Research Database

Author: Pooja Bhardwaj and Deepa Khanna

Green tea, Camellia sinensis (Theaceae), a major source of flavonoids such as catechins, has recently shown multiple cardiovascular health benefits through various experimental and clinical studies. These studies suggest that green tea catechins prevent the incidence of detrimental cardiovascular events, and also lower the cardiovascular mortality rate. Catechins present in green tea have the ability to prevent atherosclerosis, hypertension, endothelial dysfunction, ischemic heart diseases, cardiomyopathy, cardiac hypertrophy and congestive heart failure by decreasing oxidative stress, preventing inflammatory events, reducing platelet aggregation and halting the proliferation of vascular smooth muscle cells. Catechins afford an anti-oxidant effect by inducing anti-oxidant enzymes, inhibiting pro-oxidant enzymes and scavenging free radicals. Catechins present anti-inflammatory activity through the inhibition of transcriptional factor NF-κB-mediated production of cytokines and adhesion molecules. Green tea catechins interfere with vascular growth factors and thus inhibit vascular smooth muscle cell proliferation, and also inhibit thrombogenesis by suppressing platelet adhesion. Additionally, catechins could protect vascular endothelial cells and enhance vascular integrity and regulate blood pressure. In this review various experimental and clinical studies suggesting the role of green tea catechins against the markers of cardiovascular disorders and the underlying mechanisms for these actions are discussed.

 

 

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Author: K. Ide and N. Wakamiya and M. Park and N. Takuma and S. Fujii and A. Nakahara and T. Suzuki and J. Nakase and Y. Ukawa and Y.M. Sagesaka and H. Yamada

Background: In rapidly aging societies worldwide, the number of patients with disorders marked by cognitive dysfunction, such as Alzheimer's disease, is gradually increasing; however, thus far, no fundamental curative therapy has been established. Green tea, whose major constituents are catechins and theanine, is known to have various health benefits for humans. However, the effects of green tea consumption on cognitive dysfunction remain to be clinically verified. Objective: To conduct a clinical study to investigate the effects of green tea consumption on cognitive dysfunction. Patients and methods: Twelve elderly nursing home residents (2 men, 10 women; mean age, 88 years) with cognitive dysfunction (Mini Mental State Examination [MMSE] score: <28) were recruited. Written informed consent was obtained from the patients and caregivers. The patients were asked to consume green tea powder (2 g/day [containing 227 mg of catechins and 37 g of theanine]; manufactured by ITO EN Ltd., Tokyo) for 3 months. Cognitive function was assessed by performing MMSE, and serum lipid levels were measured. Results: The MMSE scores (mean ± S.D.) significantly improved after the intervention (before intervention, 15.3 ± 7.7; after intervention, 17.0 ± 8.2; p = 0.025), especially for the category recent memory. Regarding serum lipid levels, low-density lipoprotein (LDL)-cholesterol levels remained unaltered, but triglyceride levels decreased significantly (before intervention, 124 ± 80 mg/dL; after intervention, 103 ± 57 mg/ dL; p = 0.041). Conclusion: These results suggest that green tea consumption may be effective in improving cognitive function, and additional confirmatory long-term controlled studies are needed. 

 

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Author: Abdul-Lateef Molan

 

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Author: Sha-Sha BAI and Zhi LI and Xiao-Huan ZANG and Chun WANG and Zhi WANG

A novel analytical method was developed for the extraction and determination of five chloroacetanilide herbicides (alachlor, acetochlor, metolachlor, butachlor and pretilachlor) in water and green tea samples by graphene-based magnetic solid phase extraction and dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection (GC-FID). Some important experimental parameters that could influence the extraction efficiency were investigated. Under the optimum conditions, as high as 3399 to 4002 fold enrichment factors for the herbicides were achieved. A good linearity was obtained in the range of 0.1–50.0 μg L−1 for all the five herbicides with the correlation coefficients (r) varying from 0.9973 to 0.9993. The limits of detection ranged from 0.01 to 0.03μg L−1. The method was applied to the analysis of the chloroacetanilide herbicides in environmental water and green tea samples with a satisfactory result. The recoveries of the method for the analytes were in the range from 80.2% to 105.3%, and the relative standard deviations were between 3.8% and 5.8%.

 

 

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Author: Pouya Parsaei and Mehrdad Karimi and Sayyed Yazdan Asadi and Mahmoud Rafieian-kopaei

Background Adhesion formation is an important complication of abdomino-pelvic surgery. Green tea (Camellia sinensis) has anti-oxidant and anti-inflammatory effects which prevent production and accumulation of collagen and, thus, may reduce adhesion formation. The present study examined the effect of green tea alcoholic extract on intra-abdominal adhesion formation. Total phenolic, flavonoid and flavonol contents as well as anti-oxidant activity were also evaluated. Methods Thirty healthy male Wistar rats were randomly assigned to two equal groups of green tea (A) and distilled water (B). After anesthesia, the abdominal wall was opened and three shallow longitudinal and transverse incisions of 2 cm in length were made on the right side of the peritoneum by scalpel blade. A 2 × 2 cm square of the left abdominal wall peritoneum was removed by surgical scissors. Green tea extract or distilled water was introduced into the abdominal cavity of each rat. The rats were sacrificed two weeks post-laparotomy and adhesion bands were scored according to severity, extent and appearance. Fibrosis and inflammation were also scored via histopathological examination. Results There was a significant difference in mean adhesion scores between the green tea and distilled water groups (3.2 ± 3.503 and 7.33 ± 0.51, respectively) (p = 0.001). In terms of fibrosis (p = 0.002) and inflammation (p = 0.003) a statistically significant difference was also seen between the two groups following histopathological examination. Conclusion Green tea extract reduces intra-peritoneal adhesions in an animal model.

 

 

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Author: Ramalingam Sundaram and Rajendran Naresh and Palanivelu Shanthi and Panchanatham Sachdanandam

The study was undertaken to evaluate the antidiabetic effect of green tea extract on carbohydrate metabolic key enzymes in control and streptozotocin high fat diet -induced diabetic rats. The daily oral treatment of green tea extract (300 mg/kg body weight) to diabetic rats for 30 days resulted in a significant reduction in the levels of plasma glucose, glycosylated hemoglobin (HbA1c) and increase in the levels of insulin and hemoglobin. The altered activities of the key enzymes of carbohydrate metabolism such as hexokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen phosphorylase in liver of diabetic rats were significantly reverted to near normal levels by the administration of green tea extract. Further, green tea extract administration to diabetic rats improved muscle and hepatic glycogen content suggesting the antihyperglycemic potential of green tea extract in diabetic rats. The obtained results were compared with metformin, a standard oral hypoglycemic drug. Thus, this study indicates that the administration of green tea extract to diabetic rats resulted in alterations in the metabolism of glucose with subsequent reduction in plasma glucose levels.

 

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Author: Martina Bancirova

The antioxidant properties of the black and green tea are well known. The latent bloodstains are detectable by luminol. The bloodstains also can be cover up by drinks and foods containing the antioxidants; thus their presence can cause a decrease of the luminol light emission (false-negative results). The aim of this study was to quantify the light emission decrease of the chemiluminescent mixture prepared according to Weber (containing NaOH) and the chemiluminescent mixture of pH 7.4 (for the determination of the total antioxidant capacity) for the open air-dried sample. The black and green teas and white wine were used as the antioxidant's samples (high and low total antioxidant capacity). The significant decrease of the luminol chemiluminescent emission caused by the presence of the black and green teas (and comparable for both of them) was observed in comparison with the presence of white wine.

 

 

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Author: Eugenia Gallo and Valentina Maggini and Margherita Berardi and Alessandra Pugi and Rosario Notaro and Giulia Talini and Giancarlo Vannozzi and Siro Bagnoli and Paolo Forte and Alessandro Mugelli and Vito Annese and Fabio Firenzuoli and Alfredo Vannacci

A case of autoimmune liver hepatitis is reported: the onset was triggered by consumption of green tea infusion in a patient taking oral contraceptives and irbesartan. We hypothesize that our patient, carrying genetic variant of hepatic metabolism making her particularly susceptible to oxidative stress, developed an abnormal response to a mild toxic insult, afforded by a combination of agents (oral contraceptives + irbesartan + green tea) that normally would not be able to cause damage. Her particular hepatic metabolism further increased the drugs’ concentration, favoring the haptenization of liver proteins, eventually leading to the development of an autoimmune hepatitis.

 

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Author: Dominique Trudel and David P. Labbé and Monica Araya-Farias and Alain Doyen and Laurent Bazinet and Thierry Duchesne and Marie Plante and Jean Grégoire and Marie-Claude Renaud and Dimcho Bachvarov and Bernard Têtu and Isabelle Bairati

Objectives A two-stage, single-arm, phase II study was conducted to assess the effectiveness and safety of an epigallocatechin gallate (EGCG)-enriched tea drink, the double-brewed green tea (DBGT), as a maintenance treatment in women with advanced stage serous or endometrioid ovarian cancer (clinicaltrials.gov, NCT00721890). Methods Eligible women had FIGO stage III-IV serous or endometrioid ovarian cancer. They had to undergo complete response after debulking surgery followed by 6 to 8 cycles of platinum/taxane chemotherapy at the Centre Hospitalier Universitaire de Québec. They all had to drink the DBGT, 500 mL daily until recurrence or during a follow-up of 18 months. The primary endpoint was the absence of recurrence at 18 months. Statistical analyses were done according to the principle of intention to treat. Using a two-stage design, the first stage consisted of 16 enrolled patients. At the end of the follow-up, if 7 or fewer patients were free of recurrence, the trial stopped. Otherwise, accrual would continue to a total of 46 patients. Results During the first stage of the study, only 5 of the 16 women remained free of recurrence 18 months after complete response. Accordingly, the clinical trial was terminated. Women's adherence to DBGT was high (median daily intake during intervention, 98.1%, interquartile range: 89.7–100%), but 6 women discontinued the intervention before the end of their follow-up. No severe toxicity was reported. Conclusions DBGT supplementation does not appear to be a promising maintenance intervention in women with advanced stage ovarian cancer after standard treatment.

 

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Author: Maksum Radji and Rafael Adi Agustama and Berna Elya and Conny Riana Tjampakasari

Objective To evaluate antibacterial activity of the Indonesian water soluble green tea extract, Camellia sinensis, against clinical isolates of methicillin–resistant Staphylococcus aureus (S. aureus) (MRSA) and multi-drug resistant Pseudomonas aeruginosa (MDR–P. aeruginosa). Methods Antimicrobial activity of green tea extract was determined by the disc diffusion method and the minimum inhibitory concentration (MIC) was determined by the twofold serial broth dilutions method. The tested bacteria using in this study were the standard strains and multi-drug resistant clinical isolates of S. aureus and P. aeruginosa, obtained from Laboratory of Clinical Microbiology, Faculty of Medicine, University of Indonesia. Results The results showed that the inhibition zone diameter of green tea extracts for S. aureus ATCC 25923 and MRSA were (18.970±0.287) mm, and (19.130±0.250) mm respectively. While the inhibition zone diameter for P. aeruginosa ATCC 27853 and MDR-P. aeruginosa were (17.550±0.393) mm and (17.670±0.398) mm respectively. The MIC of green tea extracts against S. aureus ATCC 25923 and MRSA were 400 μg/mL and 400 μg/mL, respectively, whereas the MIC for P. aeruginosa ATCC 27853 and MDR-P. aeruginosa were 800 μg/mL, and 800 μg/mL, respectively. Conclusions Camellia sinensis leaves extract could be useful in combating emerging drug-resistance caused by MRSA and P. aeruginosa.

 

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