Oolong Tea Extract Research Articles

녹차, 오룡차, 홍차 추출물을 첨가한 돼지고기 수육의 품질특성

본 연구는 녹차, 오룡차, 홍차 추출물 0.5, 1, 1.5, 2%를 비육돈육(B 등급) 등심 수육에 첨가하여 수육의 일반성분, 보수력, 경도, pH, 색도, 미생물 수준, 휘발성 염기질소, TBARS, 관능검사의 품질특성을 측정하였다. 녹차의 수분 함량은 3.4%, 조단백질 31.8%, 조회분 5.5%, 탄수화물 57.7%였으며 차 종류에 따른 유의적인 차이는 없었다. 그러나 조지방은 녹차 1.6%, 오룡차 1.0%, 홍차 0.9%로 녹차의 조지방 함량이 오룡차나 홍차보다 유의적으로 높았다(p<0.05). 돼지고기 수육의 수분 함량은 55.1%, 조단백질 38.6%, 조지방 5.2%, 조회분 0.9%이었다. 보수력은 모든 차 추출물 첨가 수육에서 유의적으로 증가하였으며(p<0.05) 차 종류에 따른 차이는 없었다. 경도는 모든 차 첨가 수육에서 추출물 농도가 높아질수록 유의적으로 증가하였으며(p<0.05) 홍차 수육이 녹차와 오룡차 수육보다 경도가 낮았다. 수육의 pH는 제조일에는 각 처리구와의 유의적인 차이는 없었다. 그러나 저장기간이 경과함에 따라 무처리 수육과 모든 차 0.5% 수육에서 pH는 유의적으로 감소하였으나(p<0.05) 1, 1.5, 2% 녹차, 오룡차, 홍차 수육에서는 저장 중 pH의 유의적인 차이는 없었다. 녹차 수육은 추출물 농도가 증가할수록 명도와 황색도는 감소하였고 적색도는 감소하다가 2% 녹차 수육에서는 증가하여 0.5% 녹차 수육과 같은 수준이었다. 오룡차 수육은 추출물 첨가 농도가 증가함에 따라 명도와 황색도는 감소하였고 적색도는 증가하였다. 홍차 수육은 추출물 첨가 농도가 증가함에 따라 명도, 적색도, 황색도가 유의적으로 감소하였다. 미생물 수준은 모든 차 처리 수육에서 추출물 농도가 증가함에 따라 미생물 수준이 유의적으로 낮았으며(p<0.05) 저장 기간이 증가함에 따라 미생물 수준이 증가하였다. 수육의 휘발성 염기질소 함량은 제조일에는 각 처리구와의 유의적인 차이는 없었으며 저장 기간이 경과함에 모든 수육에서 유의적으로 증가하였다(p<0.05). TBARS 값은 제조일에는 무처리 수육보다 1, 1.5, 2% 녹차 수육과 오룡차 수육, 모든 홍차 수육이 유의적으로 낮았으며, 저장 기간이 경과함에 따라 모든 수육에서 TBARS 값이 높아졌다. 관능검사 결과 홍차와 오룡차 1% 추출물 첨가 수육이 색, 향, 종합적 기호도의 점수가 가장 높았으나 유의적인 차이는 없었으며 맛 점수는 유의적으로 높았다. 이상의 결과를 종합하여 볼 때 녹차보다 오룡차와 홍차 추출물의 첨가가 돼지고기 수육의 이취를 감소시키고, 특유의 색상을 부여하여 관능적 품질을 향상시킬 뿐만 아니라 가열 조리 및 저장 중 지방산패를 방지하여 품질 변화를 최소화하는데 효과적인 것으로 평가되었다. 특히 돼지고기 수육의 품질향상을 위해서는 홍차 추출물의 이용이 가장 좋았으며 오룡차와 홍차 추출물의 최적 첨가 농도는 1%로 나타났다.

Antibacterial, Antiadherence, Antiprotease, and Anti-Inflammatory Activities of Various Tea Extracts: Potential Benefits for Periodontal Diseases

Porphyromonas gingivalis is a key etiologic agent of chronic periodontitis. This Gram-negative anaerobic bacterium produces several virulence factors and can induce a host inflammatory response that contributes to periodontal disease. In the present study, we investigated green tea, white tea, oolong tea, and black tea extracts with a high polyphenol content for their effects on (i) the growth and adherence of P. gingivalis, (ii) the activity of host and bacterial proteases, and (iii) cytokine secretion by oral epithelial cells. All the tea extracts inhibited the growth of P. gingivalis (minimal inhibitory concentrations ranging from 200 to 500 μg/mL; minimal bactericidal concentrations=500 μg/mL). In addition, they dose dependently reduced the adherence of P. gingivalis to oral epithelial cells. Tea extracts also inhibited the catalytic activity of matrix metalloproteinase (MMP)-9, neutrophil elastase, and P. gingivalis collagenase. Lastly, the tea extracts dose dependently inhibited the secretion of interleukin (IL)-6, IL-8, and chemokine (C-C motif) ligand 5 (CCL-5) by P. gingivalis-stimulated oral epithelial cells. No marked differences in the various effects were observed among the four tea extracts. Extracts from green tea, white tea, oolong tea, and black tea show promise for controlling periodontal disease by their capacity to interfere with P. gingivalis growth and virulence properties, host destructive enzymes, and inflammatory mediator secretion. Such extracts may be incorporated to oral hygiene products or locally delivered into diseased periodontal sites.

Histological study on the treatment of vascular malformations resistant to pulsed dye laser

The pulsed dye laser (PDL) is recognized both as an effective treatment for vascular malformations and the as first treatment of choice for these lesions. However, PDL irradiation has poor efficacy in some patients, particularly the elderly. The present study histologically assessed such patients to try to elucidate the reason.A pulsed dye laser was used in 3 subjects in whom previous laser treatment was ineffective. Three-millimeter punch biopsies were obtained before laser treatment, 1 week and 3 months after the laser treatment. Each specimen was stained with toluidine blue and examined under light microscopy followed by electron microscopy with oolong tea extract (OTE) staining.Microscopy revealed an increase in the vasculature at baseline and an increased number of dermal fibroblasts. One week post-irradiation, inflammatory cell infiltration was observed together with extensive interstitial perivascular edema. At 1 week and 3 months after laser irradiation, normal structures were observed for both blood vessels and capillary endothelial cells. Mild changes were noted in other interstitial features, but findings obtained 3 months after irradiation were almost similar to those before irradiation.The lower efficacy of PDL treatment in the elderly was possibly due to the markedly low amount of red blood cells in our subjects' blood vessels, a major chromophore for the PDL, was markedly low. It is possible that age-related denaturation of dermal matrix collagen plays some role in maintaining the vasculature in the interstitium with edema, and inflammatory cell infiltration could lead to the cellular release of some cytokines which favor reconstruction of the vasculature.

Histological study on the treatment of vascular malformations resistant to pulsed dye laser.

The pulsed dye laser (PDL) is recognized both as an effective treatment for vascular malformations and the as first treatment of choice for these lesions. However, PDL irradiation has poor efficacy in some patients, particularly the elderly. The present study histologically assessed such patients to try to elucidate the reason. A pulsed dye laser was used in 3 subjects in whom previous laser treatment was ineffective. Three-millimeter punch biopsies were obtained before laser treatment, 1 week and 3 months after the laser treatment. Each specimen was stained with toluidine blue and examined under light microscopy followed by electron microscopy with oolong tea extract (OTE) staining. Microscopy revealed an increase in the vasculature at baseline and an increased number of dermal fibroblasts. One week post-irradiation, inflammatory cell infiltration was observed together with extensive interstitial perivascular edema. At 1 week and 3 months after laser irradiation, normal structures were observed for both blood vessels and capillary endothelial cells. Mild changes were noted in other interstitial features, but findings obtained 3 months after irradiation were almost similar to those before irradiation. The lower efficacy of PDL treatment in the elderly was possibly due to the markedly low amount of red blood cells in our subjects' blood vessels, a major chromophore for the PDL, was markedly low. It is possible that age-related denaturation of dermal matrix collagen plays some role in maintaining the vasculature in the interstitium with edema, and inflammatory cell infiltration could lead to the cellular release of some cytokines which favor reconstruction of the vasculature.

Analysis of metabolic markers of tea origin by UHPLC and high resolution mass spectrometry

Tea is an infusion made from the dried leaves of Camellia sinensis L. and is the second most consumed beverage in the world. It has been shown that factors such as fermentation methods, cultivar, geographical origin and season can affect the biochemical composition of tea. In this study, the biochemical composition of green, oolong and black commercial tea samples from around the world was studied using a non-targeted method utilising reversed phase ultra high pressure liquid chromatography (UHPLC) and high resolution mass spectrometry. Principal component analysis of green, oolong and black tea extracts clearly showed that fermented tea can be resolved from non-fermented tea. When the non-targeted data were combined with the supervised multivariate technique, partial least squares discriminant analysis, the method was able to clearly distinguish ‘country of origin’ within green tea and to a lesser extent within a black tea sample set, plus provide indicative marker ions for the country of origin. Many of the significant components detected in this study are unknowns, emphasising the importance of un-biased non-targeted analytical techniques. This study highlights the potential efficacy of non-targeted UHPLC–mass spectrometry when combined with multivariate statistics to differentiate fermented from non-fermented tea and provide potential indicators of provenance of tea samples for further examination.

Microwaves and tea: new tools to process plant tissue for transmission electron microscopy

Optimizing sample processing, reducing the duration of the preparation of specimen, and adjusting procedures to adhere to new health and safety regulations, are the current challenges of plant electron microscopists. To address these issues, plant processing protocols for TEM, combining the use of polyphenolic compounds as substitute for uranyl acetate with microwave technology are being developed. In the present work, we optimized microwave-assisted processing of different types of plant tissue for ultrastuctural and immunocytochemical studies. We also explored Oolong tea extract as alternative for uranyl acetate for the staining of plant samples. We obtained excellent preservation of cell ultrastructure when samples were embedded in epoxy resin, and of cell antigenicity, when embedded in LR-White resin. Furthermore, Oolong tea extract successfully replaced uranyl acetate as a counterstain on ultrathin sections, and for in block staining. These novel protocols reduce the time spent at the bench, and improve safety conditions for the investigator. The preservation of the cell components when following these approaches is of high quality. Altogether, they offer significant simplification of the procedures required for electron microscopy of plant ultrastructure.

Effect of different types of tea on Streptococcus mutans: An in vitro study

If tea can be shown to have an inhibitory effect on the growth of Streptococcus mutans there can be a basis for using it as an agent for reducing caries. The aim of the study was to determine the effect of aqueous and organic extracts of three types of tea (green, oolong, and black tea) on the growth of S. mutans. In vitro study. Qualitative and quantitative phytochemical analysis of the three types of tea was done. Organic extracts of methanol and ethanol and aqueous extracts (50% and 100%) of tea were prepared. Fifty microliters of these extracts were inoculated into wells prepared on Mueller-Hinton agar plates that had been previously smeared with S. mutans. The agar plates were incubated at 37΀C for 24 hours. A similar procedure was followed using 0.2% chlorhexidine, which served as the positive control. Analysis of variance (ANOVA), post hoc Tukey test, Student's 't ' test (two-tailed, dependent), and Student's 't' test (two-tailed, independent) were used for analysis of the data. All the phytochemicals were found to be higher in oolong tea. Both aqueous and organic extracts of oolong tea showed greatest zones of inhibition, followed by green tea and black tea. Aqueous extracts of oolong and green tea showed greater zone of inhibition than chlorhexidine. All the three types of tea inhibited growth of S. mutans. The greatest inhibition was observed with aqueous extract of oolong tea. Oolong tea extracts (aqueous and organic) showed a greater inhibitory effect on the growth of S. mutans than the other tea extracts .

Proximate Composition, Total Phenolic Content, and Antioxidant Activity of Seagrape (Caulerpa lentillifera)

The proximate composition of seagrape (Caulerpa lentillifera) from culture ponds in Penghu, Taiwan was analyzed. The phenolic content and the antioxidant activities including the 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activity, ferric ion-reducing activity, hydrogen peroxide scavenging activity, and ferrous ion chelating (FIC) activity of the ethanolic extracts of dry seagrape samples using 2 drying methods of freeze drying and thermal drying were compared with the ethanolic extract of Oolong tea as a reference. The contents (dry weight basis) of carbohydrate, crude protein, crude lipid, crude fiber, and ash of seagrape obtained from culture ponds in Taiwan were 64.00%, 9.26%, 1.57%, 2.97%, and 22.20%, respectively. The total phenolic content (1.30 mg gallic acid equivalent [GAE]/g dry weight) of the ethanolic extract of thermally dried seagrape was significantly lower (P < 0.05) than that (2.04 mg GAE/g dry weight) of freeze-dried seagrape, and both were significantly lower than that (13.58 mg GAE/g dry weight) of Oolong tea. At the same phenolic content, the antioxidant activities of freeze-dried seagrape were significantly higher (P < 0.05) than those of thermally dried seagrape. Compared with Oolong tea, seagrape, irrespective of drying method used, generally had strong hydrogen peroxide scavenging activity; but it was weak in DPPH radical scavenging activity, ferric ion-reducing activity, and FIC activity. The antioxidant activity of seagrape and Oolong tea was significantly influenced by their phenolic contents. The proximate composition, total phenolic content, and antioxidant activity of seagrape (Caulerpa lentillifera) in Taiwan were determined in this research to indicate nutritionally of this edible seaweed to human health, and compared these results to previous studies.

The Effect of Green and Oolong Tea Extracts Supplementation on Body Composition in Wrestlers

The Effect of Green and Oolong Tea Extracts Supplementation on Body Composition in Wrestlers

Use of different buffers for detection and separation in determination of physio‐active components in oolong tea infusion by CZE with amperometric detection

With a view of simultaneous determination of physio-active ingredients in oolong tea infusion: sugars, amino acids, epigallocatechin gallate and ascorbic acid, a novel CZE with amperometric detection method was studied. Operated in a wall-jet configuration, 100 mmol/L NaOH was used in detecting cell to lead the electrocatalysis oxidation behaviors of the analytes on a 300 mum diameter copper-disc electrode (working electrode), while in separating capillary, a mild alkaline running buffer consisting in a mixture of 30 mmol/L borate and 40 mmol/L phosphates charged and carried analytes to detecting end. The methodology research was performed for system stability and suitability. Under the optimal CE conditions, analytes could be separated within moderate time period. Good linearity between peak area and concentration existed over three orders of magnitude; lower RSD and LOD were achieved. The oolong tea infusion was assayed and result was satisfactory.

Application of method of OTE staining of ultrathin sections based on example of microsporidia (Protozoa: Microsporidia)

A comparative analysis of ultrastructure of some organelles stained by different methods of staining of ultrathin sections has been performed using the example of intracellular parasites, i.e., microsporidia. The distinctive peculiarities are revealed and the advantages and disadvantages are substantiated of the traditional method of contrasting with uranyl acetate and the nontraditional method of contrasting using black Chinese tea extract, i.e., oolong tea extract (OTE). The OTE-staining method dies the basic intracellular structures of microsporidia, which is a matter of taxonomic significance; it also reveals additional layers of the polar filament with more distinct boundaries between them. However, traditional UA-staining better reveals some structures (membranes, layers of envelope of mature spores, structure of the rough endoplasmic reticulum, Golgi complex, nuclear chromatin) and provides for higher general contrast. The OTE solution is safe to use and can be longer kept in light at room temperature without losing its activity. However, the OTE-method is time-consuming. Hence, this staining method has both advantages and disadvantages. On the whole, it can be used as an alternative to the traditional staining with uranyl acetate.

A Novel Dietary Supplement Containing Multiple Phytochemicals and Vitamins Elevates Hepatorenal and Cardiac Antioxidant Enzymes in the Absence of Significant Serum Chemistry and Genomic Changes

A novel dietary supplement composed of three well-known phytochemicals, namely, Salvia officinalis (sage) extract, Camellia sinensis (oolong tea) extract, and Paullinia cupana (guarana) extract, and two prominent vitamins (thiamine and niacin) was designed to provide nutritional support by enhancing metabolism and maintaining healthy weight and energy. The present study evaluated the safety of this dietary supplement (STG; S=sage; T=tea; G=guarana) and assessed changes in target organ antioxidant enzymes (liver, kidneys and heart), serum chemistry profiles and organ histopathology in Fisher 344 rats. Adult male and female Fisher 344 rats were fed control (no STG) or STG containing (1X and 7X, 1X=daily human dose) diets and sacrificed after 2 and 4 months. Serum chemistry analysis and histopathological examination of three vital target organs disclosed no adverse influence on protein, lipid and carbohydrate profiles, genomic integrity of the liver and/or the tissue architecture. However, analysis of the most important antioxidant components in the liver, kidney and heart homogenates revealed a dramatic increase in total glutathione concentrations, glutathione peroxidase and superoxide dismutase enzyme activities. Concomitantly, oxidative stress levels (malondialdehyde accumulation) in these three organs were less than control. Organ specific serum markers (ALT/AST for the liver; CPK/AST for the heart; BUN/creatinine for kidneys) and the genomic integrity disclosed no STG-induced alteration. Some of the serum components (lipid and protein) showed insignificant changes. Overall, STG-exposed rats were more active, and the results suggest that STG exposure produces normal serum chemistry coupled with elevated antioxidant capacity in rats fed up to seven times the normal human dose and does not adversely influence any of the vital target organs. Additionally, this study reiterates the potential benefits of exposure to a pharmacologically relevant combination of phytochemicals compared to a single phytochemical entity.

A novel dietary supplement containing multiple phytochemicals and vitamins elevates hepatorenal and cardiac antioxidant enzymes in the absence of significant serum chemistry and genomic changes

A novel dietary supplement composed of three well-known phytochemicals, namely, Salvia officinalis (sage) extract, Camellia sinensis (oolong tea) extract, and Paullinia cupana (guarana) extract, and two prominent vitamins (thiamine and niacin) was designed to provide nutritional support by enhancing metabolism and maintaining healthy weight and energy. The present study evaluated the safety of this dietary supplement (STG; S, sage; T, tea; G, guarana) and assessed changes in target organ antioxidant enzymes (liver, kidneys and heart), serum chemistry profiles and organ histopathology in Fisher 344 rats. Adult male and female Fisher 344 rats were fed control (no STG) or STG containing (1X and 7X, 1X = daily human dose) diets and sacrificed after 2 and 4 months. Serum chemistry analysis and histopathological examination of three vital target organs disclosed no adverse influence on protein, lipid and carbohydrate profiles, genomic integrity of the liver and/or the tissue architecture. However, analysis of the most important antioxidant components in the liver, kidney and heart homogenates revealed a dramatic increase in total glutathione concentrations, glutathione peroxidase and superoxide dismutase enzyme activities. Concomitantly, oxidative stress levels (malondialdehyde accumulation) in these three organs were less than control. Organ specific serum markers (ALT/AST for the liver; CPK/AST/LDH for the heart; BUN/creatinine for kidneys) and the genomic integrity disclosed no STG-induced alteration. Some of the serum components (lipid and protein) showed insignificant changes. Overall, STG-exposed rats were more active, and the results suggest that STG exposure produces normal serum chemistry coupled with elevated antioxidant capacity in rats fed up to seven times the normal human dose and does not adversely influence any of the vital target organs. Additionally, this study reiterates the potential benefits of exposure to a pharmacologically relevant combination of phytochemicals compared to a single phytochemical entity.

Examination of electron stains as a substitute for uranyl acetate for the ultrathin sections of bacterial cells

Electron staining reagents were examined to find a possible substitute for uranyl acetate (UA) in electron microscopy of bacterial ultrathin sections. Four kinds of stains, platinum blue (Pt-blue), oolong tea extract (OTE), potassium permanganate (KMnO(4)) and phosphotungstic acid (PTA), were examined in comparison with UA either with or without post-staining with lead citrate (Pb). Electron microscopy was performed on sections from Spurr-embedded cells of a Gram-positive bacterium, Bacillus cereus NBRC 13597, and a Gram-negative bacterium, Escherichia coli NBRC 3301. Both Pt-blue and OTE showed staining similar to each other and to that of double staining with UA and Pb in B. cereus, while in E. coli the cytoplasmic membrane appeared less dense when compared with UA and Pb. KMnO(4) stained excessively to some extent, but showed images of the best contrast in the cytoplasmic membrane comparable with UA and Pb among the four reagents. PTA could stain the peptidoglycan layer but gave images of low quality for both bacteria. This study demonstrated that none of the reagents examined showed staining results of the same quality or better than the conventional method with UA and Pb. However, stains of Pt-blue, OTE and KMnO(4) could possibly be an alternative candidate for the UA according to the structure in question.

Quantitation of Chafurosides A and B in Tea Leaves and Isolation of Prechafurosides A and B from Oolong Tea Leaves

A procedure was developed for the quantitative determination of chafuroside A, a flavone C-glycoside with potent anti-inflammatory activity, and its regioisomer chafuroside B, as well as isovitexin and vitexin, by selected reaction monitoring liquid chromatography-tandem mass spectrometry (SRM LC-MS/MS) analysis. This method was successfully applied to commercial leaves of green tea, houji tea, oolong tea, and black tea. High levels of chafurosides A and B were found in oolong tea leaves that had been heated at >140 degrees C. Next, their precursors, prechafurosides A and B, were isolated from methanol extract of oolong tea leaves prepared from Shizu 7132, Camellia sinensis (L.) O. Kuntze, by partition with n-butanol and H2O and chromatography on Diaion SP-825, Sephadex LH-20, and ODS C-18, guided by assay of chafuroside formation. Prechafurosides A and B gave chafurosides A and B, respectively, in good yields when heated at 160 degrees C for 0.5 h. Solvolysis of prechafurosides A and B with pyridine and dioxane quantitatively afforded isovitexin and vitexin, respectively. On the basis of these results and physicochemical data (MS, UV, and NMR), prechafurosides A and B were concluded to be new flavone C-glycoside sulfates, isovitexin-2''-sulfate and vitexin-2''-sulfate, respectively.

Beneficial effects of oolong tea consumption on diet-induced overweight and obese subjects

To determine the anti-obesity effects of oolong tea on diet-induced overweight or obesity. A total of 8 g of oolong tea a day for 6 weeks was ingested by 102 diet-induced overweight or obese subjects. The body fat level of the subjects was determined at the same time by taking body weight, height and waist measurements. The thickness of the subcutaneous fat layer was also determined on the abdomen 3 cm to the right of the navel by the ultrasonic echo method. On the other hand, effects of oolong tea ingestion on plasma triglyceride (TG) and total cholesterol (TC) were determined. Inhibitions of pancreatic lipase by oolong tea extract and catechins in vitro were also determined. A total of 70% of the severely obese subjects did show a decrease of more than 1 kg in body weight, including 22% who lost more than 3 kg. Similarly, 64% of the obese subjects and 66% of the overweight subjects lost more than 1 kg during the experiment, and the subcutaneous fat content decreased in 12% of the subjects. The correlation between weight loss and subcutaneous fat decrease in men (r=0.055) was obviously lower than that in women (r=0.440, P<0.01). Body weight loss was signifificantly related to the decrease of the waist size in men (r=0.730, P<0.01) and women (r=0.480, P<0.01). Also, the correlation between subcutaneous fat reduction and decreased waist size was signifificant in women (r=0.554, P<0.01), but not in men (r=0.050, P>0.05). Moreover, the plasma levels of TG and TC of the subjects with hyperlipidemia were remarkably decreased after ingesting oolong tea for 6 weeks. In vitro assays for the inhibition of pancreatic lipase by oolong tea extract and catechins suggest that the mechanism for oolong tea to prevent hyperlipidemia may be related to the regulative action of oolong tea catechins in lipoprotein activity. Oolong tea could decrease body fat content and reduce body weight through improving lipid metabolism. Chronic consumption of oolong tea may prevent against obesity.

A comparative study of antioxidant activity between black tea from Rwandan highlands with green and oolong teas from China

Antioxidant activity of the aqueous extract of black tea from Rwandan highlands was compared with that of green and oolong teas from China and was determined by use of 2, 2-diphenyl-1-picrylhydryzyl (DPPH) radical scavenging method. The higher the concentration of the extract, the higher was free radical scavenging activity. Antioxidant activity of the teas extracts decreased in the order: green > oolong > black. The extraction methods were hot water method, methanolic method and ethyl acetate method. The hot water method gave the highest yield in all teas extraction methods. The phenolic content of all teas extracts were analysed according to the Folin?ciocalteu method and were expressed as mg gallic acid equivalents/g of dry extract. Green tea, oolong tea and black tea extracts showed the highest phenolic content of 162, 144 and 124 mg GAE/g dry extract, respectively.

Structural Determination and DPPH Radical-Scavenging Activity of Two Acylated Flavonoid Tetraglycosides in Oolong Tea (Camellia sinensis)

Two major acylated flavonoid tetraglycosides were isolated from the methanol extract of oolong tea. Their structures were elucidated by spectroscopic methods as quercetin 3-O-[2(G)-(E)-coumaroyl-3(G)-O-beta-D-glucosyl-3(R)-O-beta-D-glucosylrutinoside] (1) and kaempferol 3-O-[2(G)-(E)-coumaroyl-3(G)-O-beta-D-glucosyl-3(R)-O-beta-D-glucosylrutinoside] (2). Compounds 1 and 2 exhibited scavenging activity against DPPH radical with EC(50) values of 30.5 and 487.2 microM, respectively.

Oolong tea extract as a substitute for uranyl acetate in staining of ultrathin sections

In conventional transmission electron microscopy, uranyl acetate staining is used to enhance the cellular components. However, uranyl acetate is considered a radioactive material that is very toxic if ingested or inhaled and subject to restrictions in many countries. In an attempt to introduce a substitute for uranyl acetate, we evaluated oolong tea extract (OTE) for staining of ultrathin sections. Tissue sections from normal rat liver representing an ideal model organ were processed according to a routine electron microscopic fixation and embedding procedure. Serial ultrathin sections were cut and processed with either routine double electron staining or 0.2% OTE staining for 30-40 min at room temperature followed by lead citrate staining (OTE staining method). Transmission electron microscopy observations revealed that all sub-cellular structures in hepatocytes were clearly visible with OTE staining and the quality of staining was highly compatible with those of routine double staining methods. It is suggested that OTE could be used as a non-radioactive and hazard-free substitute for uranyl acetate in transmission electron microscopy staining.

Polyphenolic Profile and Antioxidant Activities of Oolong Tea Infusion under Various Steeping Conditions

The phenolic profile and antioxidant activities of oolong tea extract wereinvestigated after tea was steeped in 90 or 100 oC water for 3 or 10 min. The extractionyield increased with increasing temperature and extended steeping time. However, highertemperature and longer time (100 oC water for 10 min) led to loss of phenolics. Theaqueous extract of oolong tea (AEOT) at 100 oC for 3 min exhibited the strongestantioxidant activity. The major polyphenolic components of the AEOT were identified as(-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin-3-gallate (ECG). The two major catechins (EGC and EGCG) in the tea infusion contributedsignificantly to the investigated antioxidant activities [i.e., the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging and superoxide radical scavengingactivities] with high correlation values in r = 0.9486 and 0.9327 for the EGC and r =0.9592 and 0.8718 for the EGCG, respectively.