HEALTH SPECIAL..FLAVONOIDS TO INHIBIT CANCER

Flavonoids, the pigments that give colour to flowers, can stop the growth of tumours, say scientists at JNU. So, add colour to your diet

Some ordinary vegetables and fruits may contain elements that can inhibit the growth of cancerous tumours or help keep them dormant, says studies conducted by Jawaharlal Nehru University and Delhi University. Red kattha (used in paan), ajwain (carom seeds), artichokes, milk thistle, strawberries and onions are the miracle plants named in the study published in the December 2011 edition of the Carcinogenesis journal.
Plant flavonoids — the pigments responsible for the colour of flowers — have become a significant area of research not just for cancer but neuro-degenerative diseases such as Alzheimer’s and Parkinson’s as well, say scientists. According to the research paper put together by JNU’s School of Life Sciences, these plants are rich in a cancer inhibiting flavonoid called fisetin.
“The genesis of a tumour happens a long time before it actually starts showing symptoms. The tumour can be dormant for as long as ten years. In our study we have found that fisetin, a powerful flavonoid, has the potential to prevent tumour angiogenesis,” said Rana P Singh of JNU life sciences school. Angiogenesis is a process involving the growth of new blood vessels from existing ones; it may also be responsible for the transition of tumours from dormant to malignant ones.
Studies have shown earlier that the consumption of a fibre rich diet and lots of yellow-green vegetables is associated with reduced cancer risk. The aim of this study was to use plant-derived agents for cancer prevention.
“The growth of solid tumor is critically dependent upon the formation of new blood vessels in tumours. Tumours secrete angiogenic factors to activate nearby endothelial cells, the innermost lining of the blood vessel. Then, endothelial cells undergo various important stages in a blood vessel formation. We found that fisetin strongly inhibits all these stages in endothelial cells as well as the formation of angiogenic factors in cancer cells. Fisetin retards human tumor xenograft growth in mice,” says Singh.
Another study conducted by Singh found that silibinin, a favonol compound present in the extract of milk thistle plant and artichoke, is very good at generating anti-oxidant activity and is being explored for a broad spectrum of anti-cancer properties. “Compared to Vitamin E, silibinin has ten times more antioxidant activity. It is a wellknown hepato-protective agent, used clinically in many countries of the European Union as well as in India,” he adds.
To understand the efficacy of the compound, the JNU team tested it on transgenic mice. “Our studies show that dietary silibinin strongly inhibits the growth and progression of prostate cancer in transgenic adeno carcinoma of the mouse prostate. Based on these studies, silibinin is currently under phase II clinical trial to study its chemopreventive efficacy against human prostate cancer,” says Rana. The JNU Cancer Biology Group is collaborating with scientists at the University of Colorado on these studies.
The plant chemistry lab at Delhi University has also recently found that flavonoids rich in antioxidants could possible protect the body against the effects of radiation. “In our lab we found that many polyphenolic compounds recently isolated from important medicinal plants such as Thymus vulgaris (ajwain), Mangifera indica (mango), Acacia catechu (kattha) and Carissa carrandus (karaunda) are good antioxidants and radio protectors even at 1µm-5µm concentration in vitro. The Delhi University team is collaborating with researchers at ENEA Casaaccia Research Center in Italy on such studies,” says professor Subhash Chand Jain of Delhi University.
Explaining the role of flavonoids in cancer therapy, Jain says: “One of the main causes of diseases such as cancer, diabetes, Alzheimer’s or Parkinson’s is oxidative stress, which is aggravated when a balance between Reactive Oxygen Species production and antioxidant is disturbed. The production of these species is kept under control by taking antioxidants such as flavonoids in our daily diet.”
However, most of these studies have indicated that antioxidants are more effective in prevention of the disease rather than curing it when it is at a well established stage.
Independent experts agree that flavanoids contain anti-cancer properties, but say more research needs to be done in this area. “As of now, we believe it would be beneficial to make our diet as colourful as possible and eat a variety of vegetables and fruits, especially berries. We should not eat the same food every day. Many fruits and vegetables contain flavonoids that have antioxidant activity and are therefore good for health,” says Dr Anthony Pais, oncologist at the Narayana Hrudalaya Mazumdar Shaw Cancer Centre in Bangalore.

(JAYASHREE NANDI TOICREST120331)