Phenol content and antioxidant activity of green, yellow and black tea leaves

BackgroundGreen, black and yellow tea leaves are rich in phenolic compounds that are known for their antioxidant activity thus beneficial effect on human health. In practice, different methods are used to determine antioxidant activity. The objective of this study was to determine content of phenols, flavonoids and tannins, as well as antioxidant activity of tea leaves.ResultsGreen, yellow and black tea leaves (intact and pulverised leaves) were used for extraction by methanol or acidified methanol. Spectrophotometric methods were used for determination of selected parameters. Antioxidant activity was determined in extracts and pulverised tea leaves by application of 2,2-diphenyl-1-picrilhydrazyl (DPPH) and 2,2′azinobis-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) free radicals. For determination of antioxidant activity of the pulverised leaves, ‘QUENCHER’ method was used. The method is based on the direct treatment of dry sample with free radicals. Extracts obtained by extraction of pulverised tea leaves with acidified methanol had the highest phenolic content (3.823, 4.226 and 6.829 g/kg for green, black and yellow tea, respectively). In methanol extracts, phenol content decreased in order yellow > green > black tea and, in acidified methanol extracts, yellow > black > green tea, regardless of particle size of tea leaves for extraction. Flavonoid and tannin contents followed the same tendency as phenol content. The highest antioxidant activity had acidified methanol extracts of pulverised tea leaves, regardless of used method (DPPH and ABTS). Results of antioxidant activity obtained with ‘QUENCHER’ method were compared with results of acidified methanol extracts. Green and yellow tea had higher antioxidant activity when ‘QUENCHER’ method was used in contrast to the black tea where higher antioxidant activity was determined in extract.ConclusionsParticle size and extraction solvent had high influence on total phenolic compounds, total flavonoid and tannin content as well as on antioxidant activity. Also, antioxidant activity of samples highly depended on used free radicals and sample preparation prior their application.

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

[2]  M. B. Arnao,et al.  The hydrophilic and lipophilic contribution to total antioxidant activity , 2001 .

[3]  M. Planinić,et al.  Study of solid–liquid extraction kinetics of total polyphenols from grape seeds , 2007 .

[4]  Cornelius S. Ough,et al.  Methods for analysis of musts and wines , 1980 .

[5]  M. Tabernero,et al.  Updated methodology to determine antioxidant capacity in plant foods, oils and beverages: Extraction, measurement and expression of results , 2008 .

[6]  V. Fogliano,et al.  Direct measurement of the total antioxidant capacity of foods: the ‘QUENCHER’ approach , 2009 .

[7]  George Boskou,et al.  Polyphenolic content and in vitro antioxidant characteristics of wine industry and other agri-food solid waste extracts , 2007 .

[8]  T. Yokozawa,et al.  Study on the inhibitory effect of tannins and flavonoids against the 1,1-diphenyl-2 picrylhydrazyl radical. , 1998, Biochemical pharmacology.

[9]  R. J. Robbins,et al.  Phenolic acids in foods: an overview of analytical methodology. , 2003, Journal of agricultural and food chemistry.

[10]  V. Fogliano,et al.  Solvent effects on total antioxidant capacity of foods measured by direct QUENCHER procedure , 2012 .

[11]  N. Miller.  THE RELATIVE ANTIOXIDANT ACTIVITIES OF PLANT-DERIVED POLYPHENOLIC FLAVONOIDS , 1996 .

[12]  E. Lissi,et al.  Review of methods to determine chain-breaking antioxidant activity in food , 2005 .

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

[14]  T. Yokozawa,et al.  Study on the Inhibitory Effect of Tannins and Flavonoids against the 1,1-Diphenyl-2-picrylhydrazyl Radical - A newly found effect of hydrolysable-type tannin-containing crude drug and gallotannin , 1998 .

[15]  N. Pellegrini,et al.  Total antioxidant capacity of plant foods, beverages and oils consumed in Italy assessed by three different in vitro assays. , 2003, The Journal of nutrition.

[16]  V. Fogliano,et al.  A new procedure to measure the antioxidant activity of insoluble food components. , 2007, Journal of agricultural and food chemistry.

[17]  Abdul Shakoor Chaudhry,et al.  Chemical composition, plant secondary metabolites, and minerals of green and black teas and the effect of different tea-to-water ratios during their extraction on the composition of their spent leaves as potential additives for ruminants. , 2013, Journal of agricultural and food chemistry.

[18]  S. Pastoriza,et al.  A physiologic approach to test the global antioxidant response of foods. The GAR method , 2011 .

[19]  A. Bast,et al.  A critical appraisal of the use of the antioxidant capacity (TEAC) assay in defining optimal antioxidant structures , 2003 .

[20]  G. Ferraro,et al.  Total polyphenol content and antioxidant capacity of commercially available tea (Camellia sinensis) in Argentina. , 2008, Journal of agricultural and food chemistry.

[21]  Kelly E Heim,et al.  Flavonoid antioxidants: chemistry, metabolism and structure-activity relationships. , 2002, The Journal of nutritional biochemistry.

[22]  F. Shahidi,et al.  Extraction and analysis of phenolics in food. , 2004, Journal of chromatography. A.

[23]  M. Pinelo,et al.  Processing of Rosa rubiginosa: extraction of oil and antioxidant substances. , 2007, Bioresource technology.

[24]  J. Rufián‐Henares,et al.  A combined procedure to evaluate the global antioxidant response of bread , 2010 .

[25]  Yumiko Nakamura,et al.  Analysis of Proanthocyanidins in Grape Seed Extracts, Health Foods and Grape Seed Oils , 2003 .

[26]  F. Malcata,et al.  Effect of particle size upon the extent of extraction of antioxidant power from the plants Agrimonia eupatoria, Salvia sp. and Satureja montana , 2009 .