Human colon cancer cells undergo apoptosis by theaflavin digallate, epigallocatechin gallate, and oolong tea polyphenol extract.

The effects of theaflavin digallate, a main component of black tea theaflavins; epigallocatechin gallate, a main component of green tea catechins; and polyphenol extract, containing an OTP trimer as a major component of oolong tea, was tested on human colon cancer COLO 205 cells and normal lymphocytes. Treatment with theaflavin digallate, epigallocatechin, and polyphenol extract resulted in growth inhibition and induced apoptosis in the COLO 205 cells, but not in normal human lymphocytes. Morphological examination of the tissue showed apoptotic bodies in cells treated with the chemical compounds. DNA fragmentation and the formation of oligonucleosomal-sized fragments in treated cells, characteristic of apoptosis, were concentration and time dependent. The data provide the first evidence that tea extracts induce apoptosis in human colon cancer cells. [ABSTRACT FROM AUTHOR]