Conserving nature for human benifit

Tropical forestry: Storehouse of medicinal plants

As it appears to-day, more than 11,000 species of animals and plants are known to be threatened with extinction, about a third of all coral reefs are expected to vanish in just 30 years and about 15 million hectares of forest are being razed annually. In Bangladesh we are now left with only 7 percent forest zones as against 19 percent required for ecological balance.

The damage being done is more than aesthetic. Many vanishing species provide humans with both food and medicine. Take for example, a potent new 'weapon', a non-quinine based drink called "artemisinin" that is now providing an effective cure against cerebral malaria. In the world of disease and medicine, artemisinin is like a gem discovered in a river bed. For thousands of years, the plant it is derived from was used in the traditional Chinese medicine to subdue fever. During China's brief war with Vietnam in 1979 the Chinese government gave its soldiers a crude antimalaria pill based on artemisinin -- and it worked. Today, scientists at the Sanghai Institute of Materia Medica, where artemisinin was first isolated have further refined the compound into what is now "simply the most effective antimalaria drug we have ever had", says Francois Nosten, a physician who has spent 16 years combating malaria at the Thai-Burmese border. This non-quinine-based drug has proved to be vastly effective in places where the malarial parasite is resistant to all the main forms of quinine.

After a delay caused in part by skepticism that a drug based on Chinese medicine could be effective, the World Health Organisation recently gave official backing for the distribution of an artemisinin-based medicine in Africa. Artemisinin is the biotech world's latest gift. It is a crystalline compound extracted from sweet wormwood, a weedy plant indigenous in China. The curative power of such plants are the basis of Asian traditional medicine -- and from China through the rest of the continent there are literally millions of plants, combinations and household remedies claiming to beat disease and boost health. But these are now on the verge of extinction because of human assault on nature. If we are clearing forests, if we are killing biodiversity, then the chance of testing plants and species for medicinal purposes are totally lost. Appallingly true, the pharmaceutical world has yet to come up with potent weapon for certain diseases like arthritis and cancer.

In 1995, Ryoo Byung Hwan, vice-president of life science planning for SK Chemicals, a pioneer company in herbal remedy research launched the "joins project" to develop a new way of treating arthritis which afflicts 10 percent of the world's over-60 population. Ryoo decided to submit traditional Korean herbal remedies to stringent tests based on Western scientific methods. "Western medicines can't completely cure arthritis because they don't know its exact cause", he says. Ryoo scoured about 600 herbs used for centuries in Korea, performing a long screening process that included tests on animals and finally narrowed the field to three herbs. Ryoo combined them into a yellow pill, the size of an aspirin, and christened it. After some encouraging initial results, Ryoo decided to compare "joins" with the toughest competitor from the West, "voltaren", a powerful anti-inflammatory drug widely prescribed for arthritis. (In 2001 Voltaren raked in sales of more than $500 million for its Swiss manufacturer, Novartis). Ryoo was sure Joins would produce fewer side effects than Voltaren, which can cause severe gastric problems.

Comparing the efficacy of herbal medicine with a chemical medicine like Voltaren is still too early. Because chemicals are like sharp knives: if you use them properly they will do their jobs perfectly but if you miss your target, they might cause serious side effects. Herbs are like dull knives, -- they are not as swift but they have fewer side effects. Tests by five major Seoul-based hospitals showed Joins was as good a painkiller as Voltaren and did indeed produce fewer side effects. Ryoo now wants to prove that Joins can also protect the joints curing arthritis instead of just relieving its symptoms. Experiments conducted at Seoul National University and Cardiff University in Wales show Joins may reduce joint tissue degradation.

In an effort to find how do traditional medicines achieve results at the molecular level, Liu Jkai, a researcher at the Kunming Institute of Botany, China's Premier Centre for the study of traditional medicine thinks he has the beginnings of an answer. Liu who holds degrees in both traditional Chinese and Western medicines says the common thread running through the most effective traditional formulas is the high proportion of two classes of compounds: polyphenols and saponins. Polyphenols are commonly found in tea, chocolate and fruits while saponins occur in a wide range of grains and vegetables from spinach to tomatoes.

Western laboratories are likewise scrutinising polyphenols and saponins, which appear to play a role in preventing cancer killing tumours, lowering cholesterol, fighting infection and even countering depression. So far science has been unable to explain how they work. The Chinese haven't figured it out either but Liu thinks the same mechanism underlies China's ancient ways of healing. Western medicine is like a key in a lock but Chinese medicine is non-specific, just like saponins and polyphenols. That's why traditional medicine doctors can prescribe the same formula for different diseases. It also explains why traditional cures are better for disease prevention and the treatment of chronic conditions that are usually caused by combination of factors, not a single bacterium or virus.

Taiwan has made spectacular advances in the traditional medicine-based drugs. Chemist T.S. Jiang is running a trial of a drug there called Zue Bao ("blood treasure") derived from yellow root, a purple flowering plant. Zue Bao reduces the side effects of chemotherapy on cancer patients, says Jiang, so that appetite improves, normal sleep patterns resume and hair grows back. Critically, Zue Bao has produced no side effects, unlike the two western drugs GCSF and EPO, which are most widely used in conjunction with chemotherapy. So far the drug has been tested on 500 patients in Taiwan and China with encouraging results. It still has to pass the third and final trial stagesbut Jiang has already taken his faith to the public.

Meanwhile, the promise of artemisinin looks richer than ever. Henry Lai, a bioengineering professor at the University of Washington, recently published a paper detailing experiments in which artemisinin killed virtually all breast cancer cells exposed to it within 16 hours, while having no impact on normal cells. "Not only does it appear to be highly effective," says Lai, "but it's very, very selective." In tests at other universities in the U.S. and Germany, artemisinin has also shown early promise in combating diseases like leukemia and bone cancer.

But as Lai knows, scientists must keep testing all of the weapons in the arsenal -- no matter where they come from. If he is right and artemisinin can help vanquish cancer, it will be one of nature's greatest gifts. How strange it would be if the cure were indeed derived from sweet wormwood, a healing plant first mentioned in a Chinese medical test 2200 years ago.

Bangladesh offers immense prospect of having such herbs and plants that go extinct because of neglect, lack of care and effective research programme. It would be interesting to know how the life and living of some five thousand people in a village of Natore has changed through cultivation of medicinal plants. Reports carried by Prothom Alo on February 27 last has revealed that medicinal plants worth 50 lakh taka are being sold to herbal doctors in 52 districts of the country from a village Kholabaria in Natore every month. Researchers in our country could have unraveled the secrets of the plants like 'Shimul, Shatamul, Ghrita Kanchan, Misridana, Ashwagandha, Nilkantha, Kalomegh, Patharkuchi, Shankhamul, Neem, Tulshi, Ultakamol, Basak, Chirota, White Dhutra, Black Dhutra etc. by analysing their contents. It won't be unfair to expect that remedies to combat diseases like HIV/AIDS, Cancer, Malaria and some viral infections could have been found out in these potent herbal plants that are being ravaged in the name of creating new habitat for the growing population in the country.

Md. Asadullah Khan, formerly a Physics teacher, is Controller of Examination, BUET.