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Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements.
J Diet Suppl. 2016; 13(2):171-84.JD

Abstract

Green tea (Camellia sinensis) preparations are among the top selling products in the United States dietary supplements market. Numerous manufacturers claim different levels of specific catechin markers in their products while many others use total phenolic concentration instead, or not at all. Limited quality control results have been published for green tea dietary supplements over the past seven years. Thus, the goal of this work was to correlate determined levels of phenolics, catechins, and caffeine with manufacturer label claims for selected dietary supplement products (26 total) purchased in the United States. The Folin-Ciocalteu (FC) method was used to determine the total phenolic content while reversed-phase (RP) HPLC was used to quantify the major catechins: epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG). The developed HPLC method was validated for accuracy and precision. It utilized a C8 column with gradient elution of acetonitrile in 0.1% aqueous formic acid over 11 min total run time. Peak detection was performed at 280 nm. Caffeine was also included in the HPLC method as another non-phenolic alkaloid marker commonly found in green tea. Both methods showed a good correlation between the content of catechins and polyphenolic compounds in the selected products. The ranges of total catechins and polyphenol concentrations were 3.8-70.2% and 3.6-95.8%, respectively, while that of caffeine was 0.8-11.2%. The selected products displayed a wide range of marker levels. A lack of conformity in disclosing the actual levels of marker compounds was also noticed in the labeling of many products.

Authors+Show Affiliations

a 1 Department of Pharmaceutical Sciences, College of Pharmacy, Chicago State University , Chicago , IL , USA.b 2 Pharmacy Practice, College of Pharmacy, Chicago State University , Chicago , IL , USA.c 3 Chicago State University , Chicago , IL , USA.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25299974

Citation

Abourashed, Ehab A., et al. "Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements." Journal of Dietary Supplements, vol. 13, no. 2, 2016, pp. 171-84.
Abourashed EA, Roberson CL, Elsharkawy N. Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements. J Diet Suppl. 2016;13(2):171-84.
Abourashed, E. A., Roberson, C. L., & Elsharkawy, N. (2016). Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements. Journal of Dietary Supplements, 13(2), 171-84. https://doi.org/10.3109/19390211.2014.965868
Abourashed EA, Roberson CL, Elsharkawy N. Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements. J Diet Suppl. 2016;13(2):171-84. PubMed PMID: 25299974.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements. AU - Abourashed,Ehab A, AU - Roberson,Cindy Leslie A, AU - Elsharkawy,Nancy, Y1 - 2014/10/09/ PY - 2014/10/10/entrez PY - 2014/10/10/pubmed PY - 2016/8/31/medline KW - Caffeine KW - Folin-Ciocalteu method KW - HPLC analysis KW - catechins KW - dietary supplements KW - green tea KW - quality control KW - total phenolic content SP - 171 EP - 84 JF - Journal of dietary supplements JO - J Diet Suppl VL - 13 IS - 2 N2 - Green tea (Camellia sinensis) preparations are among the top selling products in the United States dietary supplements market. Numerous manufacturers claim different levels of specific catechin markers in their products while many others use total phenolic concentration instead, or not at all. Limited quality control results have been published for green tea dietary supplements over the past seven years. Thus, the goal of this work was to correlate determined levels of phenolics, catechins, and caffeine with manufacturer label claims for selected dietary supplement products (26 total) purchased in the United States. The Folin-Ciocalteu (FC) method was used to determine the total phenolic content while reversed-phase (RP) HPLC was used to quantify the major catechins: epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG). The developed HPLC method was validated for accuracy and precision. It utilized a C8 column with gradient elution of acetonitrile in 0.1% aqueous formic acid over 11 min total run time. Peak detection was performed at 280 nm. Caffeine was also included in the HPLC method as another non-phenolic alkaloid marker commonly found in green tea. Both methods showed a good correlation between the content of catechins and polyphenolic compounds in the selected products. The ranges of total catechins and polyphenol concentrations were 3.8-70.2% and 3.6-95.8%, respectively, while that of caffeine was 0.8-11.2%. The selected products displayed a wide range of marker levels. A lack of conformity in disclosing the actual levels of marker compounds was also noticed in the labeling of many products. SN - 1939-022X UR - https://www.unboundmedicine.com/medline/citation/25299974/Content_Variation_of_Catechin_Markers_Total_Phenolics_and_Caffeine_in_Green_Tea_Dietary_Supplements_ L2 - https://www.tandfonline.com/doi/full/10.3109/19390211.2014.965868 DB - PRIME DP - Unbound Medicine ER -