Characterization of anthocyanins in Kenyan teas: Extraction and identification

Characterization and quantification of anthocyanins in selected tea cultivars processed into black (aerated) and green (unaerated) tea products was carried out in this study. The anthocyanins were extracted from tea products processed from a number of newly bred purple leaf coloured Kenyan tea cultivars (Camellia sinensis) using acidified methanol/HCl (99:1 v/v). Extracted anthocyanins were purified by C₁₈ solid phase extraction (SPE) catridges and characterised by HPLC-UV-Visible. They were identified according to their HPLC retention times, elution order and comparison with authentic standards that were available. Total monomeric anthocyanins were determined by the pH-differential method. Although the tea cultivars gave different yields of anthocyanins, the unaerated (green) teas had significantly (p ? 0.05) higher anthocyanin content than the aerated (black) teas. This was attributed to the degradation of anthocyanins by polyphenol oxidase products (catechin O-quinones) formed during the auto-oxidation (fermentation) process of black tea manufacture. Of the six most common natural anthocyanidins, five were identified in the purified extracts from purple leaf coloured tea, in both aerated (black) and unaerated (green) teas namely; delphinidin, cyanidin, pelargonidin, peonidin and malvidin. The most predominant anthocyanidin was malvidin in both tea products. In addition, two anthocyanins namely, cyanidin-3-O-galactoside and cyanidin-3-O-glucoside were also identified. Tea catechins were also identified in the tea products derived from the purple coloured tea cultivars namely, epigallocatechin (EGC), catechin (+C), epicatechin (EC), epigallocatechin gallate (EGCG), and epicatechin gallate (ECG). Correlation between the total catechins versus the total anthocyanins and anthocyanin concentration in unaerated teas revealed significant negative correlations (r = −0.723^∗ and r = −0.743^∗∗, p ? 0.05 and p ? 0.01, respectively). However, in aerated (black) tea the correlations were insignificant (r = −0.182 and r = −0.241, p > 0.05).     

Green tea preparation and its influence on the content of bioactive compounds

The effect of different extraction conditions and storage time of prepared infusions on the content of bioactive compounds of green teas and their antioxidant capacity were investigated. The content of total phenols, total flavonoids and total non-flavonoids in green teas was determined spectrophotometrically, while 7 flavan-3-ols, 6 phenolic acids and 3 methylxanthines were identified and quantified by using high performance liquid chromatography (HPLC–PDA). Among the tested green teas bagged green tea Twinings of London was recognized as the richest source of phenolic compounds (3585 mg/L GAE of total phenols). The most abundant phenolic constituents of green tea were flavan-3-ols, of which EGCG was prevailing in all teas (94.54–357.07 mg/L). The highest content of caffeine, as the most abundant methylxanthine, was determined in powdered green tea. The findings of this investigation suggest that extraction efficiency of studied bioactive compounds from green tea depends on the extraction conditions and that maximum extraction efficiency is achieved during aqueous extraction at 80 °C, for 5′ (powder), 15′ (bagged) and 30′ (loose leaf). In order to determine the antioxidant capacity of teas the DPPH, ABTS and FRAP assays were applied. Regardless of the extraction conditions all green teas exhibited significant antioxidant capacity in vitro, which was in correlation with their phenolic content, confirming that green tea is one of the best dietary sources of antioxidants.     

Daily green tea extract supplementation reduces prothrombotic and inflammatory states in dialysis patients

Cardiovascular disease (CVD) remains the most common cause for excess morbidity and mortality in patients with chronic kidney disease (CKD) and end stage renal disease (ESRD) under chronic dialysis. ESRD patients have increased oxidative stress and endothelial dysfunction alongside increased levels of inflammation related proteins, which has prompted the exploration of anti-inflammatory and antioxidant treatments to improve outcomes. As green tea is increasingly well recognized for its antioxidant properties, we probed the effect of consumption of 1 capsule daily of green tea as a commercially available, decaffeinated green tea capsule (1 g, catechin content 68 mg) for 6 months on fibrinogen and inflammation in dialysis patients. Chronic hemodialysis patients (N = 25) were recruited and fibrinogen, FDP-D-dimer, high sensitivity (hs) CRP and the mononuclear cell protein expression of p22^phox, were assessed before, i.e. baseline and after 6 months of ingestion of 1 green tea capsule per day. After 6 months of daily green tea capsule ingestion, dialysis patients showed reduced protein expression of p22^phox (p < 0.0001), reduced hsCPR (p = 0.032) and fibrinogen (p = 0.022) levels and increased FDP-D-dimer (p = 0.0019) compared to their values at baseline. These results document lower oxidative stress and inflammation with green tea capsule ingestion and suggest a likely positive impact of green tea treatment on the atherosclerotic process of ESRD patients under dialysis.     

Comparison of the antioxidant capacity and the antimicrobial activity of black and green tea

Tea is a common beverage. The green tea is preferentially recommended for its strong antioxidant properties and also for its antimicrobial activity. The antioxidant capacities of 30 samples (black and green tea) were determined by the chemiluminescent Trolox equivalent antioxidant capacity (TEAC) determination. The average value of TEAC of the non-fermented (green tea) and semi-fermented tea samples was 1.43 mM and the average value of TEAC of the fermented teas (black tea) samples was 1.43 mM. All samples were stored in freezer (?20 °C) and the TEAC determination was repeated after a year. The average values of TEAC of non-fermented and semi-fermented tea samples were twofold lower in comparison to fermented tea samples and only 20% of average value of TEAC of the fresh tea infusion. The parallel determinations of minimal inhibitory concentration (MIC) on gram-positive and gram-negative bacterial strains (Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli) were done. Also the MIC was possible to determine after a year. The assumed prevailing antioxidant and antimicrobial activities of non-fermented tea infusions were not confirmed as well as the dominant antioxidant and antimicrobial properties of specific type of tea infusion.     

White and green tea polyphenols inhibit pancreatic lipase in vitro

Green, white and black teas were assayed for inhibition of pancreatic lipase activity in vitro. White tea proved to be more effective than green tea with black tea showing little inhibition even at 200 μg GAE/ml. The EC₅₀ values for inhibition were 22 μg/ml for white tea and 35 μg/ml for green tea; both easily achievable from normal infusions of tea. Liquid chromatography-mass spectroscopy analysis showed that white and green teas had essentially equal amounts of flavan-3-ols but green tea had higher levels of flavonols. White tea had higher levels of 5-galloyl quinic acid, digalloyl glucose, trigalloyl glucose and the tannin, strictinin.After chromatography on Sephadex LH-20, the main inhibitory fraction was enriched in strictinin and fractions enriched in other components were ineffective. This suggests that strictinin content may be crucial for inhibition of pancreatic lipase. However, the possibility of synergies between the polyphenols cannot be disregarded.     

Green tea from purple leaf coloured tea clones in Kenya- their quality characteristics

The Kenyan tea industry wishes to diversify its tea products, and in line with this, anthocyanin – rich teas were developed at the Tea Research Foundation of Kenya. These teas have purple-coloured leaves and the green colour is masked. In total, 12 accessions of the purple leaf coloured teas and 2 standard tea varieties were studied. Clones Hanlu and Yabukita are Chinese and Japanese tea varieties, respectively, known for good green tea, and they were used as reference standards. Little if any research had been done to characterize the quality of these purple leaf coloured teas and this study investigated their total polyphenols (TPP), catechins, caffeine, gallic acid and theanine. These are the major green tea quality parameters. Results showed that the new Kenyan tea clones had higher total polyphenols than had the reference standard tea varieties, which had 17.2% and 19.7% while the lowest among the Kenyan clones was 20.8%. On catechin quality index, K-purple and TRFK 91/1 showed high index values of 15.9 and 13.3, respectively, while clones TRFK 83/1 and 73/5 showed low index values of 0.74 and 1.0, respectively. Hanlu had the highest caffeine level with 2.42% while clones TRFK KS 3, TRFK KS 2 and TRFK 83/1 had relatively high caffeine levels among the purple leaf coloured teas, with 2.33%, 2.22% and 2.21%, respectively. Clone TRFK 73/5 had the lowest caffeine content, with 1.16%. Theanine analysis showed that most purple leaf coloured teas had more theanine than had the reference standard clones, except TRFK 83/1 and K-purple, which were lower than the reference standard clones. The implication of the green tea chemical quality parameters is also discussed. It is concluded that all the studied clones/varieties have above the minimum 14% of total polyphenols. Clones K-purple and TRFK 91/1 showed high green tea quality indices with the latter doubling with high levels of theanine; hence its highly recommended for green tea manufacture.     

Relationship between photon emission and chemopreventive potential of tea

Photon emission from tea (610–670 nm) in the H₂O₂/KHCO₃/MeCHO system and the utility of the photon detection system in tea evaluation were investigated. Photon intensity of tea depended on manufacturing method as follows: green tea (1202 ± SD 173.51 cd/m²) > oolong tea (834 ± SD 237.44 cd/m²) > black tea (222 ± SD 87.65 cd/m²). Photon intensity corresponded with polyphenol content (r²=0.8810) rather than catechin content (r²=0.7759) and showed a high correlation with chemopreventive activities against H₂O₂ (r²=0.7516), O₂⁻ (r²=0.7998) and DPPH radical (r²=0.7516). Photon intensity from green tea leaves at each manufacturing process step gave the same decreasing curve as DPPH radical scavenging activity. Chemiluminescence of tea, which gives information on the polyphenol content and chemopreventive potential, is a useful technique for tea evaluation.     

A comparative study of the phenolic compounds and the in vitro antioxidant activity of different Brazilian teas using multivariate statistical techniques

A total of 51 Brazilian teas from the species Camellia sinensis, Peumus boldus, Matricaria recutita, Baccharis trimera, Cymbopogon citratus, Pimpinella anisum, Mentha piperita, and Ilex paraguariensis were analyzed in terms of phenolic compounds, color and in vitro antioxidant capacity using ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays. Data were processed using principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). Significant (P < 0.01) correlations between antioxidant activity measured by DPPH and FRAP assays with the total phenolic compounds (r = 0.87; r = 0.90, respectively) and flavonoids (r = 0.79; r = 0.77, respectively) were attained. The compounds that displayed significant (P < 0.05) correlations with the antioxidant activity were gallic acid, catechin, epicatechin, procyanidin B2, quercetrin, and caffeine. PCA was a suitable approach to check for similarities among tea samples, explaining up to 50% of data variability. Four groups were suggested using HCA, in which cluster 3 showed the highest content of total phenolic compounds, flavonoids, antioxidant activity, gallic acid, and caffeine. All samples included in this group were from C. sinensis. The overall classification capacity obtained by LDA was 82.00%, in which 100% of samples from I. paraguariensis, C. citratus, M. recutita, and P. boldus were adroitly classified, while 60% of teas from P. anisum, 80% of M. piperita teas, and 88.24% of C. sinensis teas were correctly classified.     

The in vivo antioxidant and antifibrotic properties of green tea (Camellia sinensis,Theaceae)

The in vivo antioxidant and antifibrotic properties of green tea (Camellia sinensis, Theaceae) were investigated with a study of carbon tetrachloride (CCl₄)-induced oxidative stress and hepatic fibrosis in male ICR mice. Oral administration of green tea extract at doses of 125, 625 and 1250 mg/kg for 8 weeks significantly reduced (p < 0.05) the levels of thiobarbituric acid-reactive substances (TBARS) and protein carbonyls in the liver by at least 28% compared with that was induced by CCl₄ (1 mL/kg) in mice. Moreover, green tea extract administration significantly increased (p < 0.05) the activities of catalase, glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) in the liver. Our study found that oral administration of green tea extract prevented CCl₄-induced hepatic fibrosis, as evidenced by a decreased hydroxyproline level in the liver and a reduced incidence of hepatic fibrosis by histological observations. These results indicate that green tea exhibits potent protective effects against CCl₄-induced oxidative stress and hepatic fibrosis in mice by inhibiting oxidative damage and increasing antioxidant enzyme activities.     

Tea fluoride concentration and the pediatric patient

The purpose of this study was to measure the fluoride concentrations of various commercially available tea infusions, with a specific focus on risk of fluorosis. 100 ml infusions of 43 different tea brands were kept at a constant temperature of 85 °C and measured for fluoride concentration at 5, 15, 30, 60, and 120 min using a fluoride ion-specific electrode and millivolt meter. After 5 min at 85 °C mean fluoride concentration, in μg/ml with standard deviation, was 2.08 ± 1.24 for caffeinated tea infusions, 4.38 ± 0.97 for decaffeinated tea infusions, and 0.05 ± 0.02 for herbal teas. Caffeinated teas derived from the traditional source, Camellia sinensis, demonstrated significantly higher concentrations of fluoride than herbal teas (p < 0.01). Furthermore, decaffeinated teas demonstrated significantly higher concentrations of fluoride than caffeinated teas (p < 0.01). Some tea infusions may place a pediatric patient at higher risk for fluorosis if consumed as the primary source of hydration.     

Evaluation of bioactive properties of Indian carrot (Daucus carota L.): A chemometric approach

Sixteen Indian commercial carrot cultivars were analysed for variations in β-carotene, total phenolics, total flavonoids, total monomeric anthocyanin and antioxidant activity. Antioxidant activity was measured using four in vitro assays viz. ferric reducing antioxidant power (FRAP), cupric reducing antioxidant power (CUPRAC), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and Trolox equivalent antioxidant capacity assays (TEAC). Additionally six colour attributes were evaluated. Among carrot cultivars, significant differences (p < 0.05) were obtained with respect to antioxidant composition and antioxidant activity. Total phenols and total flavonoids varied from 7.98 to 291.48 mg/100 g fresh weight (fw) and 3.00 to 111.70 mg/100 g fw respectively. Chemometric tools like principal component analysis (PCA) and agglomerative hierarchical clustering (AHC) were applied to understand possible classification Indian carrot cultivars based on colour properties, bioactive antioxidant compounds and antioxidant potentiality. PCA revealed that the first two components represented 92.9% of the total variability in the total variation. AHC classified cultivars into four main groups on the basis of the measured parameters. Black coloured genotype was found to be rich source of phenols, flavonoids and anthocyanin with very high antioxidant activity. Orange cultivars were found to be rich sources for β-carotene compared to red & black cultivars.     

Effects of catechin-enriched green tea beverage on visceral fat loss in adults with a high proportion of visceral fat: A double-blind,placebo-controlled,randomized trial

The effects of catechin-enriched green tea on Chinese adults with a high proportion of abdominal visceral fat were evaluated. Subjects (118) were randomly assigned to consume daily a beverage containing 609.3 mg catechins and 68.7 mg caffeine or a control beverage for 12 weeks. Abdominal fat area, body weight and composition were measured at week 0, week 8, and week 12. One hundred and four subjects completed the trial. Average visceral fat area, body weight, and body fat were reduced significantly by catechin-enriched green tea treatment but these effects were not seen in the control group with per-protocol sets analysis. The decrease at week 12 in the visceral fat area in the catechin group was greater than that in the control group (P = 0.04). Thus, consumption of the catechin-enriched green tea beverage for 12 weeks induced visceral fat loss in Chinese adults with a high proportion of abdominal visceral fat.     

Characterization of the antioxidant functions of flavonoids and proanthocyanidins in Mauritian black teas

Tea drinking is associated with an improved antioxidant status in vivo which may contribute to the lowering of the risk of certain types of cancer, coronary heart disease and stroke. The polyphenolic bioactive composition and the antioxidant properties of Mauritian commercial black and fresh tea leaves were evaluated. Hot water infusates contained high levels of total phenols, total proanthocyanidins and total flavonoids. The concentrations of individual compounds, (+)-catechin, (−)-epicatechin, (−)-epicatechin 3-gallate, epigallocatechin, (−)-epigallocatechin 3-gallate, gallic acid, and procyanidin dimers B1 and B2 were high. The ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays were used to assess the antioxidant potential of tea infusates with the following order of potency: Ouvagalia tea > Buccaneer’s choice > Black Label > Red Label > Extra > Corson > Chartreuse > La Flora > 3-Pavillons. Linear regression analyses indicated high correlation coefficient with total proanthocyanidin (TEAC r = 0.96 and FRAP r = 0.95) and total phenol contents (TEAC r = 0.90 and FRAP r = 0.92) in infusates. Catechins and gallic acid significantly contributed to the overall antioxidant capacity of black tea extracts. In general, the fresh tea leaves had high levels of total phenols, total flavonoids, total proanthocyanidin and exhibited greater antioxidant potentials when compared with black teas. Thus Mauritian black teas and fresh tea leaves can be rich sources of polyphenolic compounds and antioxidants, which may be highly relevant to the maintenance of normal health and disease management, an observation that has led to the commencement of a clinical trial study to assess cardiovascular health in Mauritius.     

Milk enhances intestinal absorption of green tea catechins in in vitro digestion/Caco-2 cells model

The effect of milk on the absorption of polyphenols is still controversial so far. In order to determine the impact of milk addition on green tea catechins bioaccessibility and intestinal absorption an in vitro digestion/Caco-2 cell model was applied. Green tea extract (GTE) was solubilized in distilled water at 23 °C and 100 °C, combined with skimmed milk (GTE + 10% milk and GTE + 25% milk) and subjected to simulated gastric and intestinal digestion, followed by transepithelial absorption in Caco-2 cells monolayers. In the mixture with milk, gallated catechins: ECG and EGCG showed binding to milk proteins while EC and EGC seemed to have weaker affinity. Catechins were stable during gastric incubation and very sensitive to intestinal digestion. Bioaccessibility of green tea catechins brewed at 100 °C was higher than brewed at 23 °C. Catechins from digested GTE with 10% and 25% milk exhibited enhanced intestinal permeability in Caco-2 model in comparison to non-digested GTE and digested GTE without milk. Apparent permeability coefficients (P_app) of EGCG and ECG in digested GTE with 25% milk were significantly higher compared to those in GTE with 10% milk, and amounted to 2.41 × 10^− 6 cm/s and 1.39 × 10^− 6 cm/s. The recoveries of all catechins in GTE with milk in Caco-2 cells after 2 h incubation were significantly higher than that without milk. To summarize, these data suggest that milk addition may increase catechin bioavailability by enhancing their transepithelial absorption and uptake from green tea extract.     

Influence of addition of green tea and green coffee extracts on the properties of fine yeast pastry fried products

This study investigated the influence of antioxidants of green tea aqueous extract (GTE) and green coffee aqueous extract (GCE) in concentrations of 0.25, 0.5 and 1 g·100 g^? 1 on the nutritional properties of fine yeast pastry fried products such as donuts. Yeast donuts were made according to the traditional processing technology. In fried donuts physical properties (water activity, pH, hardness and color with the use of instrumental methods) as well as sensory properties were established. Moreover, quality of fat extracted from donuts (composition of fatty acids and peroxide value), content of acrylamide, composition of polyphenols and antioxidant activity were analyzed. Obtained extracts of GTE and GCE contained 26 and 41% of polyphenols, respectively, and the degree of polyphenol degradation during production of donuts was less when the dilution in dough was greater. Both tests indicated that the highest antioxidant activity had donuts with the highest analyzed addition of extract, however depending on the applied test or GTE or GCE had better antioxidant properties. Fatty acid composition was the most beneficial when the addition of GTE and GCE was on a level of 0.25 and 0.5 g·100 g^? 1, respectively. In fried donuts relatively low amounts of acrylamide were obtained, amounting to 18–46 μg·kg^? 1. Only the lowest addition of GTE and the highest addition of GCE caused an increase of acrylamide content in donuts, while all other levels of added extracts caused a decrease in the content of formed acrylamide.     

Antioxidant packaging with encapsulated green tea for fresh minced meat

A novel approach to incorporate green tea extract into polyethylene by extrusion technology has been studied. Green tea entrapped by inorganic capsules was incorporated into melted material and extruded without compromising its quality. The shelf-life of fresh meat from two types of active packaging was significantly extended for 3 days compared to blank samples. Significant difference was observed after 9th day of study in case of results of CIE L*a*b*, MetMb and organoleptic assay. Migration study of antioxidants from the materials was also performed by UHPLC-MS/TQ using food simulants. Amount of migrated catechins was in the range between 6.3 ± 3.3 and 228.4 ± 15.2 μg/kg (ratio 6:1). Regression coefficients (R) between 0.9925 and 0.9989 were obtained. Minimum LOD (0.001 μg/g) and LOQ (0.004 μg/g) were obtained for epicatechin gallate and catechin gallate while maximum LOD (0.057 μg/g) and LOQ (0.191 μg/g) were obtained for catechin.     

Formulation with ascorbic acid and sucrose modulates catechin bioavailability from green tea

In order to investigate the impact of common food ingredients on catechin absorption, green tea (GT) extract (50 mg) was formulated plain, with sucrose (GT + S), with ascorbic acid (GT + AA) and with sucrose and ascorbic acid (GT + S + AA). Bioavailability and bioaccessibility were assessed in Sprague Dawley rats and an in vitro digestion/Caco-2 cell model respectively. Absorption of epigallocatechin (EGC) and epigallocatechin gallate (EGCG) was significantly (P < 0.05) enhanced in GT + S + AA formulations (AUC_0–6 h = 3237.0 and 181.8 pmol h/L plasma respectively) relative to GT control (AUC_0–6 h = 1304.1 and 61.0 pmol h/L plasma respectively). In vitro digestive recovery was higher for EGC and epicatechin (EC) (～51–53%) relative to EGCG and epicatechin gallate (ECG) (<20%) and was modestly enhanced in GT + S and GT + S + AA formulations. Accumulation of EGC, EGCG and ECG by Caco-2 cells was significantly (P < 0.05) higher from GT + S + AA compared to other formulations while retention of catechins was enhanced in presence of ascorbic acid. These data suggest that formulation with sucrose and ascorbic acid may improve catechin bioavailability by enhancing bioaccessibility and intestinal uptake from tea.     

Human exposure assessment of fluoride from tea (Camellia sinensis L.): A UK based issue?

Fluoride concentrations in UK tea, including the leading supermarket economy labelled products, were determined. Fluoride ranged from 93 to 820 mg/kg in the products and 0.43 to 8.85 mg/L in the infusions. The UK supermarket economy teas contained elevated fluoride, ranging from 3.60 to 7.96 mg/L in a 2 minute brewing infusion, comparable to Chinese brick tea, indicating the use of mature leaves in their manufacture. Considering the dietary reference intake (DRI) of 4 mg/day of fluoride for an adult consuming 1 L of tea, prepared from an economy tea, containing 6.0 mg/L fluoride, 75–120% of the DRI fluoride is available for absorption by the human system in the presence of food, increasing to 150% when fasting. Excess fluoride in the diet can lead to detrimental health effects such as fluorosis of the teeth and skeletal fluorosis and consuming economy branded tea will lead to exposure.     

Yerba mate tea (Ilex paraguariensis): Phenolics,antioxidant capacity and in vitro inhibition of colon cancer cell proliferation

Mate tea (MT) is a rich source of phenolic compounds that vary depending on geographical origin and mode of preparation. Total phenolic concentration and antioxidant capacity of Mate tea (Ilex paraguariensis) products were determined in this work. In addition, a representative MT was tested for in vitro inhibition of human colon carcinoma cell proliferation. Total polyphenol concentration, was measured using Folin–Ciocalteau method, ranged from 90 to 176 mg gallic acid eq (GAE)/g dry leaves (DL) in traditional MT and from 40 to 113 mg GAE/g DL in MT added with other flavouring ingredients. It was estimated that a cup of tea (250 ml) containing one teaspoon (5 g) of instant MT could provide an average intake of 1.5 g GAE. Fresh tea (FT) from Mate leaves displayed high antioxidant capacity (85 ± 1%) and preferentially inhibited 50% of net growth of human colorectal adenocarcinoma cells CaCo-2 (GI₅₀ = 1.0 ± 0.03 μg/ml) and HT-29 (GI₅₀ = 105.2 ± 15.2 μg/ml) when compared with the CCD-33Co normal colon fibroblast cell line (GI₅₀ > 300 μg/ml). MT inhibited in vitro colon cancer cell proliferation possibly mediated via pro-oxidant activities, therefore represents a potential source of chemopreventive agents that deserve further investigation.     

The phenolic profiles and antioxidant activity in different types of tea

Phenolics are suggested to be the major bioactive compounds responsible for the health benefits of tea. Seven types of tea were extracted using boiling water. The extraction kinetics was investigated. To more fully characterise the antioxidant profiles and possible associated health benefits of these tea types, the total water‐soluble solid content, phenolics, flavonoids, and antioxidant and antiproliferative activities were quantified. Green tea leaves (GTL) were found to have the highest phenolic content (128.7 ± 1.7 mg g^?1, P < 0.05), followed by teas of decaffeinated green tea bag (dGTB), green tea bag (GTB), black tea bag (BTB), decaffeinated BTB, black tea leaves and oolong tea leaves (OTL). Among the three leaf teas, GT displayed the greatest antioxidant activity (4850.2 ± 60.7 μmol g^?1, P < 0.05), followed by black tea (BT) and oolong tea (OT). As for the four bag teas, decaffeinated GT possessed the strongest antioxidant activity (4431.1 ± 335.0 μmol g^?1, P < 0.05), followed by GT, BT and decaffeinated BT. The results display that phenolic/flavonoid content well correlated with antioxidant activity. Proliferation of three human cancer cells was significantly inhibited in a dose‐dependent manner after exposure to some tea extracts. This may influence consumers in selecting the type of tea and tea brewing times, exhibiting greater health benefits.