Research Database

Author: Monika Gupta and Anupam Sharma and Adarsh Shanker

Imidacloprid is a systemic insecticide used widely in controlling mites, mealy bugs and other related pests in fruits, vegetables and tea. The dissipation behaviour of imidacloprid residues in green tea shoots, made tea and its transfer potential from made tea to infusion in hot water was studied. Analysis in tea matrices of imidacloprid was carried out using high-performance liquid chromatography with diode array detection. Under field conditions, imidacloprid dissipation rate was found to be faster in the wet season than the dry season. Half lives in green shoots were in the range 1.14–1.23 and 1.03–1.09 days, and 1.14–1.25, 1.04–1.07 days in made tea, for the dry and wet season, respectively. The percent transfer of imidacloprid residue from made tea to infusion was in the range of 29.2–42.0% during the dry and wet season; however, 38.2% and 57.9% of the residues remained stuck to the spent leaves during the dry and wet seasons, respectively. On the basis of transfer of residues from made tea to hot water infusion, a waiting period of 7 days after pesticide application at a recommended dose for tea plucking is suggested.

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Author:Christopher P. Chengelis and Jeannie B. Kirkpatrick and Karen S. Regan and Ann E. Radovsky and Melissa J. Beck and Osamu Morita and Yasushi Tamaki and Hiroyuki Suzuki

The beneficial health effects associated with drinking green tea are widely considered to be due primarily to tea catechins. Heat treatment of marketed green tea beverages for sterilization causes epimerization and/or polymerization of tea catechins. Safety studies on heat-treated tea catechins are limited. The objective of the present study was to evaluate potential adverse effects, if any, of two standardized green tea catechin (GTC) preparations: one that underwent heat sterilization (GTC-H) and one that was not heat-sterilized (GTC-UH). A decaffeinated preparation of the GTC-H (GTC-HDC) was also evaluated to ascertain if any effects were due to caffeine. The GTC preparations were administered to rats once daily at levels up to 2000 mg/kg/day for 28 days. There were no deaths attributable to the GTC preparations. The clinical condition of the animals, functional observational battery, motor activity, clinical pathology evaluations, organ weights, and gross necropsy findings were unaffected by any of the GTC preparations. GTC-HDC or GTC-UH dosing had no effects on body weights or microscopic findings, whereas lower body weights and food consumption were observed in the 1000 and 2000 mg/kg/day GTC-H group males. The no observed-adverse-effect level (NOAEL) for localized gastric effects for GTC-H was 1000 mg/kg/day. No other target organs were identified. Thus, the NOAEL for systemic toxicity following oral administration was 2000 mg/kg/day for GTC-H, GTC HDC, and GTC-UH under the conditions of this study.

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Author: Maurizio Brausi and Federica Rizzi and Saverio Bettuzzi

Author: P.J. Werba, M. Giroli, V. Cavalca, M.C. Nava, E. Tremoli

Objective: Statin myopathy may occur as a result of interaction not only with other drugs but also with particular foods (i.e. grapefruit juice). We report a case of statin muscle intolerance probably triggered by consumption of green tea (GT). Methods: Our patient was a 61-year-old man with primary hypercholesterolemia (HC). Treatments with simvastatin (S), atorvastatin, or rosuvastatin (all at 10mg/d) had been hampered by early myalgia and cramps (with normal CPK levels) and mild rise of liver enzymes. The patient was in good health except for hypertension treated with amlodipine, 10mg/d. The only relevant lab finding was isolated HC (LDL-C: 219 mg/dL). Anamnesis revealed that he drank 3 cups of GT each day "to reinforce his health". We assessed S bioavailability during usual GT consumption (kinetic 1) and after stopping GT consumption for 1 month (kinetic 2). For each study, the patient took S, 20mg/d, at 8:00 a.m. for 5 days. On day 6, S, 20mg, was ingested at fasting with either a cup of GT (kinetic 1) or water (kinetic 2), and serial blood samples were collected throughout 2,5 hours. Plasma levels of S lactone and S acid were determined by using tandem liquid chromatography-mass spectrometry. Results: We observed an evident GT-S interaction, restricted in the time period assessed to S lactone. Having stopped drinking GT, the patient continued taking S 10 mg with optimal tolerance. Conclusion: The results of the kinetic studies and the improved tolerance to S after the patient stopped drinking GT suggest a clinically relevant GT-S interaction, an observation not previously reported, to the best of our knowledge. Given the increasing popularization of GT as a "natural" strategy to prevent diseases, it may be time to consider this herb to be among unexpected triggers of statin toxicity.

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Green tea – A potential preservative for extending the shelf life of fresh mutton at ambient temperature (25 ± 2 °C)

Author: K.V. Kumudavally and H.S. Phanindrakumar and Aisha Tabassum and K. Radhakrishna and A.S. Bawa

This investigation was taken up to evaluate the feasibility of using green tea (GT) to extend the shelf life of fresh mutton, at ambient storage conditions (25 ± 2 °C and 85 ± 5% RH). The ethanolic extract of GT (GTE) was found to significantly inhibit (P < 0.01) spoilage microflora, including certain pathogens of acidulant treated mutton (pH 3.8) for up to 4 days. Application of GTE did not cause any deleterious change in sensorial and physical quality and the mutton was acceptable for up to 4 days. While the control samples showed initial signs of spoilage between 20 and 24 h and registered an increase in free fatty acids (FFA) from 1.24 g to 4.1 g/100 g lipid and biogenic amine index (BAI) from 0.27 mg to 4.63 mg/100 g mutton, at the end of two days of storage, the GTE treated sample showed FFA levels of 1.5 g/100 g lipid and BAI of 0.25 mg/100 g mutton at the end of the 4 days. GTE treatment could be effectively used to extend the shelf life of fresh mutton for up to 4 days in Indian climatic conditions, since it significantly (P < 0.01) inhibits the formation of these lipolytic and proteolytic degradation products, which are responsible for sensorial spoilage.

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Author: Hajime Fujii and Hiroshi Nishioka and Koji Wakame and Bernadene A. Magnuson and Ashley Roberts

Author: Sheng-Dun Lin and En-Hui Liu and Jeng-Leun Mau

The extracts were prepared from cold or hot brewed steaming green tea at different concentrations (2, 6, and 10%), its antioxidant properties studied and potential antioxidant components determined. The yields of hot water extracts (17.49–28.27%) were significantly higher than those of cold water extracts (11.72–14.70%). EC50 values in antioxidant activity determined by the conjugated diene method and reducing power were 2.19–3.10 and 0.22–0.28 mg/ml, respectively. EC50 values in scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals were 29.45–43.80 and 2.88–3.22 mg/ml, respectively. EC50 values in chelating ability on ferrous ions were 6.45–13.51 mg/ml. Contents of total phenols were 221.71–330.22 mg/g whereas those of total catechins in cold and hot water extracts were 135.05–193.14 and 161.57–195.05 mg/g, respectively. Based on the results obtained, hot water extracts were more effective in antioxidant activity and reducing power. However, cold water extracts were more effective in scavenging ability on DPPH and hydroxyl radicals, and chelating ability on ferrous ions. Summarily, the cold brewing method would be a new alternative way to make a tea.

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Author: Deia Abd El-Hady and Nagwa Abo El-Maali

A simple and reliable analytical electrophoretic method using chiral capillary electrophoresis (CCE) with a high-sensitivity cell of special design has been established for simultaneous determination of (+)-catechin (C) and (−)-epicatechin (EC) in aqueous and human plasma media. The application of a capillary with high-sensitivity cell has led to an improvement of 10-fold and 5-fold time-corrected peak area over a standard cell and a capillary with bubble cell, respectively. Analysis has involved the electrophoretic separation of C and EC in less than 4.0 min at 210 nm. The running buffer consist of 50.0 mmol L−1 borate buffer with 1.0 mmol L−1 β-cyclodextrin at pH 8.5. CCE system has been proved for its intended use by applying procedure starting from calibration of CE instrument into validation of all experimental parameters. The resolution between catechin isomers under optimal conditions has been found to be more than 3.0. The detection limits of C and EC have been calculated to be 3.2 and 1.0 ng mL−1, respectively. Good linearity has been obtained with correlation coefficient (r2) ranging between 0.995 and 0.996 at 99% confidence level (CL). Application of the proposed method to human plasma after ingestion of green tea has successfully been achieved and has statistically been proved. The unchanged amounts of C and EC in plasma were about 17.4 and 1.8% of the administered dose after 2 h of starting tea ingestion. The detection limits of C and EC in human plasma at 210 nm were 4.1 and 1.5 ng mL−1, respectively.

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Identification of green tea’s (Camellia sinensis (L.)) quality level according to measurement of main catechins and caffeine contents by HPLC and support vector classification pattern recognition

Author: Quansheng Chen and Zhiming Guo and Jiewen Zhao

High performance liquid chromatography (HPLC) was identified green tea’s quality level by measurement of catechins and caffeine content. Four grades of roast green teas were attempted in this work. Five main catechins ((−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG), (−)-epicatechin (EC), and (+)-catechin (C)) and caffeine contents were measured simultaneously by HPLC. As a new chemical pattern recognition, support vector classification (SVC) was applied to develop identification model. Some parameters including regularization parameter (R) and kernel parameter (K) were optimized by the cross-validation. The optimal SVC model was achieved with R = 20 and K = 2. Identification rates were 95% in the training set and 90% in the prediction set, respectively. Finally, compared with other pattern recognition approaches, SVC algorithm shows its excellent performance in identification results. Overall results show that it is feasible to identify green tea’s quality level according to measurement of main catechins and caffeine contents by HPLC and SVC pattern recognition.

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Author: V.R. Sinija and H.N. Mishra

Moisture adsorption isotherms of green instant tea powder and green tea granules were determined at 20, 30, 40 and 50 °C. A gravimetric static method was used under 0.11–0.90 water activity ranges for the determination of sorption isotherms that were found to be typical type II sigmoid. Experimental data were fitted to various mathematical models and found that Peleg model suits best in describing equilibrium moisture content–equilibrium relative humidity (EMC–ERH) relationships for instant green tea samples as well as green tea granules, over the entire range of temperatures. The net isosteric heat of sorption was determined from the equilibrium data at different temperatures. The isosteric heat of sorption varied between 48.54 and 44.71 kJ/mol at moisture levels varying between 1 and 9 g/g dry matter for instant green tea powder and 47.96 and 44.10 kJ/mol at moisture level varying between 0.2 and 1.4 g/g dry matter for green tea granules.

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