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Optimization of Aeration Time in the Development Theaflavin-3,3’-Digallate Rich Black Teas  [PDF]
Samuel Kimutai, Thomas Kinyanjui, John Wanyoko, Francis Wachira, Stephen Karori, Augustine Muthiani
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.619295
Abstract: This study involved the selection of 11 cultivars out of 201 screened cultivars of fresh green and purple coloured tea leaves for use in the manufacture of black teas with optimized antioxidant activities. Individual cultivars containing a combination of high leaf concentrations of the catechin fractions; epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) were used in the processing of theaflavin-3,3’ digallate (TF3) rich black tea. The black tea enrichment with TF3 was carried out through optimization of the processing conditions of each cultivar by varying the aeration times between 0 min and 80 min at an interval of 20 min. The differently processed teas were then assayed for the TF3 contents. The data analysis was carried out using the GENSTAT at p ≤ 0.05. The optimal processing time for Ejulu, TRFK 832/8, TRFK 831/11, TRFK 824/1, SC 31/37, SC 12/28, K-Purple and TRFK 6/8 was found to be 60 min while that of TRFK 301/6, TRFK 301/3 and TRFK 655/1 was 40 min. The optimal TF3 levels were found to range from 0.19% to 0.60%.
Effects of thermally modified green tea catechins on the oxidative and hydrolytic stability of butter  [PDF]
Magdalena Mika, Agnieszka Wikiera, Krzysztof ?y?a
Health (Health) , 2009, DOI: 10.4236/health.2009.13032
Abstract: Green tea catechins are classified as (-)-epi-forms (2R, 3R) or (-)-forms (2S, 3R) with respect to stereoisomerism. The (-)-forms (2S, 3R) in catechin preparations obtained from green tea amounts to approximately 10% of total catechins, whereas the other 90% are (-)-epiforms (2R, 3R). High temperature induces the conversion of (-)-epiforms (2R, 3R) to (-)-forms (2S, 3R). This study investigated the effect of catechin prepa-rations containing 10, 20 and 30% (-)-forms (2S, 3R) on the oxidative and hydrolytic stability of butter. For comparison, butter with δ-tocopherol and BHT and butter without stabilizer were analysed. Butter stability was examined under conditions of refrigeration (8 oC) and freezing (-22 oC) and at temperature of 50 oC and 100 oC. Catechin preparations were more efficient butter stabilizers than BHT and δ-tocopherol. Thermal modification of catechins that led to the genera-tion of 20% of (-) forms (2S, 3R) improved their antioxidative efficacy, but longer treatment lead- ing to the formation of 30% of (-) forms (2S, 3R) decreased their antioxidative activity. The hy-drolytic stability of butter, however, increased as the amount of (-) forms (2S, 3R) increased.
Determination of Residual Catechins, Polyphenolic Contents and Antioxidant Activities of Developed Theaflavin-3,3’-Digallate Rich Black Teas  [PDF]
Samuel Kimutai, John Wanyoko, Thomas Kinyanjui, Stephen Karori, Augustine Muthiani, Francis Wachira
Food and Nutrition Sciences (FNS) , 2016, DOI: 10.4236/fns.2016.73020
Abstract: This study was carried out to characterize total residual catechins and their fractions, polyphenolic contents and antioxidant activities of black teas enriched with high levels of theaflavin-3,3’-digallate. The made teas were processed from eleven selected cultivars. A comparative study was carried out between the processed teas and those from commercially grown Kenyan cultivars in relation to the above chemical parameters. A correlation matrix analysis was also conducted to find out whether a relationship existed between the antioxidant activities and the said chemical parameters. The total residual catechins were found to range between 3.10% and 8.08%. The total polyphenol levels varied between 19.00% and 28.90%, while the antioxidant activities of the teas ranged from 82.70% to 91.70%. There was a significant p < 0.001 correlation between the antioxidant activity and total polyphenols (r = 0.8948). There was also a high correlation p < 0.001 between the antioxidant activity and total catechins (r = 0.8878). Out of the four catechin fractions, the antioxidant activity correlated most with EGCG (r = 0.8774). The total polyphenolic contents and antioxidant activities for most of the cultivars were comparable to those of the green tea reference standard. From the figures obtained, it can be concluded that the most of the newly developed black teas of the selected cultivars have higher quality and enhanced antioxidant activities and that they can be recommended for commercial production.
Variations of Antioxidant Properties and NO Scavenging Abilities during Fermentation of Tea
Yang Xu,Hang Zhao,Min Zhang,Chun-Jie Li,Xue-Zhen Lin,Jun Sheng,Wei Shi
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12074574
Abstract: Tea is known as one of the most popular beverages in the world, which is believed to be beneficial for health. The main components in tea will change a lot depending on the different processes of fermentation, and thus the effects of different teas on human health may differ. The aim of this study is to explore the varied abilities of reactive oxygen species (ROS) and nitric oxide (NO) scavenging during the fermentation of tea. In this study, we conducted the in vitro experiments which involved some reaction systems indicating the abilities of scavenging ROS and NO. We also investigated the effects of tea and their components (catechins, theabrownins, caffeine) on the intracellular levels of ROS and NO, using Raw 264.7 cells as the model. We found that regardless of whether it was out of cell system or in Raw 264.7 cells, the abilities of scavenging ROS would decrease during the fermentation of tea. Further, the post-fermented pu-erh tea showed the best effect on inhibiting the lipopolysaccharide (LPS)-induced production of NO. These findings indicated that the fermentation process caused a change of the components which might be due to the changes of their antioxidant properties and NO scavenging abilities.
The effect of green tea catechins as novel antithyroid compounds in hyperthyroid rabbits induced by levothyroxine sodium
Arwa H. AL-Saeed,Niran J. AL-Salihi,Iqbal J. AL-Assadi
Topclass Journal of Herbal Medicine , 2013,
Abstract: This study was undertaken to extract catechins from green tea leaves. It is to show the curative effect of green tea catechins after a short term daily oral administration for 8 days (200 mg?kg b.w) on serum level of thyroid hormones and thyroid-stimulating hormone in hyperthyroid rabbits induced by levothyroxine sodium (L-T4). Rabbits were divided into 4 groups, 6 rabbits in each group. Group 1 animals received only 3 ml normal saline orally as control group, group 2 was treated with (L-T4) 0.3 mg?kg b.w as hyperthyroidic. The 3rd group hyperthyroidic rabbits were post-treated with green tea catechins extract (200 mg?k g b.w) while the 4th group hyperthyroidic rabbits were post-treated with carbimazole (5 mg ? kg b.w). The results indicated high significantly increased (p< 0.001) in serum level of total triiodothyronine (TT3), total thyroxine (TT4) and high significantly stimulating hormone in hyperthyroid rabbits
Lipopolysaccharide-Deficient Mutants of Salmonella enterica Have Increased Sensitivity to Catechins  [PDF]
Miho Yoshii, Akira Okamoto, Michio Ohta
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.35054

Antimicrobial activity is one of the well-known biological characteristics of catechins, the main extract of green tea leaves. It is thought that catechins intercalate into the bacterial cell membrane and damage the lipid bilayer. However, the association between catechins and lipopolysaccharides, which consist of an O side chain, core oligosaccharide, and lipid A, has not been previously investigated. In this study, we evaluated the catechin sensitivity of Salmonella enterica mutants that lack the O side chain and have core oligosaccharides of different lengths. These rough mutants were more sensitive to catechins than a bacterial strain with intact lipopolysaccharide. We conclude that the O side chain and core oligosaccharide play an important role in protecting Gram-negative bacteria against the antimicrobial activity of catechins.

Quantitation of the Total Catechin Content in Oils Extracted from Seeds of Selected Tea (Camellia sinensis (L) O. Kuntze, Theaceae) Clones by RP-HPLC  [PDF]
Kelvin Omondi George, Kelvin Okong’o Moseti, John Kanyiri Wanyoko, Thomas Kinyanjui, Francis Nyamu Wachira
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.67112
Abstract: Catechins (flavan-3-ols) are polyphenolic plant secondary metabolites that have been strongly associated with a wide variety of beneficial health effects in vitro, in vivo and clinically. This study reports findings on the content of catechins in tea seed oil (TSO) extracted by Soxhlet extraction from seeds of different clones of Kenyan tea. Extraction of catechins from the crude oils was achieved by sequential liquid-liquid extraction (LLE) using methanol and quantified by reverse phase High Performance Liquid Chromatography (RP-HPLC). Results obtained revealed that all the crude test oils contained catechins, with oils extracted from clones TRFK K-Purple and GW-Ejulu having the highest total catechin content of 9.8 ± 0.25 and 9.0 ± 0.83 (×10-3% flavonoids) respectively. Statistically significant differences (p < 0.05) were evident in the total catechin contents of crude oils extracted from tea seeds with those extracted from corn, sunflower and soybean seeds. Moreover, clonal variations were evident, as the total catechin contents of oils extracted from clones TRFK K-Purple and GW-Ejulu were statistically different (p < 0.05) from those extracted from clones TRFK 301/3, TRFK 301/4, TRFK 301/5, TRFK 306, TRFK 91/1 and TRFCA SFS 150. Thus, the current findings strongly suggest that oils from seeds of Kenyan tea cultivars can be a potential source of potent natural antioxidants.
Influence of Geographical Regions on Catechin and Caffeine Levels in Tea (Camellia sinensis)  [PDF]
Augustine Mutuku, John Wanyoko, Francis Wachira, Samson Kamunya, Richard Chalo, Samuel Kimutai, Kelvin Moseti, Stephen Karori
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.73049
Abstract: This study aimed at investigating the influence of different growing conditions in two regions, Timbilil and Kangaita, on the levels of catechins and caffeine. Fresh leaf samples of 60 clones cultivated in both sites were obtained, processed and assayed for levels of caffeine, total and individual catechins using Reverse Phase High Performance Liquid Chromatography (RP-HPLC). The obtained data was subjected to analysis of variance using GENSTAT-C statistical software. Safe for a few clones in the Kangaita site had significantly higher total and individual catechins than those grown in the Timbilil site. A mean epigallocatechin gallate (EGCG) content of 7.9% was observed for Kangaita clones compared to 6.7% in Timbilil. A similar trend was observed for the rest of the individual catechin fractions with a mean epicatechin gallate (ECG) of 3.3% in Kangaita and 2.5% in Timbilil, a mean epigallocatechin (EGC) of 5.2% in Kangaita compared to 5.0% in Timbilil and a mean epicatechin (EC) content of 1.5% in Kangaita compared to 1.4% in Timbilil. Similarly in the total catechins analyses, clones in Kangaita had a mean value of 18.7% compared to 16.2% observed for the Timbilil site clones. However, the Timbilil site clones had significantly high caffeine contents (mean, 4.2%) compared to the Kangaita site clones (mean, 3.9%) although with a few exceptions. Significant interactions (P < 0.05) between clone and region are also observed, suggesting that levels of these biomolecules are bound to differ with the growing region but the extent of variation will vary depending on the clonal genotype. The observed differences in levels of these biologically important biomolecules among the two regions shows the importance of the underlying conditions on the production of tea.
Ascorbate protects (+)-catechin from oxidation both in a pure chemical system and human plasma
Biological Research , 2000, DOI: 10.4067/S0716-97602000000200015
Abstract: we evaluated the interaction between ascorbic acid (aa) and (+)-catechin (ctch) in potassium phosphate solution, ph 7.4 (pps) and in human plasma. in both systems, the oxidation was started by adding 2,2?-azobis-(2-amidinopropane) clorhidrate (aaph). the concentrations of aa and ctch were determined by hplc using electrochemical detection. in pps, ctch was oxidized by aaph (50 mm), in either the absence or presence of different initial concentrations of aa (25-200 mm). in the presence of aa, ctch depletion was delayed, an effect that was dependent upon the initial concentration of aa. when 100 mm aa was added after the oxidation had begun, ctch depletion was arrested for 30 min. the kinetics of aa oxidation by aaph was also characterized in pps. aa (100 mm) was completely consumed after 60 min of reaction at 37 mc, in both the absence and presence of 100 mm ctch. when human plasma was incubated with 50 mm aaph in the absence of added ctch, aa was completely consumed after 45-60 min. ctch did not prevent aa depletion in human plasma at the concentrations tested (10, 50 100 mm). the results point out that aa is able to protect other aqueous soluble antioxidants, e.g.: ctch
Quantification of Catechins and Proanthocyanidins in Several Portuguese Grapevine Varieties and Red Wines
Sun,Baoshan; Ricardo-da-Silva,J.M.; Spranger,M.Isabel;
Ciência e Técnica Vitivinícola , 2001,
Abstract: catechins, oligomeric proanthocyanidins (degree of polymerization ranging from 2 to 12-15) and polymeric proanthocyanidins (degree of polymerization > 12-15) in several portuguese grapevine varieties (fern?o pires, castel?o, vital, vinh?o, espadeiro, azal tinto) harvested from the west and the north of portugal in 1993 and 1994, and in some red wines from several portuguese regions (estremadura, d?o and vinhos verdes), were quantified using modified vanillin assay. in most grapevine varieties studied, the levels of catechins and proanthocyanidins in seeds in 1993 were roughly equal to those in 1994, although the climatological conditions were different between the two years. however, these values in skins of all tested varieties except fern?o pires, obtained in 1994, were much smaller than those in 1993. catechins and proanthocyanidins were located essentially in seeds, being 77,2% of total catechins of grape berry, 80,8% of total oligomeric proanthocyanidins of grape berry and 60,3% of total polymeric proanthocyanidins of grape berry, then in skins, being 19,7% of total catechins of grape berry, 19,0% of total oligomeric proanthocyanidins of grape berry and 38,9% of total polymeric proanthocyanidins of grape berry, and very little in pulp, being 3,1% of total catechins of grape berry, 0,2% of total oligomeric proanthocyanidins of grape berry and 0,8% of total polymeric proanthocyanidins of grape berry (mean values of two years). in seeds, the percentages of catechins, oligomeric and polymeric proanthocyanidins were respectively 4,2%, 29,4% and 66,4%; in skins, on the other hand, these values were respectively 1,8%, 13,0% and 85,2% (mean values of two years). the results also show the differences between the grapevine varieties from the west of portugal and those from the north of portugal. for all red wines analyzed, polymeric proanthocyanidins were predominant (averaging 65.5%), followed by oligomeric proanthocyanidins (averaging 27.9%), and catechins were present
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