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[SANET-MG] Tea Compounds against Human Cancer Cells
If tea is like strawberries then organic tea should be even better
J. Agric. Food Chem., ASAP Article 10.1021/jf062276h S0021-8561(06)02276-X
Web Release Date: December 16, 2006
Structure-Activity Relationships of Tea Compounds against Human Cancer
Mendel Friedman,* Bruce E. Mackey, Hyun-Jeong Kim, In-Seon Lee, Kap-Rang
Lee, Seung-Un Lee,# Etsuko Kozukue,# and Nobuyuki Kozukue#
Western Regional Research Center, Agricultural Research Service, U.S.
Department of Agriculture, Albany, California 94710; The Center for
Traditional Microorganism Resources, Keimyung University, 704-701 Daegu,
South Korea; College of Human Ecology and Kinesiology, Yeungnam
University, 712-149 Gyeongsan, South Korea; and Department of Food
Service Industry, Uiduk University, 780-713 Gangdong, Gyeongju,
Gyongbuk, South Korea
Received for review August 7, 2006. Revised manuscript received October
11, 2006. Accepted November 2, 2006.
The content of the biologically active amino acid theanine in 15
commercial black, green, specialty, and herbal tea leaves was determined
as the 2,4-dinitrophenyltheanine derivative (DNP-theanine) by a
validated HPLC method. To define relative anticarcinogenic potencies of
tea compounds and teas, nine green tea catechins, three black tea
theaflavins, and theanine as well as aqueous and 80% ethanol/water
extracts of the same tea leaves were evaluated for their ability to
induce cell death in human cancer and normal cells using a tetrazolium
microculture (MTT) assay. Compared to untreated controls, most
catechins, theaflavins, theanine, and all tea extracts reduced the
numbers of the following human cancer cell lines: breast (MCF-7), colon
(HT-29), hepatoma (liver) (HepG2), and prostate (PC-3) as well as normal
human liver cells (Chang). The growth of normal human lung (HEL299)
cells was not inhibited. The destruction of cancer cells was also
observed visually by reverse phase microscopy. Statistical analysis of
the data showed that (a) the anticarcinogenic effects of tea compounds
and of tea leaf extracts varied widely and were concentration dependent
over the ranges from 50 to 400 g/mL of tea compound and from 50 to 400
g/g of tea solids; (b) the different cancer cells varied in their
susceptibilities to destruction; (c) 80% ethanol/water extracts with
higher levels of flavonoids determined by HPLC were in most cases more
active than the corresponding water extracts; and (d) flavonoid levels
of the teas did not directly correlate with anticarcinogenic activities.
The findings extend related observations on the anticarcinogenic
potential of tea ingredients and suggest that consumers may benefit more
by drinking both green and black teas.
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