• Natural Product Sciences
• /
• v.22 no.4
• /
• pp.270-274
• /
• 2016

Green tea, the leaves of Camellia sinsneis (Theaceae), is generally acknowledged as the most consumed beverage with multiple pharmacological functions including antioxidant activity. This study was performed to analyze the effect of extraction conditions of green tea on its antioxidant effects using DPPH assay. Three extraction factors such as extraction solvent (EtOH, 0 - 100%), extraction time (3 - 15 min) and extraction temperature ($10-70^{\circ}C$) were analyzed and optimized extraction condition for antioxidant activity of green tea extract (GTE) was determined using response surface methodology with three-level-three-factor Box-Behnken design (BBD). Regression analysis showed a good fit of data and the optimal conditions of extraction were found to be 57.7% EtOH, 15 min and $70^{\circ}C$. Under this condition, antioxidant activity of experimental data was 88.4% which was almost fit to the ideal value of 88.6%. As epigallocatechin gallate (EGCG) is known for the major ingredient for antioxidant activity of green tea, we investigated the effect of EGCG on antioxidant activity of GTE. EGCG showed antioxidant activity with the $IC_{50}$ value of $4.2{\mu}g/ml$ and a positive correlation was observed between EGCG content and the antioxidant activity of GTE with $R^2=0.7134$. Interestingly, however, GTE with 50 - 70% antioxidant activity contain less than $1.0{\mu}g/ml$ of EGCG, which is much lower than $IC_{50}$ value of EGCG. Therefore, we suppose that EGCG together with other constituents contribute to antioxidant activity of GTE. Taken together, these results suggest that green tea is more beneficial than EGCG alone for antioxidant ability and optimal extraction condition of green tea will be useful for the development of food and pharmaceutical applications

• Journal of Nutrition and Health
• /
• v.35 no.1
• /
• pp.24-29
• /
• 2002

Present study investigates the protective effects of green tea against acute ethanol administration on lipid peroxidation and antioxidant system in various regions of rat brain ; cortex, cerebellum, striatum and hippofampus. The following parameters were examined : malondialdehyde(MDA) concentrations and activities of superoxide dismutase(SOD), catalase and glutathione peroxidase(GSH-Px). Male Sprague-Dawley rats of 9 month old were given control diets or those containing 1% green tea powder for 4 weeks, and at tole end of feeding each diet group was received acute ethanol(5g/kg body weight) or equicaloric sucrose solution administration. Results indicated that green tea powder significantly decreased malondialdehyde(MDA) levels in the striatum(81.85nmol/g tissue) and hippocampus(71.68nmol/g tissue), compared to control group(145.68nmol/g tissue in the striatum, 119.04nmol/g tissue in the hippocampus). Also, a significant decrease was observed in the striatum of green tea-ethanol treated group compared to control group. Green tea significantly blocked an ethanol-induced catalase activation in the hippocampus, which means an ethanol administration drew a significant increase only in control diet groups. In conclusion, these results suggest that moderate consumption of green tea leaves ctrl have protective effects against ethanol induced oxidative stress on various regions of rat brain, by significantly reducing MDA concentrations in the striatum and hippocampus and inhibiting ethanol induced catalase activation in the hippocampus.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.8
• /
• pp.1043-1047
• /
• 2007

The physicochemical characteristics of green tea prepared by four kinds of alkaline ionized water (AIW; pH 8.57, 8.85, 9.23, and 10.06, respectively) were evaluated. Green tea was made by soaking commercial green tea leaves in AIW at $75^{\circ}C$ for 10 min (1.0 g/100 mL). Total phenol contents, total flavonol contents, and ascorbic acid contents of green tea decreased with increasing pH of AIW. Increasing pH of AIW tended to decrease lightness (L) and redness (a) of green tea but increase yellowness (b) in Hunter color values. The amount of epicatechins and radical scavenging activity of green tea also decreased with increasing pH of AIW, while caffeine was not significantly affected. Tyrosinase inhibition activity was the highest in AIW of pH 8.85.

• Korean Journal of Food Science and Technology
• /
• v.29 no.6
• /
• pp.1275-1280
• /
• 1997

The possible use of tea catechins as natural preservatives for kimchi was investigated in this study. Tea catechins separated from tea leaves had antimicrobial activity against microorganisms related to kimchi fermentation, such as Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus brevis, Pediococcus cerevisiae, Streptococcus faecalis. The degree of antimicrobial activity of catechins were different among microorganisms; that is 2 mg/mL to Leuconostoc mesenteroides, Lactobacillus plantarum, and Pediococcus cerevisiae, 4 mg/mL to Streptococcus faecalis, and 5 mg/mL to Lactobacillus brevis; however, Saccharomyces cerevisiae can not be inhibited. The effect of tea catechins on retardation of kimchi fermentation was tested by measuring changes in pH and acidity. The changes of pH and acidity of baechu-kimchi and mul-kimchi were remarkably inhibited by adding the tea catechins at the level of 2 mg/g fresh baechu. These results suggest that the tea catechins can be successfully used for the extension of shelf-life of kimchi.

• Journal of the Korean Society of Food Culture
• /
• v.22 no.2
• /
• pp.261-265
• /
• 2007

The antidepressant effects of Cirsium japonicum was revealed in previous studies using open field test and forced swimming test. The contents of total flavonoids and apigenin of Cirsium japonicum were analyzed and sensory evaluation of Cirsium japonicum tea was performed in order to develop Cirsium japonicum tea as an antidepressant. Among the different plant parts of Cirsium japonicum, leaves had the highest level of total flavonoids and apigenin contents and were followed by flowers and stems. Drying method affected total flavonoids and apigenin content of Cirsium japonicum, but regular pattern was not revealed. In sensory evaluation, overall acceptance of Cirsium japonicum flower-leaf mix tea was higher than those of Cirsium japonicum leaf tea. Also purchase intention of Cirsium japonicum flower-leaf mix tea was higher than those of Cirsium japonicum leaf tea.

• Food Science and Preservation
• /
• v.15 no.3
• /
• pp.461-468
• /
• 2008

To obtain basic da1a on the preparation of Cudrania tricuspidata leaves tea, the quality and anti-oxidative characteristics of dried raw leaves (RT), pan-fired leaves tea (PT) and fermented leaves tea (FT) were investigated. General characteristics of RT, PT and FT, respectively, were: moisture content 18.47, 6.23 and 8.50%; crude protein content 17.77, 20.46 and 19.13%; and carbohydrate content 54.42, 62.52 and 61.96%. The crude lipid and ash contents were in the range 0.05 - 0.07% and 9.27 -10.74% respectively; the water soluble solid content was in the order FT > PT > RT and ranged from 23.10 - 37.38%; there were no significant differences in the total polyphenol content (815.24 - 835.16 mg%). Although $L^*$ values of PT (20.94) and FT (20.85) were lower than those of RT (34.71), the $a^*$ value in PT and the $b^*$ value in FT were highest. In all ethanol extracts the reducing power, electron-donating ability and superoxide dismutase (SOD)-like activity increased in a concentration-dependent manner. Furthermore, the activity in FT was higher than in PT or RT. The total free amino-acid content was higher in FT (1429.93 mg%) than RT (1108.94 mg%) or PT (833.13 mg%). The major amino acids were L-asparagine and L-valine in RT, L-cysteine and L-glutamic acid in PT and L-proline in FT. In a sensory evaluation of PT and FT, bitter and astringent tastes were decreased relative to RT, while sweet and savory tastes, flavor, color and overall acceptability were increased. These results indicate that FT bas a higher antioxidant effect and free-amino-acid content than PT, while the sensory quality of FT is similar to that of PT.

• Journal of the East Asian Society of Dietary Life
• /
• v.17 no.5
• /
• pp.696-702
• /
• 2007

The purpose of this paper is to describe the differences in mineral, ascorbic acid, and total polyphenol content, and also the relationship between polyphenol content and antioxidant activity(DPPH radical scavenging, FTC, and TBA methods) in three sizes of Cudrania tricuspidata leaves. For the mineral contents of the leaves, Ca was highest(17.26 mg/g.d.w.), followed by K(15.53 mg), P(2.61 mg), and Mg(1.99 mg). Ascorbic acid was found to be slightly higher(43.4 mg/100g.f.w.) in the basal parts of the medium size leaves and lowest in the whole parts(9.9 mg) of the small size leaves. Total polyphenol content was highest($1,384{\sim}1,258mg/100g.f.w.$) in the leaves, for all sizes, when extracted with 80% ethanol, followed by the stem bark(543 mg%), roots(369 mg%), stems(243 mg%), and thorns(223 g%). By determining DPPH activity, we found that antioxidant activity was higher in the ethanol extracts of the leaves than in the ethanol extracts of the thorns, stems, roots, and stem bark. While in the tea, no differences were found between the ethanol and water extracts.

• Journal of Applied Biological Chemistry
• /
• v.55 no.1
• /
• pp.19-25
• /
• 2012

Green tea leaves were fermented for 15 and 30 days with Monascus pilosus which is known to produce functional statins (TMs), and the content of various biochemical constituents such as total polyphenol (TP), total flavonoid (TF), theaflavin, and thearubigin were analyzed and compared with that of non-fermented green tea (GT) and Pu-erh Chinese post-fermented tea (PU). In addition to the electron donating ability (EDA), ferric iron reducing power (FIRP), xanthine oxidase (XO) inhibitory activity, superoxide dismutase (SOD)-like activity, iron chelating activity (ICA) and hydrogen peroxide contents were also measured and compared with that of GT and PU. Content of TP and TF in the water and ethanol extracts in TMs were lower than those in GT and PU. Theaflavin and thearubigin contents of water and ethanol extracts in TMs were higher than those of GT. And, these components were increased depending on the period of fermentation. While, EDA and FIRP of TMs were lower than those of GT, XO inhibitory activity of TMs was higher than non-fermented tea. While, ICA of TMs was slightly higher than GT and PU, the content of hydrogen peroxide in TMs was markedly lower than GT. This results suggested that the green tea fermented by M. pilosus was valuable for oxidative stress-induced diseases by decreasing hydrogen peroxide, and forming theaflavins and thearubigins with functionality of genus Monascus.

• Journal of agriculture & life science
• /
• v.43 no.3
• /
• pp.27-34
• /
• 2009

Green tea was prepared by soaking 1.5 g of green tea leaves into 100 mL of distilled water at $75^{\circ}C$ for 5 min. The green tea was stored at three different conditions - (A) green tea was stored at not-artificially excluding natural light condition, at natural air condition, and without addition of vitamin C; (B) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and with addition of 30 mg/100 mL of vitamin C; and (C) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and without addition of vitamin C. After 28 days of storage at $4^{\circ}C$, the chemical quality of the green tea was evaluated. Total phenolic contents of (A), (B), and (C) green tea decreased to 71.50, 73.88 and 75.07%, respectively, after storing for 28 days compared to those of beginning state. DPPH radical scavenging activities of (A), (B), and (C) green tea were 87.87, 92.93 and 88.39%, respectively. Epigallocatechin gallate (EGCG), the main active compounds of green tea, contents of (A), (B), and (C) green tea were 130.61, 136.47 and 4.34%, respectively. The results indicated that light, air condition, and vitamin C were significantly important to the chemical quality of green tea during storage.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.1
• /
• pp.66-70
• /
• 2005

The experiment was carried out to investigate the effects of gamma radiation on the early growth performance and physiological traits of BT2 clone tea, the most promising cultivar released by Bangladesh Tea Research Institute. The fresh shoot cuttings were irradiated with seven different levels of gamma radiation such as 0, 10, 20, 30, 40, 50 and 60 Gy from Cobalt 60Co source (Dept. of PlantBreeding, Bangladesh Institute of Nuclear Agriculture). Thereafter, the irradiated shoot cuttings were planted in polythene bags and kept under natural conditions. It was observed that callusing was initiated from 8th weeks after placement of tea shoot cuttings in the polythene bags and completed by 12th weeks. The morphological growth of tea shoot cuttings were recorded under varying levels of gamma radiation and growth stages. It was observed that the number of leaves, number of primary branches, base diameter, root length and total leaf area per plant significantly increased with the progress of time and increasing levels of gamma radiation, however, the plant height showed decreasing trend with the increasing levels of gamma radiation, which could be due to the change in chromosomal structure and genetic makeup. After 56 weeks of planting, the plant height, the number of leaves and primary branches per plant, base diameter, root length and total leaf area per plant recorded were 65.70 cm, 30.67, 7.33, 1.48 cm, 23.50 cm, and 1250.67 cm2 per plant respectively under the radiation level 60 Gy, whereas the corresponding figures of the above parameters at the control treatment were 76.21 cm, 18.33, 3.67, 0.92 cm, 17.75 cm and 778.33 cm2 per plant, respectively. A significant relationship was observed among the physiological growth parameters with the increasing levels of gamma radiation. The total dry matter gain, leaf area index, absolute growth rate and relative growth rate were significantly influenced with the rising levels of gamma radiation (up to 60 Gy), whereas the net assimilation rate of individual tea plant non-significantly responded as compared to those of control treatment. Finally after 56 weeks of planting, the maximum total dry weight gain, leaf area index, absolute growth rate, relative growth rate and net assimilation rate recorded under 60 Gay radiation level were 40.25 g/plant/week, 4.25, 1.18 g/week, 0.0621g/g/week and 17.07 g/m2/week respectively.