accumulates in Camellia species, especially C. sinensis. Most plants contain the enzyme/gene catalyzing the conversion of ethylamine and l-glutamic acid to l-theanine. After supplementation with [²H₅]ethylamine, all the plants produce [²H₅]l-theanine, which suggests that ethylamine availability is the reason for the difference in l-theanine accumulation between C. sinensis and other plants.

Anxiolytic activity of aqueous extract of Camellia sinensis in rats

Objectives:

The present study was undertaken to evaluate anxiolytic effect of Camellia sinensis (CS) and possible mechanism on acute and chronic administration in rats.

Materials and Methods:

Eight groups of rats with six in each group were used. Group I served as control. Group II received diazepam (1 mg/kg). Groups III, IV, and V received CS in doses of 3.3, 16.5, and 33 mg/kg, respectively. Three pharmacologically validated experimental models – elevated plus maze (EPM), light and dark box (LDB), and open field tests (OFT) – were employed. Each animal was tested initially in the EPM and then in the LDB, followed by the OFT in a single setting. In EMP, number of entries into, time spent in, and number of rears in each arm in a 5-min period were noted. In LDB, number of entries and time spent in bright arena, number of rears, and duration of immobility were noted. In OFT, number of peripheral and central squares crossed, time spent, and number of rears in central squares were observed for a 5-min period. One-way ANOVA followed by post hoc least significant difference test was performed.

Results:

In EPM and LDB, CS at 3.3, 16.5, and 33 mg/kg (acute and chronic models) increased the number of entries and time spent and rearing in the open arms and bright arena, respectively, compared to control. In the OFT, CS at 16.5 and 33 mg/kg significantly increased the number of squares crossed, time spent, and the number of rears in the central squares compared to control. Anxiolytic effect was dose dependent in EPM and LDB and CS at 33 mg/kg showed better anxiolytic activity compared to diazepam (1 mg/kg) in all models. Flumazenil (0.5 mg/kg) and bicuculline (1 mg/kg) completely inhibited while picrotoxin (1 mg/kg) partially inhibited the anxiolytic effect of CS. Diazepam and CS at 33 mg/kg reduced the locomotor activity in rats.

Conclusion:

CS has dose-dependent anxiolytic activity which is comparable to diazepam. Anxiolytic action of CS is likely mediated through GABA_A-benzodiazepine receptor – Cl − channel complex – since flumazenil and bicuculline inhibited the anxiolytic effect.