• Nutrition Research and Practice
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• v.17 no.4
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• pp.682-697
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• 2023

BACKGROUND/OBJECTIVES: Tibetan tea is a kind of dark tea, due to the inherent complexity of natural products, the chemical composition and beneficial effects of Tibetan tea are not fully understood. The objective of this study was to unravel the composition of Tibetan tea using knowledge-guided multilayer network (KGMN) techniques and explore its potential antioxidant and hypolipidemic mechanisms in mice. MATERIALS/METHODS: The C57BL/6J mice were continuously gavaged with Tibetan tea extract (T group), green tea extract (G group) and ddH2O (H group) for 15 days. The activity of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) in mice was detected. Transcriptome sequencing technology was used to investigate the molecular mechanisms underlying the antioxidant and lipid-lowering effects of Tibetan tea in mice. Furthermore, the expression levels of liver antioxidant and lipid metabolism related genes in various groups were detected by the real-time quantitative polymerase chain reaction (qPCR) method. RESULTS: The results showed that a total of 42 flavonoids are provisionally annotated in Tibetan tea using KGMN strategies. Tibetan tea significantly reduced body weight gain and increased T-AOC and SOD activities in mice compared with the H group. Based on the results of transcriptome and qPCR, it was confirmed that Tibetan tea could play a key role in antioxidant and lipid lowering by regulating oxidative stress and lipid metabolism related pathways such as insulin resistance, P53 signaling pathway, insulin signaling pathway, fatty acid elongation and fatty acid metabolism. CONCLUSIONS: This study was the first to use computational tools to deeply explore the composition of Tibetan tea and revealed its potential antioxidant and hypolipidemic mechanisms, and it provides new insights into the composition and bioactivity of Tibetan tea.

• New & Renewable Energy
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• v.9 no.3
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• pp.36-42
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• 2013

To secure raw materials of biodiesel production, the possibility of camellia (C. japonica L.) and tea (C. sinensis L.) seed oil was studied to produce biodiesel. In this research, crude oil contents and fatty acid compositions of seeds were analyzed by Solxlet and Gas chromatography (GC). The oil contents in the seeds of camellia were 69.8%~73.8%, and tea were 26.3%~29.4%. Among the fatty acids of camellia and tea oil, oleic acid was dominant. The unsaturated fatty acids accounted for 88.4% and 80.2% of the whole fatty acids of camellia and tea seed oil. Total seed oil content and fatty acid composition of tea seed were influenced by collecting date. Across maturation period, oil content of tea seed averaged 18.3% on $6^{th}$ September increasing to 27.9% by $11^{th}$ October. For largest seed yield and oil content, the optimum time to harvest tea is in middle october, and camellia is late september and thereafter. The extraction efficiency of oil from seeds by extraction methods was determined. Biodiesel were synthesized in 92.1~92.8% yields from camellia and tea oils by transesterification. The biodiesel was characterized by its physical and fuel properties including oxidation stability, iodine value and cold filter plugging point (CFPP). Oxidation stability of camellia was 8.6~8.8 hours and tea was 2.9~3.6 at $110^{\circ}C$. Camellia oil had considerably better oxidation stability and CFPP than tea oil.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.747-754
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• 2005

Liquid chromatographic methods with UV and fluorescence detection have been used to determine the levels of (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate in Korean green tea infusions. The extracts of Korean green tea leaves or powders in water at various temperatures (100 ${^{\circ}C}$, 80 ${^{\circ}C}$, 60 ${^{\circ}C}$) and time, were washed with chloroform and re-extracted to ethyl acetate. The ethyl acetate phase was dried and re-dissolved in methanol and analyzed. Five catechin compounds were separated by gradient elution. The flavonoids were found decomposed on prolonged extraction, thus exhaustive extraction by a Soxhlet apparatus was found useless for green tea. Some unknown components were found in the extracts at 100 ${^{\circ}C}$. When the green tea was filtered and re-extracted with new fresh water, still some flavonoids were extracted. However, the contents of flavonoids in the third extract were found negligible. The flavonoid extraction rate of green tea powders was higher than that of green tea leaves, but flavonoid decomposition of green tea powders was also faster than that of green tea leaves. The traditional way of drinking green tea was found appropriate in view of flavonoids intake.

• The Korean Journal of Community Living Science
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• v.19 no.3
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• pp.365-371
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• 2008

This study was conducted to determine the potent physiological activity of traditional wild tea ("Don tea"; coin-shaped tea) as affected by different harvesting times, aging periods and extracting temperatures, No difference in anti-oxidative activities in the harvesting time and extracting temperature of tea leaves was observed. However, short aging periods of Don tea showed high ABTS {2-2-azonobis (3-ethylbenzothiazolin-6-sulphonic acid)} activity, ranging from 71.52 to 79.96%. DPPH (${\alpha},\;{\alpha}-diphenyl-{\beta}-picryl-hydrazyl$) radical scavenging activity of Don tea was 71.10 to 91.40%. Especially, longer aging period and an extracting temperature of $100^{\circ}C$ showed higher DPPH radical scavenging activity. With longer aging periods and an extraction at $90^{\circ}C$, nitrite radical scavenging activity of Don tea ranged from 74.04 to 94.92%. On the other hand, angiotensin 1-converting enzyme (ACE) inhibition activity of Don tea was 59.77-81.97%. It showed higher activity when harvested in June and August, aged for longer periods, and extracted at $100^{\circ}C$. These results suggested Korean traditional Don tea exhibited the highest physiological activity when aged over 8 months.

• Journal of the Korean Society of Food Culture
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• v.18 no.3
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• pp.226-234
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• 2003

The effects of dried green tea leaf powders on serum lipid concentrations were evaluated in rats. Sixty male Sprague-Dawley rats weighing $100{\pm}10g$ were divided into six groups and fed high fat diets for six weeks. Experimental groups were administered with following diets; Normal fat diet and normal and high fat diets with 1% dried green tealeaf powders. Tissue weights of liver, lung, stomach, heart, kidney and spleen of high fat diet exposed rats were reduced by dried green tea leaf powders groups. The concentrations of serum triglyceride in rats fed the dried green tea leaf powders were lower than those in other groups. The concentrations of total cholesterol in green tea leaf powders the were lower than those in high fat diet groups. The concentrations of HDL-cholesterol in serum of the dried leaf powders green tea were significantly higher than those of other groups. The levels of LDL-cholesterol in serum of the dried green tea leaf powders groups were tended to be lower than those of other groups. GPT and GOT were decreased in dried green tea leaf powders groups and than in the high fat group. LDHase was lower in the dried green tea leaf powders groups than in the high fat group. These results suggest that dried leaf powders green tea groups may reduce elevated levels of serum lipid concentrations in rats fed high fat diets.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.468-471
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• 1998

Regarding the characterstics of allergic diseases, preventive and continuous treatment is desirable, and tea would be the one of the best functional food formula for it. Here we report the development of tea processing method for the leaves of Castnaea crenata. Two forms of Castnaea crenata leaf tea were prepared, non-fermented steaming tea and semi-fermented rolling tea. Anti-allergic actions of Castanea crenata leaf tea were asessed by testing their effects on the degranulation of mast cells. For this, hexosaminidase release (degranulation marker) from RBL-2H3 cells (mast cell line) was used. At the concentration of $300\;{\mu}g/mL$ of the water extract, the degranulation of RBL-2H3 cells were inhibited 50.4% and 35.4% by non-fermented steaming tea and semi-fermented rolling tea, respectively. These results suggest that the tea processing method we developed could provide a valuable resource for the treatment of allergic diseases.

• Korean Journal of Veterinary Research
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• v.42 no.4
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• pp.475-483
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• 2002

We performed this study to determine the effect of Korean favorite teas (green tea, ginseng tea, coffee and barley tea) on jejunal crypt survival, endogenous spleen colony formation and apoptosis in jejunal crypt cells of mice irradiated with high and low dose of ${\gamma}$-radiation. Jejunal crypts were protected by pretreatment of green tea (P.O.: 1.25% water extract, for 7 days before irradiation., I.P.: 50 mg/kg of body weight, at 12 and 36 hours before irradiation, p<0.01) or ginseng (I.P.: 50 mg/kg of body weight, at 12 and 36 hours before irradiation, p<0.05). Green tea (p<0.05) or ginseng (p<0.05) administration before irradiation (I.P. at 12 and 36 hours before irradiation) resulted in an increase of t formation of endogenous spleen colony. The frequency of radiation-induced apoptosis was also reduced by pretreatment of green tea (P.O.: p<0.005, I.P.: p<0.05), pretreatment of ginseng (P.O.: p<0.005, I.P.: p<0.005) or posttreatment of ginseng (I.P.: 50 mg/kg of body weight, at 30 minutes after irradiation, p<0.05). Treatment with coffee or barley tea showed no significant modifying effects on the radiation-induced damages. These results indicated that green tea and ginseng might be a useful radioprotector, especially since it is a relatively nontoxic natural product. Further studies are needed to characterize better the promotion nature of green tea, ginseng and its components.

• The Korea Journal of Herbology
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• v.30 no.4
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• pp.129-135
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• 2015

Objectives : Clerodendron trichotomumThunberg grows wild fields and mountains in South Korea and China. They have been used for anti-hypertension disease. This study was performed in order to observe the effects ofClerodendron trichotomumThunberg tea on anti-hypertension.Methods : For the study ofClerodendron trichotomumThunberg tea, we had divided male SHR (Spontaneously Hypertensive Rat) to ten groups. Control group is SHR. The treatment group is SHR which is administered tea extract at dose of 200 mg/kg/day and 500 mg/kg/day orally for 8 weeks. We measured systolic blood pressure, diastolic blood pressure, number of pulse, body weight, total cholesterol and triglyceride from blood serum.Results : The level of systolic and diastolic blood pressure were significantly decreased by 12.5% and 44.9% inClerodendron trichotomumThunberg tea groups than control group. Heart rate ofClerodendron trichotomumThunberg tea groups, 24.5%, was significantly lower than control group. We found that treatment with the water extract fromClerodendron trichotomumThunberg leave and flower significantly decreased weight of body, total cholesterol and triglyceride to 20.4% and 27.7% compared to untreated control group, significantly (P< 0.05).Conclusions : These results suggest that leaf and flower tea ofClerodendron trichotomumThunberg tea is effective in prevention and treatment of hypertension and decreasing cholesterol. Long term consumption ofClerodendron trichotomumThunberg leaf and flower tea can be help in lowering high systolic and blood diastolic pressure, heart rate and blood serum in SHR.

• The Korean Journal of Food And Nutrition
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• v.25 no.3
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• pp.447-453
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• 2012

Various types of tea are consumed as a popular beverage worldwide particularly in Asian countries such as Korea, China, and Japan. The purpose of this study was to investigate the mineral contents, antioxidant properties and anticancer activity of Yak-Sun tea that is prepared by six oriental medicinal herbs. The results of the mineral contents were as follows; Ca, Mg, and Na contents were higher than those of green tea, whereas Fe, P, and K contents were lower than those of green tea. The total phenolics and flavonoid content of the Yak-Sun tea were higher than those of green and black teas. The $IC_{50}$ values of DPPH radical, hydroxyl radical, hydrogen peroxide radical scavenging of Yak-Sun tea were 0.78, 1.58, and 2.04 $mg/m{\ell}$, respectively, whereas the radical scavenging values of ${\alpha}$-tocopherol was 0.06, 0.05, and 0.09 $mg/m{\ell}$, respectively. When cancer cells were treated with Yak-Sun tea, the anticancer activity increased in a dose dependent manner. HCT116 colon cancer cell lines were dramatically increased, as compared to other cancer cell lines, such as MCF-7, H460, and MKN45 cell lines. The results of this study demonstrated that Yak-Sun tea could function as a tea to enhance health conditions for antioxidant and anticancer activity.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.1649-1654
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• 2016

Tea derived from the leaves and buds of Camellia sinensis (Theaceae) is consumed worldwide. Green tea contains various components with specific health-promoting effects, and is believed to exert protective effects against diseases including cancer, diabetes and hepatitis, as well as obesity. Of the various tea components, the polyphenol catechins have been the subject of extensive investigation and among the catechins, (-)-epigallocatechin gallate has the strongest bioactivity in most cases. Our research group has postulated that hepatocyte nuclear factor-$4{\alpha}$, sterol regulatory element-binding proteins, and tumor necrosis factor-${\alpha}$ are targets of green tea constituents including (-)-epigallocatechin gallate for their anti-diabetes, anti-obesity, and anti-hepatitis effects, respectively. Published papers were reviewed to determine whether the observed changes in these factors can be correlated with anti-cancer effects of green tea. Two major action mechanisms of (-)-epigallocatechin gallate have been proposed; one associated with its anti-oxidative properties and the other with its pro-oxidative activity. When reactive oxygen species are assumed to be involved, our findings that (-)-epigallocatechin gallate downregulated hepatocyte nuclear factor-$4{\alpha}$, sterol regulatory element-binding proteins, and tumor necrosis factor-${\alpha}$ may explain the anti-cancer effect of green tea as well. However, further studies are required to elucidate which determinant directs (-)-epigallocatechin gallate action as an anti-oxidant or a pro-oxidant for favorable activity.