Green tea exerts antioxidant action in vitro and its consumption increases total serum antioxidant potential in normal and dyslipidemic subjects

Antioxidant defenses can be characterized as agents (enzymes and low-molecular-mass antioxidants) in biological systems that prevent the noxious action of free radicals or other reactive species. The present study examined whether the use of green tea may exert antioxidant action in vitro and improve antioxidant defenses and serum lipids in normal and dyslipidemic subjects. Forty-one hypercholesterolemic individuals, 18 women and 23 men (age [mean ± SD], 44.81 ± 14.41), were evaluated before and after the daily intake of 6 g of green tea in 500 mL of water for 1 month. Likewise, 27 normolipidemic individuals, 12 women and 15 men (age, 37.07 ± 16.08), were also evaluated. Serum lipids were measured by an automated clinical chemistry system. The total serum antioxidant potential (TRAP) and serum levels of lipid hydroperoxides were quantified using the chemiluminescence method. Total polyphenols present in green tea ingested by the patients were verified by using Folin-Ciocalteau reagent. The in vitro evaluation of green tea antioxidant activity was performed using microsomes obtained from rat liver, which was oxidized by tert-butyl hydroperoxide. From this system, thiobarbituric acid reactive substances were measured. In the in vitro test, green tea polyphenols proved to be efficient at protecting microsomes from the oxidant activity of tert-butyl hydroperoxide. There were no significant alterations in the lipid profiles of the normolipidemic or hypercholesterolemic subject groups. Although there was no decrease in lipid hydroperoxides, both groups showed increased antioxidant defenses, which was evidenced by TRAP. In conclusion, the results obtained indicate that besides achieving antioxidant action in vitro, the consumption of green tea increased the TRAP of normal and dyslipidemic subjects.     

Antioxidant activity and recovery of green tea catechins in full-fat cheese following gastrointestinal simulated digestion

Green tea extract (GTE) was incorporated into full-fat cheeses at 250, 500, and 1000 ppm to investigate the effect of green tea catechins on antioxidant properties and microstructure of cheese, and recovery of catechins. Cheeses were ripened for 90 days at 8 °C followed by simulated gastrointestinal digestion. The composition on Day 0, and pH, total phenolic content (TPC), and antioxidant activity (AA) of the cheeses on Days 0, 30, and 90, were determined. The concentrations of the major GTE catechins in the curd and from the digesta of mature cheeses were determined using HPLC. Addition of GTE significantly (p ≤ 0.05) decreased the pH of whey and curd during cheese manufacture and ripening, however there was no significant (p > 0.05) effect on moisture, protein, or fat contents. Addition of GTE increased TPC and AA at all concentrations, but in a non-linear manner. Individual catechins were selectively retained in the curd, whereas different portions were recovered from the cheese digesta. Transmission electron microscopy showed that the ripened control cheese had a regular distribution of milk fat globules entrapped in a homogeneous structure of casein proteins, which was disrupted by GTE. Interactions between green-tea catechins and cheese fat were confirmed by Fourier transform infrared spectroscopy.     

Extract of green tea leaves partially attenuates streptozotocin-induced changes in antioxidant status and gastrointestinal functioning in rats

Rats with severe streptozotocin (STZ)-induced diabetes were subjected to dietary green tea extract supplementation at 2 doses (0.01% and 0.2%; GTL and GTH groups, respectively) to evaluate their effects on antioxidant, gastrointestinal, and renal parameters of experimental animals. The lower dietary supplementation reflects daily consumption of 3 cups of green tea for an average adult weighing 70 kg. Supplementation of a diet with green tea extract had no influence on elevated food intake, body weight loss, increased glucose concentration, or declined antioxidant capacity of water-soluble substances in plasma in the diabetic rats. In cases of intestinal maltase activity, attenuation of liver and kidney hypertrophy, triacylglycerol concentration, and aspartate aminotransferase activity in the serum, both dietary treatments normalized metabolic disorders caused by STZ injection to a similar extent. Unlike the GTL group, the GTH treatment significantly ameliorated development of diabetes-induced abnormal values for small intestinal saccharase and lactase activities, renal microalbuminuria, thiobarbituric acid-reactive substance content in kidney tissue, as well as total antioxidant status in the serum of rats. The GTH group was also characterized by higher antioxidant capacity of lipid-soluble substances in plasma and superoxide dismutase activity in the serum. Although the higher dose of green tea extract did not completely protect against STZ-induced hyperglycemia and oxidative stress in experimental rats, this study suggests that green tea extract ingested at high amounts may prove to be a useful therapeutic option in the reversal of diabetic dysfunction.     

Studies of the antioxidative effects of green and black tea (Camellia sinensis) extracts in rats

This paper reports a comparative study of the antioxidative effects of black and green tea extracts in sodium oxalate-challenged rats. A dose of 10 mg/kg of body weight of sodium oxalate was used to induce lipid peroxidation in vivo. Rats treated with sodium oxalate had 42.06 +/- 3.10 nM/hour, 45.39 +/- 9.75 mg/100 mL, 10.95 +/- 1.52%, 15.95 +/- 3.19 mg/dL, 112.25 +/- 5.15 mg/dL, 59.21 +/- 2.95 IU, 39.55 +/- 2.51 IU, and 150.62 +/- 9.62 KA/unit for serum levels of malondialdehyde, reduced ascorbic acid, catalase, cholesterol, phospholipid, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP), respectively. These values are significantly (P < .05) different from values obtained from normal rats. Rats pretreated with 100 mg/kg of body weight of green tea had 27.59 +/- 3.56 nM/hour, 79.11 +/- 5.13 mg/100 mL, 4.23 +/- 0.36%, 50.09 +/- 5.24 mg/dL, 97.58 +/- 4.73 mg/dL, 23.10 +/- 1.59 IU, 31.14 +/- 1.26 IU, and 96.48 +/- 2.36 KA/unit for serum levels of malondialdehyde, reduced ascorbic acid, catalase, cholesterol, phospholipid, AST, ALT, and ALP, respectively, compared with 37.28 +/- 2.07 nM/hour, 72.62 +/- 2.10 mg/100 mL, 6.23 +/- 1.52%, 37.25 +/- 2.84 mg/dL, 78.05 +/- 2.36 mg/dL, 36.08 +/- 1.80 IU, 29.00 +/- 3.02 IU, and 109.23 +/- 6.32 KA/unit recorded for the same parameters in rats treated with black tea. The cholesterol to phospholipid ratio was increased from 0.14 +/- 0.04 in control rats to 0.47 +/- 0.02 and 0.51 +/- 0.01 by black and green tea extracts, respectively. These results suggest that tea extracts have antioxidant properties and that green tea extract is more potent.     

Catechins from green tea (Camellia sinensis) inhibit bovine and human cartilage proteoglycan and type II collagen degradation in vitro

Polyphenolic compounds from green tea have been shown to reduce inflammation in a murine model of inflammatory arthritis, but no studies have been undertaken to investigate whether these compounds are protective to joint tissues. We therefore investigated the effects of catechins found in green tea on cartilage extracellular matrix components using in vitro model systems. Bovine nasal and metacarpophalangeal cartilage as well as human nondiseased, osteoarthritic and rheumatoid cartilage were cultured with and without reagents known to accelerate cartilage matrix breakdown. Individual catechins were added to the cultures and the amount of released proteoglycan and type II collagen was measured by metachromatic assay and inhibition ELISA, respectively. Possible nonspecific or toxic effects of the catechins were assessed by lactate output and proteoglycan synthesis. Catechins, particularly those containing a gallate ester, were effective at micromolar concentrations at inhibiting proteoglycan and type II collagen breakdown. No toxic effects of the catechins were evident. We conclude that some green tea catechins are chondroprotective and that consumption of green tea may be prophylactic for arthritis and may benefit the arthritis patient by reducing inflammation and slowing cartilage breakdown. Further studies will be required to determine whether these compounds access the joint space in sufficient concentration and in a form capable of providing efficacy in vivo.     

Effect of acute ingestion of fresh and stored lettuce (Lactuca sativa) on plasma total antioxidant capacity and antioxidant levels in human subjects

The present study investigated whether storage under modified-atmosphere packaging (MAP) affected the antioxidant properties of fresh lettuce (Lactuca sativa). Eleven healthy volunteers (six men, five women) consumed 250 g fresh lettuce, and blood was sampled before (0 h) and 2, 3 and 6 h after consumption. The protocol was repeated 3 d later with the same lettuce stored at 5 degrees C under MAP conditions (O2-N2 (5:95, v/v)). Results showed that after ingestion of fresh lettuce, plasma total radical-trapping antioxidant potential (TRAP), measured as area under the curve, was significantly higher (1.3 (sem 0.3) mmol/l per 6 h; P<0.05) than the value obtained with MAP-stored lettuce (0.1 (sem 0.2) mmol/l per 6 h). Plasma TRAP, quercetin and p-coumaric acid were significantly different from baseline values (P相似文献   

Effects of green tea or Sasa quelpaertensis bamboo leaves on plasma and liver lipids, erythrocyte Na efflux, and platelet aggregation in ovariectomized rats

This study was conducted to investigate the effects of Sasa quelpaertensis bamboo and green tea on plasma and liver lipids, platelet aggregation, and erythrocyte membrane Na channels in ovariectomized (OVX) rats. Thirty female rats were OVX, and ten female rats were sham-operated at the age of 6 weeks. The rats were divided into four groups at the age of 10 weeks and fed the experiment diets: sham-control, OVX-control, OVX-bamboo leaves (10%), or OVX-green tea leaves (10%) for four weeks. Final body weight increased significantly in the OVX groups compared with that in the sham-control, whereas body weight in the OVX-green tea group decreased significantly compared with that in the OVX-control (P < 0.01). High density lipoprotein (HDL)-cholesterol level decreased in all OVX groups compared with that in the sham-control rats (P < 0.05) but without a difference in plasma total cholesterol. Plasma triglycerides in the OVX-green tea group were significantly lower than those in the sham-control or OVX-control group (P < 0.05). Liver triglycerides increased significantly in the OVX-control compared with those in the sham-control (P < 0.01) but decreased significantly in the OVX-green tea group compared with those in the OVX-control or OVX-bamboo group (P < 0.01). Platelet aggregation in both maximum and initial slope tended to be lower in all OVX rats compared with that in the sham-control rats but was not significantly different. Na-K ATPase tended to increase and Na-K cotransport tended to decrease following ovariectomy. Na-K ATPase decreased significantly in the OVX-green tea group compared with that in the OVX-control group (P < 0.01), and Na-K cotransport increased significantly in the OVX-bamboo and OVX-green tea groups compared with that in the OVX-control (P < 0.05). Femoral bone mineral density tended to be lower in OVX rats than that in the sham-control, whereas the green tea and bamboo leaves groups recovered bone density to some extent. The results show that ovariectomy caused an increase in body weight and liver triglycerides, and that green tea was effective for lowering body weight and triglycerides in OVX rats. Ovariectomy induced an increase in Na efflux via Na-K ATPase and a decrease in Na efflux via Na-K cotransport. Furthermore, consumption of green tea and bamboo leaves affected Na efflux channels, controlling electrolyte and body water balance.     

Both aluminum and polyphenols in green tea decoction (<Emphasis Type="Italic">Camellia sinensis</Emphasis>) affect iron status and hematological parameters in rats

Background Green tea leaves naturally contain high levels of polyphenols and aluminum (Al). Polyphenols in green tea decoction are considered to be one of the major factors responsible of low iron status. However, the effects of Al from green tea decoction on iron status and hematological parameters remained unclear. Aim of the study The objective was to investigate the Al absorption from green tea decoction and studied its influence on iron status and hematological parameters in rats. Methods During the experiment period, rats were given the experimental diet + a simple dose of Al sulfate with or without graded doses of green tea decoction (25, 50 and 100 g/l). The Al absorption was evaluated in the serum; however, iron status was evaluated by the iron concentration in the liver, kidney, spleen and femur. In addition, the hemoglobin and hematocrit were evaluated. Results Our results showed that the serum Al significantly increased between 61.5 and 342%, as tea doses-dependant. The Al sulfate significantly decreased the reserve of iron in all studied organs between 21.7 and 17% (P < 0.05). In groups receiving green tea decoction alone or Al + graded doses of tea, the reserve of iron significantly decreased in all studied organs between 59.4 and 18.5% (P < 0.01). Al alone or associated with drinking doses of tea significantly decreased hemoglobin concentration between 23.6 and 9% (P < 0.05) and hematocrit between 12.7 and 7% (P < 0.01). Conclusion Our data showed that Al from green tea decoction was more absorbed in the serum than Al sulfate. Al absorption was associated with low iron status and reduction of hemoglobin and hematocrit. Considering that Al competes with iron in different stage of erythropoiesis including transferrin binding, so we could assume that the negative effect of tea on iron status arises not only from polyphenols iron complexes but also from Al released in tea decoction.     

Desalinated underground seawater of Jeju Island (Korea) improves lipid metabolism in mice fed diets containing high fat and increases antioxidant potential in t-BHP treated HepG2 cells

This study was performed to investigate the effect of desalinated underground seawater (named as ''magma seawater'', MSW) of Jeju Island in Korea on lipid metabolism and antioxidant activity. MSW was collected from underground of Han-Dong in Jeju Island, and freely given to high fat diet (HFD)-fed C57BL/6 mice for 10 weeks. Although there were no significant differences in the body weight changes and plasma lipid levels, hepatic triglyceride levels were significantly lower in the MSW group than in the normal tap water (TW)-drunken control group. Furthermore, the activity of fatty acid synthase (FAS) was significantly decreased and carnitine palmitoyltransferase (CPT) activity was increased in MSW group compared to TW group. Similarly, real-time PCR analysis revealed that mRNA expressions of lipogenic genes were lowered in MSW groups compared to the control group. In a morphometric observation on the liver tissue, accumulation of fats was remarkably reduced in MSW group. Meanwhile, in vitro assay, free radical scavenging activity measured by using diphenylpicrylhydrazyl (DPPH) was increased in MSW group. The 2''-7''-dichlorofluorescein diacetate (DCF-DA) staining followed with fluorescent microscopy showed a low intensity of fluorescence in MSW-treated HepG2 cells, compared to TW-treated HepG2 cells, which indicated that the production of reactive oxygen species by tert-butyl hydroperoxide (t-BHP) in HepG2 cells was decreased by MSW treatment. The antioxidant effect of MSW on t-BHP-induced oxidative stress in HepG2 cells was supported by the increased activities of intracellular antioxidant enzymes such as catalase and glutathione reductase. From these results, we speculate that MSW has an inhibitory effect on lipogenesis in liver and might play a protective role against cell damage by t-BHP-induced oxidative stress.     

Association between drinking behaviors and components of metabolic syndrome in subjects in their 20s and 30s: data obtained from the Korea National Health and Nutrition Examination Survey (2016–2018)

BACKGROUND/OBJECTIVESNumerous studies have examined the relationship between drinking behaviors and metabolic syndrome (MetS) for adults, but these include very few studies for young adults. This study therefore undertook to investigate the association between drinking behaviors and components of MetS among adult drinkers aged 20–30 years.SUBJECTS/METHODSUsing the 2016–2018 Korea National Health and Nutrition Examination Survey data, drinking behaviors of adults in the age group 20–30 years were divided into 4 groups: 1) group A, good drinking habits; 2) group B, frequent binge drinking but not frequent drinking; 3) group C, frequent drinking but not frequent binge drinking; 4) group D, frequent drinking and binge drinking. The association between MetS components and drinking behaviors was analyzed by applying multiple logistic regression analysis.RESULTSWe determined the prevalence risk compared to group A. In men, the prevalence risk of high triglyceride (TG) increased 2.051-fold in group C and 1.965-fold in group D. Moreover, in group D, the prevalence risk of low high density lipoprotein cholesterol (HDL-C) increased 0.668-fold, high blood pressure (BP) increased 2.147-fold, and MetS increased 1.567-fold. In women, there was an increased prevalence risk of low HDL-C (0.353-fold) and MetS (3.438-fold) in group C, whereas group D showed increased prevalence risk of abdominal obesity (2.959-fold), high TG (1.824-fold, and low HDL-C (0.424-fold).CONCLUSIONSOur study indicates that frequent drinking increases the risk of high TG, whereas frequent and binge drinking increases the risk of high TG, low HDL-C, high BP, and prevalence of MetS in men. In women, frequent drinking without binge drinking increases the risk of low HDL-C and MetS, whereas frequent and binge drinking increases the risk of abdominal obesity, high TG, and low HDL-C. We propose that improvements in the drinking behaviors can reduce the prevalence of MetS.