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Cited by 271

The DOI matches its Crossref record; 22 of the 22 references it cites were found in a registry or an index.

Catechin and Caffeine Content of Green Tea Dietary Supplements and Correlation with Antioxidant Capacity

Seeram, Navindra P., Henning, Susanne M., Niu, Yantao, Lee, Rupo, Scheuller, H. Samuel, Heber, David·2006·Journal of Agricultural and Food Chemistry
DOI 10.1021/jf052857r
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Abstract

The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. Polyphenols are antioxidants, and EGCG, due to its high levels, is widely accepted as the major antioxidant in green tea. Therefore, commercial green tea dietary supplements (GTDS) may be chemically standardized to EGCG levels and/or biologically standardized to antioxidant capacity. However, label claims on GTDS may not correlate with actual phytochemical content or antioxidant capacity nor provide information about the presence and levels of caffeine. In the current study, 19 commonly available GTDS were evaluated for catechin and caffeine content (using high-performance liquid chromatography) and for antioxidative activity [using trolox equivalent antioxidant capacity (TEAC) and oxygen radical antioxidant capacity (ORAC) assays]. Product labels varied in the information provided and were inconsistent with actual phytochemical contents. Only seven of the GTDS studied made label claims of caffeine content, 11 made claims of EGCG content, and five specified total polyphenol content. Caffeine, EGCG, and total polyphenol contents in the GTDS varied from 28 to 183, 12-143, and 14-36% tablet or capsule weight, respectively. TEAC and ORAC values for GTDS ranged from 187 to 15340 and from 166 to 13690 mumol Trolox/g for tablet or capsule, respectively. The antioxidant activities for GTDS determined by TEAC and ORAC were well-correlated with each other and with the total polyphenol content. Reliable labeling information and standardized manufacturing practices, based on both chemical standardization and biological assays, are recommended for the quality control of botanical dietary supplements.

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Metadata

Authors
Seeram, N. P., Henning, S. M., Niu, Y., Lee, R., Scheuller, H. S., & Heber, D.
Venue
Journal of Agricultural and Food Chemistry
Publisher
American Chemical Society (ACS)
Published
2006-02-11
Volume
54
Issue
5
Pages
1599-1603
ISSN
  • 0021-8561 (ISSN-L)
  • 1520-5118
DOI
10.1021/jf052857r
OpenAlex
W2020353422
Cited by
271
References
22
FWCI
5.83
Type
journal article
Language
en
Open access
closed

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