Assessment of the polyphenolic composition of the organic extracts of Mauritian black teas: A potential contributor to their antioxidant functions

There is increasing interest in the emerging view that tea improves the antioxidant status in vivo and thereby helps to lower risk of certain types of cancer, coronary heart disease and stroke and its component biofactors could provide prophylactic potential for these diseases. The polyphenolic composition and the antioxidant properties of organic extracts (acetone/methanol) of Mauritian commercial black teas were evaluated. HPLC data of the individual compounds revealed remarkably high levels (+)‐Catechin ((+)‐C), (−)‐epicatechin ((−)‐EC), (−)‐epicatechin 3‐gallate ((−)‐ECG), (−)‐epigallocatechin ((−)‐EGC), (−)‐epigallocatechin 3‐gallate ((−)‐EGCG) and gallic acid. Analysis of hydrolysed extracts indicated that quercetin was the dominant flavonol aglycone with traces of myricetin and kaempferol. Based on the Ferric Reducing Antioxidant Power (FRAP) and the Trolox Equivalent Antioxidant Capacity (TEAC) assays Extra tea from Bois Chéri exhibited the highest antioxidant potential. Linear regression analyses showed that the antioxidant capacities of the organic extracts are strongly influenced by total phenols (TEAC: r=0.95 and FRAP: r=0.96) and to a lesser extent by total proanthocyanidin and total flavonoid contents. Catechins and gallic acid seem to add up to the overall antioxidant capacity of black tea extracts. The fresh tea leaves had high levels of total phenols, total flavonoids, total proanthocyanidin and exhibited greater antioxidant potential when compared with black teas. Organic extracts of endemic teas represent useful source of phenolic antioxidants supplements for prophylactic use.

[1]  R. Seshadri,et al.  Influence of polyphenol oxidase activity and polyphenol content of tea shoot on quality of black tea , 1990 .

[2]  Huafu Wang,et al.  HPLC determination of catechins in tea leaves and tea extracts using relative response factors , 2003 .

[3]  S. Khokhar,et al.  Total phenol, catechin, and caffeine contents of teas commonly consumed in the United kingdom. , 2002, Journal of agricultural and food chemistry.

[4]  V. L. Singleton,et al.  Colorimetry of Total Phenolics with Phosphomolybdic-Phosphotungstic Acid Reagents , 1965, American Journal of Enology and Viticulture.

[5]  Anne S. Meyer,et al.  The problems of using one-dimensional methods to evaluate multifunctional food and biological antioxidants , 2000 .

[6]  H. Bui,et al.  Quantitative structure-activity relationship analysis of phenolic antioxidants. , 1999, Free radical biology & medicine.

[7]  X. Cheng,et al.  Green tea catechins inhibit the cultured smooth muscle cell invasion through the basement barrier. , 2003, Atherosclerosis.

[8]  S. Azam,et al.  Prooxidant property of green tea polyphenols epicatechin and epigallocatechin-3-gallate: implications for anticancer properties. , 2004, Toxicology in vitro : an international journal published in association with BIBRA.

[9]  N. Miller,et al.  Structure-antioxidant activity relationships of flavonoids and isoflavonoids , 1998 .

[10]  S. Murugesan,et al.  Impact of sources and doses of potassium on biochemical and greenleaf parameters of tea , 2005 .

[11]  Jen-kun Lin,et al.  Composition of polyphenols in fresh tea leaves and associations of their oxygen-radical-absorbing capacity with antiproliferative actions in fibroblast cells , 1996 .

[12]  N. Lin,et al.  Antioxidative properties of hydroxycinnamic acid derivatives and a phenylpropanoid glycoside. A pulse radiolysis study , 1998 .

[13]  H. Shi,et al.  Antioxidative effect of polyphenol extract prepared from various Chinese teas. , 1992, Preventive medicine.

[14]  Y. Zuo,et al.  Simultaneous determination of catechins, caffeine and gallic acids in green, Oolong, black and pu-erh teas using HPLC with a photodiode array detector. , 2002, Talanta.

[15]  G. De Backer,et al.  Epidemiological evidence for an association between habitual tea consumption and markers of chronic inflammation. , 2006, Atherosclerosis.

[16]  Y. J. Chen,et al.  Procyanidins from the seeds of Vitis amurensis. , 2000, Phytochemistry.

[17]  O. Aruoma,et al.  Methodological considerations for characterizing potential antioxidant actions of bioactive components in plant foods. , 2003, Mutation research.

[18]  S. Wiseman,et al.  Antioxidants in tea. , 1997, Critical reviews in food science and nutrition.

[19]  Alan Crozier,et al.  Quantitative analysis of the flavonoid content of commercial tomatoes , 1997 .

[20]  T. Osawa,et al.  Antioxidative and antimutagenic effects of theaflavins from black tea. , 1994, Mutation research.

[21]  Chung S. Yang,et al.  Effects of tea polyphenols on signal transduction pathways related to cancer chemoprevention. , 2004, Mutation research.

[22]  V. Böhm,et al.  Assessment of Antioxidant Activity by Using Different In Vitro Methods , 2002, Free radical research.

[23]  P. Trouillas,et al.  Antioxidant, anti-inflammatory and antiproliferative properties of sixteen water plant extracts used in the Limousin countryside as herbal teas , 2003 .

[24]  F. Orallo,et al.  (−)-Epigallocatechin-3-gallate induces contraction of the rat aorta by a calcium influx-dependent mechanism , 2004, Naunyn-Schmiedeberg's Archives of Pharmacology.

[25]  A. Sarkar,et al.  Black tea is a powerful chemopreventor of reactive oxygen and nitrogen species: comparison with its individual catechin constituents and green tea. , 2001, Biochemical and biophysical research communications.

[26]  J. Keaney,et al.  Effects of black tea consumption on plasma catechins and markers of oxidative stress and inflammation in patients with coronary artery disease. , 2005, Free radical biology & medicine.

[27]  B. G. Chan,et al.  The conversion of procyanidins and prodelphinidins to cyanidin and delphinidin , 1985 .

[28]  Erwan Bezard,et al.  Protective effect of green tea polyphenols on the SH-SY5Y cells against 6-OHDA induced apoptosis through ROS-NO pathway. , 2005, Free radical biology & medicine.

[29]  Chung S. Yang,et al.  Cancer chemopreventive activity and bioavailability of tea and tea polyphenols. , 2003, Mutation research.

[30]  J J Strain,et al.  The ferric reducing ability of plasma (FRAP) as a measure of "antioxidant power": the FRAP assay. , 1996, Analytical biochemistry.

[31]  S. Sakanaka,et al.  Preparation and antioxidant properties of extracts of Japanese persimmon leaf tea (kakinoha-cha) , 2005 .

[32]  Z. Apostolides,et al.  Analysis of the theaflavin composition in black tea (Camellia sinensis) for predicting the quality of tea produced in Central and Southern Africa , 2002 .

[33]  H N Graham,et al.  Green tea composition, consumption, and polyphenol chemistry. , 1992, Preventive medicine.

[34]  N. Lin,et al.  ESR studies of γ-irradiated histone octamer and the histone H3 , 1998 .

[35]  E. Lissi,et al.  Kinetics of the reaction between 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) derived radical cations and phenols , 1997 .

[36]  J. Halder,et al.  Protective role of black tea against oxidative damage of human red blood cells. , 1998, Biochemical and biophysical research communications.

[37]  A. Crozier,et al.  On-line high-performance liquid chromatography analysis of the antioxidant activity of phenolic compounds in green and black tea. , 2005, Molecular nutrition & food research.

[38]  K. Shimada,et al.  Oolong tea increases plasma adiponectin levels and low-density lipoprotein particle size in patients with coronary artery disease. , 2004, Diabetes research and clinical practice.

[39]  Yongquan Li,et al.  Research progress on property and application of theaflavins , 2006 .

[40]  C. Rice-Evans,et al.  Black Tea Represents a Major Source of Dietary Phenolics Among Regular Tea Drinkers , 2002, Free radical research.

[41]  S. Kallithraka,et al.  Survey of solvents for the extraction of grape seed phenolics , 1995 .