14 results on '"Wanyoko, J. K."'
Search Results
2. Fortification of alcoholic beverages (12% v/v) with tea (Camellia sinensis) reduces harmful effects of alcohol ingestion and metabolism in mouse model
- Author
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Ochanda, S. O., Rashid, K., Wanyoko, J. K., Ngotho, M., Faraj, A. K., Onyango, C. A., Wachira, F. N., Maranga, D. N., Ochanda, S. O., Rashid, K., Wanyoko, J. K., Ngotho, M., Faraj, A. K., Onyango, C. A., Wachira, F. N., and Maranga, D. N.
- Abstract
Background: An animal model was used to study the health benefits inherent in tea fortified alcoholic beverages fed to laboratory mice. Objectives: An investigation of the effects of tea fortified alcoholic beverages 12% alcohol (v/v) on antioxidant capacity and liver dysfunction indicators in white Swiss mice including packed cell volume (PCV), albumin, total protein, alkaline phosphatase (ALP) and glutathione (GSH) was carried out. Methods: Plain, black, green and purple tea fortified alcohols were developed with varying tea concentrations of 1, 2 and 4 g/250 mL in 12% v/v. Control alcoholic beverages without teas were also developed. A permit (number IRC/13/12) was obtained for the animal research from the National Museums of Kenya, Institute of Primate Research prior to the start of the study. Alcoholic beverages were orally administered every 2 days for 4 weeks at 1 mL per mouse, and thereafter animals were euthanised and liver and blood samples harvested for analyses. Assays on body weight (bwt), packed cell volume (PCV) albumin, total protein, ALP and GSH were performed. Results were statistically analysed using GraphPad statistical package and significant differences of means of various treatments determined. Results: Consumption of tea fortified alcohols significantly decreased (p=0.0001) bwt at 0.32-9.58% and PCV at 5.56-22.75% for all teas. Total protein in serum and liver of mice fed on different tea fortified alcohols ranged between 6.26 and 9.24 g/dL and 2.14 and 4.02 g/dL, respectively. Albumin, ALP and GSH range was 0.92-2.88 mu g/L, 314.98-473.80 mu g/L and 17.88-28.62 mu M, respectively. Fortification of alcoholic beverages lowered liver ALP, replenished antioxidants and increased liver albumin, improving the nutritional status of the mice. Conclusions: The findings demonstrate tea's hepatoprotective mechanisms against alcohol-induced injury through promotion of endogenous antioxidants. The beneficial effects of tea in the fortified alcoholic bever
- Published
- 2016
3. Fortification of alcoholic beverages (12% v/v) with tea (Camellia sinensis) reduces harmful effects of alcohol ingestion and metabolism in mouse model
- Author
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Ochanda, S O, primary, Rashid, K, additional, Wanyoko, J K, additional, Ngotho, M, additional, Faraj, A K, additional, Onyango, C A, additional, Wachira, F N, additional, and Maranga, D N, additional
- Published
- 2016
- Full Text
- View/download PDF
4. Optimization of manufacturing conditions of the new purple leafed Kenyan teas (TRFK 306) - maceration style and withering duration.
- Author
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Kilel, E. C., Faraj, A. K., Ngoda, P., and Wanyoko, J. K.
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GREEN tea ,CATECHIN ,ANTIOXIDANTS ,POLYPHENOLS ,EPIGALLOCATECHIN gallate - Abstract
Purple tea in Kenya, TRFK 306, has received great attention due to its perceived health benefits though how it should be optimally manufactured has not been researched on exhaustively. The current study investigated on the two possible methods of manufacture - Cut Tear and Curl (CTC) and orthodox manufacture - with varying withering time of 0, 5, 10, 15 and 20 hours. Catechins, gallic acid, caffeine, total polyphenols and antioxidant activity were assayed as quality indicators. If gallic acid and caffeine are the main chemicals targeted, then orthodox type with longer withering, 15 - 20 hours, is usually recommended. When targeting catechins especially epigallocatechin gallate and high total polyphenols, orthodox type of manufacture whichever the withering time is proposed. CTC with withering hours of 15-20 produces teas with high antioxidant activity. It was concluded that TRFK 306 is best processed by orthodox or CTC but with longer withering time. [ABSTRACT FROM AUTHOR]
- Published
- 2018
5. Antifungal activity of crude tea extracts
- Author
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Koech, K R, primary, Wachira, F N, additional, Ngure, R M, additional, Orina, I A, additional, Wanyoko, J K, additional, Bii, C, additional, and Karori, S M, additional
- Published
- 2013
- Full Text
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6. CHARACTERIZATION OF ESSENTIAL AND TOXIC ELEMENTS IN THE KENYAN TEA SEEDS HUSKS.
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Njuguna, D. G., Wanyoko, J. K., Kinyanjui, T., and Wachira, F. N.
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TEA -- Composition , *COMPOSITION of seeds , *TOXICOLOGY , *CALCIUM content of plants , *ZINC content of plants , *ATOMIC absorption spectroscopy , *FLAME photometry - Abstract
A study was conducted to quantify essential and toxic elements from seed husks of six tea cultivars in Kenya. The seed husks were analysed for Ca, Zn, Mg, Cu, Pb, Cd and Mn by use of Atomic Absorption Spectroscopy, and Na and K by flame photometry. The P levels were determined by the use of UV-Visible spectrophotometer and the total nitrogen content was analyzed using Association of Analytical Chemist method. Results on dry matter basis showed that nitrogen was in the range of 0.13-0.66% whereas P ranged from 0.19-1.00µg/g. Other macro elements namely K, Na and Mg ranged from 0.03-0.26 µg/g, 4.8-12.6µg/g, 0.13-0.40%, respectively. Microelements including Zn, Mn and Cu ranged between 2.6-6.3µg/g, 0.07-0.17% and 2.9-7.0µg/g, respectively. Toxic elements i.e. cadmium and lead were not detected in all tea seed husks. The study concluded that tea husks contained all essential elements with none toxic elements and recommended that the by-products should be used as filler materials in animal feeds and fertilizer manufacture. [ABSTRACT FROM AUTHOR]
- Published
- 2012
7. VARIATION IN THEAFLAVINS AND CATECHIN CONTENTS IN PROCESSED LEAF FROM THE PURPLE TEA VARIETIES IN KENYA.
- Author
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Kilel, E. C., Wanyoko, J. K., Faraj, A. K., and Wachira, F. N.
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THEAFLAVINS , *TEA -- Composition , *COMPOSITION of leaves , *CULTIVARS , *HIGH performance liquid chromatography - Abstract
A study was conducted to determine the levels of theaflavins in newly developed purple leaf coloured teas. A total of 13 green leaf were evaluated alongside 14 pigmented test clones in tea improvement programme. Catechins, known to influence the formation of flavonoids, and theaflavins contents were determined using HPLC. Sensory evaluation of teas produced from various clones was also done using trained panelist. Data obtained was subjected to statistical analysis. The results showed that GW Ejulu and TRFK K-Purple had the highest mean values of theaflavins digallate (TF dg) having 6.52 and 5.37 µmol/g, respectively. TF dg is the most important theaflavins since it influences liquor characteristics even at very low concentration. It was concluded that TRFK K-Purple, TRFK KS 3, TRFK KS 2 and TRFK 91/2 would result in higher quality black liquors than that of the standard quality clone TRFK 6/8, whereas clones TRFK 6/8 and TRFK 73/5 had low caffeine and are potential candidate clones for low caffeine tea production. [ABSTRACT FROM AUTHOR]
- Published
- 2012
8. POTENTIAL EXTRACTABILITY OF ESSENTIAL AND NON-ESSENTIAL ELEMENTS IN TEA LIQUOR: QUANTIFICATION AND SAFETY EVALUATION.
- Author
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Moseti, K. O., Wanyoko, J. K., Kinyanjui, T., Too, J. C., Omondi, K. G., and Wachira, F. N.
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TEA , *LIQUORS , *EXTRACTION (Chemistry) , *IRON , *ZINC , *COPPER , *ATOMIC absorption spectroscopy - Abstract
A study was conducted to examine the water extractable levels of Fe, Zn, Cu, Pb and Cd into tea liquor from black CTC tea from Kenya, Rwanda, Uganda and Tanzania with the intent of assessing the potential of exposure to these elements via tea consumption. These elements were quantified using Flame Atomic Absorption Spectroscopy (FAAS) and were found to be 2.2 - 12.5µg/ml for Fe, 1.5 - 5.9µg/ml for Zn, 0.7 - 3.0µg/ml for Cu, 0.02 - 0.08µg/ml for Pb and below detectable limit (BDL) to 7.0µg/L (0.007µg/ml) for Cd. The general extractability pattern of the elements of interest was in the order Fe > Zn > Cu > Pb > Cd, confirming that tea consumption is indeed an important dietary source of Fe, Zn and Cu. With respect to their element content, Kenyan teas were comparable with those from Rwanda, Uganda and Tanzania. Based on international food safety standards for tea, these teas were found to be safe for human consumption. However, these data is best regarded as the extractability potential of the tea liquor and does not reflect the actual concentrations contained in the tea liquor that is actually consumed owing to the high tea to water ratio used in preparing the analysed tea extracts. [ABSTRACT FROM AUTHOR]
- Published
- 2012
9. EFFECTS OF KENYAN PURPLE TEA ANTHOCYANINS IN THE BRAIN AND INTERACTION WITH COENZYME-Q10 IN A MOUSE MODEL.
- Author
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Rashid, K., Wachira, F. N., Wanyoko, J. K., Kerio, L. C., Korir, M. W., Koech, K. R., and Isaac, A. O.
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TEA -- Physiological effect ,ANTHOCYANINS ,BRAIN ,COENZYMES ,ANTIOXIDANTS ,LABORATORY mice - Abstract
Studies on antioxidants as neuroprotective agents have been hampered by the impermeability of the blood brain barrier (BBB) to many compounds. However, previous studies have shown that a group of tea flavonoids, the catechins are brain permeable and neuroprotective. This study investigated the ability of Kenyan purple tea anthocyanins (ACNs) to cross the BBB and boost the brain antioxidant capacity. Mice were orally administered with purified and characterized Kenyan purple tea ACNs or a combination of Kenyan purple tea ACN's and coenzyme-Q
10 at a dose of 200mg/kg body weight in an experiment that lasted for 15 days. Twenty four hours post the last dosage of antioxidants; CO2 was used to euthanize the mice after which the brain was excised used for various biochemical analyses. Brain extracts were analyzed by HPLC for ACNs metabolites and spectrophotometry for cellular glutathione (GSH). Kenyan purple tea ACNs significantly (P=0.05) raised brain GSH levels implying boost in brain antioxidant capacity. However, co-administration of both antioxidants caused a reduction of these beneficial effects implying a negative interaction. Notably, ACN metabolites were detected in brain tissue of ACN fed mice. Our results constitute the first demonstration that Kenyan purple tea ACNs can cross the BBB reinforcing the brain's antioxidant capacity. Hence the need to study them as suitable candidates for dietary supplements that could support antioxidant capacity in the brain and have potential to provide neuroprotection in neurodegenerative conditions. [ABSTRACT FROM AUTHOR]- Published
- 2012
10. POTENTIAL ANTIBACTERIAL AND ANTIOXIDANT ACTIVITY OF DIFFERENT TEA EXTRACTS.
- Author
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Koech, K. R., Wachira, F. N., Wanyoko, J. K., Kerio, L. C., Khalid, R., Ngure, R. M., and Bii, C.
- Subjects
THERAPEUTIC use of tea ,THERAPEUTIC use of plant extracts ,ANTIBACTERIAL agents ,ANTIOXIDANTS ,CATECHIN - Abstract
Biochemical profiles of various types of tea extracts were determined and antibacterial and antioxidant activities studied using standard methods. Kenyan green teas were more superior to Chinese and Japanese green teas in their biochemical profiles. Black, green, purple coloured leaf and white (silvery tips) tea products differed significantly in the levels of total polyphenols, total catechins, catechins fractions, theaflavins and thearubigins (P≤0.05). White and green teas contained significantly (P≤0.05) higher amounts of total polyphenols and total catechins than black teas. Black tea from two leaves and a bud and black tea from terminal buds contained significantly higher amounts of theaflavins and thearubigins than white and green teas. Green, purple coloured leaf (aerated), black tea from terminal buds and white tea products analyzed in this study exhibited slightly higher antioxidant activity with a higher DPPH radical scavenging activity as compared to black tea. The study shows that the different types of tea products assayed exhibited significant influence on the inhibition zone diameters against bacteria exposed to the tea extracts. Methicillin and penicillinase resistant S. aureus ATCC 25923 was most susceptible to all tea extracts than E. coli and a clinical isolate of S. typhi. The highest antibacterial activity occurred in samples with the highest total polyphenols and antioxidant activity. The study demonstrates a potential antibacterial activity of tea extracts. [ABSTRACT FROM AUTHOR]
- Published
- 2012
11. The fortification of tea with sweeteners and milk and its effect on in vitro antioxidant potential of tea product and glutathione levels in an animal model.
- Author
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Korir MW, Wachira FN, Wanyoko JK, Ngure RM, and Khalid R
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- Animals, Biflavonoids analysis, Camellia sinensis chemistry, Carbohydrates chemistry, Catechin analogs & derivatives, Catechin analysis, Female, Flavonoids analysis, Food Analysis, Food Handling, Honey analysis, Mice, Models, Animal, Plant Extracts analysis, Polyphenols analysis, Stevia chemistry, Antioxidants analysis, Food Additives analysis, Glutathione metabolism, Milk chemistry, Sweetening Agents analysis, Tea chemistry
- Abstract
Several studies have demonstrated that tea flavonoids protect cells and tissues against free radicals which have been implicated in the etiology of oxidative stress-related disease disorders. However, black tea is commonly consumed with additives that could otherwise affect the bioavailability of the active tea molecules. In this study, the biochemical parameters of Kenyan teas were determined and the effect of added milk and sweeteners on the antioxidant activity of Kenyan teas was investigated. The effect of tea antioxidants on glutathione (GSH) was also evaluated in vivo in a time series study using Swiss mice. Green teas had the highest levels of total polyphenols, total and individual catechins, while black teas had high levels of total thearubigins, total theaflavins and theaflavin fractions. The antioxidant activity was high in green teas though some of the black teas were as efficacious as the green teas. The addition of milk, sugar and honey significantly (p<0.05) decreased the antioxidant activity of tea in a concentration-dependent manner. Addition of the sweetener, stevia (Stevia rebaudiana Bertoni), showed no significant (p>0.05) influence on the antioxidant activity of tea and therefore can be recommended as a preferred sweetener for tea. Significantly (p<0.001) higher levels of GSH were observed in plasma than in other tissues. GSH levels were generally highest 2h after tea consumption, which indicates the need to repeatedly take tea every 2h to maximise its potential health benefits., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
12. Green tea from purple leaf coloured tea clones in Kenya- their quality characteristics.
- Author
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Kilel EC, Faraj AK, Wanyoko JK, Wachira FN, and Mwingirwa V
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- Caffeine analysis, Camellia sinensis classification, Catechin analysis, Flavonoids analysis, Gallic Acid analysis, Kenya, Polyphenols, Quality Control, Camellia sinensis chemistry, Plant Extracts analysis, Plant Leaves chemistry
- Abstract
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., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
13. Total polyphenols, catechin profiles and antioxidant activity of tea products from purple leaf coloured tea cultivars.
- Author
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Kerio LC, Wachira FN, Wanyoko JK, and Rotich MK
- Subjects
- Antioxidants isolation & purification, Catechin isolation & purification, Plant Extracts isolation & purification, Polyphenols isolation & purification, Antioxidants analysis, Camellia sinensis chemistry, Catechin analysis, Plant Extracts analysis, Plant Leaves chemistry, Polyphenols analysis
- Abstract
Black (aerated) and green (unaerated) tea products, processed from 10 green and 18 purple leaf coloured cultivars of Kenyan origin, and two tea products, from the Japanese cultivars, Yabukita and Yutakamidori, were assayed for total polyphenols (TP) content, individual catechin profiles and in vitro antioxidant capacity (AA). In addition, the phenolic content of the tea products was determined using the Folin-Ciocalteu phenol reagent. Catechin fractions were identified using reverse phase high performance liquid chromatography (HPLC) with a binary gradient elution system. The AA% of the tea products was determined using a 2,2'-diphenyl picrylhydrazyl (DPPH) radical assay method. The results showed that TPs, catechin profiles and antioxidant activities were significantly (p≤0.05) higher in unaerated than in aerated teas. Tea products from the purple leaf coloured tea cultivars had levels of TPs, total catechin (TC) and antioxidant activities similar to those from the green leaf coloured cultivars, except for teas from the Japanese cultivars that were very low in the assayed parameters. Caffeine content was significantly (p≤0.05) lower in products from the purple leaf coloured cultivars than in those from the green leaf coloured tea cultivars. Antioxidant activity (%) was higher in tea products from the Kenyan germplasm than in those from the Japanese cultivars. Antioxidant potency of tea products was significantly (r=0.789(∗∗), p≤0.01) influenced by the total anthocyanin content of the purple leaf coloured cultivars. Cyanidin-3-O-glucoside was the anthocyanin most highly correlated with AA% (r=0.843(∗∗), p≤0.01 in unaerated tea). Total catechins in the unaerated products from the green leaf coloured tea cultivars were also significantly correlated with antioxidant capacity (r=0.818(∗∗), p≤0.01). Results from this study suggest that the antioxidant potency of teas is dependent on the predominant flavonoid compound, the type of tea cultivar and the processing method., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
14. Different types of tea products attenuate inflammation induced in Trypanosoma brucei infected mice.
- Author
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Karori SM, Ngure RM, Wachira FN, Wanyoko JK, and Mwangi JN
- Subjects
- Anemia diagnosis, Animals, Kenya, Male, Mice, Plant Extracts administration & dosage, Plant Extracts therapeutic use, Serum Albumin metabolism, Treatment Outcome, Trypanocidal Agents administration & dosage, Trypanocidal Agents pharmacology, Trypanocidal Agents therapeutic use, Trypanosoma brucei brucei pathogenicity, Inflammation drug therapy, Inflammation immunology, Inflammation parasitology, Inflammation physiopathology, Parasitemia drug therapy, Parasitemia immunology, Parasitemia parasitology, Plant Extracts pharmacology, Tea chemistry, Trypanosoma brucei brucei drug effects, Trypanosomiasis, African drug therapy, Trypanosomiasis, African immunology, Trypanosomiasis, African parasitology, Trypanosomiasis, African physiopathology
- Abstract
An in vivo study was carried out to determine the effect of different types of Kenyan tea extracts on male Swiss albino mice infected with Trypanosoma brucei brucei isolate KETRI 2710. The isolate produced a similar clinical picture after a pre-patent period of 5 days post-infection (DPI). Parasitemia levels in the untreated mice and those given different teas developed exponentially at similar rates reaching similar densities at the peak of parasitemia 8 DPI. Between 9 and 13 DPI parasitemia decreased more rapidly in tea treated compared to the untreated mice which indicated that tea lowered parasitemia level. Anaemia indicated by a fall in erythrocyte packed cell volume (PCV) occurred within 4 DPI and remained below the normal levels until the terminal stages of the disease. A significant difference (P<0.05) was observed 11 DPI between the tea treated and the untreated mice indicating that tea enhanced resistance to erythrocyte destruction. Mice treated with tea exhibited significantly (P<0.01) reduced parasite-induced hypoalbuminemia as compared to the untreated. Since albumin is a negative acute phase protein, it shows a decrease during inflammatory conditions and therefore its elevation in the mice given tea in this study clearly demonstrated that tea ameliorated inflammation induced by T. b. brucei. Although green and white teas were superior in most of these characteristics, black tea, which is the principle tea product from Kenya, displayed remarkable properties some even comparable to those of green tea. Interestingly, tea was more efficacious than dexamethasone an established anti-inflammatory drug, demonstrating its therapeutic potential.
- Published
- 2008
- Full Text
- View/download PDF
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