Tuesday, June 3, 2014

Ecosystem Sciences Part 3: Medicines

In the previous part, we read about how earth provides us our food and helps us to create new foods. Just like the crops, Drugs are the gifts of biodiversity to human kind.
Natural remedies have been used to fight diseases from ancient times. Old medicine systems like the Indian, Islamic and Chinese made extensive use of plant and animal derived substances in treatment. The forefather of Western Medicine, Hippocrates, has listed about 400 herbs for their therapeutic use. Apart from the established medicinal systems, local knowledge of medicinal properties of plants has been conserved by common people for thousands of years. As an example, the Korku tribe in Central India relies on traditional knowledge of herbs for treating diseases. They use around 40 different herb in their medical practise. Like the Korkus, around 3.4 billion or 50% of the world’s people are dependent on plant based medicines even today.
Modern medicine uses chemically synthesized compounds as drugs. But an astonishing number of these drugs have been discovered using natural products. Most of the pharmaceutical compounds are naturally occurring in organisms like fungi, bacteria, plants and others. The natural substances removed from these sources are processed and used in making a drug. In some cases, a chemical having the same structure as the natural substance is prepared artificially. Penicillin, the first important drug to be discovered, was isolated from a fungi. Out of the 150 top selling prescription drugs in the US, 118 are based on natural resources. In fact, nine out of top ten best selling drugs are based on a natural product. And this is despite the fact that only 10% plants and 0.1% microorganisms (like bacteria) have been examined for possible medicinal property. Just like the superfood, our superdrugs in future may also be coming from the nature.
As an example, let’s see the story of an important cancer drug. In 1960, the National Cancer Institute (NCI) in the USA started a program to screen 1000 plants a year in search of an anti-cancer drug. In 1963, they found a possible ingredient in the bark of the Pacific yew tree. It took a further four years of research and in 1967, the efforts were rewarded in form of a drug called Taxol (current name paclitaxel). Taxol is used in the treatment of ovarian, breast and lung, bladder, prostate and many other cancers. For twenty years, its production was dependent on the Pacific yew tree. It was only 1993 that production without the tree bark was achieved, but it still uses a microorganism called endophytic fungus.
It is estimated that as many as 40% of all drugs have their origins in natural products. Knowing that the world pharmaceutical market is 300 billion dollars a year, we can quickly link it with the value of the natural ecosystem. New Drug Discovery from natural resources is an ongoing process today. The diversity of compounds found in nature is huge and it provides ‘leads’ for discovering new drugs to the pharmaceutical industry. Sophisticated methods like High Throughput Screening (HTS) are used to screen more than 100,000 substances per week. But it is needless to mention that these efforts are based on the biodiversity in the ecosystem. The variety in nature gives us two of our most important substances – food and drug.
We have seen a few examples of the Provisioning ecosystem service. We have begun to realize that the ecosystems are providing us with goods that are extremely valuable in money terms. In the next part, we turn to the next type of ecosystem service – Regulating.

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