The study published in Food Chemistry, investigated the effect white tea (Camellia sinensis) had on the proliferation of colon cancer cell HT-29. White tea is made from the buds and young leaves of the tea plant which are steamed and dried, whilst undergoing minimal oxidation.
The researchers from Malaysia found white tea was a powerful antioxidant with an ability to slow the proliferation of colon cancer cells.
“The present study demonstrates the antioxidant, anticancer and DNA protective effects of white tea,” they wrote. “In conclusion, white tea extracts show potential as chemotherapeutic agents. Regular consumption of white tea could maintain good health and protect the body against disease.”
The researchers tested Silver needle white tea, infused in hot water for five minutes.
Findings showed the tea extract contained a total flavonoid content of 530 ± 10.6 mg of quercetin per gram of dried weight tea. “These results indicate that Silver needle white tea, extracted for only five minutes, is a rich source of flavonoids, when extracted in hot water, since the total flavonoid content is comparable to that of rutin [a pure flavonoid],” the researchers wrote.
Radical scavenging activity was also high and increased with increasing concentrations of the white tea extract. The white tea extract reduced the oxidant free radical DPPH.
The researchers said the high antioxidant activity in the extract “correlated significantly” to the phenolic content.
In vitro testing indicated the tea extract also showed “high anti-proliferative activity against HT-29 cells, without being toxic to normal fibroblasts”, the researchers said.
The white tea extract worked to slow HT-29 proliferation by activating caspases (specifically caspase-8 and caspase-9) which worked to induce apoptosis – the killing off cells, the researchers explained.
The lack of toxicity to normal cells was important, they added.
Findings showed the extract could protect normal cells against H202-induced DNA damage by up to 64.3%. Such oxidative damage, caused by reactive oxygen species (ROS), damaged cellular macromolecules like DNA, proteins, fatty acids and carbohydrates – damage that was often associated with degenerative diseases like cancer, the researchers explained.
“Our results indicate that the white tea extract could significantly protect DNA damage even at low concentrations and this increases with increasing concentrations of the white tea extract,” the researchers wrote.
Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2014.07.005 February 2015, Volume 169, pages 401-410
“White tea (Camellia sinensis) inhibits proliferation of the colon cancer cell line, HT-29, activates caspases and protects DNA of normal cells against oxidative damage”
Authors: F. Hajiaghaalipour, MS. Kanthimathi, J. Sanusi and J. Rajarajeswaran