Author
 |
Bronner, William |
|
Beecher, Gary |
|
Submitted to: The Journal of Chromatography B: Biomedical Applications
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/14/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Epidemiologic and laboratory studies suggest an association between the consumption of tea and reduced risk of cancer. It has been assumed that most of the cancer-inhibitory activity of tea is due to the polyphenols resent in tea and their associated antioxidant activity. There is a dearth of data on the level of prominent polyphenols in teas. The current research improved a high-performance liquid chromatography method for the measurement of catechins (the prominent polyphenols) in teas. Levels of the major catechins subsequently were quantified in three types of brewed teas (black, green and jasmine). Epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate were found in all the teas examined, ranging in concentration from 1 - 13 milligrams per deciliter. These levels indicate that even moderate tea consumption can contribute a substantial quantity of flavanols to the diet. Although some differences between the three brewed teas were evident, all were comparably good sources of these catechins. These observations indicate that teas are good sources of at least one family of phytochemicals which have antioxidant activity and which may explain, to some extent, the association between tea consumption and decreased risk of cancer. Technical Abstract: A high-performance liquid chromatography method employing diode array detection was developed to determine levels of the major catechins present in black, green, and Jasmine tea infusions. Reverse-phase separations were performed on an octadecylsilyl column using three different aqueous mobile phasegradients:acetonitrile/acetate buffer; methanol/acetate buffer; and acetonitrile/acetate buffer with ascorbic acid. The identities of the tea catechins were established by comparing absorbance spectra and retention times to reference standards chromatographed under identical conditions. Epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate were found in all the tea infusions examined, ranging in concentration from 1 - 13 milligrams per deciliter. These levels indicate that even moderate tea consumption can contribute a substantial quantity of flavanols to the diet. Although some differences between the three brewed teas were evident, all were comparably good sources of these catechins. |
