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Don't Destroy Drugs
Milk and sugar diminish
nutritional value of tea, reports Biplab Das
The next time you make tea, don't add milk and sugar. "Because adding these ingredients reduces the nutritional value of tea," said P. Roy of Eastern Organic
Fertiliser. He was highlighting the benefits of drinking green and black tea, at a four-day international symposium on 'Plant Biodiversity: Conservation and Evaluation', held recently at the Bose Institute auditorium.
According to Roy, unprocessed green leaves of tea are four per cent carbohydrate, 30 per cent protein and 20 per cent lipid. "Besides these, green leaves have minerals, vitamins, enzymes and free amino acids," said Roy. "But the most vital ingredient is polyphenol which has shown anti-cancer
effect." After processing, the green leaves turn black, and the
polyphenols lose their anti-cancer effect, but the tea is still
useful. "Studies have shown that black tea lowers blood glucose levels in diabetic patients and keeps cholesterol in check," said Roy.
Like leaves, plant roots too are rich in proteins, fats and other nourishing compounds. Dr. Suchitra Banerjee from the Central Institute of Medicinal and Aromatic Plants discussed the various aspects of hairy root cultures. "In hairy root cultures, uprooting and killing a whole plant are avoided," said
Banerjee. "Instead, a small piece of hairy root is cut and infected with a bacteria called
Agrobacterium rhizogenes which thrives in soil."
This sort of culture takes place in a special type of vessel called bioreactor, producing an enormous quantity of a desired plant cell. Plant cells cultured this way are rich in salt and sugar and inexpensive to produce. "What is more, proteins derived from plant cells are safer than those derived from mammalian cells, which are often contaminated with harmful viruses and bacteria," explained
Banerjee. The chief goal of this technique is to produce proteins with therapeutic value to humans. Using hairy root cultures, she said, many such proteins have been extracted from a host
of medicinal plants like the Rauvolfia serpentina and Atropa
belladonna.
In recent years, plant derivatives have played a key role in producing essential drugs. Dr. A. C. Ghosh of Chembiotek described the contribution of medicinal plants to the pharmaceutical industry. "India is home to nearly 45,000 medicinal plants used by 550 tribal communities," said he. "About 25 per cent of present medicines come from natural products."
Medicinal plants have been used to produce drugs for skin diseases, asthma, cancer and various other diseases. "Among plant-derived chemicals, hypericin has an inhibitory effect on HIV (human immunodeficiency virus) infection," said
Ghosh. "Cephalotaxine, a plant alkaloid, has been identified as an anti-cancer agent."
Artemisinin, another plant-derived chemical has been shown to be effective antidote to malaria.
But many of these medicinal plants may soon become extinct. To meet human needs, mindless deforestation has taken place, putting the existence of the whole plant community at stake. "Due to the threat of global warming, we need to understand plant diversity, so as to be able to exploit it in a sustainable manner," said plant geneticist Dr. Swati Sen
Mandi, the organising secretary of the meet.
Ecologists have responded to the situation by forming a Global Strategy for Plant Conservation
(GSPC). Dr. Clare Tenner from the Royal Botanical Gardens, Kew, UK, discussed it. According to her, the cardinal aim of GSPC is to understand and document plant diversity. A project called the Millennium Seed Bank Project has also been launched to conserve as seeds, 10 per cent of the world's flora, mostly from
drylands, by 2010, said Tenner. "The drylands were given priority for conservation because they are the second most threatened plant habitat."
Dr. Bonnie J. Furman from Western Kentucky University pointed out how agriculture and hewing of trees for fuel have thinned the population of pine trees. While forested land has shrunk alarmingly to make way for human activities, in agriculture the attention has shifted from increasing cultivable land to increasing crop productivity. For that, foreign genes have been introduced into crops, to make them adapt to a wide range of ecosystems. These modified species are known as transgenic crops. Dr. Swapan Dutta from the International Rice Research Institute, Manila, Philippines, shed light on the benefits of creating transgenic rice.
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