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Asian Tribune is published by World Institute For Asian Studies|Powered by WIAS Vol. 12 No. 2830

Therapeutic effects of flavonoids from Ceylon green tea in the prevention of stroke

By Dr. Ranil de Silva & Prof. Y.Z. Zhu

On average, one heart attack occurs every four seconds and a stroke occurs every five seconds worldwide (WHO) and also, 20 million people suffer from stroke each year, of which five million die. Of those 15 million who survive, five million are disabled. In succession to diseases of the heart and cancer stroke is the next big killer.

Stroke occurs as a result of reduced blood supply to the brain which results in inadequate delivery of oxygen to it resulting in ischemia. It has been reported that high oxidative stress is involved in ischemic diseases, which include ischemic stroke and neurodegenerative diseases such as Alzheimer's disease.

Despite several drugs being developed for the treatment of stroke, an effective natural remedy for the treatment of stroke is yet to be found. In a joint collaborative study between Prof. Y. Z. Zhu, Faculty of Medicine, National University of Singapore (NUS) and Dr. Ranil De Silva, Principal Investigator, Genetic Diagnostic & Research Laboratory, Dept. of Anatomy, Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka, purified flavonoids extracted from Ceylon green tea were analyzed to test for the ability in preventing damage to cells caused by reduced supply of oxygen to human brain epithelial cells (HBEC).

In this study we tested the ability of flavonoids extracted from Ceylon green tea (Dilmah) to act as agents which could reduce the stress in cells experiencing a reduction in oxygen supply (hypoxia) and their ability of reducing the death and damage of HBEC.

We extracted and purified flavonoids as active ingredients from Ceylon green tea (Dilmah) and studied an in vitro hypoxic model using HBEC. HBEC were cultured under two separate conditions: one group with normal oxygen delivery, another with inadequate oxygen delivery – achieving a hypoxia induced model. Into the second group flavonoids of Ceylon tea extract were added before inducing hypoxia. A group of HBEC without the tea extract was used as control.

The results were very promising. Free radicals damage cellular DNA and other macromolecules due to oxidative stress (when the production of oxygen derived species (ODS) or reactive oxygen species (ROS) is not balanced by the antioxidant defense system level in the body). It was found in this study that hypoxia + flavonoids extract treated HBEC appears to be more resistant to oxidative stress causing DNA damage. Pretreatment with flavonoids extract significantly increased the cell viability of hypoxic HBEC.

The results show that the activity levels for antioxidant enzymes were significantly increased after hypoxia in the flavonoid extract treated group. This observation is consistent with the important antioxidative enzymes found in the body as natural defense against oxygen free radicals. This suggests that flavonoids extract could have a twofold effect on oxygen free radicals in the body when consumed actively. Therefore, cerebral protection could be helped by the consumption of Ceylon green tea as supplements in a form of antioxidant therapy. This may be complimentary to the western therapeutic regime. It has been a long established fact that tea is a wonderfully refreshing beverage. The findings of modern science in reference to its therapeutic value, makes tea the ideal drink for our times.

To conclude, this study demonstrates the ability of Ceylon green tea to display cerebral protective effects on HBEC. Future studies can be done to isolate the individual active compounds in Ceylon tea that contribute to its antioxidant properties. This study further facilitates the acceptance of the fact that frequent drinking of Ceylon tea helps to treat ischemic disease.

The study is published: "Therapeutic effects of flavonoids from Ceylon green tea on hypoxic human brain epithelial cells, Journal of Chinese Pharmaceutical Sciences 17 (2008) 324–331"

We wish to extend our sincere thanks and gratitude to Dr. Tissa Amarakoon from Biochemistry Division, Tea Research Institute, Talawakelle, Sri Lanka for being so supportive in this project.

- Asian Tribune -

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