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Background: Tea (Camellia sinensis) infusions are widely consumed beverages with numerous health benefits. However, physiological and molecular responses mediating these activities are poorly understood. Method: Three replicates of 4TI cancer cell suspension (2.0 x 105 cells/ml) were challenged in vitro with various concentrations of green, black and purple tea infusions to asseses their cytoxicity and associated differentially expressed genes in the cells. Inhibitory activity was tested by using serial dilutions of respective tea infusions in a 96 well ELISA plate. Results: Green tea had the highest inhibition on 4TI cells proliferation at a concentration of IC50 = 13.12 µg/ml. Further analysis of the 4TI cancer cell line treated with tea using 454 pyrosequencing generated 425,696 reads with an input mean length of 286.54. Trimmed sequences were imported on a CLC genomic workbench v7.03 and annotated on a reference mouse genome (Mus musculus strain C57BL/6 J). Results revealed a differential expression of apoptosis related genes in the transcriptome. Casp8, Casp9, Casp3, Casp6, Casp8AP2, Aifm1, Aifm2 and Apopt1 genes were significantly upregulated indicating the process of apoptosis was initiated and executed. Conclusion: These findings on caspases offer valuable information on the mechanism of tea as an anticancer agent and will contribute to further research in future novel treatments. [ABSTRACT FROM AUTHOR]

Abstract: Reliable and quantifiable green leaf parameters for predicting black tea quality potential of tea bushes at the single bush stage are necessary to shorten tea breeding and clonal selection programmes. Green leaf flavan-3-ols (catechins) and plain black tea quality of 11 popular Kenyan clones were determined. The individual green leaf flavan-3-ols, and all the black tea quality parameters and sensory evaluations, except total flavan-3-ols were significantly different. The green leaf epigallocatechin gallate (EGCg) levels significantly correlated with black tea total theaflavin (r =0.749, P ⩽0.007), liquor brightness (r =0.898, P ⩽0.0001) levels and Taster B (r =0.595, P ⩽0.051) sensory evaluations, and negatively with thearubigins (r =−0.652, P ⩽0.027), while green leaf epicatechin (EC) levels correlated positively with thearubigins (r =0.694, P ⩽0.016) and negatively with theaflavin digallate equivalent (r =−0.751, P ⩽0.007), and sensory evaluation by Taster A (r =−0.785, P ⩽0.003) and Taster B (r =−0.679, P ⩽0.020). Thus, high levels of EGCg and low levels of EC in tea green leaf can be used as indicators of plain black tea quality potential of tea plants. The sum of gallated flavan-3-ols correlated significantly and positively with theaflavin digallate equivalent (r =0.669, P ⩽0.022) levels, but negatively correlated with the black tea thearubigins (r =−0.582, P ⩽0.052). The sum of trihydroxyflavan-3-ols (gallocatechins) positively correlated with brightness (r =0.750, P ⩽0.007), and sensory evaluation by Taster A (r =0.656, P ⩽0.026), but negatively with thearubigins (r =−0.641, P ⩽0.031). However, the sum of dihydroxyflavan-3-ols (simple catechins) correlated positively with thearubigins (r =0.716, P ⩽0.012) and negatively with total theaflavins (r =−0.6694, P ⩽0.022), theaflavin digallate equivalent (r =−0.631, P ⩽0.035), brightness (r =−0.843, P ⩽0.001), Taster A (r =−0.775, P ⩽0.004) and Taster B (r =−0.638, P ⩽0.032) sensory evaluation. The ratios of trihydroxyflavan-3-ols to dihydroxyflavan-3-ols correlated positively with brightness (r =0.678, P ⩽0.020) and sensory evaluation of Taster A (r =0.667, P ⩽0.023), but negatively with thearubigins (r =−0.697, P ⩽0.015). In addition to green leaf high levels of EGCg and low levels of EC, high levels of the sum of gallated catechins, trihydroxyflavan-3-ols, and the ratio of trihydroxyflavan-3-ols to dihydroxyflavan-3-ols are parameters in green tea leaf that may be used in predicting plain black tea quality potential of Kenyan tea clones. [Copyright &y& Elsevier]

Objective: To examine the influence of variety and brewing technique on the catechins, theaflavins, and thearubigins in black tea using published data.Methods and materials: Differences due to tea variety were examined by comparing values for the characteristic flavanols that are responsible in part for the distinct flavors of the various teas. These included catechins, theaflavins, and thearubigins in varieties of blended teas (from several regions) and unblended teas (from only one region) in the published literature. Total catechins, theaflavins, and thearubigins were calculated per 180 mL serving of tea for teabags of different weights. For brewing techniques, calculations by infusion strength of 1.25% (2.25 g teabag per 180 mL water) and by an illustrative extraction efficiency were compared to analytical results at a 2 min brewing time.Results: The unblended teas (e.g. Assam, Kenya, Ceylon, China, and Darjeeling) varied greatly in the amount and pattern of their flavonoid content. Compared to unblended teas, the blended teas were lower in total catechins and mid-range in theaflavins. Differences in flavonoid content per tea serving were the result of tea variety, weight of tea used, and, to a lesser extent, brewing technique.Significance: Tea variety, weight of tea or teabag, and brewing techniques all affect estimates of flavonoid intake. Databases that include flavonoid data for different varieties of teas and different brewing techniques will be useful for dietary assessment studies. For research purposes it would be helpful to list tea type (black, green, oolong, pu’er), unblended or blended, and if data suffice, for unblended by region (Assam, China, Darjeeling) and for blended by name (Earl Gray, English Breakfast). More research is needed on the effects of brewing techniques so accurate formulas can be developed to determine flavonoid content. [Copyright &y& Elsevier]