A combination of green tea extract and l-theanine (LGNC-07) has been reported to have beneficial effects on cognition in animal studies. In this randomized, double-blind, placebo-controlled study, the effect of LGNC-07 on memory and attention in subjects with mild cognitive impairment (MCI) was investigated. Ninety-one MCI subjects whose Mini Mental State Examination-K (MMSE-K) scores were between 21 and 26 and who were in either stage 2 or 3 on the Global Deterioration Scale were enrolled in this study. The treatment group (13 men, 32 women; 57.58 ± 9.45 years) took 1,680 mg of LGNC-07, and the placebo group (12 men, 34 women; 56.28 ± 9.92 years) received an equivalent amount of maltodextrin and lactose for 16 weeks. Neuropsychological tests (Rey-Kim memory test and Stroop color-word test) and electroencephalography were conducted to evaluate the effect of LGNC-07 on memory and attention. Further analyses were stratified by baseline severity to evaluate treatment response on the degree of impairment (MMSE-K 21-23 and 24-26). LGNC-07 led to improvements in memory by marginally increasing delayed recognition in the Rey-Kim memory test (P = .0572). Stratified analyses showed that LGNC-07 improved memory and selective attention by significantly increasing the Rey-Kim memory quotient and word reading in the subjects with MMSE-K scores of 21-23 (LGNC-07, n = 11; placebo, n = 9). Electroencephalograms were recorded in 24 randomly selected subjects hourly for 3 hours in eye-open, eye-closed, and reading states after a single dose of LGNC-07 (LGNC-07, n = 12; placebo, n = 12). Brain theta waves, an indicator of cognitive alertness, were increased significantly in the temporal, frontal, parietal, and occipital areas after 3 hours in the eye-open and reading states. Therefore, this study suggests that LGNC-07 has potential as an intervention for cognitive improvement.
"Recent research indicates that green tea extract or its main ingredients has a beneficial impact on cognitive functioning in humans. For instance, it has been demonstrated that the consumption of green tea improved memory and attention in subjects with mild cognitive impairments (Park et al. 2011) and that the consumption of flavonoid-rich foods such as green tea reduced beta-amyloid-mediated cognitive impairments in Alzheimer transgenic mice, suggesting a potential therapeutic utility in dementia (Rezai-Zadeh et al. 2008; Williams and Spencer 2012). Furthermore, higher consumption of green tea has also been associated with a lower prevalence of cognitive impairments in older adults (Kuriyama et al. 2006). "
[Show abstract][Hide abstract] ABSTRACT: It has been proposed that green tea extract may have a beneficial impact on cognitive functioning, suggesting promising clinical implications. However, the neural mechanisms underlying this putative cognitive enhancing effect of green tea extract still remain unknown.
This study investigates whether the intake of green tea extract modulates effective brain connectivity during working memory processing and whether connectivity parameters are related to task performance.
Using a double-blind, counterbalanced, within-subject design, 12 healthy volunteers received a milk whey-based soft drink containing 27.5 g of green tea extract or a milk whey-based soft drink without green tea as control substance while undergoing functional magnetic resonance imaging. Working memory effect on effective connectivity between frontal and parietal brain regions was evaluated using dynamic causal modeling.
Green tea extract increased the working memory induced modulation of connectivity from the right superior parietal lobule to the middle frontal gyrus. Notably, the magnitude of green tea induced increase in parieto-frontal connectivity positively correlated with improvement in task performance.
Our findings provide first evidence for the putative beneficial effect of green tea on cognitive functioning, in particular, on working memory processing at the neural system level by suggesting changes in short-term plasticity of parieto-frontal brain connections. Modeling effective connectivity among frontal and parietal brain regions during working memory processing might help to assess the efficacy of green tea for the treatment of cognitive impairments in psychiatric disorders such as dementia.
"L-theanine (γ-glutamylet-hylamide) is a major component accounting for 40~60% of the total amino acid in green tea (Juneja et al, 1999). Since it is a neurotransmitter with neuroprotective effects, there are many reports about its pharmacodynamics in the neuroscientific field (Cho et al, 2008; Kimura et al, 2007; Nathan et al, 2006; Park et al, 2011). In the immunological filed, administration of L-theanine together with L-cystine has been shown to induce a significant increase of endogenous antioxidant levels in the liver, and antigen-specific IgG antibody and T helper cytokine in serum of animal models (Bukowski and Percival, 2008; Kurihara et al, 2007). "
[Show abstract][Hide abstract] ABSTRACT: L-theanine was examined for its effects on the generation of superoxide anion, lysozyme and anti-protease in the plasma of catfish (Silurus asotus) by a single intraperitoneal injection with five different concentrations (0, 3, 6, 9 and 12 mg/kg). When compared with the mock-injected group (0 mg/kg), both groups injected with 6 and 9 mg/kg were significantly enhanced in levels of superoxide anion in leukocytes, lysozyme and anti-protease in plasma. Based on the results, L-theanine is thought to function as an immunostimulant and/or immunomodulator on non-specific immune responses in catfish.
[Show abstract][Hide abstract] ABSTRACT: Although tea leaves are rich in secondary metabolites, not enough transcriptomic information is available to aid understanding of the molecular mechanisms underlying plant growth, development, and secondary metabolite production. In this study, a total of 437,908 reads were generated from the tea leaf transcriptome using 454 sequencing. De novo assembly yielded 25,637 unigenes, 22,872 of which were annotated by BLAST searches against public databases. Most of these unigenes mapped to carbohydrate metabolism, energy metabolism and secondary metabolite biosynthetic pathways. Some abundant transcripts related to photomorphogenesis and development in plants, including ubiquitin/26S proteasome, lipid transfer protein, PPR-containing protein, small GTPase, expansin, transport inhibitor response 1 and thioredoxin, were identified in the transcriptome. Most of the genes encoding the main enzymes involved in flavonoid, caffeine and theanine biosynthesis were also found, and six MYB and two bHLH genes known to regulate flavonoid synthesis were identified. ABC transporter and glutathione S-transferase, generally responsible for secondary metabolite transport, and CYP450, broadly involved in oxidation steps in secondary metabolism, were also present in a large number of unigenes. Additionally, 3,767 EST-SSRs were identified as potential molecular markers in our unigenes. A total of 100 PCR primer pairs used in initial screening tests among 20 tea genotypes successfully identified 36 polymorphic loci. Overall, the tea leaf transcriptome sequences generated in this study reveal novel gene expression profiles and offer important clues for further study of the molecular mechanism of tea leaf growth, development and secondary metabolite synthesis. The thousands of EST-SSR markers identified will facilitate marker-assisted selection in tea breeding.
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